Southwest Quantum Information and Technology

Continuous variable quantum repeater networks based on noiseless linear amplification and mode multiplexing

Presenting Author: Ian Tillman, University of Arizona
Contributing Author(s): Kaushik P. Seshadreesan, Allison Rubenok, Saikat Guha

Quantum repeaters are a main focus of study in quantum communications, whose aim is to boost the rates of entanglement and secret key distribution over the direct transmission capacity and increase the range of communications. The so-called “two-way” quantum repeaters, when interspersed between two end nodes, work by probabilistically distributing entanglement across the lossy divided channel segments between every pair of adjacent nodes, followed by entanglement distillation and entanglement swapping at the nodes. In continuous variable (CV) entanglement distribution, previous works have shown that noiseless linear amplifiers (NLAs) can be realized using so-called quantum scissors and, when paired with mode multiplexing, can function as repeaters. In this work we study a general quantum channel consisting of two lossy elementary links, each containing several multiplexed two-mode squeezed vacuum (TMSV) CV entanglement sources and quantum scissor NLAs, whose entanglements are swapped to the end users via dual homodyne detection (DHD). Specifically, we calculate the full two-mode Fock basis expansion of the resulting state given completely general (notably asymmetric) TMSV, NLA, and loss parameters. Using this general state description we analyze optimal placement of a central hub node that connects any pair of users in a 4-user square network and find the percentage of placement area for which this approach surpasses the repeaterless bound or direct DHD without the NLA.

(Session 5 : Thursday from 12:00pm-2:00 pm)