Superconducting circuit protected by two-Cooper-pair tunneling

Smith, W. C.; Kou, Angela; Xu, Xiao; Vool, Uri; Devoret, Michel

doi:10.1038/s41534-019-0231-2

Cited by 94 publications

(74 citation statements)

References 52 publications

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“…Inductive loss due to quasiparticle tunneling in Josephson junction chains that are used to implement superinductances [22,24] t1 _ quasiparticle _ tunneling…”

Section: Methods Name Descriptionmentioning

confidence: 99%

“…Loss due to quasiparticle tunneling across a single Josephson junction [22,24] T φ pure-dephasing processes…”

Section: Methods Name Descriptionmentioning

confidence: 99%

“…Below is sample code showing an initialization of a 0−π qubit. Here, we include a 5% disorder in the Josephson junction energies, but assume there is no disorder in the superinductors and (non-junction) capacitors, allowing us to use the ZeroPi class: The cos 2φ qubit was proposed in [24]. Its circuit includes a superconducting loop, threaded by an external flux Φ ext , which consists of two superinductors and two Josephson junctions, with an appropriately placed shunt capacitance:…”

Section: Avi 0-π Qubitmentioning

confidence: 99%

“…Such topology can be engineered to only allow pairs of cooper pairs to tunnel, leading a level of intrinsic protection from noise [24]. The Hamiltonian of a cos 2φ qubit can be written as Similarly to the 0 − π qubit, cos 2φ circuit consists of three degrees of freedom: θ, φ and ζ, with their respective conjugates defined as nθ , nφ and nζ .…”

Section: Avi 0-π Qubitmentioning

confidence: 99%

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Scqubits: a Python package for superconducting qubits

Groszkowski

Koch

2021

Quantum

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scqubits is an open-source Python package for simulating and analyzing superconducting circuits. It provides convenient routines to obtain energy spectra of common superconducting qubits, such as the transmon, fluxonium, flux, cos(2ϕ) and the 0-π qubit. scqubits also features a number of options for visualizing the computed spectral data, including plots of energy levels as a function of external parameters, display of matrix elements of various operators as well as means to easily plot qubit wavefunctions. Many of these tools are not limited to single qubits, but extend to composite Hilbert spaces consisting of coupled superconducting qubits and harmonic (or weakly anharmonic) modes. The library provides an extensive suite of methods for estimating qubit coherence times due to a variety of commonly considered noise channels. While all functionality of scqubits can be accessed programatically, the package also implements GUI-like widgets that, with a few clicks can help users both create relevant Python objects, as well as explore their properties through various plots. When applicable, the library harnesses the computing power of multiple cores via multiprocessing. scqubits further exposes a direct interface to the Quantum Toolbox in Python (QuTiP) package, allowing the user to efficiently leverage QuTiP's proven capabilities for simulating time evolution.

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“…Inductive loss due to quasiparticle tunneling in Josephson junction chains that are used to implement superinductances [22,24] t1 _ quasiparticle _ tunneling…”

Section: Methods Name Descriptionmentioning

confidence: 99%

“…Loss due to quasiparticle tunneling across a single Josephson junction [22,24] T φ pure-dephasing processes…”

Section: Methods Name Descriptionmentioning

confidence: 99%

Section: Avi 0-π Qubitmentioning

confidence: 99%

Section: Avi 0-π Qubitmentioning

confidence: 99%

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Scqubits: a Python package for superconducting qubits

Groszkowski

Koch

2021

Quantum

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“…These examples suggest that a qubit Hamiltonian with full noise protection against relaxation and dephasing, i.e., exponentially large T 1 and T ϕ , cannot be implemented in a single-mode superconducting quantum device. This conflict, however, can be reconciled by the so-called "fewbody" qubits [11] that incorporate more than one degree of freedom in the qubit Hamiltonian (the dimensionality D > 1) [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Bifluxon: Fluxon-Parity-Protected Superconducting Qubit

et al. 2020

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We develop and characterize a symmetry-protected superconducting qubit that offers simultaneous exponential suppression of energy decay from charge and flux noises, and dephasing from flux noise. The qubit consists of a Cooper-pair box (CPB) shunted by a superinductor, forming a superconducting loop. Provided the offset charge on the CPB island is an odd number of electrons, the qubit potential corresponds to that of a cos (φ/2) Josephson element, preserving the parity of fluxons in the loop via Aharonov-Casher interference. In this regime, the logical-state wavefunctions reside in disjoint regions of Hilbert space, thereby ensuring protection against energy decay. By switching the protection on, we observe a tenfold increase of the decay time, reaching up to 100 μs. Though the qubit is sensitive to charge noise, the sensitivity is much reduced in comparison with the charge qubit, and the charge-noise-induced dephasing time of the current device exceeds 1 μs. Implementation of full dephasing protection can be achieved in the next-generation devices by combining several cos(φ/2) Josephson elements in a small array.

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Subgap States in Semiconductor-Superconductor Devices for Quantum Technologies: Andreev Qubits and Minimal Majorana Chains

Seoane Souto,

Aguado

2024

Lecture Notes in Physics

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Superconducting circuit protected by two-Cooper-pair tunneling

Cited by 94 publications

References 52 publications

Scqubits: a Python package for superconducting qubits

Scqubits: a Python package for superconducting qubits

Bifluxon: Fluxon-Parity-Protected Superconducting Qubit

Subgap States in Semiconductor-Superconductor Devices for Quantum Technologies: Andreev Qubits and Minimal Majorana Chains

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