Non-Hermitian Topological Sensors

by Oscar Arandes Tejerina (Stockholm University)

Wednesday 28 May 2025, 13:15 → 15:15 Europe/Stockholm

AlbaNova A4:3001 (AlbaNova Main Building)

Abstract:
Non-Hermitian physics plays a significant role in a wide variety of physical systems,
particularly those involving gain and loss, finite lifetimes, or interactions with an external
environment. These interactions with the environment often give rise to non-Hermitian
behaviour. This Licentiate thesis aims to review some of the intriguing and unconventional
properties of non-Hermitian matrices and examine how these properties have been proposed
for the development of novel sensor technologies. We present some of the main features of
non-Hermitian systems, along with relevant techniques from the theory of open quantum
systems—tools essential for modelling quantum sensor setups. In particular, an in-depth
discussion of the input-output formalism is provided. Following this, we introduce the basics
of estimation theory, a mathematical framework used to evaluate sensor performance. Finally,
we review some of the proposals for sensor designs that leverage non-Hermitian effects, as
documented in the recent literature.