title: Storage of multiple coherent microwave excitations in an electron spin ensemble.
abstract: Strong coupling between a microwave photon and electron spins, which could enable a long-lived quantum memory element for superconducting qubits, is possible using a large ensemble of spins. This represents an inefficient use of resources unless multiple photons, or qubits, can be orthogonally stored and retrieved. Here we employ holographic techniques to realize a coherent memory using a pulsed magnetic field gradient and demonstrate the storage and retrieval of up to 100 weak 10 GHz coherent excitations in collective states of an electron spin ensemble. We further show that such collective excitations in the electron spin can then be stored in nuclear spin states, which offer coherence times in excess of seconds.
authors.affiliation: Department of Materials, Oxford University, Oxford OX1 3PH, United Kingdom.
authors.forename: Hua
authors.initials: H
authors.lastname: Wu
authors.forename: Richard E
authors.initials: RE
authors.lastname: George
authors.forename: Janus H
authors.initials: JH
authors.lastname: Wesenberg
authors.forename: Klaus
authors.initials: K
authors.lastname: Mølmer
authors.forename: David I
authors.initials: DI
authors.lastname: Schuster
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Schoelkopf
authors.forename: Kohei M
authors.initials: KM
authors.lastname: Itoh
authors.forename: Arzhang
authors.initials: A
authors.lastname: Ardavan
authors.forename: John J L
authors.initials: JJ
authors.lastname: Morton
authors.forename: G Andrew D
authors.initials: GA
authors.lastname: Briggs