Heat-Bath Algorithmic Cooling with optimal thermalization strategies

Understand

Heat-Bath Algorithmic Cooling is a set of techniques for producing highly pure quantum systems by utilizing a surrounding heat-bath and unitary interactions.

• These techniques originally used the thermal environment only to fully thermalize ancillas at the environment temperature.
• Here we extend HBAC protocols by optimizing over the thermalization strategy.
• We find, for any $d$-dimensional system in an arbitrary initial state, provably optimal cooling protocols with surprisingly simple structure and exponential convergence to the ground state.