Quasiparticles in superconducting qubits with asymmetric junctions

Abstract

Designing the spatial profile of the superconducting gap -- gap engineering -- has long been recognized as an effective way of controlling quasiparticles in superconducting devices. In aluminum films, their thickness modulates the gap; therefore, standard fabrication of Al/AlOx/Al Josephson junctions, which relies on overlapping a thicker film on top of a thinner one, always results in gap-engineered devices. Here we reconsider quasiparticle effects in superconducting qubits to explicitly account for the unavoidable asymmetry in the gap on the two sides of a Josephson junction. We find that different regimes can be encountered in which the quasiparticles have either similar densities in the two junction leads, or are largely confined to the lower-gap lead. Qualitatively, for similar densities the qubit's excited state population is lower but its relaxation rate higher than when the quasiparticles are confined; therefore, there is a potential trade-off between two desirable properties in a qubit.

Revised version. To be published in PRX Quantum

References in corpus (13)

• Supplementary information for "Quantum supremacy using a programmable superconducting processor"
• Charge insensitive qubit design derived from the Cooper pair box
• Strong quantum computational advantage using a superconducting quantum processor
• Measurement and Control of Quasiparticle Dynamics in a Superconducting Qubit
• Thermal and Residual Excited-State Population in a 3D Transmon Qubit
• Quasiparticle relaxation of superconducting qubits in the presence of flux
• Non-Poissonian Quantum Jumps of a Fluxonium Qubit due to Quasiparticle Excitations
• Minimal resonator loss for circuit quantum electrodynamics
• Universal scaling of the critical temperature for thin films near the superconducting-to-insulating transition
• Phonon downconversion to suppress correlated errors in superconducting qubits
• Energy gap measurement of nanostructured thin aluminium films for use in single Cooper-pair devices
• Distinguishing parity-switching mechanisms in a superconducting qubit
• Fermi-liquid effects in the gapless state of marginally thin superconducting films

Cited by in corpus (30)

• Observation of Josephson Harmonics in Tunnel Junctions
• Coexistence of nonequilibrium density and equilibrium energy distribution of quasiparticles in a superconducting qubit
• Resisting high-energy impact events through gap engineering in superconducting qubit arrays
• Mitigation of quasiparticle loss in superconducting qubits by phonon scattering
• Modeling phonon-mediated quasiparticle poisoning in superconducting qubit arrays
• Quasiparticle dynamics in epitaxial Al-InAs planar Josephson junctions
• Quasiparticle effects in magnetic-field-resilient 3D transmons
• Dissipative protection of a GKP qubit in a high-impedance superconducting circuit driven by a microwave frequency comb
• Nonequilibrium quasiparticle distribution in superconducting resonators: effect of pair-breaking photons
• Dephasing in Fluxonium Qubits from Coherent Quantum Phase Slips
• Charge-parity switching effects and optimisation of transmon-qubit design parameters
• Andreev spin relaxation time in a shadow-evaporated InAs weak link
• Development of a Nb-based semiconductor-superconductor hybrid platform
• Microwave-assisted thermoelectricity in SIS' tunnel junctions
• Magnetic-field dependence of a Josephson traveling-wave parametric amplifier and integration into a high-field setup
• Characterization of Asymmetric Gap-Engineered Josephson Junctions and 3D Transmon Qubits
• Recovery dynamics of a gap-engineered transmon after a quasiparticle burst
• Nonequilibrium regimes for quasiparticles in superconducting qubits with gap-asymmetric junctions
• Quantum error mitigation in optimized circuits for particle-density correlations in real-time dynamics of the Schwinger model
• Averting multi-qubit burst errors in surface code magic state factories
• Theory of quasiparticle generation by microwave drives in superconducting qubits
• Mitigating cosmic ray-like correlated events with a modular quantum processor
• Signatures of superconducting Higgs mode in irradiated Josephson junctions
• Evidence of the inverse proximity effect in tunnel magnetic Josephson Junctions
• A Study of Superconducting Behavior in Ruthenium Thin Films
• Charge Parity Rates in Transmon Qubits with Different Shunting Capacitors
• Nonequilibrium Quasiparticles in Superconducting Circuits: Energy Relaxation, Charge and Flux Noise
• AC Josephson Signatures of the Superconducting Higgs Mode
• Dissipation and noise in strongly driven Josephson junctions
• Quasiparticle-induced decoherence of a driven superconducting qubit