Revealing missing charges with generalised quantum fluctuation relations

Understand

The non-equilibrium dynamics of quantum many-body systems is one of the most fascinating problems in physics.

• Open questions range from how they relax to equilibrium to how to extract useful work from them.
• A critical point lies in assessing whether a system has conserved quantities (or 'charges'), as these can drastically influence its dynamics.
• Here we propose a general protocol to reveal the existence of charges based on a set of exact relations between out-of-equilibrium fluctuations and equilibrium properties of a quantum system.