title: Coherent Spin Control at the Quantum Level in an Ensemble-Based Optical Memory.
abstract: Long-lived quantum memories are essential components of a long-standing goal of remote distribution of entanglement in quantum networks. These can be realized by storing the quantum states of light as single-spin excitations in atomic ensembles. However, spin states are often subjected to different dephasing processes that limit the storage time, which in principle could be overcome using spin-echo techniques. Theoretical studies suggest this to be challenging due to unavoidable spontaneous emission noise in ensemble-based quantum memories. Here, we demonstrate spin-echo manipulation of a mean spin excitation of 1 in a large solid-state ensemble, generated through storage of a weak optical pulse. After a storage time of about 1 ms we optically read-out the spin excitation with a high signal-to-noise ratio. Our results pave the way for long-duration optical quantum storage using spin-echo techniques for any ensemble-based memory.
authors.affiliation: Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland.
authors.forename: Pierre
authors.initials: P
authors.lastname: Jobez
authors.affiliation: Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland.
authors.forename: Cyril
authors.initials: C
authors.lastname: Laplane
authors.affiliation: Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland.
authors.forename: Nuala
authors.initials: N
authors.lastname: Timoney
authors.affiliation: Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Gisin
authors.affiliation: PSL Research University, Chimie ParisTech CNRS, Institut de Recherche de Chimie Paris, 75005 Paris, France.|Sorbonne Universités, UPMC Université Paris 06, Paris 75005, France.
authors.forename: Alban
authors.initials: A
authors.lastname: Ferrier
authors.affiliation: PSL Research University, Chimie ParisTech CNRS, Institut de Recherche de Chimie Paris, 75005 Paris, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Goldner
authors.affiliation: Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland.
authors.forename: Mikael
authors.initials: M
authors.lastname: Afzelius