poster: Guiding a non-classical state of light propagating through a multiply scattering medium
speaker: Hugo Defienne (Institut Langevin, Paris)abstract: Guiding a non-classical state of light propagating through a multiply scattering medium
(1)Institut Langevin, UMR787 CNRS et ESPCI ParisTech, 1 rue Jussieu, 75005 Paris, France
(2) Clarendon Laboratory, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom
(3) Laboratoire de Collisions, Agrégats, Réactivité (CNRS UMR 5589), IRSAMC, Université Paul Sabatier, 31062 Toulouse, France
Hugo Defienne(1) , Marco Barbieri(2), Benoit Chalopin(3), Beatrice Chatel(3), Ian Walmsley(2), Brian Smith(2), Sylvain Gigan(1)
We investigate the possibility to use wavefront shaping techniques in order to generate and control non-classical states of light propagating through a multiply scattering medium. We experimentally show efficient guiding of a single-photon into a single-mode fiber placed at arbitrary positions after propagation in the medium, and demonstrate generation of an entangled state by focusing the single photons into two fibers simultaneously.
Quantum random walks offer an interesting playground for applications ranging from quantum simulation to computing. Complex media are a promising platform, since they naturally provide coherent coupling between a huge number of modes 1. However, losses and scattering severely reduce their efficiency and such a system is generally considered unpractical for quantum applications. Recently, wavefront shaping techniques have been proposed to control the light propagating through a complex media 2. Working with a linear non-absorptive medium, we can learn the scattering matrix of the medium and use it to control the output field 3. This method permits for instance to focus classical light in one or more output modes using a spatial light modulator.
In our experiment, we generate a single-photon state of light using an heralding process based on a spontaneous parametric down conversion pair-generation setup. The scattering matrix is measured using a bright classical light in the same mode as the heralded single-photon, which means the medium is characterized for this specific optical mode 3.
First, we show that we can use the scattering matrix to strongly enhance the probability to detect a single photon in one specific output mode of our system, namely a single mode fiber. Moreover, the knowledge of the scattering matrix allows us to focus light in two different fibers with a well-controlled relative phase. By this mean, we generate the one-photon entangled state phase with a complete control of the position of the output modes A and B and of the . We characterize the purity of the entangled state generated by observing single-photon interferences on a beam splitter and by measuring the concurrence.
This experiment shows that the wavefront shaping methods in complex media can be applied to non-classical light and can be used to generate an arbitrary one-photon entangled state, with potential applications in quantum information.
References:
1 Peeters, W. H., J. J. D. Moerman, and M. P. van Exter. "Observation of two-photon speckle patterns." Physical review letters 104.17 (2010): 173601.
2 Mosk, Allard P., et al. "Controlling waves in space and time for imaging and focusing in complex media." Nature photonics 6.5 (2012): 283-292.
3 Popoff, S. M., et al. "Measuring the transmission matrix in optics: an approach to the study and control of light propagation in disordered media." Physical review letters 104.10 (2010): 100601.
4 Huisman, Thomas J., et al. "Controlling single-photon Fock-state propagation through opaque scattering materials." arXiv preprint arXiv:1210.8388 (2012).
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