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Improving QKD for entangled states with low squeezing via non-Gaussian operations

Robert Malaney
Robert Malaney

Prof. Robert Malaney
School of Electrical Engineering and Telecommunications
University of New South Wales (UNSW), Sydney


Eduardo Villasenor and Robert Malaney
School of Electrical Engineering and Telecommunications, University of New South Wales (UNSW), Sydney, Australia

In this work we focus on evaluating the effectiveness of two non-Gaussian operations, photon subtraction (PS) and quantum scissors (QS) in terms of Continuous Variable (CV)-Quantum Key Distribution (QKD) over lossy channels. Each operation is analysed in two scenarios, one with the operation applied transmitter-side to a Two-Mode Squeezed Vacuum (TMSV) state and a second with the operation applied to the TMSV state receiver-side. We numerically evaluate the entanglement and calculate the QKD key rates produced in all four possible scenarios. Our results show that for a fixed value of initial squeezing in the TMSV state, the states produced by the non-Gaussian operations are more robust to loss, being capable of generating higher key rates for a given loss. More specifically, we find that for values of initial TMSV squeezing below 1.5dB the highest key rates are obtained by means of transmitter-QS. On the other hand, for squeezing above 1.5dB we find that receiver-PS produces the best key rates. Our results will be important for future CV-QKD implementations over free-space channels, such as the satellite-Earth channel.

Brief Bio

Robert has been awarded a Double First-Class Honours BSc in physics and astronomy from the University of Glasgow, Scotland, and the Ph.D. in physics from the University of St. Andrews, Scotland. He was previously a NATO Postdoctoral Fellow for three years at the California Institute of Technology, a Postdoctoral Fellow for three years at the University of California at Berkeley, and a Senior Research Fellow for five years at the University of Toronto. He moved to Australia in 1998 becoming a Principal Research Scientist with the Australian Government National Research Laboratories - the CSIRO. He is currently an Associate Professor with the School of Electrical Engineering and Telecommunications, University of New South Wales (UNSW), Sydney, Australia. His research focusses on the intersection of classical and quantum communications, with an emphasis on satellite communications. He currently leads a group of 10 researchers in this area at UNSW. Robert has approximately 200 scientific publications and is a Senior Member of the IEEE. In recognition of his research achievements Robert was awarded in 2017 the Northrop Grumman Inaugural Professorial Award, presented by the Australian Education Minister, Senator Birmingham, at Parliament House, Canberra.