Upcoming seminars

Steady technological advances are paving the way for the implementation of the quantum internet, a network of locations interconnected by quantum channels. In this talk I will describe a model to simulate a quantum internet based on optical fibers and employ network-theory techniques to characterize the statistical properties of the photonic networks it generates. This model predicts (i) a phase transition between a disconnected and a highly-connected phase, (ii) that the typical photonic networks do not present the small world property, but that (iii) they are highly aggregated.

We propose a general-purpose quantum algorithm for preparing ground states of quantum Hamiltonians from a given trial state. The algorithm is based on techniques recently developed in the context of solving the quantum linear systems problem [Childs, Kothari, Somma'15]. We show that, compared to algorithms based on phase estimation, the runtime of our algorithm is exponentially better as a function of the allowed error, and at least quadratically better as a function of the overlap with the trial state.

The recently established resource theory of quantum thermodynamics offers a framework to determine the ultimate possibilities and limitations in the manipulation of quantum states and in the implementation of nanoscale thermal machines. A core endeavour of this programme is to determine under which conditions can a nonequilibrium quantum state be converted into another using thermal operations. Here we settle this question in the important case of Gaussian quantum states and channels.

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.