Overcoming temperature limitations in laser cooling using dressed states and diamond vacancies

TL;DR

This paper proposes a novel laser cooling method using dressed states in diamond vacancies, overcoming the temperature limitations of traditional anti-Stokes fluorescence cooling and enabling cooling at any temperature.

Contribution

It introduces a new cooling technique based on dressed states that can operate at arbitrary temperatures, unlike traditional methods constrained by impurity level spacing.

Findings

The proposed method can theoretically cool to any temperature.

Dressed states enable tunable heat absorption spectra.

Potential to surpass existing temperature limits in laser cooling.

Abstract

The established approach to laser cooling of solids relies on anti-Stokes fluorescence, for example from rare earth impurities in glass. Although successful, there is a minimum temperature to which such a process can cool set by the electronic level spacing in the impurity. We propose an alternative method which does not suffer from this limitation. Our approach relies on the formation of dressed states under strong laser driving, which generates a spectrum in which the gaps can be tuned to optimize the heat absorption. This allows for a cooling cycle which operates at any temperature with a power comparable to the maximum dictated by thermodynamic principles. While this cooling cycle will compete with heating due to non-radiative decay and other mechanisms, it could in principle allow laser cooling to temperatures which are unachievable with anti-Stokes fluorescence.