Parity-Protected Superconductor-Semiconductor Qubit

Larsen, T. W.; Gershenson, M. E.; Casparis, Lucas; Kringhøj, Anders; Pearson, Natalie; McNeil, Robert; Kuemmeth, Ferdinand; Krogstrup, Peter; Petersson, K. D.; Marcus, C. M.

doi:10.1103/physrevlett.125.056801

Cited by 75 publications

(52 citation statements)

References 42 publications

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“…Another interesting avenue of further investigation would be to design tunneling circuits that allow coherent control of the collective motion of quartets. Such a device could serve as a building block for parity-protetected cos 2ϕ electromagnetic qubits [21][22][23].…”

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confidence: 99%

Multiplet supercurrent in Josephson tunneling circuits

2022

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The multi-terminal Josephson effect allows DC supercurrent to flow at finite commensurate voltages. Existing proposals to realize this effect rely on nonlocal Andreev processes in superconductor-normal-superconductor junctions. However, this approach requires precise control over microscopic states and is obscured by dissipative current. We show that standard tunnel Josephson circuits also support multiplet supercurrent mediated only by local tunneling processes. Furthermore, we observe that the supercurrents persist even in the high charging energy regime in which only sequential Cooper transfers are allowed. Finally, we demonstrate that the multiplet supercurrent in these circuits has a quantum geometric component that is distinguishable from the well-known adiabatic contribution.

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confidence: 99%

Multiplet supercurrent in Josephson tunneling circuits

2022

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“…Variants of the conventional metallic transmon qubit [1,2] based on a semiconductor nanowires (NWs) with an epitaxial superconducting shell have appeared recently and shown great promise for qubit applications, offering atomically precise interfaces and electrostatic control of junction properties [3][4][5][6][7]. By now, qubit spectroscopy [3], coherence [4], two-qubit operation [5], gatecontrolled qubit coupling [8], and dc monitoring [9] have been demonstrated, along with investigations of applied magnetic field [7], junction Andreev bound states [6,10], anharmonicity [11], charge dispersion [12,13], spin [14], and parity protection [15]. However, axial flux effects from a fully surrounding Al shell on Josephson coupling have not been considered previously.…”

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Destructive Little-Parks Effect in a Full-Shell Nanowire-Based Transmon

et al. 2020

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A semiconductor transmon with an epitaxial Al shell fully surrounding an InAs nanowire core is investigated in the low E J =E C regime. Little-Parks oscillations as a function of flux along the hybrid wire axis are destructive, creating lobes of reentrant superconductivity separated by a metallic state at a half quantum of applied flux. In the first lobe, phase winding around the shell can induce topological superconductivity in the core. Coherent qubit operation is observed in both the zeroth and first lobes. Splitting of parity bands by coherent single-electron coupling across the junction is not resolved beyond line broadening, placing a bound on Majorana coupling, E M =h < 10 MHz, much smaller than the Josephson coupling E J =h ∼ 4.7 GHz.

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“…Specifically, the superconducting qubits 3 have been considered as promising candidates, making use of the bound states formed inside the pairing gap 4 . Their implementations could protect the parity of Cooper pairs on proximitized superconducting nonoscopic islands 5 . Further perspectives for the proximitized double quantum dots appeared with the topological superconductors 6 , where the zero energy in-gap modes are protected by symmetry reasons.…”

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Subgap dynamics of double quantum dot coupled between superconducting and normal leads

Baran

Taranko

Domański

2021

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Dynamical processes induced by the external time-dependent fields can provide valuable insight into the characteristic energy scales of a given physical system. We investigate them here in a nanoscopic heterostructure, consisting of the double quantum dot coupled in series to the superconducting and the metallic reservoirs, analyzing its response to (i) abrupt bias voltage applied across the junction, (ii) sudden change of the energy levels, and imposed by (iii) their periodic driving. We explore subgap properties of this setup which are strictly related to the in-gap quasiparticles and discuss their signatures manifested in the time-dependent charge currents. The characteristic multi-mode oscillations, their beating patters and photon-assisted harmonics reveal a rich spectrum of dynamical features that might be important for designing the superconducting qubits.

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Parity-Protected Superconductor-Semiconductor Qubit

Cited by 75 publications

References 42 publications

Multiplet supercurrent in Josephson tunneling circuits

Multiplet supercurrent in Josephson tunneling circuits

Destructive Little-Parks Effect in a Full-Shell Nanowire-Based Transmon

Subgap dynamics of double quantum dot coupled between superconducting and normal leads

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