The superconducting quasicharge qubit

Pechenezhskiy, Ivan; Mencia, Raymond; Nguyen, Long B.; Lin, Yen-Hsiang; Manucharyan, Vladimir

doi:10.1038/s41586-020-2687-9

Cited by 79 publications

(66 citation statements)

References 35 publications

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“…For realistic cQED parameters E J / = 2π × 20 GHz, E C = E J /67 [25], E Σ / = 2π × 30 GHz ≡ 1.5 E J [48] and d = 0.02, we obtain ω q = 2π × 3.28 GHz. Moreover, for an LC oscillator (or transmission line resonator) having values ω r L r = 200 kΩ [42], we eventually achieve g z (t) = 2π × 2.57 GHz corresponding to max(g z )/ω r = 0.5793. With this maximal value, it is possible to estimate the minimal time required to measure the qubit t min = π/(2ω r ), on a subnanosecond time scale, from optimal control theory.…”

mentioning

confidence: 89%

“…To achieve larger values of the coupling strength resulting in a faster measuring time, we require large impedance [41]. Along with it, the technological progress has made it possible to engineer inductances in the µH regime using arrays of Josephon junctions or taking into account kinetic inductors [42][43][44][45]. To estimate the value of the coupling strength we regard φ x /ϕ 0 = ϕ x /ϕ 0 = π/4, hence the qubit frequency turns into ω q = E 2 C + dE 2 Σ / .…”

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confidence: 99%

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Shortcuts to Adiabaticity for Fast Qubit Readout in Circuit Quantum Electrodynamics

Cárdenas-López,

Chen

2022

Preprint

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We propose how to engineer the longitudinal coupling to accelerate the measurement of a qubit longitudinally coupled to a cavity, motivated by the concept of shortcuts to adiabaticity. Different modulations are inversely designed from two methods of inverse engineering and counter-diabatic driving, for achieving larger values of the signal-to-noise ratio (SNR) at nanosecond scale. By comparison, we demonstrate that our protocols outperform the usual periodic modulations on the pointer state separation and SNR. Finally, we show a possible implementation considering state-of-the-art circuit quantum electrodynamics architecture, estimating the minimal time allowed for the measurement process.

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confidence: 89%

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confidence: 99%

Shortcuts to Adiabaticity for Fast Qubit Readout in Circuit Quantum Electrodynamics

Cárdenas-López,

Chen

2022

Preprint

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“…[24][25][26][27][28] ). The inductive shunt makes the device insensitive to charge noise 29 , while fluxnoise insensitivity can be reached for large values of the superinductance 30 . Recent realizations of the fluxonium qubit have shown long coherence times 31 , making these devices very attractive for quantum information processing.…”

Section: Dmrg Implementation Of the Fluxonium-qubit Hamiltonianmentioning

confidence: 99%

Efficient modeling of superconducting quantum circuits with tensor networks

et al. 2021

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We use a tensor network method to compute the low-energy excitations of a large-scale fluxonium qubit up to a desired accuracy. We employ this numerical technique to estimate the pure-dephasing coherence time of the fluxonium qubit due to charge noise and coherent quantum phase slips from first principles, finding an agreement with previously obtained experimental results. By developing an accurate single-mode theory that captures the details of the fluxonium device, we benchmark the results obtained with the tensor network for circuits spanning a Hilbert space as large as 15180. Our algorithm is directly applicable to the wide variety of circuit-QED systems and may be a useful tool for scaling up superconducting quantum technologies.

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“…Superconducting materials with high kinetic inductance offer new opportunities in the design of highsensitivity photon detectors, wideband quantum amplifiers, and high-coherence quantum processors [1][2][3][4]. In particular, for the noise-resilient superconducting-qubits, a non-dissipative circuit element as characterized by a considerably high inductance (i.e., several hundred nanohenry to a few microhenry) is indispensable for charge-and flux-noise protection [5][6][7][8][9][10]. The magnitude of such inductance, as it is often the case, utterly exceeds the achievable geometric inductance in the nanofabricated superconducting circuits, making the utilization of intrinsic material properties such as kinetic inductance essential for its practical realizations.…”

Section: Introductionmentioning

confidence: 99%

“…The magnitude of such inductance, as it is often the case, utterly exceeds the achievable geometric inductance in the nanofabricated superconducting circuits, making the utilization of intrinsic material properties such as kinetic inductance essential for its practical realizations. Extensive research have thus been performed on superconducting materials with a large kinetic inductance, such as Josephsonjunction arrays (JJAs) [7,[10][11][12] and granular aluminum [13][14][15][16], for the high-inductance implementations.…”

Section: Introductionmentioning

confidence: 99%

Ultrahigh-inductance materials from spinodal decomposition

Gao,

Ku,

Deng

et al. 2021

Preprint

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Disordered superconducting nitrides with kinetic inductance have long been considered a leading material candidate for high-inductance quantum-circuit applications. Despite continuing efforts in reducing material dimensions to increase the kinetic inductance and the corresponding circuit impedance, it becomes a fundamental challenge to improve further without compromising material qualities. To this end, we propose a method to drastically increase the kinetic inductance of superconducting materials via spinodal decomposition while keeping a low microwave loss. We use epitaxial Ti0.48Al0.52N as a model system, and for the first time demonstrate the utilization of spinodal decomposition to trigger the insulator-to-superconductor transition with a drastically enhanced material disorder. The measured kinetic inductance has increased by 2-3 orders of magnitude compared with all the best reported disordered superconducting nitrides. Our work paves the way for substantially enhancing and deterministically controlling the inductance for advanced superconducting quantum circuits.

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The superconducting quasicharge qubit

Cited by 79 publications

References 35 publications

Shortcuts to Adiabaticity for Fast Qubit Readout in Circuit Quantum Electrodynamics

Shortcuts to Adiabaticity for Fast Qubit Readout in Circuit Quantum Electrodynamics

Efficient modeling of superconducting quantum circuits with tensor networks

Ultrahigh-inductance materials from spinodal decomposition

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