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15 results on '"Lucero, Erik"'

1. 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, Aleiner, Igor, 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, FOS: Physical sciences, Quantum Physics (quant-ph)
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

2. Quantum information phases in space-time: measurement-induced entanglement and teleportation on a noisy quantum processor

Author

Hoke, Jesse C., Ippoliti, Matteo, Abanin, Dmitry, Acharya, Rajeev, Ansmann, Markus, Arute, Frank, Arya, Kunal, Asfaw, Abraham, Atalaya, Juan, Bardin, Joseph C., Bengtsson, Andreas, Bortoli, Gina, Bourassa, Alexandre, Bovaird, Jenna, Brill, Leon, Broughton, Michael, Buckley, Bob B., Buell, David A., Burger, Tim, Burkett, Brian, Bushnell, Nicholas, Chen, Zijun, Chiaro, Ben, Chik, Desmond, Chou, Charina, Cogan, Josh, Collins, Roberto, Conner, Paul, Courtney, William, Crook, Alexander L., Curtin, Ben, Dau, Alejandro Grajales, Debroy, Dripto M., Barba, Alexander Del Toro, Demura, Sean, Di Paolo, Augustin, Drozdov, Ilya K., Dunsworth, Andrew, Eppens, Daniel, Erickson, Catherine, Faoro, Lara, Farhi, Edward, Fatem, Reza, Ferreira, Vinicius S., Burgos, Leslie Flores, Forati, Ebrahim, Fowler, Austin G., Foxen, Brooks, Giang, William, Gidney, Craig, Gilboa, Dar, Giustina, Marissa, Gosula, Raja, Gross, Jonathan A., Habegger, Steve, Hamilton, Michael C., Hansen, Monica, Harrigan, Matthew P., Harrington, Sean D., Heu, Paula, Hoffmann, Markus R., Hong, Sabrina, Huang, Trent, Huff, Ashley, Huggins, William J., Isakov, Sergei V., Iveland, Justin, Jeffr, Evan, Jones, Cody, Juhas, Pavol, Kafri, Dvir, Kechedzhi, Kostyantyn, Khattar, Tanuj, Khezri, Mostafa, Kieferová, Mária, Kim, Seon, Kitaev, Alexei, Klimov, Paul V., Klots, Andrey R., Korotkov, Alexander N., Kostritsa, Fedor, Kreikebaum, John Mark, Landhuis, David, Laptev, Pavel, Lau, Kim-Ming, Laws, Lily, Lee, Joonho, Lee, Kenny W., Lensky, Yuri D., Lester, Brian J., Lill, Alexander T., Liu, Wayne, Locharla, Aditya, Malone, Fionn D., Martin, Orion, McClean, Jarrod R., McCourt, Trevor, McEwen, Matt, Miao, Kevin C., Mieszala, Amanda, Montazeri, Shirin, Morvan, Alexis, Movassagh, Ramis, Mruczkiewicz, Wojciech, Neeley, Matthew, Neill, Charles, Nersisyan, Ani, Newman, Michael, Ng, Jiun H., Nguyen, Anthony, Nguyen, Murray, Niu, Murphy Yuezhen, O'Brien, Tom E., Omonije, Seun, Opremcak, Alex, Petukhov, Andre, Potter, Rebecca, Pryadko, Leonid P., Quintana, Chris, Rocque, Charles, Rubin, Nicholas C., Sank, Negar Saei Daniel, Sankaragomathi, Kannan, Satzinger, Kevin J., Schurkus, Henry F., Schuster, Christopher, Shearn, Michael J., Shorter, Aaron, Shutty, Noah, Shvarts, Vlad, Skruzny, Jindra, Smith, W. Clarke, Sterling, Rolando D. Somma George, Strain, Douglas, Szalay, Marco, Torres, Alfredo, Vidal, Guifre, Villalonga, Benjamin, Heidweiller, Catherine Vollgraff, White, Ted, Woo, Bryan W. K., Xing, Cheng, Yao, Z. Jamie., Yeh, Ping, Yoo, Juhwan, Young, Grayson, Zalcman, Adam, Zhang, Yaxing, Zhu, Ningfeng, Zobrist, Nicholas, Neven, Harmut, Babbush, Ryan, Bacon, Dave, Boixo, Sergio, Hilton, Jeremy, Lucero, Erik, Megrant, Anthony, Kelly, Julian, Chen, Yu, Smelyanskiy, Vadim, Mi, Xiao, Khemani, Vedika, and Roushan, Pedram

Subjects
High Energy Physics - Theory, Quantum Physics, Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th), FOS: Physical sciences, Quantum Physics (quant-ph), Condensed Matter - Statistical Mechanics
Abstract

Measurement has a special role in quantum theory: by collapsing the wavefunction it can enable phenomena such as teleportation and thereby alter the "arrow of time" that constrains unitary evolution. When integrated in many-body dynamics, measurements can lead to emergent patterns of quantum information in space-time that go beyond established paradigms for characterizing phases, either in or out of equilibrium. On present-day NISQ processors, the experimental realization of this physics is challenging due to noise, hardware limitations, and the stochastic nature of quantum measurement. Here we address each of these experimental challenges and investigate measurement-induced quantum information phases on up to 70 superconducting qubits. By leveraging the interchangeability of space and time, we use a duality mapping, to avoid mid-circuit measurement and access different manifestations of the underlying phases -- from entanglement scaling to measurement-induced teleportation -- in a unified way. We obtain finite-size signatures of a phase transition with a decoding protocol that correlates the experimental measurement record with classical simulation data. The phases display sharply different sensitivity to noise, which we exploit to turn an inherent hardware limitation into a useful diagnostic. Our work demonstrates an approach to realize measurement-induced physics at scales that are at the limits of current NISQ processors.

Published
2023

3. Measurement-Induced State Transitions in a Superconducting Qubit: Within the Rotating Wave Approximation

Author

Khezri, Mostafa, Opremcak, Alex, Chen, Zijun, Bengtsson, Andreas, White, Theodore, Naaman, Ofer, Acharya, Rajeev, Anderson, Kyle, Ansmann, Markus, Arute, Frank, Arya, Kunal, Asfaw, Abraham, Bardin, Joseph C., Bourassa, Alexandre, Bovaird, Jenna, Brill, Leon, Buckley, Bob B., Buell, David A., Burger, Tim, Burkett, Brian, Bushnell, Nicholas, Campero, Juan, Chiaro, Ben, Collins, Roberto, Crook, Alexander L., Curtin, Ben, Demura, Sean, Dunsworth, Andrew, Erickson, Catherine, Fatemi, Reza, Ferreira, Vinicius S., Burgos, Leslie Flores, Forati, Ebrahim, Foxen, Brooks, Garcia, Gonzalo, Giang, William, Giustina, Marissa, Gosula, Raja, Dau, Alejandro Grajales, Hamilton, Michael C., Harrington, Sean D., Heu, Paula, Hilton, Jeremy, Hoffmann, Markus R., Hong, Sabrina, Huang, Trent, Huff, Ashley, Iveland, Justin, Jeffrey, Evan, Kelly, Julian, Kim, Seon, Klimov, Paul V., Kostritsa, Fedor, Kreikebaum, John Mark, Landhuis, David, Laptev, Pavel, Laws, Lily, Lee, Kenny, Lester, Brian J., Lill, Alexander T., Liu, Wayne, Locharla, Aditya, Lucero, Erik, Martin, Steven, McEwen, Matt, Megrant, Anthony, Mi, Xiao, Miao, Kevin C., Montazeri, Shirin, Morvan, Alexis, Neeley, Matthew, Neill, Charles, Nersisyan, Ani, Ng, Jiun How, Nguyen, Anthony, Nguyen, Murray, Potter, Rebecca, Quintana, Chris, Rocque, Charles, Roushan, Pedram, Sankaragomathi, Kannan, Satzinger, Kevin J., Schuster, Christopher, Shearn, Michael J., Shorter, Aaron, Shvarts, Vladimir, Skruzny, Jindra, Smith, W. Clarke, Sterling, George, Szalay, Marco, Thor, Douglas, Torres, Alfredo, Woo, Bryan W. K., Yao, Z. Jamie, Yeh, Ping, Yoo, Juhwan, Young, Grayson, Zhu, Ningfeng, Zobrist, Nicholas, Sank, Daniel, Korotkov, Alexander, Chen, Yu, and Smelyanskiy, Vadim

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

Superconducting qubits typically use a dispersive readout scheme, where a resonator is coupled to a qubit such that its frequency is qubit-state dependent. Measurement is performed by driving the resonator, where the transmitted resonator field yields information about the resonator frequency and thus the qubit state. Ideally, we could use arbitrarily strong resonator drives to achieve a target signal-to-noise ratio in the shortest possible time. However, experiments have shown that when the average resonator photon number exceeds a certain threshold, the qubit is excited out of its computational subspace, which we refer to as a measurement-induced state transition. These transitions degrade readout fidelity, and constitute leakage which precludes further operation of the qubit in, for example, error correction. Here we study these transitions using a transmon qubit by experimentally measuring their dependence on qubit frequency, average photon number, and qubit state, in the regime where the resonator frequency is lower than the qubit frequency. We observe signatures of resonant transitions between levels in the coupled qubit-resonator system that exhibit noisy behavior when measured repeatedly in time. We provide a semi-classical model of these transitions based on the rotating wave approximation and use it to predict the onset of state transitions in our experiments. Our results suggest the transmon is excited to levels near the top of its cosine potential following a state transition, where the charge dispersion of higher transmon levels explains the observed noisy behavior of state transitions. Moreover, occupation in these higher energy levels poses a major challenge for fast qubit reset.

Published
2022

4. Non-Abelian braiding of graph vertices in a superconducting processor

Author

Andersen, Trond I., Lensky, Yuri D., Kechedzhi, Kostyantyn, Drozdov, Ilya, Bengtsson, Andreas, Hong, Sabrina, Morvan, Alexis, Mi, Xiao, Opremcak, Alex, Acharya, Rajeev, Allen, Richard, Ansmann, Markus, Arute, Frank, Arya, Kunal, Asfaw, Abraham, Atalaya, Juan, Babbush, Ryan, Bacon, Dave, Bardin, Joseph C., Bortoli, Gina, Bourassa, Alexandre, Bovaird, Jenna, Brill, Leon, Broughton, Michael, Buckley, Bob B., Buell, David A., Burger, Tim, Burkett, Brian, Bushnell, Nicholas, Chen, Zijun, Chiaro, Ben, Chik, Desmond, Chou, Charina, Cogan, Josh, Collins, Roberto, Conner, Paul, Courtney, William, Crook, Alexander L., Curtin, Ben, Debroy, Dripto M., Barba, Alexander Del Toro, Demura, Sean, Dunsworth, Andrew, Eppens, Daniel, Erickson, Catherine, Faoro, Lara, Farhi, Edward, Fatemi, Reza, Ferreira, Vinicius S., Burgos, Leslie Flores, Forati, Ebrahim, Fowler, Austin G., Foxen, Brooks, Giang, William, Gidney, Craig, Gilboa, Dar, Giustina, Marissa, Gosula, Raja, Dau, Alejandro Grajales, Gross, Jonathan A., Habegger, Steve, Hamilton, Michael C., Hansen, Monica, Harrigan, Matthew P., Harrington, Sean D., Heu, Paula, Hilton, Jeremy, Hoffmann, Markus R., Huang, Trent, Huff, Ashley, Huggins, William J., Ioffe, Lev B., Isakov, Sergei V., Iveland, Justin, Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Juhas, Pavol, Kafri, Dvir, Khattar, Tanuj, Khezri, Mostafa, Kieferová, Mária, Kim, Seon, Kitaev, Alexei, Klimov, Paul V., Klots, Andrey R., Korotkov, Alexander N., Kostritsa, Fedor, Kreikebaum, John Mark, Landhuis, David, Laptev, Pavel, Lau, Kim-Ming, Laws, Lily, Lee, Joonho, Lee, Kenny, Lester, Brian J., Lill, Alexander, Liu, Wayne, Locharla, Aditya, Lucero, Erik, Malone, Fionn D., Martin, Orion, McClean, Jarrod R., McCourt, Trevor, McEwen, Matt, Miao, Kevin C., Mieszala, Amanda, Mohseni, Masoud, Montazeri, Shirin, Mount, Emily, Movassagh, Ramis, Mruczkiewicz, Wojciech, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Nersisyan, Ani, Newman, Michael, Ng, Jiun How, Nguyen, Anthony, Nguyen, Murray, Niu, Murphy Yuezhen, O'Brien, Thomas E., Omonije, Seun, Petukhov, Andre, Potter, Rebecca, Pryadko, Leonid P., Quintana, Chris, Rocque, Charles, Rubin, Nicholas C., Saei, Negar, Sank, Daniel, Sankaragomathi, Kannan, Satzinger, Kevin J., Schurkus, Henry F., Schuster, Christopher, Shearn, Michael J., Shorter, Aaron, Shutty, Noah, Shvarts, Vladimir, Skruzny, Jindra, Smith, W. Clarke, Somma, Rolando, Sterling, George, Strain, Doug, Szalay, Marco, Torres, Alfredo, Vidal, Guifre, Villalonga, Benjamin, Heidweiller, Catherine Vollgraff, White, Theodore, Woo, Bryan W. K., Xing, Cheng, Yao, Z. Jamie, Yeh, Ping, Yoo, Juhwan, Young, Grayson, Zalcman, Adam, Zhang, Yaxing, Zhu, Ningfeng, Zobrist, Nicholas, Neven, Hartmut, Boixo, Sergio, Megrant, Anthony, Kelly, Julian, Chen, Yu, Smelyanskiy, Vadim, Kim, Eun-Ah, Aleiner, Igor, and Roushan, Pedram

Subjects
Condensed Matter - Other Condensed Matter, Quantum Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), FOS: Physical sciences, Quantum Physics (quant-ph), Other Condensed Matter (cond-mat.other)
Abstract

Indistinguishability of particles is a fundamental principle of quantum mechanics. For all elementary and quasiparticles observed to date - including fermions, bosons, and Abelian anyons - this principle guarantees that the braiding of identical particles leaves the system unchanged. However, in two spatial dimensions, an intriguing possibility exists: braiding of non-Abelian anyons causes rotations in a space of topologically degenerate wavefunctions. Hence, it can change the observables of the system without violating the principle of indistinguishability. Despite the well developed mathematical description of non-Abelian anyons and numerous theoretical proposals, the experimental observation of their exchange statistics has remained elusive for decades. Controllable many-body quantum states generated on quantum processors offer another path for exploring these fundamental phenomena. While efforts on conventional solid-state platforms typically involve Hamiltonian dynamics of quasi-particles, superconducting quantum processors allow for directly manipulating the many-body wavefunction via unitary gates. Building on predictions that stabilizer codes can host projective non-Abelian Ising anyons, we implement a generalized stabilizer code and unitary protocol to create and braid them. This allows us to experimentally verify the fusion rules of the anyons and braid them to realize their statistics. We then study the prospect of employing the anyons for quantum computation and utilize braiding to create an entangled state of anyons encoding three logical qubits. Our work provides new insights about non-Abelian braiding and - through the future inclusion of error correction to achieve topological protection - could open a path toward fault-tolerant quantum computing.

Published
2022

5. Suppressing quantum errors by scaling a surface code logical qubit

Author

Acharya, Rajeev, Aleiner, Igor, Allen, Richard, Andersen, Trond I., Ansmann, Markus, Arute, Frank, Arya, Kunal, Asfaw, Abraham, Atalaya, Juan, Babbush, Ryan, Bacon, Dave, Bardin, Joseph C., Basso, Joao, Bengtsson, Andreas, Boixo, Sergio, Bortoli, Gina, Bourassa, Alexandre, Bovaird, Jenna, Brill, Leon, Broughton, Michael, Buckley, Bob B., Buell, David A., Burger, Tim, Burkett, Brian, Bushnell, Nicholas, Chen, Yu, Chen, Zijun, Chiaro, Ben, Cogan, Josh, Collins, Roberto, Conner, Paul, Courtney, William, Crook, Alexander L., Curtin, Ben, Debroy, Dripto M., Barba, Alexander Del Toro, Demura, Sean, Dunsworth, Andrew, Eppens, Daniel, Erickson, Catherine, Faoro, Lara, Farhi, Edward, Fatemi, Reza, Burgos, Leslie Flores, Forati, Ebrahim, Fowler, Austin G., Foxen, Brooks, Giang, William, Gidney, Craig, Gilboa, Dar, Giustina, Marissa, Dau, Alejandro Grajales, Gross, Jonathan A., Habegger, Steve, Hamilton, Michael C., Harrigan, Matthew P., Harrington, Sean D., Higgott, Oscar, Hilton, Jeremy, Hoffmann, Markus, Hong, Sabrina, Huang, Trent, Huff, Ashley, Huggins, William J., Ioffe, Lev B., Isakov, Sergei V., Iveland, Justin, Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Juhas, Pavol, Kafri, Dvir, Kechedzhi, Kostyantyn, Kelly, Julian, Khattar, Tanuj, Khezri, Mostafa, Kieferová, Mária, Kim, Seon, Kitaev, Alexei, Klimov, Paul V., Klots, Andrey R., Korotkov, Alexander N., Kostritsa, Fedor, Kreikebaum, John Mark, Landhuis, David, Laptev, Pavel, Lau, Kim-Ming, Laws, Lily, Lee, Joonho, Lee, Kenny, Lester, Brian J., Lill, Alexander, Liu, Wayne, Locharla, Aditya, Lucero, Erik, Malone, Fionn D., Marshall, Jeffrey, Martin, Orion, McClean, Jarrod R., Mccourt, Trevor, McEwen, Matt, Megrant, Anthony, Costa, Bernardo Meurer, Mi, Xiao, Miao, Kevin C., Mohseni, Masoud, Montazeri, Shirin, Morvan, Alexis, Mount, Emily, Mruczkiewicz, Wojciech, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Nersisyan, Ani, Neven, Hartmut, Newman, Michael, Ng, Jiun How, Nguyen, Anthony, Nguyen, Murray, Niu, Murphy Yuezhen, O'Brien, Thomas E., Opremcak, Alex, Platt, John, Petukhov, Andre, Potter, Rebecca, Pryadko, Leonid P., Quintana, Chris, Roushan, Pedram, Rubin, Nicholas C., Saei, Negar, Sank, Daniel, Sankaragomathi, Kannan, Satzinger, Kevin J., Schurkus, Henry F., Schuster, Christopher, Shearn, Michael J., Shorter, Aaron, Shvarts, Vladimir, Skruzny, Jindra, Smelyanskiy, Vadim, Smith, W. Clarke, Sterling, George, Strain, Doug, Szalay, Marco, Torres, Alfredo, Vidal, Guifre, Villalonga, Benjamin, Heidweiller, Catherine Vollgraff, White, Theodore, Xing, Cheng, Yao, Z. Jamie, Yeh, Ping, Yoo, Juhwan, Young, Grayson, Zalcman, Adam, Zhang, Yaxing, and Zhu, Ningfeng

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

Practical quantum computing will require error rates that are well below what is achievable with physical qubits. Quantum error correction offers a path to algorithmically-relevant error rates by encoding logical qubits within many physical qubits, where increasing the number of physical qubits enhances protection against physical errors. However, introducing more qubits also increases the number of error sources, so the density of errors must be sufficiently low in order for logical performance to improve with increasing code size. Here, we report the measurement of logical qubit performance scaling across multiple code sizes, and demonstrate that our system of superconducting qubits has sufficient performance to overcome the additional errors from increasing qubit number. We find our distance-5 surface code logical qubit modestly outperforms an ensemble of distance-3 logical qubits on average, both in terms of logical error probability over 25 cycles and logical error per cycle ($2.914\%\pm 0.016\%$ compared to $3.028\%\pm 0.023\%$). To investigate damaging, low-probability error sources, we run a distance-25 repetition code and observe a $1.7\times10^{-6}$ logical error per round floor set by a single high-energy event ($1.6\times10^{-7}$ when excluding this event). We are able to accurately model our experiment, and from this model we can extract error budgets that highlight the biggest challenges for future systems. These results mark the first experimental demonstration where quantum error correction begins to improve performance with increasing qubit number, illuminating the path to reaching the logical error rates required for computation., Main text: 6 pages, 4 figures. v2: Update author list, references, Fig. S12, Table IV

Published
2022

6. Overcoming leakage in scalable quantum error correction

Author

Miao, Kevin C., McEwen, Matt, Atalaya, Juan, Kafri, Dvir, Pryadko, Leonid P., Bengtsson, Andreas, Opremcak, Alex, Satzinger, Kevin J., Chen, Zijun, Klimov, Paul V., Quintana, Chris, Acharya, Rajeev, Anderson, Kyle, Ansmann, Markus, Arute, Frank, Arya, Kunal, Asfaw, Abraham, Bardin, Joseph C., Bourassa, Alexandre, Bovaird, Jenna, Brill, Leon, Buckley, Bob B., Buell, David A., Burger, Tim, Burkett, Brian, Bushnell, Nicholas, Campero, Juan, Chiaro, Ben, Collins, Roberto, Conner, Paul, Crook, Alexander L., Curtin, Ben, Debroy, Dripto M., Demura, Sean, Dunsworth, Andrew, Erickson, Catherine, Fatemi, Reza, Ferreira, Vinicius S., Burgos, Leslie Flores, Forati, Ebrahim, Fowler, Austin G., Foxen, Brooks, Garcia, Gonzalo, Giang, William, Gidney, Craig, Giustina, Marissa, Gosula, Raja, Dau, Alejandro Grajales, Gross, Jonathan A., Hamilton, Michael C., Harrington, Sean D., Heu, Paula, Hilton, Jeremy, Hoffmann, Markus R., Hong, Sabrina, Huang, Trent, Huff, Ashley, Iveland, Justin, Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Kelly, Julian, Kim, Seon, Kostritsa, Fedor, Kreikebaum, John Mark, Landhuis, David, Laptev, Pavel, Laws, Lily, Lee, Kenny, Lester, Brian J., Lill, Alexander T., Liu, Wayne, Locharla, Aditya, Lucero, Erik, Martin, Steven, Megrant, Anthony, Mi, Xiao, Montazeri, Shirin, Morvan, Alexis, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Nersisyan, Ani, Newman, Michael, Ng, Jiun How, Nguyen, Anthony, Nguyen, Murray, Potter, Rebecca, Rocque, Charles, Roushan, Pedram, Sankaragomathi, Kannan, Schuster, Christopher, Shearn, Michael J., Shorter, Aaron, Shutty, Noah, Shvarts, Vladimir, Skruzny, Jindra, Smith, W. Clarke, Sterling, George, Szalay, Marco, Thor, Douglas, Torres, Alfredo, White, Theodore, Woo, Bryan W. K., Yao, Z. Jamie, Yeh, Ping, Yoo, Juhwan, Young, Grayson, Zalcman, Adam, Zhu, Ningfeng, Zobrist, Nicholas, Neven, Hartmut, Smelyanskiy, Vadim, Petukhov, Andre, Korotkov, Alexander N., Sank, Daniel, and Chen, Yu

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

Leakage of quantum information out of computational states into higher energy states represents a major challenge in the pursuit of quantum error correction (QEC). In a QEC circuit, leakage builds over time and spreads through multi-qubit interactions. This leads to correlated errors that degrade the exponential suppression of logical error with scale, challenging the feasibility of QEC as a path towards fault-tolerant quantum computation. Here, we demonstrate the execution of a distance-3 surface code and distance-21 bit-flip code on a Sycamore quantum processor where leakage is removed from all qubits in each cycle. This shortens the lifetime of leakage and curtails its ability to spread and induce correlated errors. We report a ten-fold reduction in steady-state leakage population on the data qubits encoding the logical state and an average leakage population of less than $1 \times 10^{-3}$ throughout the entire device. The leakage removal process itself efficiently returns leakage population back to the computational basis, and adding it to a code circuit prevents leakage from inducing correlated error across cycles, restoring a fundamental assumption of QEC. With this demonstration that leakage can be contained, we resolve a key challenge for practical QEC at scale., Comment: Main text: 7 pages, 5 figures

Published
2022
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7. Information Scrambling in Computationally Complex Quantum Circuits

Author

Mi, Xiao, Roushan, Pedram, Quintana, Chris, Mandra, Salvatore, Marshall, Jeffrey, Neill, Charles, Arute, Frank, Arya, Kunal, Atalaya, Juan, Babbush, Ryan, Bardin, Joseph C., Barends, Rami, Bengtsson, Andreas, Boixo, Sergio, Bourassa, Alexandre, Broughton, Michael, Buckley, Bob B., Buell, David A., Burkett, Brian, Bushnell, Nicholas, Chen, Zijun, Chiaro, Benjamin, Collins, Roberto, Courtney, William, Demura, Sean, Derk, Alan R., Dunsworth, Andrew, Eppens, Daniel, Erickson, Catherine, Farhi, Edward, Fowler, Austin G., Foxen, Brooks, Gidney, Craig, Giustina, Marissa, Gross, Jonathan A., Harrigan, Matthew P., Harrington, Sean D., Hilton, Jeremy, Ho, Alan, Hong, Sabrina, Huang, Trent, Huggins, William J., Ioffe, L. B., Isakov, Sergei V., Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Kafri, Dvir, Kelly, Julian, Kim, Seon, Kitaev, Alexei, Klimov, Paul V., Korotkov, Alexander N., Kostritsa, Fedor, Landhuis, David, Laptev, Pavel, Lucero, Erik, Martin, Orion, McClean, Jarrod R., McCourt, Trevor, McEwen, Matt, Megrant, Anthony, Miao, Kevin C., Mohseni, Masoud, Mruczkiewicz, Wojciech, Mutus, Josh, Naaman, Ofer, Neeley, Matthew, Newman, Michael, Niu, Murphy Yuezhen, O'Brien, Thomas E., Opremcak, Alex, Ostby, Eric, Pato, Balint, Petukhov, Andre, Redd, Nicholas, Rubin, Nicholas C., Sank, Daniel, Satzinger, Kevin J., Shvarts, Vladimir, Strain, Doug, Szalay, Marco, Trevithick, Matthew D., Villalonga, Benjamin, White, Theodore, Yao, Z. Jamie, Yeh, Ping, Zalcman, Adam, Neven, Hartmut, Aleiner, Igor, Kechedzhi, Kostyantyn, Smelyanskiy, Vadim, and Chen, Yu

Subjects
High Energy Physics - Theory, Quantum Physics, Condensed Matter - Strongly Correlated Electrons, Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), ComputerSystemsOrganization_MISCELLANEOUS, FOS: Physical sciences, TheoryofComputation_GENERAL, Quantum Physics (quant-ph)
Abstract

Interaction in quantum systems can spread initially localized quantum information into the many degrees of freedom of the entire system. Understanding this process, known as quantum scrambling, is the key to resolving various conundrums 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 the two mechanisms associated with quantum scrambling, operator spreading and operator entanglement, and experimentally observe their respective signatures. We show that while operator spreading is captured by an efficient classical model, operator entanglement 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

8. Exponential suppression of bit or phase flip errors with repetitive error correction

Author

Chen, Zijun, Satzinger, Kevin J., Atalaya, Juan, Korotkov, Alexander N., Dunsworth, Andrew, Sank, Daniel, Quintana, Chris, McEwen, Matt, Barends, Rami, Klimov, Paul V., Hong, Sabrina, Jones, Cody, Petukhov, Andre, Kafri, Dvir, Demura, Sean, Burkett, Brian, Gidney, Craig, Fowler, Austin G., Putterman, Harald, Aleiner, Igor, Arute, Frank, Arya, Kunal, Babbush, Ryan, Bardin, Joseph C., Bengtsson, Andreas, Bourassa, Alexandre, Broughton, Michael, Buckley, Bob B., Buell, David A., Bushnell, Nicholas, Chiaro, Benjamin, Collins, Roberto, Courtney, William, Derk, Alan R., Eppens, Daniel, Erickson, Catherine, Farhi, Edward, Foxen, Brooks, Giustina, Marissa, Gross, Jonathan A., Harrigan, Matthew P., Harrington, Sean D., Hilton, Jeremy, Ho, Alan, Huang, Trent, Huggins, William J., Ioffe, L. B., Isakov, Sergei V., Jeffrey, Evan, Jiang, Zhang, Kechedzhi, Kostyantyn, Kim, Seon, Kostritsa, Fedor, Landhuis, David, Laptev, Pavel, Lucero, Erik, Martin, Orion, McClean, Jarrod R., McCourt, Trevor, Mi, Xiao, Miao, Kevin C., Mohseni, Masoud, Mruczkiewicz, Wojciech, Mutus, Josh, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Newman, Michael, Niu, Murphy Yuezhen, O'Brien, Thomas E., Opremcak, Alex, Ostby, Eric, Pató, Bálint, Redd, Nicholas, Roushan, Pedram, Rubin, Nicholas C., Shvarts, Vladimir, Strain, Doug, Szalay, Marco, Trevithick, Matthew D., Villalonga, Benjamin, White, Theodore, Yao, Z. Jamie, Yeh, Ping, Zalcman, Adam, Neven, Hartmut, Boixo, Sergio, Smelyanskiy, Vadim, Chen, Yu, Megrant, Anthony, and Kelly, Julian

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

Realizing the potential of quantum computing will require achieving sufficiently low logical error rates. Many applications call for error rates in the $10^{-15}$ regime, but state-of-the-art quantum platforms typically have physical error rates near $10^{-3}$. Quantum error correction (QEC) promises to bridge this divide by distributing quantum logical information across many physical qubits so that errors can be detected and corrected. Logical errors are then exponentially suppressed as the number of physical qubits grows, provided that the physical error rates are below a certain threshold. QEC also requires that the errors are local and that performance is maintained over many rounds of error correction, two major outstanding experimental challenges. Here, we implement 1D repetition codes embedded in a 2D grid of superconducting qubits which demonstrate exponential suppression of bit or phase-flip errors, reducing logical error per round by more than $100\times$ when increasing the number of qubits from 5 to 21. Crucially, this error suppression is stable over 50 rounds of error correction. We also introduce a method for analyzing error correlations with high precision, and characterize the locality of errors in a device performing QEC for the first time. Finally, we perform error detection using a small 2D surface code logical qubit on the same device, and show that the results from both 1D and 2D codes agree with numerical simulations using a simple depolarizing error model. These findings demonstrate that superconducting qubits are on a viable path towards fault tolerant quantum computing.

Published
2021
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9. Observation of Time-Crystalline Eigenstate Order on a Quantum Processor

Author

Mi, Xiao, Ippoliti, Matteo, Quintana, Chris, Greene, Ami, Chen, Zijun, Gross, Jonathan, Arute, Frank, Arya, Kunal, Atalaya, Juan, Babbush, Ryan, Bardin, Joseph C., Basso, Joao, Bengtsson, Andreas, Bilmes, Alexander, Bourassa, Alexandre, Brill, Leon, Broughton, Michael, Buckley, Bob B., Buell, David A., Burkett, Brian, Bushnell, Nicholas, Chiaro, Benjamin, Collins, Roberto, Courtney, William, Debroy, Dripto, Demura, Sean, Derk, Alan R., Dunsworth, Andrew, Eppens, Daniel, Erickson, Catherine, Farhi, Edward, Fowler, Austin G., Foxen, Brooks, Gidney, Craig, Giustina, Marissa, Harrigan, Matthew P., Harrington, Sean D., Hilton, Jeremy, Ho, Alan, Hong, Sabrina, Huang, Trent, Huff, Ashley, Huggins, William J., Ioffe, L. B., Isakov, Sergei V., Iveland, Justin, Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Kafri, Dvir, Khattar, Tanuj, Kim, Seon, Kitaev, Alexei, Klimov, Paul V., Korotkov, Alexander N., Kostritsa, Fedor, Landhuis, David, Laptev, Pavel, Lee, Joonho, Lee, Kenny, Locharla, Aditya, Lucero, Erik, Martin, Orion, McClean, Jarrod R., McCourt, Trevor, McEwen, Matt, Miao, Kevin C., Mohseni, Masoud, Montazeri, Shirin, Mruczkiewicz, Wojciech, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Newman, Michael, Niu, Murphy Yuezhen, Brien, Thomas E. O\', Opremcak, Alex, Ostby, Eric, Pato, Balint, Petukhov, Andre, Rubin, Nicholas C., Sank, Daniel, Satzinger, Kevin J., Shvarts, Vladimir, Su, Yuan, Strain, Doug, Szalay, Marco, Trevithick, Matthew D., Villalonga, Benjamin, White, Theodore, Yao, Z. Jamie, Yeh, Ping, Yoo, Juhwan, Zalcman, Adam, Neven, Hartmut, Boixo, Sergio, Smelyanskiy, Vadim, Megrant, Anthony, Kelly, Julian, Chen, Yu, Sondhi, S. L., Moessner, Roderich, Kechedzhi, Kostyantyn, Khemani, Vedika, and Roushan, Pedram

Subjects
Quantum Physics, Condensed Matter - Strongly Correlated Electrons, Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el), FOS: Physical sciences, Disordered Systems and Neural Networks (cond-mat.dis-nn), Condensed Matter - Disordered Systems and Neural Networks, Quantum Physics (quant-ph), Condensed Matter - Statistical Mechanics
Abstract

Quantum many-body systems display rich phase structure in their low-temperature equilibrium states. However, much of nature is not in thermal equilibrium. Remarkably, it was recently predicted that out-of-equilibrium systems can exhibit novel dynamical phases that may otherwise be forbidden by equilibrium thermodynamics, a paradigmatic example being the discrete time crystal (DTC). Concretely, dynamical phases can be defined in periodically driven many-body localized systems via the concept of eigenstate order. In eigenstate-ordered 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, wherein few select states can mask typical behavior. Here we implement a continuous family of tunable CPHASE gates on an array of superconducting qubits to experimentally observe an eigenstate-ordered DTC. We demonstrate the characteristic spatiotemporal response of a DTC for generic initial states. Our work employs a time-reversal protocol that discriminates external decoherence from intrinsic thermalization, and leverages quantum typicality to circumvent the exponential cost of densely sampling the eigenspectrum. In addition, we locate the phase transition out of the DTC with an experimental finite-size analysis. These results establish a scalable approach to study non-equilibrium phases of matter on current quantum processors.

Published
2021
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10. Hartree-Fock on a superconducting qubit quantum computer

Author

Arute, Frank, Arya, Kunal, Babbush, Ryan, Bacon, Dave, Bardin, Joseph C., Barends, Rami, Boixo, Sergio, Broughton, Michael, Buckley, Bob B., Buell, David A., Burkett, Brian, Bushnell, Nicholas, Chen, Yu, Chen, Zijun, Chiaro, Benjamin, Collins, Roberto, Courtney, William, Demura, Sean, Dunsworth, Andrew, Eppens, Daniel, Farhi, Edward, Fowler, Austin, Foxen, Brooks, Gidney, Craig, Giustina, Marissa, Graff, Rob, Habegger, Steve, Harrigan, Matthew P., Ho, Alan, Hong, Sabrina, Huang, Trent, Huggins, William J., Ioffe, Lev, Isakov, Sergei V., Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Kafri, Dvir, Kechedzhi, Kostyantyn, Kelly, Julian, Kim, Seon, Klimov, Paul V., Korotkov, Alexander, Kostritsa, Fedor, Landhuis, David, Laptev, Pavel, Lindmark, Mike, Lucero, Erik, Martin, Orion, Martinis, John M., McClean, Jarrod R., McEwen, Matt, Megrant, Anthony, Mi, Xiao, Mohseni, Masoud, Mruczkiewicz, Wojciech, Mutus, Josh, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Neven, Hartmut, Niu, Murphy Yuezhen, O'Brien, Thomas E., Ostby, Eric, Petukhov, Andre, Putterman, Harald, Quintana, Chris, Roushan, Pedram, Rubin, Nicholas C., Sank, Daniel, Satzinger, Kevin J., Smelyanskiy, Vadim, Strain, Doug, Sung, Kevin J., Szalay, Marco, Takeshita, Tyler Y., Vainsencher, Amit, White, Theodore, Wiebe, Nathan, Yao, Z. Jamie, Yeh, Ping, and Zalcman, Adam

Subjects
Superconductivity, Chemical Physics (physics.chem-ph), Quantum Physics, Multidisciplinary, Hartree–Fock method, FOS: Physical sciences, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, Qubit, Quantum mechanics, Physics - Chemical Physics, 0103 physical sciences, 010306 general physics, 0210 nano-technology, Quantum Physics (quant-ph), Quantum, Quantum computer
Abstract

As the search continues for useful applications of noisy intermediate scale quantum devices, variational simulations of fermionic systems remain one of the most promising directions. Here, we perform a series of quantum simulations of chemistry the largest of which involved a dozen qubits, 78 two-qubit gates, and 114 one-qubit gates. We model the binding energy of ${\rm H}_6$, ${\rm H}_8$, ${\rm H}_{10}$ and ${\rm H}_{12}$ chains as well as the isomerization of diazene. We also demonstrate error-mitigation strategies based on $N$-representability which dramatically improve the effective fidelity of our experiments. Our parameterized ansatz circuits realize the Givens rotation approach to non-interacting fermion evolution, which we variationally optimize to prepare the Hartree-Fock wavefunction. This ubiquitous algorithmic primitive corresponds to a rotation of the orbital basis and is required by many proposals for correlated simulations of molecules and Hubbard models. Because non-interacting fermion evolutions are classically tractable to simulate, yet still generate highly entangled states over the computational basis, we use these experiments to benchmark the performance of our hardware while establishing a foundation for scaling up more complex correlated quantum simulations of chemistry., updated link to experiment code, new version containing expanded data sets and corrected figure label

Published
2020

11. Supplementary information for 'Quantum supremacy using a programmable superconducting processor'

Author

Arute, Frank, Arya, Kunal, Babbush, Ryan, Bacon, Dave, Bardin, Joseph C., Barends, Rami, Biswas, Rupak, Boixo, Sergio, Brandao, Fernando G. S. L., Buell, David A., Burkett, Brian, Chen, Yu, Chen, Zijun, Chiaro, Ben, Collins, Roberto, Courtney, William, Dunsworth, Andrew, Farhi, Edward, Foxen, Brooks, Fowler, Austin, Gidney, Craig, Giustina, Marissa, Graff, Rob, Guerin, Keith, Habegger, Steve, Harrigan, Matthew P., Hartmann, Michael J., Ho, Alan, Hoffmann, Markus R., Huang, Trent, Humble, Travis S., Isakov, Sergei V., Jeffrey, Evan, Jiang, Zhang, Kafri, Dvir, Kechedzhi, Kostyantyn, Kelly, Julian, Klimov, Paul V., Knysh, Sergey, Korotkov, Alexander N., Kostritsa, Fedor, Landhuis, David, Lindmark, Mike, Lucero, Erik, Lyakh, Dmitry, Mandra, Salvatore, McClean, Jarrod R., McEwen, Matt, Megrant, Anthony, Mi, Xiao, Michielsen, Kristel, Mohseni, Masoud, Mutus, Josh, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Niu, Murphy Yuezhen, Ostby, Eric, Petukhov, Andre, Platt, John C., Quintana, Chris, Rieffel, Eleanor G., Roushan, Pedram, Rubin, Nicholas C., Sank, Daniel, Satzinger, Kevin J., Smelyanskiy, Vadim, Sung, Kevin J., Trevithick, Matthew D., Vainsencher, Amit, Villalonga, Benjamin, White, Theodore, Yao, Z. Jamie, Yeh, Ping, Zalcman, Adam, Neven, Hartmut, and Martinis, John M.

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

This is an updated version of supplementary information to accompany "Quantum supremacy using a programmable superconducting processor", an article published in the October 24, 2019 issue of Nature. The main article is freely available at https://www.nature.com/articles/s41586-019-1666-5. Summary of changes since arXiv:1910.11333v1 (submitted 23 Oct 2019): added URL for qFlex source code; added Erratum section; added Figure S41 comparing statistical and total uncertainty for log and linear XEB; new References [1,65]; miscellaneous updates for clarity and style consistency; miscellaneous typographical and formatting corrections., 67 pages, 51 figures

Published
2019

12. Learning Non-Markovian Quantum Noise from Moir��-Enhanced Swap Spectroscopy with Deep Evolutionary Algorithm

Author

Niu, Murphy Yuezhen, Smelyanskyi, Vadim, Klimov, Paul, Boixo, Sergio, Barends, Rami, Kelly, Julian, Chen, Yu, Arya, Kunal, Burkett, Brian, Bacon, Dave, Chen, Zijun, Chiaro, Ben, Collins, Roberto, Dunsworth, Andrew, Foxen, Brooks, Fowler, Austin, Gidney, Craig, Giustina, Marissa, Graff, Rob, Huang, Trent, Jeffrey, Evan, Landhuis, David, Lucero, Erik, Megrant, Anthony, Mutus, Josh, Mi, Xiao, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Quintana, Chris, Roushan, Pedram, Martinis, John M., and Neven, Hartmut

Subjects
FOS: Computer and information sciences, Computer Science::Emerging Technologies, FOS: Physical sciences, Hardware_PERFORMANCEANDRELIABILITY, Quantum Physics, Hardware_ARITHMETICANDLOGICSTRUCTURES, Quantum Physics (quant-ph), Machine Learning (cs.LG)
Abstract

Two-level-system (TLS) defects in amorphous dielectrics are a major source of noise and decoherence in solid-state qubits. Gate-dependent non-Markovian errors caused by TLS-qubit coupling are detrimental to fault-tolerant quantum computation and have not been rigorously treated in the existing literature. In this work, we derive the non-Markovian dynamics between TLS and qubits during a SWAP-like two-qubit gate and the associated average gate fidelity for frequency-tunable Transmon qubits. This gate dependent error model facilitates using qubits as sensors to simultaneously learn practical imperfections in both the qubit's environment and control waveforms. We combine the-state-of-art machine learning algorithm with Moir��-enhanced swap spectroscopy to achieve robust learning using noisy experimental data. Deep neural networks are used to represent the functional map from experimental data to TLS parameters and are trained through an evolutionary algorithm. Our method achieves the highest learning efficiency and robustness against experimental imperfections to-date, representing an important step towards in-situ quantum control optimization over environmental and control defects.

Published
2019
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13. Simulating weak localization using superconducting quantum circuits

Author

Chen, Yu, Roushan, P., Sank, D., Neill, C., Lucero, Erik, Mariantoni, Matteo, Barends, R., Chiaro, B., Kelly, J., Megrant, A., Mutus, J. Y., O'Malley, P. J. J., Vainsencher, A., Wenner, J., White, T. C., Yin, Yi, Cleland, A. N., and Martinis, John M.

Subjects
Superconductivity (cond-mat.supr-con), Quantum Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Superconductivity, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), FOS: Physical sciences, Quantum Physics (quant-ph)
Abstract

Understanding complex quantum matter presents a central challenge in condensed matter physics. The difficulty lies in the exponential scaling of the Hilbert space with the system size, making solutions intractable for both analytical and conventional numerical methods. As originally envisioned by Richard Feynman, this class of problems can be tackled using controllable quantum simulators. Despite many efforts, building an quantum emulator capable of solving generic quantum problems remains an outstanding challenge, as this involves controlling a large number of quantum elements. Here, employing a multi-element superconducting quantum circuit and manipulating a single microwave photon, we demonstrate that we can simulate the weak localization phenomenon observed in mesoscopic systems. By engineering the control sequence in our emulator circuit, we are also able to reproduce the well-known temperature dependence of weak localization. Furthermore, we can use our circuit to continuously tune the level of disorder, a parameter that is not readily accessible in mesoscopic systems. By demonstrating a high level of control and complexity, our experiment shows the potential for superconducting quantum circuits to realize scalable quantum simulators., Comment: 9 pages, including supplement

Published
2014
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14. Uncollapsing of a quantum state in a superconducting phase qubit

Author

Katz, Nadav, Neeley, Matthew, Ansmann, M., Bialczak, Radoslaw C., Hofheinz, M., Lucero, Erik, O'Connell, A., Wang, H., Cleland, A. N., Martinis, John M., and Korotkov, Alexander N.

Subjects
Superconductivity (cond-mat.supr-con), Quantum Physics, Condensed Matter - Superconductivity, FOS: Physical sciences, Quantum Physics (quant-ph)
Abstract

We demonstrate in a superconducting qubit the conditional recovery ("uncollapsing") of a quantum state after a partial-collapse measurement. A weak measurement extracts information and results in a non-unitary transformation of the qubit state. However, by adding a rotation and a second partial measurement with the same strength, we erase the extracted information, effectively canceling the effect of both measurements. The fidelity of the state recovery is measured using quantum process tomography and found to be above 70% for partial-collapse strength less than 0.6., Comment: 4 pages, 4 figures

Published
2008
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15. Observation of separated dynamics of charge and spin in the Fermi-Hubbard model

Author

Arute, Frank, Arya, Kunal, Babbush, Ryan, Bacon, Dave, Bardin, Joseph C., Barends, Rami, Bengtsson, Andreas, Boixo, Sergio, Broughton, Michael, Buckley, Bob B., Buell, David A., Burkett, Brian, Bushnell, Nicholas, Chen, Yu, Chen, Zijun, Yu-An Chen, Chiaro, Ben, Collins, Roberto, Cotton, Stephen J., Courtney, William, Demura, Sean, Derk, Alan, Dunsworth, Andrew, Eppens, Daniel, Eckl, Thomas, Erickson, Catherine, Farhi, Edward, Fowler, Austin, Foxen, Brooks, Gidney, Craig, Giustina, Marissa, Graff, Rob, Gross, Jonathan A., Habegger, Steve, Harrigan, Matthew P., Ho, Alan, Hong, Sabrina, Huang, Trent, Huggins, William, Ioffe, Lev B., Isakov, Sergei V., Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Kafri, Dvir, Kechedzhi, Kostyantyn, Kelly, Julian, Kim, Seon, Klimov, Paul V., Korotkov, Alexander N., Kostritsa, Fedor, Landhuis, David, Laptev, Pavel, Lindmark, Mike, Lucero, Erik, Marthaler, Michael, Martin, Orion, Martinis, John M., Marusczyk, Anika, Mcardle, Sam, Mcclean, Jarrod R., Mccourt, Trevor, Mcewen, Matt, Megrant, Anthony, Mejuto-Zaera, Carlos, Mi, Xiao, Mohseni, Masoud, Mruczkiewicz, Wojciech, Mutus, Josh, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Neven, Hartmut, Newman, Michael, Niu, Murphy Yuezhen, O Brien, Thomas E., Ostby, Eric, Pató, Bálint, Petukhov, Andre, Putterman, Harald, Quintana, Chris, Reiner, Jan-Michael, Roushan, Pedram, Rubin, Nicholas C., Sank, Daniel, Satzinger, Kevin J., Smelyanskiy, Vadim, Strain, Doug, Sung, Kevin J., Schmitteckert, Peter, Szalay, Marco, Tubman, Norm M., Vainsencher, Amit, White, Theodore, Vogt, Nicolas, Yao, Z. Jamie, Yeh, Ping, Zalcman, Adam, and Zanker, Sebastian

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

Strongly correlated quantum systems give rise to many exotic physical phenomena, including high-temperature superconductivity. Simulating these systems on quantum computers may avoid the prohibitively high computational cost incurred in classical approaches. However, systematic errors and decoherence effects presented in current quantum devices make it difficult to achieve this. Here, we simulate the dynamics of the one-dimensional Fermi-Hubbard model using 16 qubits on a digital superconducting quantum processor. We observe separations in the spreading velocities of charge and spin densities in the highly excited regime, a regime that is beyond the conventional quasiparticle picture. To minimize systematic errors, we introduce an accurate gate calibration procedure that is fast enough to capture temporal drifts of the gate parameters. We also employ a sequence of error-mitigation techniques to reduce decoherence effects and residual systematic errors. These procedures allow us to simulate the time evolution of the model faithfully despite having over 600 two-qubit gates in our circuits. Our experiment charts a path to practical quantum simulation of strongly correlated phenomena using available quantum devices., 20 pages, 15 figures

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