Rapid Driven Reset of a Qubit Readout Resonator

TL;DR

This paper introduces a novel qubit measurement pulse shape in circuit QED that significantly accelerates the readout resonator’s ring-down time, improving measurement speed and efficiency.

Contribution

The authors present a simple pulse shape with additional segments that rapidly transitions the resonator between states, reducing ring-down time more than twice the cavity time constant.

Findings

Reduces cavity ring-down time by over 2x the cavity time constant.

Effective at both low and high drive powers with optimized parameters.

Achieves faster qubit measurement without complex hardware modifications.

Abstract

Using a circuit QED device, we demonstrate a simple qubit measurement pulse shape that yields fast ring-up and ring-down of the readout resonator regardless of the qubit state. The pulse differs from a square pulse only by the inclusion of additional constant-amplitude segments designed to effect a rapid transition from one steady-state population to another. Using a Ramsey experiment performed shortly after the measurement pulse to quantify the residual population, we find that compared to a square pulse followed by a delay, this pulse shape reduces the timescale for cavity ring-down by more than twice the cavity time constant. At low drive powers, this performance is achieved using pulse parameters calculated from a linear cavity model; at higher powers, empirical optimization of the pulse parameters leads to similar performance.