Enhancing the Coherence of Superconducting Quantum Bits with Electric Fields

Abstract

In the endeavour to make quantum computers a reality, integrated superconducting circuits have become a promising architecture. A major challenge of this approach is decoherence originating from spurious atomic tunneling defects at the interfaces of qubit electrodes, which may resonantly absorb energy from the qubit's oscillating electric field and reduce the qubit's energy relaxation time $T_1$. Here, we show that qubit coherence can be improved by tuning dominating defects away from the qubit resonance using an applied DC-electric field. We demonstrate a method that optimizes the applied field bias and enhances the 30-minute averaged qubit $T_1$ time by 23\%. We also discuss how local gate electrodes can be implemented in superconducting quantum processors to enable simultaneous in-situ coherence optimization of individual qubits.

5.5 pages and 4 figures (main Text), plus 11 pages with supplementary figures discussing additional loss via the DC-electrode, how the T1 improvement reduces over time after E-field optimization, and plots of the complete data set

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• Readout error mitigated quantum state tomography tested on superconducting qubits
• Decoherence induced by a sparse bath of two-level fluctuators: peculiar features of $1/f$ noise in high-quality qubits
• Why Superconducting Ta Qubits Have Fewer Tunneling Two-Level Systems at the Air-Oxide Interface Than Nb Qubits
• Resource-Efficient Cross-Platform Verification with Modular Superconducting Devices
• Parity-protected superconducting qubit based on topological insulators
• Generation of frequency-bin-encoded dual-rail cluster states via time-frequency multiplexing of microwave photonic qubits
• Concurrent Fermionic Simulation Gate