By Luiz Davidovich, Universidade Federal do Rio de Janeiro
Quantum Metrology concerns the estimation of parameters, like a phase shift in an interferometer, the magnitude of a weak force or a small displacement, or yet the time duration of a dynamical process, taking into account the quantum character of the systems and processes involved. Quantum mechanics brings in some new features to the process of parameter estimation. The precision of the estimation becomes now intimately related to the possibility of discriminating two different quantum states of the probe corresponding to two different values of the parameter to be estimated. Also, possible measurements must abide by the rules of quantum mechanics. At the same time, quantum properties, like squeezing and entanglement, may help to increase the precision. This talk will review recent results[1, 2] concerning the application of quantum metrology to open systems, with applications to optical interferometry[1, 2, 3] and the quantum speed limit. A quantum-metrology analysis of the problem of weak-value amplification5 will also be discussed.
1. B. M. Escher, R. L. de Matos Filho, and L. Davidovich, General framework for estimating the ultimate precision limit in noisy quantum-enhanced metrology, Nature Phys. 7, 406 (2011).
2. B. M. Escher, R. L. de Matos Filho, and L. Davidovich, Quantum metrology for noisy systems, Braz. J. Phys. 41, 229 (2011).
3. B. M. Escher, L. Davidovich, N. Zagury, and R. L. de Matos Filho, Quantum metrological limits via a variational approach, Phys. Rev. Lett. 109, 190404 (2012).
4. M. M. Taddei, B. M. Escher, L. Davidovich, and R. L. de Matos Filho, Quantum speed limit for physical processes, Phys. Rev. Lett. 110, 050402 (2013).
5. G. Bié Alves, B. M. Escher, R. L. de Matos Filho, N. Zagury and L. Davidovich, Weakvalue amplification as an optimal metrological protocol, Phys. Rev. A 91, 062107 (2014).