Direct estimation of decoherence rates

31 01/2013

Thursday, 31 Jan. 2013, 11:00 - 12:00

Presenter: Mario Ziman (Research Center for Quantum Information, Slovak Academy of Sciences)
Host: C.Brukner
Where: IQOQI, Seminarraum, 2nd Floor, Boltzmanngasse 3, 1090 Vienna

Abstract:

We call a parameter estimation direct, if the observed data does not contain any irrelevant parameter for the specification of the measured quantity. It is of practical interest to understand which parameters can be measured directly, thus overcoming the complete tomography.

In this talk we will discuss the estimation of unknown decoherence rate providing that zero apriori information on the nature of the noise is given. We will see that complete process tomography is not needed in order to accomplish this task. In fact, we will present a procedure in which the value of the decoherence rate is a simple function of the experimentally fixed average value of a suitable binary measurement. Moreover, the estimation scheme does not require any additional knowledge on the input state of the channel. In fact, unless the source is producing maximally mixed states it can be used in the proposed estimation scheme.