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Durham Seminar, Wednesday 22 May 2019

12:00 - 13:00

CG 60

Patrick Ledingham

Patrick Ledingham

Atomic-ensemble-based Quantum Memories for Scalable Photonic Networking

Photonics presents a promising platform for future quantum-enhanced technologies owing to its resilience to room-temperature environments and robustness over metropolitan distances. However, the efficient generation and manipulation of indistinguishable photons remains probabilistic, while the distribution of photons over continental scales suffers inherent channel-propagation losses. Therefore, the success probability of any composite photonic system falls exponentially with the number of quantum elements and channels comprising the system, presenting a barrier to scalable photonic quantum technology. A quantum optical memory (QM) provides a solution to this so-called ‘scaling catastrophe’. QMs utilise light-matter interactions to store and recall quantum states of light on-demand, allowing to multiplex over non-deterministic processes for the synchronisation of quantum networking operations. Atomic-ensembled-based systems are well suited for QMs where light can be efficiently mapped into and stored as long-lived excitations within the atomic medium. For example, warm alkali vapours combine strong light-matter interactions, high-bandwidth implementation and room-temperature operation for technical simplicity. In this presentation, I will give an overview of the progress at the University of Oxford towards a scalable implementation of a quantum memory. I will introduce QM protocols based on Lambda- and Ladder-type three-level systems in alkali vapours and show our latest results on noise suppression [1], storage of quantum light [2], and toward interfacing our QM with quantum dot sources [3]. [1] S. E. Thomas, et al., arXiv:1905.00042 (2019) [2] K. T. Kaczmarek, et al., Phys. Rev. A, 97(4):042316 (2018) [3] S. Gao, et al., arXiv:1902.07720 (2019)