Rapid on-demand generation of thermal states in superconducting quantum circuits

TL;DR

This paper demonstrates rapid, on-demand thermal state generation in superconducting circuits using a quantum-circuit refrigerator, enabling fast temperature control for quantum thermodynamics and improved quantum algorithms.

Contribution

It introduces a method for fast thermal state preparation in superconducting circuits using a quantum-circuit refrigerator, achieving temperature control within 100 ns.

Findings

Thermal states generated from 110 mK to 500 mK in 100 ns.

Fast thermal state control enables quantum heat engine demonstrations.

Potential for improved dissipative state preparation and reduced circuit depth.

Abstract

We experimentally demonstrate the fast generation of thermal states of a transmon using a single-junction quantum-circuit refrigerator (QCR) as an in-situ-tunable environment. Through single-shot readout, we monitor the transmon up to its third-excited state, assessing population distributions controlled by QCR drive pulses. Whereas cooling can be achieved in the weak-drive regime, high-amplitude pulses can generate Boltzmann-distributed populations from a temperature of 110 mK up to 500 mK within 100 ns. As we propose in our work, this fast and efficient temperature control provides an appealing opportunity to demonstrate a quantum heat engine. Our results also pave the way for efficient dissipative state preparation and for reducing the circuit depth in thermally assisted quantum algorithms and quantum annealing.