Experimental Saturation of the Heat-Bath Algorithmic Cooling bound

TL;DR

This paper reports the first experimental observation of the theoretical limit of Heat-Bath Algorithmic Cooling, demonstrating hyperpolarization of nuclear spins in diamond and benchmarking the cooling performance.

Contribution

It provides the first experimental validation of the HBAC cooling bound using nuclear spins in diamond, advancing quantum thermodynamics research.

Findings

Cooling beyond initial reset polarization achieved

Reached the theoretical HBAC cooling limit

Performance benchmarked over various initial polarizations

Abstract

Heat-Bath Algorithmic cooling (HBAC) techniques provide ways to selectively enhance the polarization of target quantum subsystems. However, the cooling in these techniques are bounded. Here we report the first experimental observation of the HBAC cooling bound. We use HBAC to hyperpolarize nuclear spins in diamond. Using two carbon nuclear spins as the source of polarization (reset) and the 14N nuclear spin as the computation bit, we demonstrate that repeating a single cooling step increases the polarization beyond the initial reset polarization and reaches the cooling limit of HBAC. We benchmark the performance of our experiment over a range of variable reset polarization. With the ability to polarize the reset spins to different initial polarizations, we envisage that the proposed model could serve as a test bed for studies on Quantum Thermodynamics.