NITheP Seminar by Dr Camille Lombard Latune “Quantum Metrology: noise in force estimation” Part 2

NITheP Seminar by Dr Camille Lombard Latune “Quantum Metrology: noise in force estimation” Part 2

After a brief recap of the main concepts we saw last week (Cramér-Rao bound, Fisher information, and quantum Fisher information), we apply the discussed method for deriving the quantum Fisher information for non-unitary evolution to the problem of estimation of classical force taking into account Markovian noise. The resulting expression for the precision of estimation describes the transition between the Heisenberg limit and the shot-noise limit (classical limit). From this expression one can evaluate how dramatic is the effect of noise on the precision of the estimation. Then, in order to reduce the drastic effect of noise we show that one can use sequential measurement. Aiming a realistic description, we show as well how to include effects of unsharp measurements.
Finally we give some brief numerical applications based on realistic parameters from optomechanics experiments.
We finish by mentioning some challenges in Quantum Metrology.