Open Up, Quantum!—How Open Quantum Systems Are Shaking the Foundations of Quantum Mechanics

The study of non-Hermitian quantum systems can be seen not as a departure from traditional quantum theory, but as an extension

Artistic illustration of a quantum system interacting with its surroundings. Image by Author.

A profound question that I have received a few times from laypeople when explaining my work as a theoretical quantum physicist is the role of mathematics in my field. Is math merely an instrument we develop to explain experimental evidence, or is it something more fundamental — something that underlies the Universe itself, something we “discover” when we look closely enough?

The answer to this chicken-and-egg conundrum is far from simple. Often, it is puzzling new experimental results that trigger the development of fresh mathematical frameworks. A novel formalism becomes necessary to extend the old paradigm, allowing it to encompass recent data and to describe the physical system self-consistently under a broader theory. However, as science advances and the energy scales we explore become larger and harder to penetrate (I’m looking at you, !), we increasingly find ourselves developing mathematical frameworks without the immediate guidance or confirmation of experimental data.