Hi all,
Tomorrow Anian Altherr will present his master's thesis, entitled "Quantum metrology for non-Markovian processes". See below for the abstract. We start at 2pm on zoom: https://ethz.zoom.us/j/362994444
Best,
Joe
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Quantum metrology is concerned with finding precision bounds in parameter estimation of a given sample. Whereas classical strategies allow the precision to scale at most linearly with the number of resources used, quantum strategies can achieve a quadratic scaling. Noise, however, in general reduces the quadratic scaling to a linear scaling. Most work so far has dealt with assessing Markovian noise, but in the future, assessing time-correlated noise, e.g. in deep quantum circuits, will be of increasing interest. A general framework to assess such non-Markovian noise has been missing. In this work, we use quantum combs to model non-Markovian noise and express its quantum Fisher information in terms of a semidefinite program and the conditional min-entropy. We apply the semidefinite program to collision models, which serve as an instance of non-Markovian noise. Numerics show that the non-Markovian setting allows for more precise estimators than the Markovian setting. Finally, we employ variational circuits to find an explicit metrological setup that achieves the maximal precision.