Demolition measurement protocol for transmon qubits

Abstract

The process of measuring a qubit and re-initializing it to the ground state practically lead to long qubit idle times between re-runs of experiments on a superconducting quantum computer. Here, we propose a protocol for a \textit{demolition measurement} of a transmon qubit that integrates qubit readout with the reset process to minimize qubit idle time. We present a three-staged implementation of this protocol, involving a combined qubit readout and resonator reset scheme that unconditionally resets the resonator at the end of the readout; a leakage removal scheme that can be integrated with the measurement stage; and an unconditional qubit reset. We demonstrate that this protocol could be implemented in $1 \, \mu$s with greater than $95 \, \%$ reset fidelity and a $99 \, \%$ readout fidelity without any hardware overhead beyond those commonly used. This provides at least a 50x speed up compared to the passive decay of the qubit, thereby significantly increasing the data-acquisition rate.