Approaching Unit Visibility for Control of a Superconducting Qubit with Dispersive Readout

TL;DR

This paper demonstrates high-visibility dispersive readout of a superconducting qubit, achieving over 90% visibility and a coherence time exceeding 500 ns, advancing qubit measurement techniques.

Contribution

It introduces a dispersive measurement method for superconducting qubits that achieves high visibility and well-characterized measurement performance.

Findings

Over 90% measurement visibility achieved.

Qubit coherence time exceeds 500 ns.

Measurement process is well characterized and understood.

Abstract

In a Rabi oscillation experiment with a superconducting qubit we show that a visibility in the qubit excited state population of more than 90 % can be attained. We perform a dispersive measurement of the qubit state by coupling the qubit non-resonantly to a transmission line resonator and probing the resonator transmission spectrum. The measurement process is well characterized and quantitatively understood. The qubit coherence time is determined to be larger than 500 ns in a measurement of Ramsey fringes.