Eur. Phys. J. D 58, 1-22 (2010)
https://doi.org/10.1140/epjd/e2010-00103-y

Colloquium

Quantum memories

A review based on the European integrated project “Qubit Applications (QAP)”

¹ Group of Applied Physics, University of Geneva, 1211 Geneva, Switzerland
² Institute for Quantum Information Science and Department of Physics and Astronomy, University of Calgary, Calgary, T2N 1N4, Canada
³ Niels Bohr Institute, Copenhagen University, Blegdamsvej 17, 2100 København Ø, Denmark
⁴ Toshiba Research Europe Limited, 208 Cambridge Science Park, Cambridge, CB4 0GZ, UK
⁵ Electrical and Electronic Engineering, University of Bristol, Bristol, BS8 1UB, UK
⁶ Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany
⁷ Department of Physics, Lund University, Box 118, 221 00 Lund, Sweden
⁸ Clarendon Laboratory, University of Oxford, Oxford, OX1 3PU, UK
⁹ Ludwig-Maximilians-Universität München, 80799 München, Germany
¹⁰ Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany

Corresponding author: christoph.simon@gmail.com

Received: 4 March 2010
Published online: 20 April 2010

Abstract

We perform a review of various approaches to the implementation of quantum memories, with an emphasis on activities within the quantum memory sub-project of the EU integrated project “Qubit Applications”. We begin with a brief overview over different applications for quantum memories and different types of quantum memories. We discuss the most important criteria for assessing quantum memory performance and the most important physical requirements. Then we review the different approaches represented in “Qubit Applications” in some detail. They include solid-state atomic ensembles, NV centers, quantum dots, single atoms, atomic gases and optical phonons in diamond. We compare the different approaches using the discussed criteria.