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arXiv:2304.11119quant-ph

Phase transition in Random Circuit Sampling

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

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.

arXiv comments
Journal reference
Nature 634, 328-333 (2024)
DOI
doi:10.1038/s41586-024-07998-6
Subjects
quant-phQuantum Physics

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Linked by 4 identifiable commenters in 4 comments across 2 threads, from Jul 2023 to Jul 2023. Found in 1 HN submission from Jul 2023 to Jul 2023. Open submission discussions.

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Discussed in comments2 threads

  1. 2048 Bit RSA and the Year 2030 2 comments

    • Google's "quantum supremacy" paper was about a 53 qubit chip in 2019 [1]. This year, they reported having 70 qubits [2]. Looking at the papers (and supplements), the gate fidelities and qubit lifetimes have stayed roughly the same. This really doesn't look like anything like…

      fshView on HNParent context

    • Do you have links to some results for this 433 processor? The only results I've seen is this [0] from April which is 70 qbit and it's all about fighting with noise. It looks like overcoming noise is exponentially harder with more qubits and this whole quantum thing may never…

      mirekrusinView on HNParent context

  2. Google claims to have proved its supremacy with new quantum computer 2 comments

    • The cited paper[1] references "random circuit sampling" which is defined in [2] which then gets so heavy into abstract math, and I give up. Can someone explain this in terms an EE or programmer can understand? [1] https://arxiv.org/abs/2304.11119 [2]…

      mikewarotView on HNParent context

    • Quantum Computing/Information researcher here. This article is largely garbage, the original (~2 month old) paper is surprisingly readable [0] and I suggest you to check it out. Here's my $0.02: The efforts of the Google team is commendable in that they're trying to squeeze as…

      deepburnerView on HNParent context

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