Verifying the security of a continuous variable quantum communication protocol via quantum metrology

Abstract

Quantum mechanics offers the possibility of unconditionally secure communication between multiple remote parties. Security proofs for such protocols typically rely on bounding the capacity of the quantum channel in use. In a similar manner, Cramér-Rao bounds in quantum metrology place limits on how much information can be extracted from a given quantum state about some unknown parameters of interest. In this work we establish a connection between these two areas. We first demonstrate a three-party sensing protocol, where the attainable precision is dependent on how many parties work together. This protocol is then mapped to a secure access protocol, where only by working together can the parties gain access to some high security asset. Finally, we map the same task to a communication protocol where we demonstrate that a higher mutual information can be achieved when the parties work collaboratively compared to any party working in isolation.

Monogamy of quantum correlations shared in a cavity-freeoptomechanical system

“…Quantum correlations are manifested in various forms namely: entanglement [1], quantum steering [2,3], Bell nonlocality [4] and discord [5,6]; in quantum systems, correlations sharing can be realized between many parts [7,8], and are useful in quantum communication tasks [9][10][11], as well as computational ones [12,13]. In this respect, the depth comprehension of the sharing structure is requested.…”