Quantum Mechanics: Axiomatics of Measurements and connections with Computing and Information Retrieval
|MILOSLAV DUSEK, Palacky University|
|Several experimental implementations of phase covariant quantum cloner|
|aula DOTTORATO - MERCOLEdì 11 ottobre, ore 11.00|
Several experimental realizations of optimal symmetric probabilistic phase-covariant 1 -> 2 cloning of qubit states is presented. We demonstrate creation of two copies of any state of a qubit with a fixed latitude on the Poincare sphere (especially of states lying at its equator). The states of qubits are encoded into polarization states of photons generated by spontaneous parametric down-conversion. Our devices are based on two main strategies. One of them is the interference of two photons at a beam splitter with different splitting ratios for horizontal and vertical polarizations. The other use a quantum-state filtering based on polarization dependent losses.
|aula DOTTORATO - MERCOLEdì 11 ottobre, ore 14.00|
|Experimental realization of the encoding of two qubits to one qutrit|
|We present an optical scheme for
the recently proposed protocol for encoding arbitrary non-entangled states
of two qubits into a state of one qutrit. Our experimental realization uses
spatial-mode encoding. I.e., each qudit is represented by a single photon
propagating in d different optical fibers. The compression of two qubits
into one qutrit is realized by an unbalanced beam splitter and a subsequent
measurement. After successful encoding of two qubits the receiver could
error-free restore any of the two encoded qubit states but not both of them
The principle of experiment is based on the interplay of the second-order and fourth-order interference. Further, we propose certain generalizations of the original protocol.