ELFT HÍRADÓ

[András Vukics <vukics.andras AT wigner.mta.hu>]

Dear Colleagues,

Our next department seminar will take place on *Tuesday, 7 May, 1pm (KFKI
Campus, Bldg. 1, 2nd floor, Conference Room)*.

*Anna Szczepanek *(Institute of Mathematics, Jagiellonian University,
Kraków)

Title: *Dynamical Entropy  of Quantum Iterated Function Systems and
Entropy-maximizing  Unitaries*
Abstract: Consider successive measurements performed on a
finite-dimensional quantum mechanical system that between each two
consecutive measurements evolves in accordance to some unitary operator. We
are interested in the irreducible randomness present in the sequences of
measurement results. This randomness can be quantified by means of the
dynamical entropy of the (partial) Iterated Function System corresponding
to the underlying quantum system and expressed by the Blackwell integral
formula. If the measurement is a rank-1 POVM, then a closed-form expression
for dynamical entropy can be easily derived. For such measurements we
investigate the unitary operators that maximize the dynamical entropy: we
explain their connection with complex Hadamard matrices and give their
characterization in dimensions 2 and 3. We also briefly discuss the problem
of calculating the dynamical entropy for other classes of measurements.

Everyone is welcome to attend.

András Vukics

Dr. András Vukics
Department of Quantum Optics and Quantum Information
Institute for Solid State Physics and Optics
Wigner Research Centre for Physics of the Hungarian Academy of Sciences
vukics.andras AT wigner.mta.hu
http://optics.szfki.kfki.hu/Vukics

*(Non nobis, Domine, non nobis, sed nomini tuo da gloriam.)*