Several experimental realizations of symmetric phase-covariant quantum cloner of single-photon qubits

We compare several optical implementations of phase-covariant cloning machines. The experiments are based on copying of the polarization state of a single photon in bulk optics by special unbalanced beam splitter or by balanced beam splitter accompanied by a state filtering. Also the all-fiber based setup is discussed, where the information is encoded into spatial modes, i.e., the photon can propagate through two optical fibers. Each of the four implementations possesses some advantages and disadvantages that are discussed.Comment: 8 pages, 11 figure

Optical implementation of the encoding of two qubits to a single qutrit

We have devised an optical scheme for the recently proposed protocol for encoding two qubits into one qutrit. In this protocol, Alice encodes an arbitrary pure product state of two qubits into a state of one qutrit. Bob can then restore error-free any of the two encoded qubit states but not both of them simultaneously. We have successfully realized this scheme experimentally using spatial-mode encoding. Each qubit (qutrit) was represented by a single photon that could propagate through two (three) separate fibers. We theoretically propose two generalizations of the original protocol. We have found a probabilistic operation that enables to retrieve both qubits simultaneously with the average fidelity above 90% and we have proposed extension of the original encoding transformation to encode N qubits into one (N+1)-dimensional system.Comment: 6 pages, 3 figures, RevTeX

Experimental asymmetric phase-covariant quantum cloning of polarization qubits

We report on two optical realizations of the $1 \to 2$ asymmetric phase-covariant cloning machines for polarization states of single photons. The experimental setups combine two-photon interference and tunable polarization filtering that enables us to control the asymmetry of the cloners. The first scheme involves a special unbalanced bulk beam splitter exhibiting different splitting ratios for vertical and horizontal polarizations, respectively. The second implemented scheme consists of a balanced fiber coupler where photon bunching occurs, followed by a free-space part with polarization filters. With this later approach we were able to demonstrate very high cloning fidelities which are above the universal cloning limit.Comment: 7 pages, 8 figure

Experimental realization of linear-optical partial SWAP gates

We present a linear-optical implementation of a class of two-qubit partial SWAP gates for polarization states of photons. Different gate operations, including the SWAP and entangling square root of SWAP, can be obtained by changing a classical control parameter -- namely the path difference in the interferometer. Reconstruction of output states, full process tomography and evaluation of entanglement of formation prove very good performance of the gates.Comment: 4 pages, 4 figures, RevTeX

The role of a midwife and a pediatric nurse in ensuring termomanagement by a physiological newborn

The theoretical part is focused in ensuring thermal management for a physiological new-born baby. To ensure the optimum thermal management for a new-born baby is very assential in order he/she can adapt to the external environment after the birth as a new-born baby is prone to loss of heat in the first moments after the birth. Body temperature regulation after childbirth is not sufficient and stable and therefore a new-born baby can get quickly cold when the surrounding temperature is low or, on contrary, he/she can get overheated when the temperature is high. That is why the nursing staff should minimize heat losses of a new-born baby and prevent his/her overheating. The first goal was to map out the knowledge of the nursing staff at the Department of Neonatology of ensuring thermal management of a physiological new-born baby at the labour ward. The other goal was to map out the way of ensuring thermal management of a physiological new-born baby at the labour ward. The research investigation was conducted by means of a qualitative survey using in-depth interviews and hidden observations of paediatric nurses at the Department of Neonatology at the Hospital in České Budějovice. All interviewed nurses have proved they know the way of ensuring thermal management of a physiological new-born baby at the labour ward correctly and at the same time all nurses observed have followed the Nursing Care Standard in Neonatology No. 513 Thermal management of a new-born baby when ensuring thermal management. This bachelor thesis could be used as a study material for students of the following years of midwifery studies. Further, it could be used as information material for the already experienced or fresh midwives and paediatric nurses. The outcome of the bachelor thesis is a leaflet providing information on ensuring thermal management of a physiological new-born baby