title: Quantum storage of a photonic polarization qubit in a solid.
abstract: We report on the quantum storage and retrieval of photonic polarization quantum bits onto and out of a solid state storage device. The qubits are implemented with weak coherent states at the single photon level, and are stored for a predetermined time of 500 ns in a praseodymium doped crystal with a storage and retrieval efficiency of 10%, using the atomic frequency comb scheme. We characterize the storage by using quantum state tomography, and find that the average conditional fidelity of the retrieved qubits exceeds 95% for a mean photon number μ=0.4. This is significantly higher than a classical benchmark, taking into account the poissonian statistics and finite memory efficiency, which proves that our crystal functions as a quantum storage device for polarization qubits. These results extend the storage capabilities of solid state quantum light matter interfaces to polarization encoding, which is widely used in quantum information science.
authors.affiliation: ICFO-Institut de Ciencies Fotoniques, Av. Carl Friedrich Gauss 3, 08860 Castelldefels (Barcelona), Spain. mustafa.gundogan@icfo.es
authors.forename: Mustafa
authors.initials: M
authors.lastname: Gündoğan
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Ledingham
authors.forename: Attaallah
authors.initials: A
authors.lastname: Almasi
authors.forename: Matteo
authors.initials: M
authors.lastname: Cristiani
authors.forename: Hugues
authors.initials: H
authors.lastname: de Riedmatten