Quantum Metrology

High precision measurements are of central importance in natural science and beyond. Quantum metrology deals with questions regarding the precision with which unknown quantities can be estimated or detected. A typical parameter estimation scenario consists of the preparation of an (entangled) probe state that undergoes dynamical evolution imprinting the unknown parameter, and a final measurement, from which an estimate of the parameter is obtained. Quantum mechanics in principle offers a quadratic scaling advantage in the achievable precision in terms of the resources (e.g., sensing time or number of sensing systems). However, this advantage is very fragile when the quantum systems in question are subjected to noise and decoherence.

We have investigated the performance of quantum metrology in the presence of noise and decoherence, where we showed that fast control [1] and quantum error correction [2] can be used to improve the performance and maintain a quantum scaling advantage for certain noise processes. We have found optimal states and protocols for various metrological tasks. We plan to apply and extend our methods to other metrological scenarios, and study e.g., multi-parameter estimation, Gaussian metrology [3], distributed sensing networks and atomic clocks. We are also interested in possible experimental realizations using different set-ups. Another goal is the use of techniques and methods from metrology to design autonomous, optimal structures that can detect noise or other environmental influences and correct for these undesirable effects.