Temperature of a Decoherent Oscillator with Strong Coupling

TL;DR

This paper clarifies that an oscillator's apparent decoherence temperature, caused by false-decoherence effects, does not reflect its true thermal state, which remains at the bath temperature, even under strong coupling.

Contribution

It demonstrates that the measured decoherence temperature is a false indicator, distinguishing it from the actual temperature of the oscillator in strong coupling regimes.

Findings

Decoherence temperature is due to false-decoherence effects.

The oscillator's true temperature remains at the bath temperature.

Strong coupling causes the heat bath to be dragged along with the oscillator.

Abstract

The temperature of an oscillator coupled to the vacuum state of a heat bath via ohmic coupling is non-zero, as measured by the reduced density matrix of the oscillator. This paper shows that the actual temperature, as measured by a thermometer is still zero (or in the thermal state of the bath, the temperature of the bath). The decoherence temperature is due to "false-decoherence", with the heat bath state being dragged along with the oscillator.