Dispersive Qubit Readout with Intrinsic Resonator Reset

TL;DR

This paper introduces a dispersive measurement technique for superconducting qubits that enables rapid measurement and resonator reset using universal analytical pulses, improving speed and accuracy without complex optimization.

Contribution

The authors develop a universal pulse-based dispersive readout method that automatically resets the resonator, applicable to multiple modes and states, simplifying quantum measurement procedures.

Findings

Achieved qubit readout with rapid resonator reset in less than 3/κ time.

Maintained a T1-limited assignment error below 1%.

Extended the method to qutrit readout with experimental validation.

Abstract

A key challenge in quantum computing is speeding up measurement and initialization. Here, we experimentally demonstrate a dispersive measurement method for superconducting qubits that simultaneously measures the qubit and returns the readout resonator to its initial state. The approach is based on universal analytical pulses and requires knowledge of the qubit and resonator parameters, but needs no direct optimization of the pulse shape, even when accounting for the nonlinearity of the system. Moreover, the method generalizes to measuring an arbitrary number of modes and states. For the qubit readout, we can drive the resonator to $\sim 10^2$ photons and back to $\sim 10^{-3}$ photons in less than $3 \kappa^{-1}$, while still achieving a $T_1$-limited assignment error below 1\%. We also present universal pulse shapes and experimental results for qutrit readout.