Robust quantum sensing via many-body scars*

In most quantum sensing schemes, interactions between the constituent particles of the sensor are expected to lead to thermalization and degraded sensitivity. Recently, however, a new mechanism to slow down, or even avoid thermalisation in isolated quantum systems was discovered theoretically and observed experimentally, and was given the name "quantum many-body scarring". It is natural to ask: can this new mechanism be exploited to protect quantum sensing against thermalisation? I show that many-body scars can indeed be exploited for sensing that is robust against certain strong interactions. In the ideal case, the sensor is completely shielded from thermalisation and the optimal sensing time diverges. I demonstrate the idea with two examples: a spin-1 model with Dzyaloshinskii-Moriya interaction and a spin-1/2 mixed-field Ising model.