Jerome Dilley

Highly efficient source for indistinguishable single photons of controlled shape

We demonstrate a straightforward implementation of a push-button like single-photon source, which is based on a strongly coupled atom?cavity system. The device operates intermittently for periods of up to 100??s, with single-photon repetition rates of 1.0?MHz and an efficiency of 60%. Atoms are loaded into the cavity using an atomic fountain, with the upper turning point near the cavitys mode centre. This ensures long interaction times without any disturbances induced by trapping potentials. The latter is the key to reaching deterministic efficiencies as high as obtained in probabilistic photon-heralding schemes. The price to pay is the random loading of atoms into the cavity and the resulting intermittency. However, for all practical purposes, this has a negligible impact as an individual atom may emit up to 100 successive photons.

Single-photon absorption in coupled atom-cavity systems

We show how to capture a single photon of arbitrary temporal shape with one atom coupled to an optical cavity. Our model applies to Raman transitions in three-level atoms with one branch of the transition controlled by a (classical) laser pulse, and the other coupled to the cavity. Photons impinging on the cavity normally exhibit partial reflection, transmission, and/or absorption by the atom. Only a control pulse of suitable temporal shape ensures impedance matching throughout the pulse, which is necessary for complete state mapping from photon to atom. For most possible photon shapes, we derive an unambiguous analytic expression for the shape of this control pulse, and we discuss how this relates to a quantum memory.

Photonic qubits, qutrits and ququads accurately prepared and delivered on demand

Reliable encoding of information in quantum systems is crucial to all approaches to quantum information processing or communication. This applies in particular to photons used in linear optics quantum computing, which is scalable provided a deterministic single-photon emission and preparation is available. Here, we show that narrowband photons deterministically emitted from an atom?cavity system fulfil these requirements. Within their 500?ns coherence time, we demonstrate a subdivision into d time bins of various amplitudes and phases, which we use for encoding arbitrary qu-d-its. The latter is done deterministically with a fidelity >95% for qubits, verified using a newly developed time-resolved quantum-homodyne method.

EIT-based quantum memory for single photons from cavity-QED

We investigate the feasibility of implementing an elementary building block for quantum information processing. The combination of a deterministic single photon source based on vacuum stimulated Raman adiabatic passage (V-STIRAP), and a quantum memory based on electromagnetically induced transparency (EIT) in atomic vapour is outlined. Both systems are able to produce and process temporally shaped wavepackets which provide a way to maintain the indistinguishability of the photons. We also propose an efficient and robust ‘repeat-until-success’ quantum computation scheme based on this hybrid architecture.

Quantum Logic with Cavity Photons From Single Atoms

Annemarie Holleczek, Oliver Barter, Allison Rubenok, Jerome Dilley, Peter B. R. Nisbet-Jones, 3 Gunnar Langfahl-Klabes, Graham D. Marshall, Chris Sparrow, 4 Jeremy L. O’Brien, Konstantinos Poulios, 5 Axel Kuhn, ∗ and Jonathan C. F. Matthews † University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK Centre for Quantum Photonics, H.H.Wills Physics Laboratory and Department of Electrical and Electronic Engineering, University of Bristol, Bristol BS8 1UB, UK now at: National Physics Laboratory, Teddington TW11 OLW, UK Department of Physics, Imperial College London, London SW7 2AZ, UK now at: IESL–FORTH, P.O. Box 1527, GR-71110 Heraklion, Crete, Greece (Dated: October 13, 2018)

Quantum memories for single photons from cavity-QED

We investigate the feasibility of implementing an elementary building block for quantum information processing. The combination of a deterministic single photon source based on vacuum stimulated adiabatic rapid passage [1,2], and a quantum memory based on electromagnetically induced transparency in atomic vapour is outlined [3]. Both systems are able to produce and process temporally shaped wavepackets which provides a way to maintain the indistinguish ability of retrieved and original photons. We also propose an efficient and robust ‘repeat-until-success’ quantum computation scheme based on this hybrid architecture.