Experimental implementation of the optimal linear-optical controlled phase gate

We report on the first experimental realization of optimal linear-optical controlled phase gates for arbitrary phases. The realized scheme is entirely flexible in that the phase shift can be tuned to any given value. All such controlled phase gates are optimal in the sense that they operate at the maximum possible success probabilities that are achievable within the framework of any postselected linear-optical implementation. The quantum gate is implemented using bulk optical elements and polarization encoding of qubit states. We have experimentally explored the remarkable observation that the optimum success probability is not monotone in the phase.Comment: 4 pages, 5 figures, 1 tabl

Scedosporium and Pseudallescheria low molecular weight metabolites revealed by database search

The potential of mMass software search tool with new compound libraries was demonstrated on metabolomics of Scedosporium prolificans, S. apiospermum and Pseudallescheria boydii sensu stricto. Cyclic peptides pseudacyclins, small molecular weight tyroscherin analogues and various lipids were annotated by open source mass spectometry tool utilising accurate matrix-assisted laser desorption/ionisation mass spectral data of intact fungal spores. Electrospray ionisation combined with tandem mass spectrometry was used for monohexosylceramide characterisation in fungal extracts

Preparation of Knill-Laflamme-Milburn states using tunable controlled phase gate

A specific class of partially entangled states known as Knill-Laflamme-Milburn states (or KLM states) has been proved to be useful in relation to quantum information processing [Knill et al., Nature 409, 46 (2001)]. Although the usage of such states is widely investigated, considerably less effort has been invested into experimentally accessible preparation schemes. This paper discusses the possibility to employ a tunable controlled phase gate to generate an arbitrary Knill-Laflamme-Milburn state. In the first part, the idea of using the controlled phase gate is explained on the case of two-qubit KLM states. Optimization of the proposed scheme is then discussed for the framework of linear optics. Subsequent generalization of the scheme to arbitrary n-qubit KLM state is derived in the second part of this paper.Comment: 5 pages, 4 figures, accepted in Journal of Physics

Photonic transistor and router using a single quantum-dotconfined spin in a single-sided optical microcavity

The future Internet is very likely the mixture of all-optical Internet with low power consumption and quantum Internet with absolute security guaranteed by the laws of quantum mechanics. Photons would be used for processing, routing and com-munication of data, and photonic transistor using a weak light to control a strong light is the core component as an optical analogue to the electronic transistor that forms the basis of modern electronics. In sharp contrast to previous all-optical tran-sistors which are all based on optical nonlinearities, here I introduce a novel design for a high-gain and high-speed (up to terahertz) photonic transistor and its counterpart in the quantum limit, i.e., single-photon transistor based on a linear optical effect: giant Faraday rotation induced by a single electronic spin in a single-sided optical microcavity. A single-photon or classical optical pulse as the gate sets the spin state via projective measurement and controls the polarization of a strong light to open/block the photonic channel. Due to the duality as quantum gate for quantum information processing and transistor for optical information processing, this versatile spin-cavity quantum transistor provides a solid-state platform ideal for all-optical networks and quantum networks

REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC SEPARATION OF 1-NAPHTHYL ISOCYANATE DERIVATIVES OF LINEAR ALCOHOL POLYETHOXYLATES

The optimization procedure for the reversed-phase HPLC separation of 1-naphthyl isocyanate derivatives of linear alcohol polyethoxylates (LAEs) is reported. Using a C-18-bonded silica stationary phase and acetonitrile-water mixtures as mobile phase, different trends in the chromatographic separation of selected 1-tetradecanol polyethyleneglycol ether ethoxymers were observed. In the investigated range of acetonitrile-mobile phase volume ratio (phi), the elution order of the ethoxymers was inverted by increasing the organic solvent content of the mobile phase, and the mobile phase composition was found which provides the co-elution of the tested compounds. On the basis of the trends of capacity factor logarithm (log k') versus the number of ethoxy units (n) at different phi, an increased retention by increasing phi. was also predicted for higher ethoxymers. The separation under the same chromatographic conditions of a C-12-C-18 LAE mixture with an average number of 10 ethoxy units, confirmed the strong variability of LAE chromatographic behaviour in the investigated cp range. The isoeluting conditions found for the C-14 LAE ethoxymers were also applied successfully to the homologue-by-homologue separation of the C-12-C-18 LAE mixture

Capillary electrophoretic enantioseparation of selegiline, methamphetamine and ephedrine using a neutral β-cyclodextrin epichlorhydrin polymer

This paper describes the development of a capillary zone electrophoretic method for chiral separation of three basic compounds of the selegiline synthetic pathway: ephedrine, methamphetamine and selegiline. The method developed allows one to separate the studied compounds in one run using a neutral ß-cyclodextrin epichlorhydrin polymer. The effect of various experimental parameters, such as chiral selector concentration, concentration and composition of background electrolyte, pH, temperature, and the addition of some organic solvents, on the resolution and migration time is discussed. For selegiline and methamphetamine, it is possible, under optimal conditions, to quantify less than 0.5% of the minor isomer in an excess of the major one

Luminescence-induced noise in single photon sources based on BBO crystals

Single-photon sources based on the process of spontaneous parametric down-conversion play a key role in various applied disciplines of quantum optics. We characterize the intrinsic luminescence of BBO crystals as a source of non-removable noise in quantum-optics experiments. By analysing its spectral and temporal properties together with its intensity, we evaluate the impact of luminescence on single-photon state preparation using spontaneous parametric down-conversion