Quantum identification system

A secure quantum identification system combining a classical identification procedure and quantum key distribution is proposed. Each identification sequence is always used just once and new sequences are ``refuelled'' from a shared provably secret key transferred through the quantum channel. Two identification protocols are devised. The first protocol can be applied when legitimate users have an unjammable public channel at their disposal. The deception probability is derived for the case of a noisy quantum channel. The second protocol employs unconditionally secure authentication of information sent over the public channel, and thus it can be applied even in the case when an adversary is allowed to modify public communications. An experimental realization of a quantum identification system is described.Comment: RevTeX, 4 postscript figures, 9 pages, submitted to Physical Review

Entanglement transformation at absorbing and amplifying four-port devices

Dielectric four-port devices play an important role in optical quantum information processing. Since for causality reasons the permittivity is a complex function of frequency, dielectrics are typical examples of noisy quantum channels, which cannot preserve quantum coherence. To study the effects of quantum decoherence, we start from the quantized electromagnetic field in an arbitrary Kramers--Kronig dielectric of given complex permittivity and construct the transformation relating the output quantum state to the input quantum state, without placing restrictions on the frequency. We apply the formalism to some typical examples in quantum communication. In particular we show that for entangled qubits the Bell-basis states $|\Psi^\pm>$ are more robust against decoherence than the states $|\Phi^\pm>$.Comment: 12 pages, revtex, 10 eps figures, minor corrections in Appendi

Experimental estimation of the dimension of classical and quantum systems

An overwhelming majority of experiments in classical and quantum physics make a priori assumptions about the dimension of the system under consideration. However, would it be possible to assess the dimension of a completely unknown system only from the results of measurements performed on it, without any extra assumption? The concept of a dimension witness answers this question, as it allows one to bound the dimension of an unknown classical or quantum system in a device-independent manner, that is, only from the statistics of measurements performed on it. Here, we report on the experimental demonstration of dimension witnesses in a prepare and measure scenario. We use pairs of photons entangled in both polarization and orbital angular momentum to generate ensembles of classical and quantum states of dimensions up to 4. We then use a dimension witness to certify their dimensionality as well as their quantum nature. Our results open new avenues for the device-independent estimation of unknown quantum systems and for applications in quantum information science.Comment: See also similar, independent and jointly submitted work of J. Ahrens et al., quant-ph/1111.127

Interakce xenobiotik s MDR pumpami u S. cerevisiae

The interactions of a number of xenobiotics with two main S. cerevisiae MDR pumps, Pdr5p and Snq2p were studied. The results showed that some compounds do not interact with MDR pumps whereas others affect one or another of the pumps, causing a loss of their ability to transport an indicator substrate out of the cells. This apparent inactivation of the pumps can be due to competition for transport with the indicator substrate or to actual (noncompetitive) inhibition of the pump

Koncepce uchování a ochrany významných prvků kulturní historické krajiny

Studie Vstupní analýza porostních struktur krajiny Březnicka je podkladem pro návrh rehabilitace porostních struktur a mikrostruktur krajiny. Byly formulovány zásady a principy pro obnovu optimálního stavu výsadeb a komponované zeleně v kulturní krajině, včetně využití informací o jejich historické podobě. Studie vymezuje zájmové území, kulturně historický potenciál krajiny, architektonické a kulturní památky a podrobně popisuje přírodní poměry. Zpráva dále obsahuje studii Červený Dvůr, dokumentace k vyhlášení krajinného parku za Přírodní památku a Dokumentaci a evidenci území krajiny, parků zahrad na listině UNESCO. CD Romy obsahují fotodokumentaci Kroměříž a Lednicko-valtický areál