Probing the strongly driven spin-boson model in a superconducting quantum circuit

TL;DR

This paper explores how intense coherent driving affects a strongly dissipative quantum system modeled by the spin-boson model, revealing a transition from coherent to incoherent states in a superconducting circuit.

Contribution

It provides the first experimental and theoretical investigation of the driven spin-boson model in a superconducting qubit, demonstrating control over coherence suppression via drive amplitude.

Findings

Drive enhances environmental suppression of quantum coherence.

A coherent-to-incoherent transition is achieved by tuning drive amplitude.

Demonstration of an out-of-equilibrium detailed balance relation.

Abstract

Quantum two-level systems interacting with the surroundings are ubiquitous in nature. The interaction suppresses quantum coherence and forces the system towards a steady state. Such dissipative processes are captured by the paradigmatic spin-boson model, describing a two-state particle, the "spin", interacting with an environment formed by harmonic oscillators. A fundamental question to date is to what extent intense coherent driving impacts a strongly dissipative system. Here we investigate experimentally and theoretically a superconducting qubit strongly coupled to an electromagnetic environment and subjected to a coherent drive. This setup realizes the driven Ohmic spin-boson model. We show that the drive reinforces environmental suppression of quantum coherence, and that a coherent-to-incoherent transition can be achieved by tuning the drive amplitude. An out-of-equilibrium detailed balance relation is demonstrated. These results advance fundamental understanding of open quantum systems and bear potential for the design of entangled light-matter states.