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24 results on '"Courtney, W."'

1. 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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2. 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., 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., Rosenberg, E., 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
Abstract

Undesired coupling to the surrounding environment destroys long-range correlations on quantum processors and hinders the coherent evolution in the nominally available computational space. This incoherent noise is an outstanding challenge to fully leverage the computation power of near-term quantum processors. It has been shown that benchmarking Random Circuit Sampling (RCS) with Cross-Entropy Benchmarking (XEB) can provide a reliable estimate of the effective size of the Hilbert space coherently available. The extent to which the presence of noise can trivialize the outputs of a given quantum algorithm, i.e. making it spoofable by a classical computation, is an unanswered question. Here, by implementing an RCS algorithm we demonstrate experimentally that there are two phase transitions observable with XEB, which we explain theoretically with a statistical model. The first is a dynamical transition as a function of the number of cycles and is the continuation of the anti-concentration point in the noiseless case. The second is a quantum phase transition controlled by the error per cycle; to identify it analytically and experimentally, we create a weak link model which allows varying the strength of noise versus coherent evolution. Furthermore, by presenting an RCS experiment with 67 qubits at 32 cycles, we demonstrate that the computational cost of our experiment is beyond the capabilities of existing classical supercomputers, even when accounting for the inevitable presence of noise. Our experimental and theoretical work establishes the existence of transitions to a stable computationally complex phase that is reachable with current quantum processors.

Published
2023
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3. 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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4. 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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5. 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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6. Incorporating the Stern-Gerlach delayed-choice quantum eraser into the undergraduate quantum mechanics curriculum

Author

Courtney, W. F., Vieira, L. B., Julienne, P. S., and Freericks, J. K.

Subjects
Physics - Physics Education
Abstract

As "Stern-Gerlach first" becomes the new paradigm within the undergraduate quantum mechanics curriculum, we show how one can extend the treatment found in conventional textbooks to cover some of the exciting new developments within the quantum field. Namely, we illustrate how one can employ Dirac notation and conventional quantum rules to describe a delayed choice variant of the quantum eraser which is realized within the Stern-Gerlach framework. Covering this material, allows the instructor to reinforce notions of changes of basis functions, quantum superpositions, quantum measurement, and the complementarity principle as expressed in whether we know "which-way" information or not. It also allows the instructor to dispel common misconceptions of when a measurement occurs and when a system is in a superposition of states. We comment at the end how a similar methodology can be employed when the more conventional two-slit experiment is treated., Comment: (20 pages, 8 figures)

Published
2017

9. Inter-Institutional Cooperation for Effective Teleconferencing.

Author

Anderson, Courtney W.

Abstract

The South Dakota Medical Information Exchange (SDMIX) is a statewide telephone teleconferencing network which was established to provide continuing health education programs to a variety of institutions and facilities in South Dakota. The project's success is predicated on the establishment and maintenance of inter-institutional coordination and cooperation. An institution needs to first gain internal cooperation, establish internal goals for the project, and decide upon control issues. Then, internal marketing can be developed and instituted within the parent institution. Once this has been accomplished, inter-institutional cooperation for the implementation of a teleconferencing network can begin. Such cooperation should be predicated upon establishing common goals, identifying those who can make decisions to implement the network, and effective marketing. By establishing the effective inter-institutional coordination and cooperation, the SDMIX project has been able to deliver continuing education programs relevant to the needs of the state's health care providers. (Author/LMM)

Published
1982

11. An Expedited Forwarding PHB (Per-Hop Behavior)

Author

Davie, B., primary, Charny, A., additional, Bennet, J.C.R., additional, Benson, K., additional, Le, J.Y., additional, Courtney, W., additional, Davari, S., additional, Firoiu, V., additional, and Stiliadis, D., additional

Published
2002
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13. Evaluation of gear materials for space applications

Author

Courtney, W. J, Farrell, J. J, and Vest, C. E

Subjects
Machine Elements And Processes
Abstract

Gear materials evaluation program for space environment application with unlubricated or solid film lubricated operation mode

Published
1970

14. Evaluation of gear materials for space applications

Author

Courtney, W. J, Farrell, J. J, and Vest, C. E

Subjects
Machine Elements And Processes
Abstract

Gear materials evaluation program for space environment application with unlubricated or solid film lubricated operation mode

Published
1969

17. CONDENSATION IN NOZZLES

Author

Courtney, W. G

Subjects
Communications
Abstract

Condensation in rocket nozzle flow and homogeneous nucleation

Published
1963

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