Quantum Optics Seminar by Mathias Jørgensen (DTU)

Quantum Optics Seminar by Mathias Jørgensen, DTU 

Title: Tight bound on finite-resolution quantum thermometry at low temperatures

Abstract: Precise thermometry is of wide importance in science and technology in general and in quantum systems in particular. In this talk, I will discuss a theoretical study of the fundamental precision limits for thermometry on cold quantum systems, taking into account limitation imposed by finite measurement resolution. I will present a tight bound on the optimal precision scaling with temperature as the temperature approaches zero, and illustrate that the bound is tight and can be saturated by monitoring the non-equilibrium dynamics of a single-qubit probe. Modeling the non-equilibrium dynamics of open quantum systems at low temperatures is technically challenging, and I will discuss one approach to the problem based on tensor-network techniques. The results presented here are relevant both fundamentally, as they illuminate the ultimate limits to quantum thermometry, and practically, in guiding the development of sensitive thermometric techniques applicable at very low temperatures.