Tuning the Gap of a Superconducting Flux Qubit

TL;DR

This paper demonstrates in situ tunability of a superconducting flux qubit's energy gap using an additional flux loop, enabling rapid and precise control over qubit properties for quantum computing applications.

Contribution

The work introduces a method to dynamically tune the energy gap of a flux qubit via an extra flux loop, enhancing control over qubit interactions.

Findings

Gap tunability over several GHz achieved within nanoseconds

Strong flux sensitivity of the gap (up to 0.7 GHz/Φ₀) demonstrated

Dependence of relaxation time and Rabi frequency on the qubit gap analyzed

Abstract

We experimentally demonstrate the in situ tunability of the minimum energy splitting (gap) of a superconducting flux qubit by means of an additional flux loop. Pulses applied via a local control line allow us to tune the gap over a range of several GHz on a nanosecond timescale. The strong flux sensitivity of the gap (up to 0.7 GHz/mPhi_0) opens up the possibility to create different types of tunable couplings that are effective at the degeneracy point of the qubit. We investigate the dependence of the relaxation time and the Rabi frequency on the qubit gap.