Quantum computation by cooling

Catherine C. McGeoch

Jia-Jin Feng, Biao Wu, Frank A. Wilczek

Interesting problems in quantum computation take the form of finding low-energy states of (pseudo)spin systems with engineered Hamiltonians that encode the problem data. Motivated by the practical possibility of producing very low-temperature spin systems, we propose and exemplify the possibility to compute by coupling the computational spins to a quantum coherent bath that serves as a heat sink. The quantum tunneling effect provides additional cooling channels to accelerate the cooling process. We demonstrate both analytically and numerically that this strategy can achieve a quantum advantage in the unstructured search problem.

H. G. J. Eenink, Luca Petit, Menno Veldhorst

M. Popp, K. G. H. Vollbrecht, J. I. Cirac

Abstract We show how to perform universal quantum computation with atoms confined in optical lattices which works both in the presence of defects and without individual addressing. We further present a scheme for cooling atoms close to the ground state of the Mott‐insulator regime. This method is based on a similar set of operations as for ensemble quantum computation and aims at cooling to temperatures which are low enough for the experimental realization of quantum simulation in present setups.

Man Hong Yung, Sergio Boixo, Alán Aspuru‐Guzik

Shinji Urabe

In an iontrap,laser-cooled ions can be confined in a small space in an ultra-high vacuum so that collisions rarely happen and the ions are well isolated from the environment. Since these conditions enable high-resolution spectroscopy of single ions, laser-cooled ions are suitable for use in developing frequency standards. The ions can be cooled to the motional ground state to give a well-defined initial quantum state for quantum state manipulation and quantum computing. In this review, principles of ion traps and laser cooling, and recent progress in optical frequency standards and quantum computing with trapped ions are described.