Nonclassicality in Quantum Communication
Abstract
Nonclassicality, being an essentially quantum behavior of physical systems, can be used in various modern quantum technologies. We will address the nonclassicality of photonic systems and review its role in quantum communication, covering both discrete-variable schemes, relying on strong nonclassicality of single-photon or non-Gaussian states of light, and continuous variables, where quadrature squeezing or entanglement can bring advantages compared to the use of semiclassical coherent states. In particular, we will show how non-Gaussianity of quantum states can be used as an indicator for security of quantum key distribution. We will further benchmark the performance of entanglement-based discrete-variable quantum communication by the ultimate bounds set by continuous-variable protocols, and discuss the possibility for the practical sources to overcome those bounds. Finally, we will discuss advantages of quadrature squeezing in continuous-variable protocols, showing the possibility to fully block the information leakage from lossy quantum channels, or demonstrating advantage of squeezed states in conditions of channel transmittance fluctuations, but will also reveal practical limitations imposed on secure quantum communication by the presence of intrinsic anti-squeezing noise.
Short Biography
Vladyslav C. Usenko obtained his Ph.D. at the Institute of Physics of the National Academy of Sciences in Kyiv, Ukraine, with a thesis on secure quantum communication using strongly correlated two-mode coherent states of light. He then worked as a post-doc at the University of Milan, Italy, supported by Landau Network – Centro Volta fellowship, studying photon-number encoding in entanglement-based quantum communication. In 2009 he joined Palacky University in Olomouc, Czech Republic, where he is now a senior researcher, working on the theory of quantum communication, particularly focusing on development of new protocols, analysis of the effects of noise and practical device imperfections as well as on the role of nonclassicality in the efficiency and robustness of the protocols, and proposing new techniques, such as multiplexing, for improving those. He is a principal or a co-investigator in numerous domestic and international research projects and maintains fruitful collaboration with several experimental groups.
