Stabilization and operation of a Kerr-cat qubit

Grimm, Alexander; Frattini, Nicholas; Puri, Shruti; Mundhada, Shantanu; Touzard, Steven; Mirrahimi, Mazyar; Girvin, S. M.; Shankar, Shyam; Devoret, Michel

doi:10.1038/s41586-020-2587-z

Cited by 358 publications

(340 citation statements)

References 36 publications

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“…smallsized systems with error rates near to threshold, can have a logical failure rate with quadratically improved scaling as a function of distance; Oðp d 2 =2 Þ. Thus, we should expect to achieve low logical failure rates using a modest number of physical qubits for experimentally plausible values of the noise bias, for example, 10 ≲ η ≲ 1000 24,25 .…”

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confidence: 99%

The XZZX surface code

et al. 2021

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Performing large calculations with a quantum computer will likely require a fault-tolerant architecture based on quantum error-correcting codes. The challenge is to design practical quantum error-correcting codes that perform well against realistic noise using modest resources. Here we show that a variant of the surface code—the XZZX code—offers remarkable performance for fault-tolerant quantum computation. The error threshold of this code matches what can be achieved with random codes (hashing) for every single-qubit Pauli noise channel; it is the first explicit code shown to have this universal property. We present numerical evidence that the threshold even exceeds this hashing bound for an experimentally relevant range of noise parameters. Focusing on the common situation where qubit dephasing is the dominant noise, we show that this code has a practical, high-performance decoder and surpasses all previously known thresholds in the realistic setting where syndrome measurements are unreliable. We go on to demonstrate the favourable sub-threshold resource scaling that can be obtained by specialising a code to exploit structure in the noise. We show that it is possible to maintain all of these advantages when we perform fault-tolerant quantum computation.

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confidence: 99%

The XZZX surface code

et al. 2021

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“…On the one hand, our work opens the experimental quest for a cubic phase state with microwave circuits. Our proposal is within reach of current cQED technology in terms of resonator quality factors, that can be as high as 3 × 10 5 in 3D architectures [67], and the ability to tune the resonator field much faster than its corresponding lifetime, with pulse synthesis resolution within nanoseconds [68]. On the other hand, the experimental realization of a universal gate set in a continuous-variable architecture would present the community with the question of what relevant quantum algorithms can be run in the near future on such an architecture, possibly with a limited circuit depth, and without fault tolerance.…”

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confidence: 86%

Universal Gate Set for Continuous-Variable Quantum Computation with Microwave Circuits

et al. 2020

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We provide an explicit construction of a universal gate set for continuous-variable quantum computation with microwave circuits. Such a universal set has been first proposed in quantum-optical setups, but its experimental implementation has remained elusive in that domain due to the difficulties in engineering strong nonlinearities. Here, we show that a realistic three-wave mixing microwave architecture based on the superconducting nonlinear asymmetric inductive element [Frattini et al., Appl. Phys. Lett. 110, 222603 (2017)] allows us to overcome this difficulty. As an application, we show that this architecture allows for the generation of a cubic phase state with an experimentally feasible procedure. This work highlights a practical advantage of microwave circuits with respect to optical systems for the purpose of engineering non-Gaussian states and opens the quest for continuous-variable algorithms based on few repetitions of elementary gates from the continuous-variable universal set.

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“…Finally, QEC with bosonic codes can also be realized using a passive approach, for instance, by designing logical qubits with highly biased-noise channels to provide intrinsic protection without the need for probing any error syndromes. Very recently, two studies [39,209] verified that the bias between phase and bit-flip errors increases exponentially with α, the size of the coherent state components of the two-cat code. This strong asymmetry between the different types of errors can be exploited to significantly reduce the hardware overhead for fault-tolerant quantum computation [87][88][89].…”

Section: Implementations Of Qecmentioning

confidence: 99%

Quantum information processing with bosonic qubits in circuit QED

Joshi

Noh²,

Gao³

2021

Quantum Sci. Technol.

109

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The unique features of quantum theory offer a powerful new paradigm for information processing. Translating these mathematical abstractions into useful algorithms and applications requires quantum systems with significant complexity and sufficiently low error rates. Such quantum systems must be made from robust hardware that can coherently store, process, and extract the encoded information, as well as possess effective quantum error correction (QEC) protocols to detect and correct errors. Circuit quantum electrodynamics (cQED) provides a promising hardware platform for implementing robust quantum devices. In particular, bosonic encodings in cQED that use multi-photon states of superconducting cavities to encode information have shown success in realizing hardware-efficient QEC. Here, we review recent developments in the theory and implementation of QEC with bosonic codes and report the progress made toward realizing fault-tolerant quantum information processing with cQED devices.

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Stabilization and operation of a Kerr-cat qubit

Cited by 358 publications

References 36 publications

The XZZX surface code

The XZZX surface code

Universal Gate Set for Continuous-Variable Quantum Computation with Microwave Circuits

Quantum information processing with bosonic qubits in circuit QED

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