title: Quantum data compression of a qubit ensemble.
abstract: Data compression is a ubiquitous aspect of modern information technology, and the advent of quantum information raises the question of what types of compression are feasible for quantum data, where it is especially relevant given the extreme difficulty involved in creating reliable quantum memories. We present a protocol in which an ensemble of quantum bits (qubits) can in principle be perfectly compressed into exponentially fewer qubits. We then experimentally implement our algorithm, compressing three photonic qubits into two. This protocol sheds light on the subtle differences between quantum and classical information. Furthermore, since data compression stores all of the available information about the quantum state in fewer physical qubits, it could allow for a vast reduction in the amount of quantum memory required to store a quantum ensemble, making even today's limited quantum memories far more powerful than previously recognized.
authors.affiliation: Centre for Quantum Information and Quantum Control and Department of Physics, University of Toronto, 60 Saint George Street, Toronto, Ontario M5S 1A7, Canada.
authors.forename: Lee A
authors.initials: LA
authors.lastname: Rozema
authors.affiliation: Centre for Quantum Information and Quantum Control and Department of Physics, University of Toronto, 60 Saint George Street, Toronto, Ontario M5S 1A7, Canada.
authors.forename: Dylan H
authors.initials: DH
authors.lastname: Mahler
authors.affiliation: Centre for Quantum Information and Quantum Control and Department of Physics, University of Toronto, 60 Saint George Street, Toronto, Ontario M5S 1A7, Canada and Department of Electrical Engineering, Technion, Haifa 32000, Israel and Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada.
authors.forename: Alex
authors.initials: A
authors.lastname: Hayat
authors.affiliation: Department of Physics, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Peter S
authors.initials: PS
authors.lastname: Turner
authors.affiliation: Centre for Quantum Information and Quantum Control and Department of Physics, University of Toronto, 60 Saint George Street, Toronto, Ontario M5S 1A7, Canada and Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada.
authors.forename: Aephraim M
authors.initials: AM
authors.lastname: Steinberg