Speaker: Mathias Rønnow Jørgensen, DTU

Title: Fundamental precision limits to quantum thermometry

Abstract:

Precise thermometry is of wide importance in science and technology in general and in quantum systems in particular. Here I will discuss the potential, and limitations, of using individual quantum probes as temperature sensors. The focus of the talk will be to understand the fundamental precision limits for thermometry on cold quantum systems, while taking into account the constraints imposed by using quantum probes. I will show that if the energetic ground state can be resolved, a two-outcome measurement is sufficient to attain the same optimal scaling as any unconstrained measurement. Furthermore I show that an inability to resolve the energetic ground state leads to a stronger bound on the optimal precision scaling with temperature, as the temperature approaches absolute zero, and argue that the derived bound can be saturated by monitoring the non-equilibrium dynamics of a single-qubit probe. Supporting the proposed protocol numerically requires accurate modeling of the qubit dynamics deep in the non-Markovian regime, we achieve this by considering the use of tensor network techniques to simulate a spin-boson model.

There is bread rolls, coffee and tea from 10:00.