# Spin based heat engine: demonstration of multiple rounds of algorithmic cooling.

Research paper by C A CA Ryan, O O Moussa, J J Baugh, R R Laflamme

Indexed on: 04 Jun '08Published on: 04 Jun '08Published in: Physical review letters

#### Abstract

We experimentally demonstrate multiple rounds of heat-bath algorithmic cooling in a 3 qubit solid-state nuclear magnetic resonance quantum information processor. By pumping entropy into a heat bath, we are able to surpass the closed system limit of the Shannon bound and purify a single qubit to 1.69 times the heat-bath polarization. The algorithm combines both high fidelity coherent control and a deliberate interaction with the environment. Given this level of quantum control in systems with larger reset polarizations, nearly pure qubits should be achievable.