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Physics Seminar - Dr Patrick Ledingham

Thursday, 30 November 2017

Physics Department

Dr Patrick Ledingham

Postdoctoral Researcher

Department of Physics

University of Oxford

"Atomic Ensemble Based Optical Memories for Quantum Networking"

Quantum interfaces between light and matter play a significant role in the field of quantum information science. Such an interface would allow for a quantum optical memory (QM), a device that enables the storage and on-demand retrieval of quantum states of light. This device therefore allows for the synchronisation of probabilistic processes within local and wide area networks, for example, multi-photon state generation [1], quantum photonic gate operations [2], as well as the generation, distribution and swapping of entanglement [3]. Atomic systems are well suited for QMs as light can efficiently interact with optical transitions and be stored for long durations as excitations in the atomic medium.

In this seminar, I will present two experimental realisations of interfacing heralded single photons with ensemble based quantum memories. These experiments consisted of differing protocols implemented on complimentary platforms; a spin-wave atomic frequency comb memory with cryogenically cooled rare earth ion dopants [4], and off-resonant cascaded two-photon absorption in warm alkali vapours [5]. In both experiments, the quantum nature of the retrieved light was confirmed, a stringent requirement for such a device to be useful within quantum photonic network, paving the way for larger scale implementations.

[1] J. Nunn, et al., Phys. Rev. Lett. 110, 133601 (2013)
[2] P. Kok, et al., Rev. Mod. Phys 79, 735 (2007)
[3] N. Sangouard, et al., Rev. Mod. Phys. 83, 33 (2011)
[4] A. Seri, et al., Phys. Rev. X 7, 021025 (2017)
[5] K. Kaczmarek, et al., arXiv:1704.00013 (2017)

WHEN: Thursday 30 November 2017
WHERE: Room 314, Science 3 Building
TIME: 3.00 pm–4.00 pm

All interested are welcome to attend

Light refreshments to follow in Common Room