Speaker: Marti Perarnau
Affiliation: University of Geneva
Date: Tuesday, 25 April 2023 at 12:00
Location: Seminar Room, Serrano 121 (CFMAC)
In this talk, I will discuss several aspects of critical quantum metrology, that is the estimation of parameters of many-body systems close to a quantum critical point. We will first derive a no-go result stating that any non-adaptive measurement strategy will fail to exploit quantum critical enhancement (i.e. precision beyond the shot-noise limit) for a sufficiently large number of particles. We will then consider different adaptive strategies that can overcome this no-go bound, and illustrate their performance in the estimation of (i) a magnetic field using as a probe a 1D spin Ising chain and (ii) the coupling strength in a Bose-Hubbard square lattice. Finally, and if time allows, I will also present on-going efforts to the understanding of the form of optimal interacting spin networks for measuring low temperatures and magnetic fields.
This talk is based on arXiv:2211.07688, and also party on arXiv:2211.01934.