A Two-Step Quantum Direct Communication Protocol Using Einstein-Podolsky-Rosen Pair Block

A protocol for quantum secure direct communication using blocks of EPR pairs is proposed. A set of ordered $N$ EPR pairs is used as a data block for sending secret message directly. The ordered $N$ EPR set is divided into two particle sequences, a checking sequence and a message-coding sequence. After transmitting the checking sequence, the two parties of communication check eavesdropping by measuring a fraction of particles randomly chosen, with random choice of two sets of measuring bases. After insuring the security of the quantum channel, the sender, Alice encodes the secret message directly on the message-coding sequence and send them to Bob. By combining the checking and message-coding sequences together, Bob is able to read out the encoded messages directly. The scheme is secure because an eavesdropper cannot get both sequences simultaneously. We also discuss issues in a noisy channel.Comment: 8 pages and 2 figures. To appear in Phys Rev

Collectivity Embedded in Complex Spectra of Finite Interacting Fermi Systems: Nuclear Example

The mechanism of collectivity coexisting with chaos in a finite system of strongly interacting fermions is investigated. The complex spectra are represented in the basis of two-particle two-hole states describing the nuclear double-charge exchange modes in $^{48}$Ca. An example of $J^{\pi}=0^-$ excitations shows that the residual interaction, which generically implies chaotic behavior, under certain specific and well identified conditions may create strong transitions, even much stronger than those corresponding to a pure mean-field picture. Such an effect results from correlations among the off-diagonal matrix elements, is connected with locally reduced density of states and a local minimum in the information entropy.Comment: 16 pages, LaTeX2e, REVTeX, 8 PostScript figures, to appear in Physical Review

THE CASE OF DERMATITIS IN THE HUMAN AS A RESULT OF THE INFLUENCE OF THE CERCARIA OF THE BIRD SCHISTOSOME

There are numerous cases of dermatitis described world-wide and resulting from the influence of the furcocercaria of the bird schistosome. The host snail species of the schistosome, producing thousands of furcocercaria are common in our country. But, because of too general symptoms of dermatitis resulting from the influence of the schistosome of the larvae, there are many unrecognisable cases. The reaction described was typical of a twenty-seven-year-old man collecting snails in the Piechota Bay in Gostynin (the Province of Kuyavia and Pomerania). In that reservoir, individuals of Lymnaea stagnalis were found, which were infected with sporocysts and furcocercaria of Trichobilharzia ocellata. In the laboratory conditions, a high expulsion of cercaria was observed, which amounted to over 8000 larvae per snail