Resonant Activation of a Current-Biased Josephson Junction Near the Classical-Quantum Crossover

TL;DR

This paper investigates how a current-biased Josephson junction transitions from quantum to classical behavior near the crossover temperature, using microwave probing to observe energy states and their broadening.

Contribution

It demonstrates the transition from quantum to classical regimes in a Josephson junction through resonant activation and microwave spectroscopy near the crossover temperature.

Findings

Quantum energy levels are distinguishable below crossover temperature.

Line widths of energy levels overlap at the crossover temperature.

The junction exhibits classical behavior above the crossover temperature.

Abstract

We examine the resonant activation of a current-biased Josephson junction near the crossover temperature in order to show the way in which the device transitions from the classical regime to the quantum regime. We use microwaves to probe the quantum energy states that exist in the potential well. The quantum features are visible until the junction is heated up to the crossover temperature, at which point the line widths of the energy levels overlap and become indistinguishable from one another. When well above this temperature, the junction behaves classically when resonantly activated with microwaves.