Measurement-based cooling of many-body quantum systems

Abstract

We introduce a novel technique for efficiently cooling many-body quantum systems with unknown Hamiltonians down to their ground states with a high fidelity. The technique involves initially applying a strong external field followed by a sequence of single-degree-of-freedom (single-qubit) measurements and radiofrequency (RF) pulses to polarize the system along the field direction. Subsequently, the field is adiabatically switched off, allowing the system to evolve towards its ground state as governed by the quantum adiabatic theorem. We present numerical simulation results demonstrating the effectiveness of the technique applied to quantum spin chains with long-range and short-range interactions as prototypes for many-body quantum systems.