Freiburg 2019 – scientific programme
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FM: Fall Meeting
FM 54: Quantum Networks: Quantum Memory and Gates
FM 54.7: Talk
Wednesday, September 25, 2019, 15:45–16:00, 1015
A temporally multiplexed quantum repeater node based on laser-cooled atoms — •Lukas Heller1, Pau Farrera1, and Hugues de Riedmatten1,2 — 1ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain — 2ICREA-Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain
Future quantum repeater architectures, capable of efficiently distributing information encoded in quantum states of light over large distances, rely on quantum memories for light. Quantum repeaters can benefit from a modal multiplexing implementation of the memory, essentially scaling up the repeater's throughput. In this work we demonstrate a temporally multiplexed quantum repeater node in a laser-cooled cloud of 87 Rb atoms [1]. We employ the DLCZ protocol where pairs of photons and single collective spin excitations (so called spin-waves) are created [2]. The latter can then be efficiently transferred into a second single photon. For selective readout, we need to control the dephasing and rephasing of the spin-waves created in different temporal modes. We achieve this by a mag netic field gradient, which induces an inhomogeneous broadening of the involved atomic hyperfine levels [3]. By employing this steering technique, combined with cavity-enhanced emission and feed forward readout, we demonstrate distinguishable retrieval of up to 10 temporal modes. For each mode, we prove non-classical correlations between the first and second photon. Furthermore, an enhancement in rates of correlated photon-photon pairs is observed as we increase the number of temporal modes stored in the memory. The reported device is a crucial key element of a quantum repeater architecture implementing multiplexed quantum memories.
[1] C. Simon, H. de Riedmatten and M. Afzelius; Phys. Rev. A 82 010304(R) (2010)
[2] L. Duan, M. Lukin, J. Cirac and P. Zoller, P; Nature 414 413 (2001)
[3] B.Albrecht, P. Farrera, G. Heinze, M. Cristiani and H. de Riedmatten; Phys. Rev. Lett. 115 160501 (2015)