The Physics & Astronomy Colloquium Series presents Stephen Gray, The Argonne Distinguished Fellow 2021 of Argonne National Laboratory, discussing "Optimum Times for Quantum Sensing in Open Systems and the Challenges of Herding Quantum Cats", on Sept. 8.

Abstract: Quantum sensing and metrology involve the use of quantum phenomena such as superposition and entanglement to increase the precision of parameter estimation. The parameters in question correspond to a system’s properties, e.g., energy level separations. The system may be one or more quantum objects or probes in the presence of some field of interest, as in the use of NV centers to infer magnetic field strengths. Such a system may not be isolated and can interact with a larger environment leading to dephasing and dissipation. This open system dynamics can be described with quantum master equations such as the Lindblad equation. A fundamental quantity in quantum sensing is the quantum Fisher information (QFI) and conditions upon which it is large are ideal, since the QFI is inversely related to the best achievable precision. By solving the Lindblad equation for a variety of open systems and determining the time evolution of the QFI, it is shown how there can exist optimum time ranges for quantum sensing. An experimental parameter estimation procedure for capitalizing on this idea is suggested.