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.