Engineering superconducting qubits to reduce quasiparticles and charge noise

Abstract

Identifying, quantifying, and suppressing decoherence mechanisms in qubits are important steps towards the goal of engineering a quantum computer or simulator. Superconducting circuits offer flexibility in qubit design; however, their performance is adversely affected by quasiparticles (broken Cooper pairs). Developing a quasiparticle mitigation strategy compatible with scalable, high-coherence devices is therefore highly desirable. Here we experimentally demonstrate how to control quasiparticle generation by downsizing the qubit, capping it with a metallic cover, and equipping it with suitable quasiparticle traps. Using a flip-chip design, we shape the electromagnetic environment of the qubit above the superconducting gap, inhibiting quasiparticle poisoning. Our findings support the hypothesis that quasiparticle generation is dominated by the breaking of Cooper pairs at the junction, as a result of photon absorption by the antenna-like qubit structure. We achieve record low charge-parity switching rate (<1Hz). Our aluminium devices also display improved stability with respect to discrete charging events.

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Cited by in corpus (39)

• Phonon downconversion to suppress correlated errors in superconducting qubits
• TLS Dynamics in a Superconducting Qubit Due to Background Ionizing Radiation
• Single Flux Quantum-Based Digital Control of Superconducting Qubits in a Multi-Chip Module
• 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
• Quasiparticles in superconducting qubits with asymmetric junctions
• Systematic study of High $E_J/E_C$ transmon qudits up to $d=12$
• Mitigation of quasiparticle loss in superconducting qubits by phonon scattering
• Modeling phonon-mediated quasiparticle poisoning in superconducting qubit arrays
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• Quasiparticle effects in magnetic-field-resilient 3D transmons
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• Parity switching in a full-shell superconductor-semiconductor nanowire qubit
• Multi-Purpose Architecture for Fast Reset and Protective Readout of Superconducting Qubits
• Charge-parity switching effects and optimisation of transmon-qubit design parameters
• Cosmic muon flux attenuation methods for superconducting qubit experiments
• Flip-chip-based fast inductive parity readout of a planar superconducting island
• Characterization of Broadband Purcell Filters with Compact Footprint for Fast Multiplexed Superconducting Qubit Readout
• Impact of time-retarded noise on dynamical decoupling schemes for qubits
• An engineering guide to superconducting quantum circuit shielding
• Microwave-assisted thermoelectricity in SIS' tunnel junctions
• Nonequilibrium regimes for quasiparticles in superconducting qubits with gap-asymmetric junctions
• Error mitigation and circuit division for early fault-tolerant quantum phase estimation
• Quasiparticle Dynamics in Superconducting Quantum-Classical Hybrid Circuits
• Recovery dynamics of a gap-engineered transmon after a quasiparticle burst
• Noise properties of a Josephson parametric oscillator
• Excess quasiparticles and their dynamics in the presence of subgap states
• Systematic Schrieffer-Wolff-transformation approach to Josephson junctions: quasiparticle effects and Josephson harmonics
• Charge Parity Rates in Transmon Qubits with Different Shunting Capacitors
• Mitigating cosmic ray-like correlated events with a modular quantum processor
• Entanglement dynamics and performance of two-qubit gates for superconducting qubits under non-Markovian effects
• Development of TiN/AlN-based superconducting qubit components
• Optimal quantum resource generation in coupled transmons immersed in Markovian baths
• Electron-phonon interactions in the Andreev Bound States of aluminum nanobridge Josephson junctions