Thermalizing channel states for rapid qubit heating

TL;DR

This paper presents an experimental method to rapidly engineer thermalization of qubits using a leaky resonator, enabling precise control of qubit temperature in nanoseconds through thermalizing channel states.

Contribution

It introduces a novel technique to control qubit heating by engineering thermal channel states via a leaky resonator, with analytical and experimental validation.

Findings

Achieved rapid qubit thermalization within hundreds of nanoseconds.

Demonstrated control of qubit temperature using engineered thermal channel states.

Validated the theoretical model with experimental data on an Xmon qubit.

Abstract

Although known for negatively impacting the operation of superconducting qubits, thermal baths are shown to exert qubit control in a positive way, provided they are properly engineered. We demonstrate an experimental method to engineer the transduction of microwave driving into heat flow through a leaky resonator. Given the precise conversion, a qubit receiving the heat flow obtains a quasi-thermal equilibrium with arbitrary target temperature in hundreds of nanoseconds. We show that the dynamics of the quantum transducing process is described by thermalizing channel states, generated from the double dressings of the resonator by the semi-classical driving and the qubit-resonator coupling. Their spectrum, coupling, and driving strength determine the channel rate of energy flow, along with the relaxation rates of photon leakage into the bath. The analytical prediction is shown to match well with the experimental measurements on an Xmon qubit circuit.