Enhancing the coherence of superconducting quantum bits with electric fields

In the endeavor 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 average 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.

Automated summary

In the quest for practical quantum computers, integrated superconducting circuits have emerged as a promising architecture. However, a major challenge is decoherence caused by atomic tunneling defects, which can absorb energy and degrade the qubit's performance. This study demonstrates that tuning these defects away from the qubit resonance using a DC-electric field can improve qubit coherence and increase the qubit's energy relaxation time. The research also explores the implementation of local gate electrodes for simultaneous in situ coherence optimization of individual qubits in superconducting quantum processors.