QSI UTS Online Seminar: Building Multiple Access Channels with a Single Particle – Prof Eric Chitambar, UIUC
September 22, 2020 @ 11:00 am - 12:00 pm
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Building Multiple Access Channels with a Single Particle
SPEAKER: Professor Eric Chitambar
AFFILIATION: University of Illinois at Urbana-Champaign, Illinois, USA
A multiple access channel describes a situation in which multiple senders are trying to forward messages to a single receiver using some communication medium. In this talk we consider scenarios in which this medium consists of just a single classical or quantum particle. In the quantum case, the particle can be prepared in a superposition state thereby allowing for a richer family of encoding strategies.
To make the comparison between quantum and classical channels precise, we introduce an operational framework in which all possible encoding strategies are restricted to particle number-preserving operations. We then apply this resource-theoretic framework to an N-port interferometer experiment in which each party controls a path the particle can traverse. When used for the purpose of communication, this setup embodies a multiple access channel. The channels built from a single classical particle are found to be characterized entirely in terms of second-order coherences, and every quantum resource state in this theory is shown to generate a channel outside the classical set.
We also discuss the notion of a “genuine multiple access channel”, in analog to genuine multipartite entanglement, and we show that an N-local channel generated by a quantum particle can simulate a genuine multiple access channel produced by a classical particle. Finally, we compare the capacity rate regions between one-particle classical and quantum MACs in various scenarios, and the quantum rate region is found to be strictly larger.