[Qubits de chat pour le calcul quantique]
Le développement des circuits quantiques Josephson a généré de grands espoirs pour le traitement fiable de l'information quantique. Alors que ces progrès se sont accompagnés de diverses expériences de principe sur des systèmes quantiques de petites tailles, il faut désormais franchir l'étape importante du passage à l'échelle supérieure en nombre de qubits pour les protocoles. Le calcul tolérant aux erreurs avec des qubits logiques protégés est cependant habituellement envisagé au prix d'un significatif surcoût en ressources matérielles. Chacun des qubits physiques impliqués devra par ailleurs toujours disposer de caractéristiques optimales (temps de cohérence, force de couplage et accordabilité). Ici, et dans le but d'explorer des approches alternatives pour dépasser ces obstacles, je passe en revue un ensemble de propositions théoriques récentes et les premières expériences correspondantes, qui rentrent dans un paradigme de protection de mémoire quantique et de calcul quantique universel qui reste peu gourmand en ressources matérielles.
The development of quantum Josephson circuits has created a strong expectation for reliable processing of quantum information. While this progress has already led to various proof-of-principle experiments on small-scale quantum systems, a major scaling step is required towards many-qubit protocols. Fault-tolerant computation with protected logical qubits usually comes at the expense of a significant overhead in the hardware. Each of the involved physical qubits still needs to satisfy the best achieved properties (coherence times, coupling strengths and tunability). Here, and in the aim of addressing alternative approaches to deal with these obstacles, I overview a series of recent theoretical proposals, and the experimental developments following these proposals, to enable a hardware-efficient paradigm for quantum memory protection and universal quantum computation.
Mot clés : Calcul quantique universel, Mémoire quantique, Correction des erreurs quantiques, États du chat de Schrödinger, Circuits quantiques supraconducteurs
@article{CRPHYS_2016__17_7_778_0,
author = {Mazyar Mirrahimi},
title = {Cat-qubits for quantum computation},
journal = {Comptes Rendus. Physique},
pages = {778--787},
publisher = {Elsevier},
volume = {17},
number = {7},
year = {2016},
doi = {10.1016/j.crhy.2016.07.011},
language = {en},
}
Mazyar Mirrahimi. Cat-qubits for quantum computation. Comptes Rendus. Physique, Volume 17 (2016) no. 7, pp. 778-787. doi : 10.1016/j.crhy.2016.07.011. https://comptes-rendus.academie-sciences.fr/physique/articles/10.1016/j.crhy.2016.07.011/
[1] Coherent control of macroscopic quantum states in a single-cooper-pair box, Nature, Volume 398 (1999), p. 786
[2] Observation of high coherence in Josephson junction qubits measured in a three-dimensional circuit QED architecture, Phys. Rev. Lett., Volume 107 (2011)
[3] Superconducting qubit in waveguide cavity with coherence time approaching 0.1 ms, Phys. Rev. B, Volume 86 (2012)
[4] Superconducting circuits for quantum information: an outlook, Science, Volume 339 (2013), pp. 1169-1174
[5] Realization of three-qubit quantum error correction with superconducting circuits, Nature, Volume 482 (2012), pp. 382-385
[6] Tracking photon jumps with repeated quantum non-demolition parity measurements, Nature, Volume 511 (2014), pp. 444-448
[7] Detecting arbitrary quantum errors via stabilizer measurements on a sublattice of the surface code, Nat. Commun., Volume 6 (2015), p. 6979
[8] Detecting bit-flip errors in a logical qubit using stabilizer measurements, Nat. Commun., Volume 6 (2015), p. 6983
[9] State preservation by repetitive error detection in a superconducting quantum circuit, Nature, Volume 519 (2015), pp. 66-69
[10] Scheme for reducing decoherence in quantum memory, Phys. Rev. A, Volume 52 (1995), pp. 2493-2496
[11] Error correcting codes in quantum theory, Phys. Rev. Lett., Volume 77 (1996) no. 5
[12] Hardware-efficient autonomous quantum memory protection, Phys. Rev. Lett., Volume 111 (2013)
[13] Deterministic protocol for mapping a qubit to coherent state superpositions in a cavity, Phys. Rev. A, Volume 87 (2013)
[14] Deterministically encoding quantum information using 100-photon Schrödinger cat states, Science, Volume 342 (2013), pp. 607-610
[15] Resolving photon number states in a superconducting circuit, Nature, Volume 445 (2007), pp. 515-518
[16] Charge-insensitive qubit design derived from the cooper pair box, Phys. Rev. A, Volume 76 (2007)
[17] Dynamically protected cat-qubits: a new paradigm for universal quantum computation, New J. Phys., Volume 16 (2014)
[18] Confining the state of light to a quantum manifold by engineered two-photon loss, Science, Volume 347 (2015), pp. 853-857
[19] Quantum non-demolition detection of single microwave photons in a circuit, Nat. Phys., Volume 6 (2010), pp. 663-667
[20] Manipulation of photons in a cavity by dispersive atom-field coupling: quantum-nondemolition measurements and génération of “Schrödinger cat” states, Phys. Rev. A, Volume 45 (1992) no. 7, pp. 5193-5214
[21] Direct measurement of the Wigner function of a one-photon Fock state in a cavity, Phys. Rev. Lett., Volume 89 (2002)
[22] Invited review article: the Josephson bifurcation amplifier, Rev. Sci. Instrum., Volume 80 (2009), p. 111101
[23] Analog information processing at the quantum limit with a Josephson ring modulator, Nat. Phys., Volume 6 (2010), pp. 296-302
[24] Widely tunable, non-degenerate three-wave mixing microwave device operating near the quantum limit, Phys. Rev. Lett., Volume 108 (2012)
[25] Quantum noise in the parametric oscillator: from squeezed states to coherent-state superpositions, Phys. Rev. Lett., Volume 60 (1988), p. 1836
[26] Black-box superconducting circuit quantization, Phys. Rev. Lett., Volume 108 (2012)
[27] Statistical Methods in Quantum Optics 2: Non-Classical Fields, Springer, 2007
[28] Observation of quantum state collapse and revival due to the single-photon Kerr effect, Nature, Volume 495 (2013), pp. 205-209
[29] Holonomic quantum computing with cat-qudits, Phys. Rev. Lett., Volume 116 (2016)
Cité par Sources :
☆ This paper, written in March 2015, is an overview of recent proposals and experiments for encoding, protecting and manipulating quantum information in so-called Schrödinger cat states of a quantum harmonic oscillator. The author acknowledges the collaboration and discussions with Zaki Leghtas, Michel H. Devoret, Robert J. Schoelkopf, and Liang Jiang, as well as many other collaborators at Yale University, the group of Benjamin Huard at the École Normale Supèrieure and the Quantronics group at CEA Saclay.
Commentaires - Politique
Quantum trajectories of superconducting qubits
Steven J. Weber; Kater W. Murch; Mollie E. Kimchi-Schwartz; ...
C. R. Phys (2016)
Towards a spin-ensemble quantum memory for superconducting qubits
Cécile Grezes; Yuimaru Kubo; Brian Julsgaard; ...
C. R. Phys (2016)