Quantum communication research is led by Dr Yaseera Ismail (QuPhoton Lab)
The focus of the research is on the development of optical tools for quantum communication specifically focusing on the development of entangled single photon sources for free-space quantum communication and investigating high-dimensional encoding in fibre and free-space. The group has numerous international collaborators.
Integrating Machine Learning to monitor a quantum communication channel
Free-space quantum communication technology has made significant advancements over the years. However, to achieve a global quantum network there are still obstacles to overcome. To date, free-space quantum communication channels are faced with challenges related to losses in the quantum channel, security, and low data rates. Classical machine learning techniques provide a resourceful method for determining the properties of the free-space quantum channel. We investigate methods of using supervised machine learning to predict the atmospheric strength of a free-space quantum channel.
Yaseera Ismail, Ilya Sinayskiy, and Francesco Petruccione, “Integrating machine learning techniques in quantum communication to characterize the quantum channel” – J. Opt. Soc. Am. B 36, B116-B121 (2019)
Influence of coincidence detection of a biphoton state through free-space atmospheric turbulence using a partially spatially coherent pump
The development of a quantum network relies on the advances of hybrid systems which include ground-to-ground communication. However, the atmospheric turbulence of the environment poses a severe challenge to the optical quantum link. We investigate the influence of atmospheric turbulence on the coincidence detection of the entangled photon pairs using a fully and partially spatially coherent pump beam. Partially spatially coherent pumps are more robust towards varying atmospheric turbulence strengths than the photon pairs produced by a fully spatially coherent pump beam.
S. Phehlukwayo, M. L. Umuhire, Y. Ismail, S. Joshi and F. Petruccione, “Influence of coincidence detection through free-space atmospheric turbulence using partial spatial coherence” – Physics Review A, 102 (3) (2020)
Polarization-entangled photon generation using partial spatially coherent pump beam
The generation of two-photon fields has been demonstrated utilizing a fully coherent pump beam. We investigate the generation of polarization entangled single photon pairs by varying the spatial coherence of the pump beam. The coherence properties of the beam are significant for free-space optical transmission in particular for long-range free-space quantum communication.
Ismail, Y., Joshi, S. & Petruccione, F., “Polarization-entangled photon generation using partial spatially coherent pump beam” – Sci Rep 7, 12091 (2017).
Phase conjugation of twisted Gaussian Schell model beams in stimulated down-conversion
Stimulated parametric down-conversion is a nonlinear optical process that can be used for phase conjugation and frequency conversion of an optical field. A precise description of the outgoing stimulated field has been developed for the case where the input pump and seed fields are coherent. However, partially coherent beams can have interesting and important characteristics that are absent in coherent beams. One example is the twist phase, a novel optical phase that can appear in partially coherent Gaussian beams and gives rise to a nonzero orbital angular momentum.
dos Santos, Gustavo H., de Oliveira, Andre G., Rubiano da Silva, Nara, Cañas, Gustavo, Gómez, Esteban S., Joshi, Stuti, Ismail, Yaseera, Souto Ribeiro, Paulo H. and Walborn, Stephen Patrick, “Phase conjugation of twisted Gaussian Schell model beams in stimulated down-conversion” – Nanophotonics, vol. 11, no. 4, 2022, pp. 763-770.
Evaluation of twisted Gaussian Schell model beams produced with phase randomized coherent fields
The twisted Gaussian Schell Model describes a family of partially coherent beams that present several interesting characteristics, and as such have attracted attention in classical and quantum optics. Recent techniques have been demonstrated to synthesize these beams from a coherent source using a discrete set of ‘pseudo-modes’, where the phase of each mode is randomized so that they are mutually incoherent.
G. Cañas, E. S. Gómez, G. H. dos Santos, A. G. de Oliveira, N. Rubiano da Silva, S. Joshi, Y. Ismail, P. H. S. Ribeiro, S. P. Walborn, “Evaluation of twisted Gaussian Schell model beams produced with phase randomized coherent fields” – Journal of Optics 24 (9), 2022