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1. Thermalization and criticality on an analogue–digital quantum simulator

Author

Andersen, T. I., Astrakhantsev, N., Karamlou, A. H., Berndtsson, J., Motruk, J., Szasz, A., Gross, J. A., Schuckert, A., Westerhout, T., Zhang, Y., Forati, E., Rossi, D., Kobrin, B., Paolo, A. Di, Klots, A. R., Drozdov, I., Kurilovich, V., Petukhov, A., Ioffe, L. B., Elben, A., Rath, A., Vitale, V., Vermersch, B., Acharya, R., Beni, L. A., Anderson, K., Ansmann, M., Arute, F., Arya, K., Asfaw, A., Atalaya, J., Ballard, B., Bardin, J. C., Bengtsson, A., Bilmes, A., Bortoli, G., Bourassa, A., Bovaird, J., Brill, L., Broughton, M., Browne, D. A., Buchea, B., Buckley, B. B., Buell, D. A., Burger, T., Burkett, B., Bushnell, N., Cabrera, A., Campero, J., Chang, H.-S., Chen, Z., Chiaro, B., Claes, J., Cleland, A. Y., Cogan, J., Collins, R., Conner, P., Courtney, W., Crook, A. L., Das, S., Debroy, D. M., Lorenzo, L. De, Barba, A. Del Toro, Demura, S., Donohoe, P., Dunsworth, A., Earle, C., Eickbusch, A., Elbag, A. M., Elzouka, M., Erickson, C., Faoro, L., Fatemi, R., Ferreira, V. S., Burgos, L. Flores, Fowler, A. G., Foxen, B., Ganjam, S., Gasca, R., Giang, W., Gidney, C., Gilboa, D., Giustina, M., Gosula, R., Dau, A. Grajales, Graumann, D., Greene, A., Habegger, S., Hamilton, M. C., Hansen, M., Harrigan, M. P., Harrington, S. D., Heslin, S., Heu, P., Hill, G., Hoffmann, M. R., Huang, H.-Y., Huang, T., Huff, A., Huggins, W. J., Isakov, S. V., Jeffrey, E., Jiang, Z., Jones, C., Jordan, S., Joshi, C., Juhas, P., Kafri, D., Kang, H., Kechedzhi, K., Khaire, T., Khattar, T., Khezri, M., Kieferová, M., Kim, S., Kitaev, A., Klimov, P., Korotkov, A. N., Kostritsa, F., Kreikebaum, J. M., Landhuis, D., Langley, B. W., Laptev, P., Lau, K.-M., Guevel, L. Le, Ledford, J., Lee, J., Lee, K. W., Lensky, Y. D., Lester, B. J., Li, W. Y., Lill, A. T., Liu, W., Livingston, W. P., Locharla, A., Lundahl, D., Lunt, A., Madhuk, S., Maloney, A., Mandrà, S., Martin, L. S., Martin, O., Martin, S., Maxfield, C., McClean, J. R., McEwen, M., Meeks, S., Miao, K. C., Mieszala, A., Molina, S., Montazeri, S., Morvan, A., Movassagh, R., Neill, C., Nersisyan, A., Newman, M., Nguyen, A., Nguyen, M., Ni, C.-H., Niu, M. Y., Oliver, W. D., Ottosson, K., Pizzuto, A., Potter, R., Pritchard, O., Pryadko, L. P., Quintana, C., Reagor, M. J., Rhodes, D. M., Roberts, G., Rocque, C., Rosenberg, E., Rubin, N. C., Saei, N., Sankaragomathi, K., Satzinger, K. J., Schurkus, H. F., Schuster, C., Shearn, M. J., Shorter, A., Shutty, N., Shvarts, V., Sivak, V., Skruzny, J., Small, S., Smith, W. Clarke, Springer, S., Sterling, G., Suchard, J., Szalay, M., Sztein, A., Thor, D., Torres, A., Torunbalci, M. M., Vaishnav, A., Vdovichev, S., Villalonga, B., Heidweiller, C. Vollgraff, Waltman, S., Wang, S. X., White, T., Wong, K., Woo, B. W. K., Xing, C., Yao, Z. Jamie, Yeh, P., Ying, B., Yoo, J., Yosri, N., Young, G., Zalcman, A., Zhu, N., Zobrist, N., Neven, H., Babbush, R., Boixo, S., Hilton, J., Lucero, E., Megrant, A., Kelly, J., Chen, Y., Smelyanskiy, V., Vidal, G., Roushan, P., Läuchli, A. M., Abanin, D. A., and Mi, X.

Published
2025
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2. Phase transitions in random circuit sampling

Author

Morvan, A., Villalonga, B., Mi, X., Mandrà, S., Bengtsson, A., Klimov, P. V., Chen, Z., Hong, S., Erickson, C., Drozdov, I. K., Chau, J., Laun, G., Movassagh, R., Asfaw, A., Brandão, L. T. A. N., Peralta, R., Abanin, D., Acharya, R., Allen, R., Andersen, T. I., Anderson, K., Ansmann, M., Arute, F., Arya, K., Atalaya, J., Bardin, J. C., Bilmes, A., Bortoli, G., Bourassa, A., Bovaird, J., Brill, L., Broughton, M., Buckley, B. B., Buell, D. A., Burger, T., Burkett, B., Bushnell, N., Campero, J., Chang, H.-S., Chiaro, B., Chik, D., Chou, C., Cogan, J., Collins, R., Conner, P., Courtney, W., Crook, A. L., Curtin, B., Debroy, D. M., Barba, A. Del Toro, Demura, S., Paolo, A. Di, Dunsworth, A., Faoro, L., Farhi, E., Fatemi, R., Ferreira, V. S., Burgos, L. Flores, Forati, E., Fowler, A. G., Foxen, B., Garcia, G., Genois, É., Giang, W., Gidney, C., Gilboa, D., Giustina, M., Gosula, R., Dau, A. Grajales, Gross, J. A., Habegger, S., Hamilton, M. C., Hansen, M., Harrigan, M. P., Harrington, S. D., Heu, P., Hoffmann, M. R., Huang, T., Huff, A., Huggins, W. J., Ioffe, L. B., Isakov, S. V., Iveland, J., Jeffrey, E., Jiang, Z., Jones, C., Juhas, P., Kafri, D., Khattar, T., Khezri, M., Kieferová, M., Kim, S., Kitaev, A., Klots, A. R., Korotkov, A. N., Kostritsa, F., Kreikebaum, J. M., Landhuis, D., Laptev, P., Lau, K.-M., Laws, L., Lee, J., Lee, K. W., Lensky, Y. D., Lester, B. J., Lill, A. T., Liu, W., Livingston, W. P., Locharla, A., Malone, F. D., Martin, O., Martin, S., McClean, J. R., McEwen, M., Miao, K. C., Mieszala, A., Montazeri, S., Mruczkiewicz, W., Naaman, O., Neeley, M., Neill, C., Nersisyan, A., Newman, M., Ng, J. H., Nguyen, A., Nguyen, M., Niu, M. Yuezhen, O’Brien, T. E., Omonije, S., Opremcak, A., Petukhov, A., Potter, R., Pryadko, L. P., Quintana, C., Rhodes, D. M., Rocque, C., Rosenberg, E., Rubin, N. C., Saei, N., Sank, D., Sankaragomathi, K., Satzinger, K. J., Schurkus, H. F., Schuster, C., Shearn, M. J., Shorter, A., Shutty, N., Shvarts, V., Sivak, V., Skruzny, J., Smith, W. C., Somma, R. D., Sterling, G., Strain, D., Szalay, M., Thor, D., Torres, A., Vidal, G., Heidweiller, C. Vollgraff, White, T., Woo, B. W. K., Xing, C., Yao, Z. J., Yeh, P., Yoo, J., Young, G., Zalcman, A., Zhang, Y., Zhu, N., Zobrist, N., Rieffel, E. G., Biswas, R., Babbush, R., Bacon, D., Hilton, J., Lucero, E., Neven, H., Megrant, A., Kelly, J., Roushan, P., Aleiner, I., Smelyanskiy, V., Kechedzhi, K., Chen, Y., and Boixo, S.

Published
2024
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3. Dynamics of magnetization at infinite temperature in a Heisenberg spin chain

Author

Rosenberg, Eliott, Andersen, Trond, Samajdar, Rhine, Petukhov, Andre, Hoke, Jesse, Abanin, Dmitry, Bengtsson, Andreas, Drozdov, Ilya, Erickson, Catherine, Klimov, Paul, Mi, Xiao, Morvan, Alexis, Neeley, Matthew, Neill, Charles, Acharya, Rajeev, Allen, Richard, Anderson, Kyle, Ansmann, Markus, Arute, Frank, Arya, Kunal, Asfaw, Abraham, Atalaya, Juan, Bardin, Joseph, Bilmes, A., Bortoli, Gina, Bourassa, Alexandre, Bovaird, Jenna, Brill, Leon, Broughton, Michael, Buckley, Bob B., Buell, David, Burger, Tim, Burkett, Brian, Bushnell, Nicholas, Campero, Juan, Chang, Hung-Shen, Chen, Zijun, Chiaro, Benjamin, Chik, Desmond, Cogan, Josh, Collins, Roberto, Conner, Paul, Courtney, William, Crook, Alexander, Curtin, Ben, Debroy, Dripto, Barba, Alexander Del Toro, Demura, Sean, Di Paolo, Agustin, Dunsworth, Andrew, Earle, Clint, Farhi, E., Fatemi, Reza, Ferreira, Vinicius, Flores, Leslie, Forati, Ebrahim, Fowler, Austin, Foxen, Brooks, Garcia, Gonzalo, Genois, Élie, Giang, William, Gidney, Craig, Gilboa, Dar, Giustina, Marissa, Gosula, Raja, Dau, Alejandro Grajales, Gross, Jonathan, Habegger, Steve, Hamilton, Michael, Hansen, Monica, Harrigan, Matthew, Harrington, Sean, Heu, Paula, Hill, Gordon, Hoffmann, Markus, Hong, Sabrina, Huang, Trent, Huff, Ashley, Huggins, William, Ioffe, Lev, Isakov, Sergei, Iveland, Justin, Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Juhas, Pavol, Kafri, D., Khattar, Tanuj, Khezri, Mostafa, Kieferová, Mária, Kim, Seon, Kitaev, Alexei, Klots, Andrey, Korotkov, Alexander, Kostritsa, Fedor, Kreikebaum, John Mark, Landhuis, David, Laptev, Pavel, Lau, Kim Ming, Laws, Lily, Lee, Joonho, Lee, Kenneth, Lensky, Yuri, Lester, Brian, Lill, Alexander, Liu, Wayne, Livingston, William P., Locharla, A., Mandrà, Salvatore, Martin, Orion, Martin, Steven, McClean, Jarrod, McEwen, Matthew, Meeks, Seneca, Miao, Kevin, Mieszala, Amanda, Montazeri, Shirin, Movassagh, Ramis, Mruczkiewicz, Wojciech, Nersisyan, Ani, Newman, Michael, Ng, Jiun How, Nguyen, Anthony, Nguyen, Murray, Niu, M., O'Brien, Thomas, Omonije, Seun, Opremcak, Alex, Potter, Rebecca, Pryadko, Leonid, Quintana, Chris, Rhodes, David, Rocque, Charles, Rubin, N., Saei, Negar, Sank, Daniel, Sankaragomathi, Kannan, Satzinger, Kevin, Schurkus, Henry, Schuster, Christopher, Shearn, Michael, Shorter, Aaron, Shutty, Noah, Shvarts, Vladimir, Sivak, Volodymyr, Skruzny, Jindra, Smith, Clarke, Somma, Rolando, Sterling, George, Strain, Doug, Szalay, Marco, Thor, Douglas, Torres, Alfredo, Vidal, Guifre, Villalonga, Benjamin, Heidweiller, Catherine Vollgraff, White, Theodore, Woo, Bryan, Xing, Cheng, Yao, Jamie, Yeh, Ping, Yoo, Juhwan, Young, Grayson, Zalcman, Adam, Zhang, Yaxing, Zhu, Ningfeng, Zobrist, Nicholas, Neven, Hartmut, Babbush, Ryan, Bacon, Dave, Boixo, Sergio, Hilton, Jeremy, Lucero, Erik, Megrant, Anthony, Kelly, Julian, Chen, Yu, Smelyanskiy, Vadim, Khemani, Vedika, Gopalakrishnan, Sarang, Prosen, Tomaž, and Roushan, Pedram

Subjects
Quantum Physics
Abstract

Understanding universal aspects of quantum dynamics is an unresolved problem in statistical mechanics. In particular, the spin dynamics of the 1D Heisenberg model were conjectured to belong to the Kardar-Parisi-Zhang (KPZ) universality class based on the scaling of the infinite-temperature spin-spin correlation function. In a chain of 46 superconducting qubits, we study the probability distribution, $P(\mathcal{M})$, of the magnetization transferred across the chain's center. The first two moments of $P(\mathcal{M})$ show superdiffusive behavior, a hallmark of KPZ universality. However, the third and fourth moments rule out the KPZ conjecture and allow for evaluating other theories. Our results highlight the importance of studying higher moments in determining dynamic universality classes and provide key insights into universal behavior in quantum systems.

Published
2023
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4. Stable Quantum-Correlated Many Body States through Engineered Dissipation

Author

Mi, X., Michailidis, A. A., Shabani, S., Miao, K. C., Klimov, P. V., Lloyd, J., Rosenberg, E., Acharya, R., Aleiner, I., Andersen, T. I., Ansmann, M., Arute, F., Arya, K., Asfaw, A., Atalaya, J., Bardin, J. C., Bengtsson, A., Bortoli, G., Bourassa, A., Bovaird, J., Brill, L., Broughton, M., Buckley, B. B., Buell, D. A., Burger, T., Burkett, B., Bushnell, N., Chen, Z., Chiaro, B., Chik, D., Chou, C., Cogan, J., Collins, R., Conner, P., Courtney, W., Crook, A. L., Curtin, B., Dau, A. G., Debroy, D. M., Barba, A. Del Toro, Demura, S., Di Paolo, A., Drozdov, I. K., Dunsworth, A., Erickson, C., Faoro, L., Farhi, E., Fatemi, R., Ferreira, V. S., Forati, L. F. Burgos E., Fowler, A. G., Foxen, B., Genois, E., Giang, W., Gidney, C., Gilboa, D., Giustina, M., Gosula, R., Gross, J. A., Habegger, S., Hamilton, M. C., Hansen, M., Harrigan, M. P., Harrington, S. D., Heu, P., Hoffmann, M. R., Hong, S., Huang, T., Huff, A., Huggins, W. J., Ioffe, L. B., Isakov, S. V., Iveland, J., Jeffrey, E., Jiang, Z., Jones, C., Juhas, P., Kafri, D., Kechedzhi, K., Khattar, T., Khezri, M., Kieferova, M., Kim, S., Kitaev, A., Klots, A. R., Korotkov, A. N., Kostritsa, F., Kreikebaum, J. M., Landhuis, D., Laptev, P., Lau, K. -M., Laws, L., Lee, J., Lee, K. W., Lensky, Y. D., Lester, B. J., Lill, A. T., Liu, W., Locharla, A., Malone, F. D., Martin, O., McClean, J. R., McEwen, M., Mieszala, A., Montazeri, S., Morvan, A., Movassagh, R., Mruczkiewicz, W., Neeley, M., Neill, C., Nersisyan, A., Newman, M., Ng, J. H., Nguyen, A., Nguyen, M., Niu, M. Y., OBrien, T. E., Opremcak, A., Petukhov, A., Potter, R., Pryadko, L. P., Quintana, C., Rocque, C., Rubin, N. C., Saei, N., Sank, D., Sankaragomathi, K., Satzinger, K. J., Schurkus, H. F., Schuster, C., Shearn, M. J., Shorter, A., Shutty, N., Shvarts, V., Skruzny, J., Smith, W. C., Somma, R., Sterling, G., Strain, D., Szalay, M., Torres, A., Vidal, G., Villalonga, B., Heidweiller, C. V., White, T., Woo, B. W. K., Xing, C., Yao, Z. J., Yeh, P., Yoo, J., Young, G., Zalcman, A., Zhang, Y., Zhu, N., Zobrist, N., Neven, H., Babbush, R., Bacon, D., Boixo, S., Hilton, J., Lucero, E., Megrant, A., Kelly, J., Chen, Y., Roushan, P., Smelyanskiy, V., and Abanin, D. A.

Subjects
Quantum Physics
Abstract

Engineered dissipative reservoirs have the potential to steer many-body quantum systems toward correlated steady states useful for quantum simulation of high-temperature superconductivity or quantum magnetism. Using up to 49 superconducting qubits, we prepared low-energy states of the transverse-field Ising model through coupling to dissipative auxiliary qubits. In one dimension, we observed long-range quantum correlations and a ground-state fidelity of 0.86 for 18 qubits at the critical point. In two dimensions, we found mutual information that extends beyond nearest neighbors. Lastly, by coupling the system to auxiliaries emulating reservoirs with different chemical potentials, we explored transport in the quantum Heisenberg model. Our results establish engineered dissipation as a scalable alternative to unitary evolution for preparing entangled many-body states on noisy quantum processors.

Published
2023
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5. Purification-based quantum error mitigation of pair-correlated electron simulations

Author

O'Brien, T. E., Anselmetti, G., Gkritsis, F., Elfving, V. E., Polla, S., Huggins, W. J., Oumarou, O., Kechedzhi, K., Abanin, D., Acharya, R., Aleiner, I., Allen, R., Andersen, T. I., Anderson, K., Ansmann, M., Arute, F., Arya, K., Asfaw, A., Atalaya, J., Bacon, D., Bardin, J. C., Bengtsson, A., Boixo, S., Bortoli, G., Bourassa, A., Bovaird, J., Brill, L., Broughton, M., Buckley, B., Buell, D. A., Burger, T., Burkett, B., Bushnell, N., Campero, J., Chen, Y., Chen, Z., Chiaro, B., Chik, D., Cogan, J., Collins, R., Conner, P., Courtney, W., Crook, A. L., Curtin, B., Debroy, D. M., Demura, S., Drozdov, I., Dunsworth, A., Erickson, C., Faoro, L., Farhi, E., Fatemi, R., Ferreira, V. S., Burgos, L. Flores, Forati, E., Fowler, A. G., Foxen, B., Giang, W., Gidney, C., Gilboa, D., Giustina, M., Gosula, R., Dau, A. Grajales, Gross, J. A., Habegger, S., Hamilton, M. C., Hansen, M., Harrigan, M. P., Harrington, S. D., Heu, P., Hilton, J., Hoffmann, M. R., Hong, S., Huang, T., Huff, A., Ioffe, L. B., Isakov, S. V., Iveland, J., Jeffrey, E., Jiang, Z., Jones, C., Juhas, P., Kafri, D., Kelly, J., Khattar, T., Khezri, M., Kieferová, M., Kim, S., Klimov, P. V., Klots, A. R., Kothari, R., Korotkov, A. N., Kostritsa, F., Kreikebaum, J. M., Landhuis, D., Laptev, P., Lau, K., Laws, L., Lee, J., Lee, K., Lester, B. J., Lill, A. T., Liu, W., Livingston, W. P., Locharla, A., Lucero, E., Malone, F. D., Mandra, S., Martin, O., Martin, S., McClean, J. R., McCourt, T., McEwen, M., Megrant, A., Mi, X., Mieszala, A., Miao, K. C., Mohseni, M., Montazeri, S., Morvan, A., Movassagh, R., Mruczkiewicz, W., Naaman, O., Neeley, M., Neill, C., Nersisyan, A., Neven, H., Newman, M., Ng, J. H., Nguyen, A., Nguyen, M., Niu, M. Y., Omonije, S., Opremcak, A., Petukhov, A., Potter, R., Pryadko, L. P., Quintana, C., Rocque, C., Roushan, P., Saei, N., Sank, D., Sankaragomathi, K., Satzinger, K. J., Schurkus, H. F., Schuster, C., Shearn, M. J., Shorter, A., Shutty, N., Shvarts, V., Skruzny, J., Smelyanskiy, V., Smith, W. C., Somma, R., Sterling, G., Strain, D., Szalay, M., Thor, D., Torres, A., Vidal, G., Villalonga, B., Heidweiller, C. Vollgraff, White, T., Woo, B. W. K., Xing, C., Yao, Z. J., Yeh, P., Yoo, J., Young, G., Zalcman, A., Zhang, Y., Zhu, N., Zobrist, N., Gogolin, C., Babbush, R., and Rubin, N. C.

Subjects
Quantum Physics
Abstract

An important measure of the development of quantum computing platforms has been the simulation of increasingly complex physical systems. Prior to fault-tolerant quantum computing, robust error mitigation strategies are necessary to continue this growth. Here, we study physical simulation within the seniority-zero electron pairing subspace, which affords both a computational stepping stone to a fully correlated model, and an opportunity to validate recently introduced ``purification-based'' error-mitigation strategies. We compare the performance of error mitigation based on doubling quantum resources in time (echo verification) or in space (virtual distillation), on up to $20$ qubits of a superconducting qubit quantum processor. We observe a reduction of error by one to two orders of magnitude below less sophisticated techniques (e.g. post-selection); the gain from error mitigation is seen to increase with the system size. Employing these error mitigation strategies enables the implementation of the largest variational algorithm for a correlated chemistry system to-date. Extrapolating performance from these results allows us to estimate minimum requirements for a beyond-classical simulation of electronic structure. We find that, despite the impressive gains from purification-based error mitigation, significant hardware improvements will be required for classically intractable variational chemistry simulations., Comment: 10 pages, 13 page supplementary material, 12 figures. Experimental data available at https://doi.org/10.5281/zenodo.7225821

Published
2022
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6. Formation of robust bound states of interacting microwave photons

Author

Morvan, A, Andersen, TI, Mi, X, Neill, C, Petukhov, A, Kechedzhi, K, Abanin, DA, Michailidis, A, Acharya, R, Arute, F, Arya, K, Asfaw, A, Atalaya, J, Bardin, JC, Basso, J, Bengtsson, A, Bortoli, G, Bourassa, A, Bovaird, J, Brill, L, Broughton, M, Buckley, BB, Buell, DA, Burger, T, Burkett, B, Bushnell, N, Chen, Z, Chiaro, B, Collins, R, Conner, P, Courtney, W, Crook, AL, Curtin, B, Debroy, DM, Del Toro Barba, A, Demura, S, Dunsworth, A, Eppens, D, Erickson, C, Faoro, L, Farhi, E, Fatemi, R, Flores Burgos, L, Forati, E, Fowler, AG, Foxen, B, Giang, W, Gidney, C, Gilboa, D, Giustina, M, Grajales Dau, A, Gross, JA, Habegger, S, Hamilton, MC, Harrigan, MP, Harrington, SD, Hoffmann, M, Hong, S, Huang, T, Huff, A, Huggins, WJ, Isakov, SV, Iveland, J, Jeffrey, E, Jiang, Z, Jones, C, Juhas, P, Kafri, D, Khattar, T, Khezri, M, Kieferová, M, Kim, S, Kitaev, AY, Klimov, PV, Klots, AR, Korotkov, AN, Kostritsa, F, Kreikebaum, JM, Landhuis, D, Laptev, P, Lau, K-M, Laws, L, Lee, J, Lee, KW, Lester, BJ, Lill, AT, Liu, W, Locharla, A, Malone, F, Martin, O, McClean, JR, McEwen, M, Meurer Costa, B, Miao, KC, Mohseni, M, Montazeri, S, Mount, E, Mruczkiewicz, W, Naaman, O, and Neeley, M

Subjects
Quantum Physics, Physical Sciences, Photons, Microwaves, Electrons, Fees and Charges, Reproduction, General Science & Technology
Abstract

Systems of correlated particles appear in many fields of modern science and represent some of the most intractable computational problems in nature. The computational challenge in these systems arises when interactions become comparable to other energy scales, which makes the state of each particle depend on all other particles1. The lack of general solutions for the three-body problem and acceptable theory for strongly correlated electrons shows that our understanding of correlated systems fades when the particle number or the interaction strength increases. One of the hallmarks of interacting systems is the formation of multiparticle bound states2-9. Here we develop a high-fidelity parameterizable fSim gate and implement the periodic quantum circuit of the spin-½ XXZ model in a ring of 24 superconducting qubits. We study the propagation of these excitations and observe their bound nature for up to five photons. We devise a phase-sensitive method for constructing the few-body spectrum of the bound states and extract their pseudo-charge by introducing a synthetic flux. By introducing interactions between the ring and additional qubits, we observe an unexpected resilience of the bound states to integrability breaking. This finding goes against the idea that bound states in non-integrable systems are unstable when their energies overlap with the continuum spectrum. Our work provides experimental evidence for bound states of interacting photons and discovers their stability beyond the integrability limit.

Published
2022

7. Realizing topologically ordered states on a quantum processor

Author

Satzinger, K. J., Liu, Y., Smith, A., Knapp, C., Newman, M., Jones, C., Chen, Z., Quintana, C., Mi, X., Dunsworth, A., Gidney, C., Aleiner, I., Arute, F., Arya, K., Atalaya, J., Babbush, R., Bardin, J. C., Barends, R., Basso, J., Bengtsson, A., Bilmes, A., Broughton, M., Buckley, B. B., Buell, D. A., Burkett, B., Bushnell, N., Chiaro, B., Collins, R., Courtney, W., Demura, S., Derk, A. R., Eppens, D., Erickson, C., Farhi, E., Foaro, L., Fowler, A. G., Foxen, B., Giustina, M., Greene, A., Gross, J. A., Harrigan, M. P., Harrington, S. D., Hilton, J., Hong, S., Huang, T., Huggins, W. J., Ioffe, L. B., Isakov, S. V., Jeffrey, E., Jiang, Z., Kafri, D., Kechedzhi, K., Khattar, T., Kim, S., Klimov, P. V., Korotkov, A. N., Kostritsa, F., Landhuis, D., Laptev, P., Locharla, A., Lucero, E., Martin, O., McClean, J. R., McEwen, M., Miao, K. C., Mohseni, M., Montazeri, S., Mruczkiewicz, W., Mutus, J., Naaman, O., Neeley, M., Neill, C., Niu, M. Y., O'Brien, T. E., Opremcak, A., Pató, B., Petukhov, A., Rubin, N. C., Sank, D., Shvarts, V., Strain, D., Szalay, M., Villalonga, B., White, T. C., Yao, Z., Yeh, P., Yoo, J., Zalcman, A., Neven, H., Boixo, S., Megrant, A., Chen, Y., Kelly, J., Smelyanskiy, V., Kitaev, A., Knap, M., Pollmann, F., and Roushan, P.

Subjects
Quantum Physics, Condensed Matter - Strongly Correlated Electrons
Abstract

The discovery of topological order has revolutionized the understanding of quantum matter in modern physics and provided the theoretical foundation for many quantum error correcting codes. Realizing topologically ordered states has proven to be extremely challenging in both condensed matter and synthetic quantum systems. Here, we prepare the ground state of the toric code Hamiltonian using an efficient quantum circuit on a superconducting quantum processor. We measure a topological entanglement entropy near the expected value of $\ln2$, and simulate anyon interferometry to extract the braiding statistics of the emergent excitations. Furthermore, we investigate key aspects of the surface code, including logical state injection and the decay of the non-local order parameter. Our results demonstrate the potential for quantum processors to provide key insights into topological quantum matter and quantum error correction., Comment: 6 pages 4 figures, plus supplementary materials

Published
2021
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8. Removing leakage-induced correlated errors in superconducting quantum error correction

Author

McEwen, M., Kafri, D., Chen, Z., Atalaya, J., Satzinger, K. J., Quintana, C., Klimov, P. V., Sank, D., Gidney, C., Fowler, A. G., Arute, F., Arya, K., Buckley, B., Burkett, B., Bushnell, N., Chiaro, B., Collins, R., Demura, S., Dunsworth, A., Erickson, C., Foxen, B., Giustina, M., Huang, T., Hong, S., Jeffrey, E., Kim, S., Kechedzhi, K., Kostritsa, F., Laptev, P., Megrant, A., Mi, X., Mutus, J., Naaman, O., Neeley, M., Neill, C., Niu, M., Paler, A., Redd, N., Roushan, P., White, T. C., Yao, J., Yeh, P., Zalcman, A., Chen, Yu, Smelyanskiy, V. N., Martinis, John M., Neven, H., Kelly, J., Korotkov, A. N., Petukhov, A. G., and Barends, R.

Subjects
Quantum Physics
Abstract

Quantum computing can become scalable through error correction, but logical error rates only decrease with system size when physical errors are sufficiently uncorrelated. During computation, unused high energy levels of the qubits can become excited, creating leakage states that are long-lived and mobile. Particularly for superconducting transmon qubits, this leakage opens a path to errors that are correlated in space and time. Here, we report a reset protocol that returns a qubit to the ground state from all relevant higher level states. We test its performance with the bit-flip stabilizer code, a simplified version of the surface code for quantum error correction. We investigate the accumulation and dynamics of leakage during error correction. Using this protocol, we find lower rates of logical errors and an improved scaling and stability of error suppression with increasing qubit number. This demonstration provides a key step on the path towards scalable quantum computing.

Published
2021
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9. Accurately computing electronic properties of a quantum ring

Author

Neill, C., McCourt, T., Mi, X., Jiang, Z., Niu, M. Y., Mruczkiewicz, W., Aleiner, I., Arute, F., Arya, K., Atalaya, J., Babbush, R., Bardin, J. C., Barends, R., Bengtsson, A., Bourassa, A., Broughton, M., Buckley, B. B., Buell, D. A., Burkett, B., Bushnell, N., Campero, J., Chen, Z., Chiaro, B., Collins, R., Courtney, W., Demura, S., Derk, A. R., Dunsworth, A., Eppens, D., Erickson, C., Farhi, E., Fowler, A. G., Foxen, B., Gidney, C., Giustina, M., Gross, J. A., Harrigan, M. P., Harrington, S. D., Hilton, J., Ho, A., Hong, S., Huang, T., Huggins, W. J., Isakov, S. V., Jacob-Mitos, M., Jeffrey, E., Jones, C., Kafri, D., Kechedzhi, K., Kelly, J., Kim, S., Klimov, P. V., Korotkov, A. N., Kostritsa, F., Landhuis, D., Laptev, P., Lucero, E., Martin, O., McClean, J. R., McEwen, M., Megrant, A., Miao, K. C., Mohseni, M., Mutus, J., Naaman, O., Neeley, M., Newman, M., O'Brien, T. E., Opremcak, A., Ostby, E., Pato, B., Petukhov, A., Quintana, C., Redd, N., Rubin, N. C., Sank, D., Satzinger, K. J., Shvarts, V., Strain, D., Szalay, M., Trevithick, M. D., Villalonga, B., White, T. C., Yao, Z., Yeh, P., Zalcman, A., Neven, H., Boixo, S., Ioffe, L. B., Roushan, P., Chen, Y., and Smelyanskiy, V.

Subjects
Quantum Physics
Abstract

A promising approach to study condensed-matter systems is to simulate them on an engineered quantum platform. However, achieving the accuracy needed to outperform classical methods has been an outstanding challenge. Here, using eighteen superconducting qubits, we provide an experimental blueprint for an accurate condensed-matter simulator and demonstrate how to probe fundamental electronic properties. We benchmark the underlying method by reconstructing the single-particle band-structure of a one-dimensional wire. We demonstrate nearly complete mitigation of decoherence and readout errors and arrive at an accuracy in measuring energy eigenvalues of this wire with an error of ~0.01 rad, whereas typical energy scales are of order 1 rad. Insight into this unprecedented algorithm fidelity is gained by highlighting robust properties of a Fourier transform, including the ability to resolve eigenenergies with a statistical uncertainty of 1e-4 rad. Furthermore, we synthesize magnetic flux and disordered local potentials, two key tenets of a condensed-matter system. When sweeping the magnetic flux, we observe avoided level crossings in the spectrum, a detailed fingerprint of the spatial distribution of local disorder. Combining these methods, we reconstruct electronic properties of the eigenstates where we observe persistent currents and a strong suppression of conductance with added disorder. Our work describes an accurate method for quantum simulation and paves the way to study novel quantum materials with superconducting qubits.

Published
2020
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10. Demonstrating a Continuous Set of Two-qubit Gates for Near-term Quantum Algorithms

Author

Foxen, B., Neill, C., Dunsworth, A., Roushan, P., Chiaro, B., Megrant, A., Kelly, J., Chen, Zijun, Satzinger, K., Barends, R., Arute, F., Arya, K., Babbush, R., Bacon, D., Bardin, J. C., Boixo, S., Buell, D., Burkett, B., Chen, Yu, Collins, R., Farhi, E., Fowler, A., Gidney, C., Giustina, M., Graff, R., Harrigan, M., Huang, T., Isakov, S. V., Jeffrey, E., Jiang, Z., Kafri, D., Kechedzhi, K., Klimov, P., Korotkov, A., Kostritsa, F., Landhuis, D., Lucero, E., McClean, J., McEwen, M., Mi, X., Mohseni, M., Mutus, J. Y., Naaman, O., Neeley, M., Niu, M., Petukhov, A., Quintana, C., Rubin, N., Sank, D., Smelyanskiy, V., Vainsencher, A., White, T. C., Yao, Z., Yeh, P., Zalcman, A., Neven, H., and Martinis, John M.

Subjects
Quantum Physics
Abstract

Quantum algorithms offer a dramatic speedup for computational problems in machine learning, material science, and chemistry. However, any near-term realizations of these algorithms will need to be heavily optimized to fit within the finite resources offered by existing noisy quantum hardware. Here, taking advantage of the strong adjustable coupling of gmon qubits, we demonstrate a continuous two-qubit gate set that can provide a 3x reduction in circuit depth as compared to a standard decomposition. We implement two gate families: an iSWAP-like gate to attain an arbitrary swap angle, $\theta$, and a CPHASE gate that generates an arbitrary conditional phase, $\phi$. Using one of each of these gates, we can perform an arbitrary two-qubit gate within the excitation-preserving subspace allowing for a complete implementation of the so-called Fermionic Simulation, or fSim, gate set. We benchmark the fidelity of the iSWAP-like and CPHASE gate families as well as 525 other fSim gates spread evenly across the entire fSim($\theta$, $\phi$) parameter space achieving purity-limited average two-qubit Pauli error of $3.8 \times 10^{-3}$ per fSim gate., Comment: 20 pages, 17 figures

Published
2020
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11. Removing leakage-induced correlated errors in superconducting quantum error correction

Author

McEwen, M, Kafri, D, Chen, Z, Atalaya, J, Satzinger, KJ, Quintana, C, Klimov, PV, Sank, D, Gidney, C, Fowler, AG, Arute, F, Arya, K, Buckley, B, Burkett, B, Bushnell, N, Chiaro, B, Collins, R, Demura, S, Dunsworth, A, Erickson, C, Foxen, B, Giustina, M, Huang, T, Hong, S, Jeffrey, E, Kim, S, Kechedzhi, K, Kostritsa, F, Laptev, P, Megrant, A, Mi, X, Mutus, J, Naaman, O, Neeley, M, Neill, C, Niu, M, Paler, A, Redd, N, Roushan, P, White, TC, Yao, J, Yeh, P, Zalcman, A, Chen, Yu, Smelyanskiy, VN, Martinis, John M, Neven, H, Kelly, J, Korotkov, AN, Petukhov, AG, and Barends, R

Subjects
Quantum Physics, Engineering, Electronics, Sensors and Digital Hardware, Physical Sciences, Atomic, Molecular and Optical Physics, quant-ph
Abstract

Quantum computing can become scalable through error correction, but logical error rates only decrease with system size when physical errors are sufficiently uncorrelated. During computation, unused high energy levels of the qubits can become excited, creating leakage states that are long-lived and mobile. Particularly for superconducting transmon qubits, this leakage opens a path to errors that are correlated in space and time. Here, we report a reset protocol that returns a qubit to the ground state from all relevant higher level states. We test its performance with the bit-flip stabilizer code, a simplified version of the surface code for quantum error correction. We investigate the accumulation and dynamics of leakage during error correction. Using this protocol, we find lower rates of logical errors and an improved scaling and stability of error suppression with increasing qubit number. This demonstration provides a key step on the path towards scalable quantum computing.

Published
2021

12. Direct measurement of non-local interactions in the many-body localized phase

Author

Chiaro, B., Neill, C., Bohrdt, A., Filippone, M., Arute, F., Arya, K., Babbush, R., Bacon, D., Bardin, J., Barends, R., Boixo, S., Buell, D., Burkett, B., Chen, Y., Chen, Z., Collins, R., Dunsworth, A., Farhi, E., Fowler, A., Foxen, B., Gidney, C., Giustina, M., Harrigan, M., Huang, T., Isakov, S., Jeffrey, E., Jiang, Z., Kafri, D., Kechedzhi, K., Kelly, J., Klimov, P., Korotkov, A., Kostritsa, F., Landhuis, D., Lucero, E., McClean, J., Mi, X., Megrant, A., Mohseni, M., Mutus, J., McEwen, M., Naaman, O., Neeley, M., Niu, M., Petukhov, A., Quintana, C., Rubin, N., Sank, D., Satzinger, K., Vainsencher, A., White, T., Yao, Z., Yeh, P., Zalcman, A., Smelyanskiy, V., Neven, H., Gopalakrishnan, S., Abanin, D., Knap, M., Martinis, J., and Roushan, P.

Subjects
Condensed Matter - Disordered Systems and Neural Networks, Condensed Matter - Statistical Mechanics, Condensed Matter - Strongly Correlated Electrons, Quantum Physics
Abstract

The interplay of interactions and strong disorder can lead to an exotic quantum many-body localized (MBL) phase. Beyond the absence of transport, the MBL phase has distinctive signatures, such as slow dephasing and logarithmic entanglement growth; they commonly result in slow and subtle modification of the dynamics, making their measurement challenging. Here, we experimentally characterize these properties of the MBL phase in a system of coupled superconducting qubits. By implementing phase sensitive techniques, we map out the structure of local integrals of motion in the MBL phase. Tomographic reconstruction of single and two qubit density matrices allowed us to determine the spatial and temporal entanglement growth between the localized sites. In addition, we study the preservation of entanglement in the MBL phase. The interferometric protocols implemented here measure affirmative correlations and allow us to exclude artifacts due to the imperfect isolation of the system. By measuring elusive MBL quantities, our work highlights the advantages of phase sensitive measurements in studying novel phases of matter., Comment: 5+28 pages, 5+22 figures, updated version

Published
2019

13. Diabatic gates for frequency-tunable superconducting qubits

Author

Barends, R., Quintana, C. M., Petukhov, A. G., Chen, Yu, Kafri, D., Kechedzhi, K., Collins, R., Naaman, O., Boixo, S., Arute, F., Arya, K., Buell, D., Burkett, B., Chen, Z., Chiaro, B., Dunsworth, A., Foxen, B., Fowler, A., Gidney, C., Giustina, M., Graff, R., Huang, T., Jeffrey, E., Kelly, J., Klimov, P. V., Kostritsa, F., Landhuis, D., Lucero, E., McEwen, M., Megrant, A., Mi, X., Mutus, J., Neeley, M., Neill, C., Ostby, E., Roushan, P., Sank, D., Satzinger, K. J., Vainsencher, A., White, T., Yao, J., Yeh, P., Zalcman, A., Neven, H., Smelyanskiy, V. N., and Martinis, John M.

Subjects
Quantum Physics
Abstract

We demonstrate diabatic two-qubit gates with Pauli error rates down to $4.3(2)\cdot 10^{-3}$ in as fast as 18 ns using frequency-tunable superconducting qubits. This is achieved by synchronizing the entangling parameters with minima in the leakage channel. The synchronization shows a landscape in gate parameter space that agrees with model predictions and facilitates robust tune-up. We test both iSWAP-like and CPHASE gates with cross-entropy benchmarking. The presented approach can be extended to multibody operations as well., Comment: Main text: 6 pages, 4 figures. Supplementary: 2 pages, 2 figures

Published
2019
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15. Bounds on quantum communication via Newtonian gravity

Author

Kafri, D., Milburn, G. J., and Taylor, J. M.

Subjects
Quantum Physics
Abstract

Newtonian gravity yields specific observable consequences, the most striking of which is the emergence of a $1/r^2$ force. In so far as communication can arise via such interactions between distant particles, we can ask what would be expected for a theory of gravity that only allows classical communication. Many heuristic suggestions for gravity-induced decoherence have this restriction implicitly or explicitly in their construction. Here we show that communication via a $1/r^2$ force has a minimum noise induced in the system when the communication cannot convey quantum information, in a continuous time analogue to Bell's inequalities. Our derived noise bounds provide tight constraints from current experimental results on any theory of gravity that does not allow quantum communication., Comment: 13 pages, 1 figure

Published
2014
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16. A classical channel model for gravitational decoherence

Author

Kafri, D., Taylor, J. M., and Milburn, G. J.

Subjects
Quantum Physics, General Relativity and Quantum Cosmology
Abstract

We show that, by treating the gravitational interaction between two mechanical resonators as a classical measurement channel, a gravitational decoherence model results that is equivalent to a model first proposed by Diosi. The resulting decoherence model implies that the classically mediated gravitational interaction between two gravitationally coupled resonators cannot create entanglement. The gravitational decoherence rate ( and the complementary heating rate) is of the order of the gravitationally induced normal mode splitting of the two resonators., Comment: 11 pages, 1 figure

Published
2014
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17. Quantum interface between an electrical circuit and a single atom

Author

Kielpinski, D., Kafri, D., Woolley, M. J., Milburn, G. J., and Taylor, J. M.

Subjects
Quantum Physics, Condensed Matter - Superconductivity, Physics - Atomic Physics
Abstract

We show how to bridge the divide between atomic systems and electronic devices by engineering a coupling between the motion of a single ion and the quantized electric field of a resonant circuit. Our method can be used to couple the internal state of an ion to the quantized circuit with the same speed as the internal-state coupling between two ions. All the well-known quantum information protocols linking ion internal and motional states can be converted to protocols between circuit photons and ion internal states. Our results enable quantum interfaces between solid state qubits, atomic qubits, and light, and lay the groundwork for a direct quantum connection between electrical and atomic metrology standards., Comment: Supplemental material available on request

Published
2011
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19. Quantum simulation of spin models on an arbitrary lattice with trapped ions

Author

Korenblit, S, Kafri, D, Campbell, WC, Islam, R, Edwards, EE, Gong, Z-X, Lin, G-D, Duan, L-M, Kim, J, Kim, K, and Monroe, C

Subjects
Physical Sciences, Fluids & Plasmas
Abstract

A collection of trapped atomic ions represents one of the most attractive platforms for the quantum simulation of interacting spin networks and quantum magnetism. Spin-dependent optical dipole forces applied to an ion crystal create long-range effective spin-spin interactions and allow the simulation of spin Hamiltonians that possess nontrivial phases and dynamics. Here we show how the appropriate design of laser fields can provide for arbitrary multidimensional spin-spin interaction graphs even for the case of a linear spatial array of ions. This scheme uses currently available trap technology and is scalable to levels where the classical methods of simulation are intractable. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Published
2012

20. Purification-based quantum error mitigation of pair-correlated electron simulations

Author

O’Brien, T. E., primary, Anselmetti, G., additional, Gkritsis, F., additional, Elfving, V. E., additional, Polla, S., additional, Huggins, W. J., additional, Oumarou, O., additional, Kechedzhi, K., additional, Abanin, D., additional, Acharya, R., additional, Aleiner, I., additional, Allen, R., additional, Andersen, T. I., additional, Anderson, K., additional, Ansmann, M., additional, Arute, F., additional, Arya, K., additional, Asfaw, A., additional, Atalaya, J., additional, Bardin, J. C., additional, Bengtsson, A., additional, Bortoli, G., additional, Bourassa, A., additional, Bovaird, J., additional, Brill, L., additional, Broughton, M., additional, Buckley, B., additional, Buell, D. A., additional, Burger, T., additional, Burkett, B., additional, Bushnell, N., additional, Campero, J., additional, Chen, Z., additional, Chiaro, B., additional, Chik, D., additional, Cogan, J., additional, Collins, R., additional, Conner, P., additional, Courtney, W., additional, Crook, A. L., additional, Curtin, B., additional, Debroy, D. M., additional, Demura, S., additional, Drozdov, I., additional, Dunsworth, A., additional, Erickson, C., additional, Faoro, L., additional, Farhi, E., additional, Fatemi, R., additional, Ferreira, V. S., additional, Flores Burgos, L., additional, Forati, E., additional, Fowler, A. G., additional, Foxen, B., additional, Giang, W., additional, Gidney, C., additional, Gilboa, D., additional, Giustina, M., additional, Gosula, R., additional, Grajales Dau, A., additional, Gross, J. A., additional, Habegger, S., additional, Hamilton, M. C., additional, Hansen, M., additional, Harrigan, M. P., additional, Harrington, S. D., additional, Heu, P., additional, Hoffmann, M. R., additional, Hong, S., additional, Huang, T., additional, Huff, A., additional, Ioffe, L. B., additional, Isakov, S. V., additional, Iveland, J., additional, Jeffrey, E., additional, Jiang, Z., additional, Jones, C., additional, Juhas, P., additional, Kafri, D., additional, Khattar, T., additional, Khezri, M., additional, Kieferová, M., additional, Kim, S., additional, Klimov, P. V., additional, Klots, A. R., additional, Korotkov, A. N., additional, Kostritsa, F., additional, Kreikebaum, J. M., additional, Landhuis, D., additional, Laptev, P., additional, Lau, K.-M., additional, Laws, L., additional, Lee, J., additional, Lee, K., additional, Lester, B. J., additional, Lill, A. T., additional, Liu, W., additional, Livingston, W. P., additional, Locharla, A., additional, Malone, F. D., additional, Mandrà, S., additional, Martin, O., additional, Martin, S., additional, McClean, J. R., additional, McCourt, T., additional, McEwen, M., additional, Mi, X., additional, Mieszala, A., additional, Miao, K. C., additional, Mohseni, M., additional, Montazeri, S., additional, Morvan, A., additional, Movassagh, R., additional, Mruczkiewicz, W., additional, Naaman, O., additional, Neeley, M., additional, Neill, C., additional, Nersisyan, A., additional, Newman, M., additional, Ng, J. H., additional, Nguyen, A., additional, Nguyen, M., additional, Niu, M. Y., additional, Omonije, S., additional, Opremcak, A., additional, Petukhov, A., additional, Potter, R., additional, Pryadko, L. P., additional, Quintana, C., additional, Rocque, C., additional, Roushan, P., additional, Saei, N., additional, Sank, D., additional, Sankaragomathi, K., additional, Satzinger, K. J., additional, Schurkus, H. F., additional, Schuster, C., additional, Shearn, M. J., additional, Shorter, A., additional, Shutty, N., additional, Shvarts, V., additional, Skruzny, J., additional, Smith, W. C., additional, Somma, R. D., additional, Sterling, G., additional, Strain, D., additional, Szalay, M., additional, Thor, D., additional, Torres, A., additional, Vidal, G., additional, Villalonga, B., additional, Vollgraff Heidweiller, C., additional, White, T., additional, Woo, B. W. K., additional, Xing, C., additional, Yao, Z. J., additional, Yeh, P., additional, Yoo, J., additional, Young, G., additional, Zalcman, A., additional, Zhang, Y., additional, Zhu, N., additional, Zobrist, N., additional, Bacon, D., additional, Boixo, S., additional, Chen, Y., additional, Hilton, J., additional, Kelly, J., additional, Lucero, E., additional, Megrant, A., additional, Neven, H., additional, Smelyanskiy, V., additional, Gogolin, C., additional, Babbush, R., additional, and Rubin, N. C., additional

Published
2023
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21. Purification-based quantum error mitigation of pair-correlated electron simulations

Author

O’Brien, TE, Anselmetti, G, Gkritsis, F, Elfving, VE, Polla, S, Huggins, WJ, Oumarou, O, Kechedzhi, K, Abanin, D, Acharya, R, Aleiner, I, Allen, R, Andersen, TI, Anderson, K, Ansmann, M, Arute, F, Arya, K, Asfaw, A, Atalaya, J, Bardin, JC, Bengtsson, A, Bortoli, G, Bourassa, A, Bovaird, J, Brill, L, Broughton, M, Buckley, B, Buell, DA, Burger, T, Burkett, B, Bushnell, N, Campero, J, Chen, Z, Chiaro, B, Chik, D, Cogan, J, Collins, R, Conner, P, Courtney, W, Crook, AL, Curtin, B, Debroy, DM, Demura, S, Drozdov, I, Dunsworth, A, Erickson, C, Faoro, L, Farhi, E, Fatemi, R, Ferreira, VS, Flores Burgos, L, Forati, E, Fowler, AG, Foxen, B, Giang, W, Gidney, C, Gilboa, D, Giustina, M, Gosula, R, Grajales Dau, A, Gross, JA, Habegger, S, Hamilton, MC, Hansen, M, Harrigan, MP, Harrington, SD, Heu, P, Hoffmann, MR, Hong, S, Huang, T, Huff, A, Ioffe, LB, Isakov, SV, Iveland, J, Jeffrey, E, Jiang, Z, Jones, C, Juhas, P, Kafri, D, Khattar, T, Khezri, M, Kieferová, M, Kim, S, Klimov, PV, Klots, AR, Korotkov, AN, Kostritsa, F, Kreikebaum, JM, Landhuis, D, Laptev, P, Lau, KM, Laws, L, Lee, J, Lee, K, Lester, BJ, Lill, AT, Liu, W, Livingston, WP, Locharla, A, Malone, FD, O’Brien, TE, Anselmetti, G, Gkritsis, F, Elfving, VE, Polla, S, Huggins, WJ, Oumarou, O, Kechedzhi, K, Abanin, D, Acharya, R, Aleiner, I, Allen, R, Andersen, TI, Anderson, K, Ansmann, M, Arute, F, Arya, K, Asfaw, A, Atalaya, J, Bardin, JC, Bengtsson, A, Bortoli, G, Bourassa, A, Bovaird, J, Brill, L, Broughton, M, Buckley, B, Buell, DA, Burger, T, Burkett, B, Bushnell, N, Campero, J, Chen, Z, Chiaro, B, Chik, D, Cogan, J, Collins, R, Conner, P, Courtney, W, Crook, AL, Curtin, B, Debroy, DM, Demura, S, Drozdov, I, Dunsworth, A, Erickson, C, Faoro, L, Farhi, E, Fatemi, R, Ferreira, VS, Flores Burgos, L, Forati, E, Fowler, AG, Foxen, B, Giang, W, Gidney, C, Gilboa, D, Giustina, M, Gosula, R, Grajales Dau, A, Gross, JA, Habegger, S, Hamilton, MC, Hansen, M, Harrigan, MP, Harrington, SD, Heu, P, Hoffmann, MR, Hong, S, Huang, T, Huff, A, Ioffe, LB, Isakov, SV, Iveland, J, Jeffrey, E, Jiang, Z, Jones, C, Juhas, P, Kafri, D, Khattar, T, Khezri, M, Kieferová, M, Kim, S, Klimov, PV, Klots, AR, Korotkov, AN, Kostritsa, F, Kreikebaum, JM, Landhuis, D, Laptev, P, Lau, KM, Laws, L, Lee, J, Lee, K, Lester, BJ, Lill, AT, Liu, W, Livingston, WP, Locharla, A, and Malone, FD

Abstract

An important measure of the development of quantum computing platforms has been the simulation of increasingly complex physical systems. Before fault-tolerant quantum computing, robust error-mitigation strategies were necessary to continue this growth. Here, we validate recently introduced error-mitigation strategies that exploit the expectation that the ideal output of a quantum algorithm would be a pure state. We consider the task of simulating electron systems in the seniority-zero subspace where all electrons are paired with their opposite spin. This affords a computational stepping stone to a fully correlated model. We compare the performance of error mitigations on the basis of doubling quantum resources in time or in space on up to 20 qubits of a superconducting qubit quantum processor. We observe a reduction of error by one to two orders of magnitude below less sophisticated techniques such as postselection. We study how the gain from error mitigation scales with the system size and observe a polynomial suppression of error with increased resources. Extrapolation of our results indicates that substantial hardware improvements will be required for classically intractable variational chemistry simulations.

Published
2023

22. Stable Quantum-Correlated Many Body States via Engineered Dissipation

Author

Mi, X., Michailidis, A. A., Shabani, S., Miao, K. C., Klimov, P. V., Lloyd, J., Rosenberg, E., Acharya, R., Aleiner, I., Andersen, T. I., Ansmann, M., Arute, F., Arya, K., Asfaw, A., Atalaya, J., Bardin, J. C., Bengtsson, A., Bortoli, G., Bourassa, A., Bovaird, J., Brill, L., Broughton, M., Buckley, B. B., Buell, D. A., Burger, T., Burkett, B., Bushnell, N., Chen, Z., Chiaro, B., Chik, D., Chou, C., Cogan, J., Collins, R., Conner, P., Courtney, W., Crook, A. L., Curtin, B., Dau, A. G., Debroy, D. M., Barba, A. Del Toro, Demura, S., Di Paolo, A., Drozdov, I. K., Dunsworth, A., Erickson, C., Faoro, L., Farhi, E., Fatemi, R., Ferreira, V. S., Forati, L. F. Burgos E., Fowler, A. G., Foxen, B., Genois, E., Giang, W., Gidney, C., Gilboa, D., Giustina, M., Gosula, R., Gross, J. A., Habegger, S., Hamilton, M. C., Hansen, M., Harrigan, M. P., Harrington, S. D., Heu, P., Hoffmann, M. R., Hong, S., Huang, T., Huff, A., Huggins, W. J., Ioffe, L. B., Isakov, S. V., Iveland, J., Jeffrey, E., Jiang, Z., Jones, C., Juhas, P., Kafri, D., Kechedzhi, K., Khattar, T., Khezri, M., Kieferova, M., Kim, S., Kitaev, A., Klots, A. R., Korotkov, A. N., Kostritsa, F., Kreikebaum, J. M., Landhuis, D., Laptev, P., Lau, K. -M., Laws, L., Lee, J., Lee, K. W., Lensky, Y. D., Lester, B. J., Lill, A. T., Liu, W., Locharla, A., Malone, F. D., Martin, O., McClean, J. R., McEwen, M., Mieszala, A., Montazeri, S., Morvan, A., Movassagh, R., Mruczkiewicz, W., Neeley, M., Neill, C., Nersisyan, A., Newman, M., Ng, J. H., Nguyen, A., Nguyen, M., Niu, M. Y., OBrien, T. E., Opremcak, A., Petukhov, A., Potter, R., Pryadko, L. P., Quintana, C., Rocque, C., Rubin, N. C., Saei, N., Sank, D., Sankaragomathi, K., Satzinger, K. J., Schurkus, H. F., Schuster, C., Shearn, M. J., Shorter, A., Shutty, N., Shvarts, V., Skruzny, J., Smith, W. C., Somma, R., Sterling, G., Strain, D., Szalay, M., Torres, A., Vidal, G., Villalonga, B., Heidweiller, C. V., White, T., Woo, B. W. K., Xing, C., Yao, Z. J., Yeh, P., Yoo, J., Young, G., Zalcman, A., Zhang, Y., Zhu, N., Zobrist, N., Neven, H., Babbush, R., Bacon, D., Boixo, S., Hilton, J., Lucero, E., Megrant, A., Kelly, J., Chen, Y., Roushan, P., Smelyanskiy, V., and Abanin, D. A.

Subjects
Quantum Physics, FOS: Physical sciences, Quantum Physics (quant-ph)
Abstract

Engineered dissipative reservoirs can steer many-body quantum systems toward correlated steady states useful for quantum simulation of high-temperature superconductivity or quantum magnetism. Using 49 superconducting qubits, we prepare low-energy states of the transverse-field Ising model via coupling to dissipative auxiliary qubits. In 1D, we observe long-range quantum correlations and a ground state fidelity that depends weakly on system sizes. In 2D, we find mutual information that extends beyond nearest neighbors. Lastly, by coupling the system to auxiliaries emulating reservoirs with different chemical potentials, we discover a new spin transport regime in the quantum Heisenberg model. Our results establish engineered dissipation as a scalable alternative to unitary evolution for preparing entangled many-body states on noisy quantum processors, and an essential tool for investigating nonequilibrium quantum phenomena.

Published
2023

23. Phase transition in Random Circuit Sampling

Author

Morvan, A., Villalonga, B., Mi, X., Mandrà, S., Bengtsson, A., Klimov, P. V., Chen, Z., Hong, S., Erickson, C., Drozdov, I. K., Chau, J., Laun, G., Movassagh, R., Asfaw, A., Brandão, L. T. A. N., Peralta, R., Abanin, D., Acharya, R., Allen, R., Andersen, T. I., Anderson, K., Ansmann, M., Arute, F., Arya, K., Atalaya, J., Bardin, J. C., Bilmes, A., Bortoli, G., Bourassa, A., Bovaird, J., Brill, L., Broughton, M., Buckley, B. B., Buell, D. A., Burger, T., Burkett, B., Bushnell, N., Campero, J., Chang, H. S., Chiaro, B., Chik, D., Chou, C., Cogan, J., Collins, R., Conner, P., Courtney, W., Crook, A. L., Curtin, B., Debroy, D. M., Barba, A. Del Toro, Demura, S., Di Paolo, A., Dunsworth, A., Faoro, L., Farhi, E., Fatemi, R., Ferreira, V. S., Burgos, L. Flores, Forati, E., Fowler, A. G., Foxen, B., Garcia, G., Genois, E., Giang, W., Gidney, C., Gilboa, D., Giustina, M., Gosula, R., Dau, A. Grajales, Gross, J. A., Habegger, S., Hamilton, M. C., Hansen, M., Harrigan, M. P., Harrington, S. D., Heu, P., Hoffmann, M. R., Huang, T., Huff, A., Huggins, W. J., Ioffe, L. B., Isakov, S. V., Iveland, J., Jeffrey, E., Jiang, Z., Jones, C., Juhas, P., Kafri, D., Khattar, T., Khezri, M., Kieferová, M., Kim, S., Kitaev, A., Klots, A. R., Korotkov, A. N., Kostritsa, F., Kreikebaum, J. M., Landhuis, D., Laptev, P., Lau, K. -M., Laws, L., Lee, J., Lee, K. W., Lensky, Y. D., Lester, B. J., Lill, A. T., Liu, W., Locharla, A., Malone, F. D., Martin, O., Martin, S., McClean, J. R., McEwen, M., Miao, K. C., Mieszala, A., Montazeri, S., Mruczkiewicz, W., Naaman, O., Neeley, M., Neill, C., Nersisyan, A., Newman, M., Ng, J. H., Nguyen, A., Nguyen, M., Niu, M. Yuezhen, O'Brien, T. E., Omonije, S., Opremcak, A., Petukhov, A., Potter, R., Pryadko, L. P., Quintana, C., Rhodes, D. M., Rocque, C., Roushan, P., Rubin, N. C., Saei, N., Sank, D., Sankaragomathi, K., Satzinger, K. J., Schurkus, H. F., Schuster, C., Shearn, M. J., Shorter, A., Shutty, N., Shvarts, V., Sivak, V., Skruzny, J., Smith, W. C., Somma, R. D., Sterling, G., Strain, D., Szalay, M., Thor, D., Torres, A., Vidal, G., Heidweiller, C. Vollgraff, White, T., Woo, B. W. K., Xing, C., Yao, Z. J., Yeh, P., Yoo, J., Young, G., Zalcman, A., Zhang, Y., Zhu, N., Zobrist, N., Rieffel, E. G., Biswas, R., Babbush, R., Bacon, D., Hilton, J., Lucero, E., Neven, H., Megrant, A., Kelly, J., Aleiner, I., Smelyanskiy, V., Kechedzhi, K., Chen, Y., and Boixo, S.

Subjects
Quantum Physics, FOS: Physical sciences, Quantum Physics (quant-ph)
Abstract

Quantum computers hold the promise of executing tasks beyond the capability of classical computers. Noise competes with coherent evolution and destroys long-range correlations, making it an outstanding challenge to fully leverage the computation power of near-term quantum processors. We report Random Circuit Sampling (RCS) experiments where we identify distinct phases driven by the interplay between quantum dynamics and noise. Using cross-entropy benchmarking, we observe phase boundaries which can define the computational complexity of noisy quantum evolution. We conclude by presenting an RCS experiment with 70 qubits at 24 cycles. We estimate the computational cost against improved classical methods and demonstrate that our experiment is beyond the capabilities of existing classical supercomputers.

Published
2023

24. Noise-resilient edge modes on a chain of superconducting qubits

Author

Mi, X., primary, Sonner, M., additional, Niu, M. Y., additional, Lee, K. W., additional, Foxen, B., additional, Acharya, R., additional, Aleiner, I., additional, Andersen, T. I., additional, Arute, F., additional, Arya, K., additional, Asfaw, A., additional, Atalaya, J., additional, Bardin, J. C., additional, Basso, J., additional, Bengtsson, A., additional, Bortoli, G., additional, Bourassa, A., additional, Brill, L., additional, Broughton, M., additional, Buckley, B. B., additional, Buell, D. A., additional, Burkett, B., additional, Bushnell, N., additional, Chen, Z., additional, Chiaro, B., additional, Collins, R., additional, Conner, P., additional, Courtney, W., additional, Crook, A. L., additional, Debroy, D. M., additional, Demura, S., additional, Dunsworth, A., additional, Eppens, D., additional, Erickson, C., additional, Faoro, L., additional, Farhi, E., additional, Fatemi, R., additional, Flores, L., additional, Forati, E., additional, Fowler, A. G., additional, Giang, W., additional, Gidney, C., additional, Gilboa, D., additional, Giustina, M., additional, Dau, A. G., additional, Gross, J. A., additional, Habegger, S., additional, Harrigan, M. P., additional, Hoffmann, M., additional, Hong, S., additional, Huang, T., additional, Huff, A., additional, Huggins, W. J., additional, Ioffe, L. B., additional, Isakov, S. V., additional, Iveland, J., additional, Jeffrey, E., additional, Jiang, Z., additional, Jones, C., additional, Kafri, D., additional, Kechedzhi, K., additional, Khattar, T., additional, Kim, S., additional, Kitaev, A. Y., additional, Klimov, P. V., additional, Klots, A. R., additional, Korotkov, A. N., additional, Kostritsa, F., additional, Kreikebaum, J. M., additional, Landhuis, D., additional, Laptev, P., additional, Lau, K.-M., additional, Lee, J., additional, Laws, L., additional, Liu, W., additional, Locharla, A., additional, Martin, O., additional, McClean, J. R., additional, McEwen, M., additional, Meurer Costa, B., additional, Miao, K. C., additional, Mohseni, M., additional, Montazeri, S., additional, Morvan, A., additional, Mount, E., additional, Mruczkiewicz, W., additional, Naaman, O., additional, Neeley, M., additional, Neill, C., additional, Newman, M., additional, O’Brien, T. E., additional, Opremcak, A., additional, Petukhov, A., additional, Potter, R., additional, Quintana, C., additional, Rubin, N. C., additional, Saei, N., additional, Sank, D., additional, Sankaragomathi, K., additional, Satzinger, K. J., additional, Schuster, C., additional, Shearn, M. J., additional, Shvarts, V., additional, Strain, D., additional, Su, Y., additional, Szalay, M., additional, Vidal, G., additional, Villalonga, B., additional, Vollgraff-Heidweiller, C., additional, White, T., additional, Yao, Z., additional, Yeh, P., additional, Yoo, J., additional, Zalcman, A., additional, Zhang, Y., additional, Zhu, N., additional, Neven, H., additional, Bacon, D., additional, Hilton, J., additional, Lucero, E., additional, Babbush, R., additional, Boixo, S., additional, Megrant, A., additional, Chen, Y., additional, Kelly, J., additional, Smelyanskiy, V., additional, Abanin, D. A., additional, and Roushan, P., additional

Published
2022
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25. Quantum Simulation of Spin Models with Trapped Ions

Author

Campbell, WC, Knoop, M1, Marzoli, I, Morigi, G, Campbell, WC, Monroe, C, Edwards, EE, Islam, R, Kafri, D, Korenblit, S, Lee, A, Richerme, P, Senko, C, Smith, J, Campbell, WC, Knoop, M1, Marzoli, I, Morigi, G, Campbell, WC, Monroe, C, Edwards, EE, Islam, R, Kafri, D, Korenblit, S, Lee, A, Richerme, P, Senko, C, and Smith, J

Published
2022

26. Direct measurement of nonlocal interactions in the many-body localized phase

Author

Chiaro, B., Neill, C., Bohrdt, A., Filippone, M., Arute, F., Arya, K., Babbush, R., Bacon, D., Bardin, J., Barends, R., Boixo, S., Buell, D., Burkett, B., Chen, Y., Chen, Z., Collins, R., Dunsworth, A., Farhi, E., Fowler, A., Foxen, B., Gidney, C., Giustina, M., Harrigan, M., Huang, T., Isakov, S., Jeffrey, E., Jiang, Z., Kafri, D., Kechedzhi, K., Kelly, J., Klimov, P., Korotkov, A., Kostritsa, F., Landhuis, D., Lucero, E., McClean, J., Mi, X., Megrant, A., Mohseni, M., Mutus, J., McEwen, M., Naaman, O., Neeley, M., Niu, M., Petukhov, A., Quintana, C., Rubin, N., Sank, D., Satzinger, K., White, T., Yao, Z., Yeh, P., Zalcman, A., Smelyanskiy, V., Neven, H., Gopalakrishnan, S., Abanin, D., Knap, M., Martinis, J., and Roushan, P.

Subjects
General Medicine
Published
2022
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27. Realizing topologically ordered states on a quantum processor

Author

Satzinger, K. J., primary, Liu, Y.-J, additional, Smith, A., additional, Knapp, C., additional, Newman, M., additional, Jones, C., additional, Chen, Z., additional, Quintana, C., additional, Mi, X., additional, Dunsworth, A., additional, Gidney, C., additional, Aleiner, I., additional, Arute, F., additional, Arya, K., additional, Atalaya, J., additional, Babbush, R., additional, Bardin, J. C., additional, Barends, R., additional, Basso, J., additional, Bengtsson, A., additional, Bilmes, A., additional, Broughton, M., additional, Buckley, B. B., additional, Buell, D. A., additional, Burkett, B., additional, Bushnell, N., additional, Chiaro, B., additional, Collins, R., additional, Courtney, W., additional, Demura, S., additional, Derk, A. R., additional, Eppens, D., additional, Erickson, C., additional, Faoro, L., additional, Farhi, E., additional, Fowler, A. G., additional, Foxen, B., additional, Giustina, M., additional, Greene, A., additional, Gross, J. A., additional, Harrigan, M. P., additional, Harrington, S. D., additional, Hilton, J., additional, Hong, S., additional, Huang, T., additional, Huggins, W. J., additional, Ioffe, L. B., additional, Isakov, S. V., additional, Jeffrey, E., additional, Jiang, Z., additional, Kafri, D., additional, Kechedzhi, K., additional, Khattar, T., additional, Kim, S., additional, Klimov, P. V., additional, Korotkov, A. N., additional, Kostritsa, F., additional, Landhuis, D., additional, Laptev, P., additional, Locharla, A., additional, Lucero, E., additional, Martin, O., additional, McClean, J. R., additional, McEwen, M., additional, Miao, K. C., additional, Mohseni, M., additional, Montazeri, S., additional, Mruczkiewicz, W., additional, Mutus, J., additional, Naaman, O., additional, Neeley, M., additional, Neill, C., additional, Niu, M. Y., additional, O’Brien, T. E., additional, Opremcak, A., additional, Pató, B., additional, Petukhov, A., additional, Rubin, N. C., additional, Sank, D., additional, Shvarts, V., additional, Strain, D., additional, Szalay, M., additional, Villalonga, B., additional, White, T. C., additional, Yao, Z., additional, Yeh, P., additional, Yoo, J., additional, Zalcman, A., additional, Neven, H., additional, Boixo, S., additional, Megrant, A., additional, Chen, Y., additional, Kelly, J., additional, Smelyanskiy, V., additional, Kitaev, A., additional, Knap, M., additional, Pollmann, F., additional, and Roushan, P., additional

Published
2021
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28. Accurately computing the electronic properties of a quantum ring

Author

Neill, C., primary, McCourt, T., additional, Mi, X., additional, Jiang, Z., additional, Niu, M. Y., additional, Mruczkiewicz, W., additional, Aleiner, I., additional, Arute, F., additional, Arya, K., additional, Atalaya, J., additional, Babbush, R., additional, Bardin, J. C., additional, Barends, R., additional, Bengtsson, A., additional, Bourassa, A., additional, Broughton, M., additional, Buckley, B. B., additional, Buell, D. A., additional, Burkett, B., additional, Bushnell, N., additional, Campero, J., additional, Chen, Z., additional, Chiaro, B., additional, Collins, R., additional, Courtney, W., additional, Demura, S., additional, Derk, A. R., additional, Dunsworth, A., additional, Eppens, D., additional, Erickson, C., additional, Farhi, E., additional, Fowler, A. G., additional, Foxen, B., additional, Gidney, C., additional, Giustina, M., additional, Gross, J. A., additional, Harrigan, M. P., additional, Harrington, S. D., additional, Hilton, J., additional, Ho, A., additional, Hong, S., additional, Huang, T., additional, Huggins, W. J., additional, Isakov, S. V., additional, Jacob-Mitos, M., additional, Jeffrey, E., additional, Jones, C., additional, Kafri, D., additional, Kechedzhi, K., additional, Kelly, J., additional, Kim, S., additional, Klimov, P. V., additional, Korotkov, A. N., additional, Kostritsa, F., additional, Landhuis, D., additional, Laptev, P., additional, Lucero, E., additional, Martin, O., additional, McClean, J. R., additional, McEwen, M., additional, Megrant, A., additional, Miao, K. C., additional, Mohseni, M., additional, Mutus, J., additional, Naaman, O., additional, Neeley, M., additional, Newman, M., additional, O’Brien, T. E., additional, Opremcak, A., additional, Ostby, E., additional, Pató, B., additional, Petukhov, A., additional, Quintana, C., additional, Redd, N., additional, Rubin, N. C., additional, Sank, D., additional, Satzinger, K. J., additional, Shvarts, V., additional, Strain, D., additional, Szalay, M., additional, Trevithick, M. D., additional, Villalonga, B., additional, White, T. C., additional, Yao, Z., additional, Yeh, P., additional, Zalcman, A., additional, Neven, H., additional, Boixo, S., additional, Ioffe, L. B., additional, Roushan, P., additional, Chen, Y., additional, and Smelyanskiy, V., additional

Published
2021
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29. Diabatic Gates for Frequency-Tunable Superconducting Qubits

Author

Barends, R., primary, Quintana, C. M., additional, Petukhov, A. G., additional, Chen, Yu, additional, Kafri, D., additional, Kechedzhi, K., additional, Collins, R., additional, Naaman, O., additional, Boixo, S., additional, Arute, F., additional, Arya, K., additional, Buell, D., additional, Burkett, B., additional, Chen, Z., additional, Chiaro, B., additional, Dunsworth, A., additional, Foxen, B., additional, Fowler, A., additional, Gidney, C., additional, Giustina, M., additional, Graff, R., additional, Huang, T., additional, Jeffrey, E., additional, Kelly, J., additional, Klimov, P. V., additional, Kostritsa, F., additional, Landhuis, D., additional, Lucero, E., additional, McEwen, M., additional, Megrant, A., additional, Mi, X., additional, Mutus, J., additional, Neeley, M., additional, Neill, C., additional, Ostby, E., additional, Roushan, P., additional, Sank, D., additional, Satzinger, K. J., additional, Vainsencher, A., additional, White, T., additional, Yao, J., additional, Yeh, P., additional, Zalcman, A., additional, Neven, H., additional, Smelyanskiy, V. N., additional, and Martinis, John M., additional

Published
2019
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34. Learning high-accuracy error decoding for quantum processors.

Author

Bausch J, Senior AW, Heras FJH, Edlich T, Davies A, Newman M, Jones C, Satzinger K, Niu MY, Blackwell S, Holland G, Kafri D, Atalaya J, Gidney C, Hassabis D, Boixo S, Neven H, and Kohli P

Abstract

Building a large-scale quantum computer requires effective strategies to correct errors that inevitably arise in physical quantum systems 1 . Quantum error-correction codes 2 present a way to reach this goal by encoding logical information redundantly into many physical qubits. A key challenge in implementing such codes is accurately decoding noisy syndrome information extracted from redundancy checks to obtain the correct encoded logical information. Here we develop a recurrent, transformer-based neural network that learns to decode the surface code, the leading quantum error-correction code 3 . Our decoder outperforms other state-of-the-art decoders on real-world data from Google's Sycamore quantum processor for distance-3 and distance-5 surface codes 4 . On distances up to 11, the decoder maintains its advantage on simulated data with realistic noise including cross-talk and leakage, utilizing soft readouts and leakage information. After training on approximate synthetic data, the decoder adapts to the more complex, but unknown, underlying error distribution by training on a limited budget of experimental samples. Our work illustrates the ability of machine learning to go beyond human-designed algorithms by learning from data directly, highlighting machine learning as a strong contender for decoding in quantum computers., Competing Interests: Competing interests: Author-affiliated entities have filed US and international patent applications related to quantum error-correction using neural networks and to use of in-phase and quadrature information in decoding, including US18/237,204, PCT/US2024/036110, US18/237,323, PCT/US2024/036120, US18/237,331, PCT/US2024/036167, US18/758,727 and PCT/US2024/036173., (© 2024. The Author(s).)

Published
2024
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35. Time-crystalline eigenstate order on a quantum processor.

Author

Mi X, Ippoliti M, Quintana C, Greene A, Chen Z, Gross J, Arute F, Arya K, Atalaya J, Babbush R, Bardin JC, Basso J, Bengtsson A, Bilmes A, Bourassa A, Brill L, Broughton M, Buckley BB, Buell DA, Burkett B, Bushnell N, Chiaro B, Collins R, Courtney W, Debroy D, Demura S, Derk AR, Dunsworth A, Eppens D, Erickson C, Farhi E, Fowler AG, Foxen B, Gidney C, Giustina M, Harrigan MP, Harrington SD, Hilton J, Ho A, Hong S, Huang T, Huff A, Huggins WJ, Ioffe LB, Isakov SV, Iveland J, Jeffrey E, Jiang Z, Jones C, Kafri D, Khattar T, Kim S, Kitaev A, Klimov PV, Korotkov AN, Kostritsa F, Landhuis D, Laptev P, Lee J, Lee K, Locharla A, Lucero E, Martin O, McClean JR, McCourt T, McEwen M, Miao KC, Mohseni M, Montazeri S, Mruczkiewicz W, Naaman O, Neeley M, Neill C, Newman M, Niu MY, O'Brien TE, Opremcak A, Ostby E, Pato B, Petukhov A, Rubin NC, Sank D, Satzinger KJ, Shvarts V, Su Y, Strain D, Szalay M, Trevithick MD, Villalonga B, White T, Yao ZJ, Yeh P, Yoo J, Zalcman A, Neven H, Boixo S, Smelyanskiy V, Megrant A, Kelly J, Chen Y, Sondhi SL, Moessner R, Kechedzhi K, Khemani V, and Roushan P

Subjects
Phase Transition, Thermodynamics, Cold Temperature
Abstract

Quantum many-body systems display rich phase structure in their low-temperature equilibrium states 1 . However, much of nature is not in thermal equilibrium. Remarkably, it was recently predicted that out-of-equilibrium systems can exhibit novel dynamical phases 2-8 that may otherwise be forbidden by equilibrium thermodynamics, a paradigmatic example being the discrete time crystal (DTC) 7,9-15 . Concretely, dynamical phases can be defined in periodically driven many-body-localized (MBL) systems via the concept of eigenstate order 7,16,17 . In eigenstate-ordered MBL phases, the entire many-body spectrum exhibits quantum correlations and long-range order, with characteristic signatures in late-time dynamics from all initial states. It is, however, challenging to experimentally distinguish such stable phases from transient phenomena, or from regimes in which the dynamics of a few select states can mask typical behaviour. Here we implement tunable controlled-phase (CPHASE) gates on an array of superconducting qubits to experimentally observe an MBL-DTC and demonstrate its characteristic spatiotemporal response for generic initial states 7,9,10 . Our work employs a time-reversal protocol to quantify the impact of external decoherence, and leverages quantum typicality to circumvent the exponential cost of densely sampling the eigenspectrum. Furthermore, we locate the phase transition out of the DTC with an experimental finite-size analysis. These results establish a scalable approach to studying non-equilibrium phases of matter on quantum processors., (© 2021. The Author(s).)

Published
2022
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36. Information scrambling in quantum circuits.

Author

Mi X, Roushan P, Quintana C, Mandrà S, Marshall J, Neill C, Arute F, Arya K, Atalaya J, Babbush R, Bardin JC, Barends R, Basso J, Bengtsson A, Boixo S, Bourassa A, Broughton M, Buckley BB, Buell DA, Burkett B, Bushnell N, Chen Z, Chiaro B, Collins R, Courtney W, Demura S, Derk AR, Dunsworth A, Eppens D, Erickson C, Farhi E, Fowler AG, Foxen B, Gidney C, Giustina M, Gross JA, Harrigan MP, Harrington SD, Hilton J, Ho A, Hong S, Huang T, Huggins WJ, Ioffe LB, Isakov SV, Jeffrey E, Jiang Z, Jones C, Kafri D, Kelly J, Kim S, Kitaev A, Klimov PV, Korotkov AN, Kostritsa F, Landhuis D, Laptev P, Lucero E, Martin O, McClean JR, McCourt T, McEwen M, Megrant A, Miao KC, Mohseni M, Montazeri S, Mruczkiewicz W, Mutus J, Naaman O, Neeley M, Newman M, Niu MY, O'Brien TE, Opremcak A, Ostby E, Pato B, Petukhov A, Redd N, Rubin NC, Sank D, Satzinger KJ, Shvarts V, Strain D, Szalay M, Trevithick MD, Villalonga B, White T, Yao ZJ, Yeh P, Zalcman A, Neven H, Aleiner I, Kechedzhi K, Smelyanskiy V, and Chen Y

Abstract

Interactions in quantum systems can spread initially localized quantum information into the exponentially many degrees of freedom of the entire system. Understanding this process, known as quantum scrambling, is key to resolving several open questions in physics. Here, by measuring the time-dependent evolution and fluctuation of out-of-time-order correlators, we experimentally investigate the dynamics of quantum scrambling on a 53-qubit quantum processor. We engineer quantum circuits that distinguish operator spreading and operator entanglement and experimentally observe their respective signatures. We show that whereas operator spreading is captured by an efficient classical model, operator entanglement in idealized circuits requires exponentially scaled computational resources to simulate. These results open the path to studying complex and practically relevant physical observables with near-term quantum processors.

Published
2021
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37. Quantum supremacy using a programmable superconducting processor.

Author

Arute F, Arya K, Babbush R, Bacon D, Bardin JC, Barends R, Biswas R, Boixo S, Brandao FGSL, Buell DA, Burkett B, Chen Y, Chen Z, Chiaro B, Collins R, Courtney W, Dunsworth A, Farhi E, Foxen B, Fowler A, Gidney C, Giustina M, Graff R, Guerin K, Habegger S, Harrigan MP, Hartmann MJ, Ho A, Hoffmann M, Huang T, Humble TS, Isakov SV, Jeffrey E, Jiang Z, Kafri D, Kechedzhi K, Kelly J, Klimov PV, Knysh S, Korotkov A, Kostritsa F, Landhuis D, Lindmark M, Lucero E, Lyakh D, Mandrà S, McClean JR, McEwen M, Megrant A, Mi X, Michielsen K, Mohseni M, Mutus J, Naaman O, Neeley M, Neill C, Niu MY, Ostby E, Petukhov A, Platt JC, Quintana C, Rieffel EG, Roushan P, Rubin NC, Sank D, Satzinger KJ, Smelyanskiy V, Sung KJ, Trevithick MD, Vainsencher A, Villalonga B, White T, Yao ZJ, Yeh P, Zalcman A, Neven H, and Martinis JM

Abstract

The promise of quantum computers is that certain computational tasks might be executed exponentially faster on a quantum processor than on a classical processor 1 . A fundamental challenge is to build a high-fidelity processor capable of running quantum algorithms in an exponentially large computational space. Here we report the use of a processor with programmable superconducting qubits 2-7 to create quantum states on 53 qubits, corresponding to a computational state-space of dimension 2 53 (about 10 16 ). Measurements from repeated experiments sample the resulting probability distribution, which we verify using classical simulations. Our Sycamore processor takes about 200 seconds to sample one instance of a quantum circuit a million times-our benchmarks currently indicate that the equivalent task for a state-of-the-art classical supercomputer would take approximately 10,000 years. This dramatic increase in speed compared to all known classical algorithms is an experimental realization of quantum supremacy 8-14 for this specific computational task, heralding a much-anticipated computing paradigm.

Published
2019
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38. Observation of Classical-Quantum Crossover of 1/f Flux Noise and Its Paramagnetic Temperature Dependence.

Author

Quintana CM, Chen Y, Sank D, Petukhov AG, White TC, Kafri D, Chiaro B, Megrant A, Barends R, Campbell B, Chen Z, Dunsworth A, Fowler AG, Graff R, Jeffrey E, Kelly J, Lucero E, Mutus JY, Neeley M, Neill C, O'Malley PJ, Roushan P, Shabani A, Smelyanskiy VN, Vainsencher A, Wenner J, Neven H, and Martinis JM

Abstract

By analyzing the dissipative dynamics of a tunable gap flux qubit, we extract both sides of its two-sided environmental flux noise spectral density over a range of frequencies around 2k_{B}T/h≈1  GHz, allowing for the observation of a classical-quantum crossover. Below the crossover point, the symmetric noise component follows a 1/f power law that matches the magnitude of the 1/f noise near 1 Hz. The antisymmetric component displays a 1/T dependence below 100 mK, providing dynamical evidence for a paramagnetic environment. Extrapolating the two-sided spectrum predicts the linewidth and reorganization energy of incoherent resonant tunneling between flux qubit wells.

Published
2017
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