Weak force detection using a double Bose-Einstein condensate

A Bose-Einstein condensate may be used to make precise measurements of weak forces, utilizing the macroscopic occupation of a single quantum state. We present a scheme which uses a condensate in a double well potential to do this. The required initial state of the condensate is discussed, and the limitations on the sensitivity due to atom collisions and external coupling are analyzed.Comment: 12 pages, 2 figures, Eq.(41) has been correcte

First-order interference of nonclassical light emitted spontaneously at different times

We study first-order interference in spontaneous parametric down-conversion generated by two pump pulses that do not overlap in time. The observed modulation in the angular distribution of the signal detector counting rate can only be explained in terms of a quantum mechanical description based on biphoton states. The condition for observing interference in the signal channel is shown to depend on the parameters of the idler radiation.Comment: 5 pages, two-column, submitted to PR

Quantum interference with beamlike type-II spontaneous parametric down-conversion

We implement experimentally a method to generate photon-number$-$path and polarization entangled photon pairs using ``beamlike'' type-II spontaneous parametric down-conversion (SPDC), in which the signal-idler photon pairs are emitted as two separate circular beams with small emission angles rather than as two diverging cones.Comment: 4 pages, two-colum

Experimental Entanglement Concentration and Universal Bell-state Synthesizer

We report a novel Bell-state synthesizer in which an interferometric entanglement concentration scheme is used. An initially mixed polarization state from type-II spontaneous parametric down-conversion becomes entangled after the interferometric entanglement concentrator. This Bell-state synthesizer is universal in the sense that the output polarization state is not affected by spectral filtering, crystal thickness, and, most importantly, the choice of pump source. It is also robust against environmental disturbance and a more general state, partially mixed$-$partially entangled state, can be readily generated as well.Comment: Minor update (Newer data

Reliability of the beamsplitter based Bell-state measurement

A linear 50/50 beamsplitter, together with a coincidence measurement, has been widely used in quantum optical experiments, such as teleportation, dense coding, etc., for interferometrically distinguishing, measuring, or projecting onto one of the four two-photon polarization Bell-states $|\psi^{(-)}>$. In this paper, we demonstrate that the coincidence measurement at the output of a beamsplitter cannot be used as an absolute identifier of the input state $|\psi^{(-)}>$ nor as an indication that the input photons have projected to the $|\psi^{(-)}>$ state.Comment: 4 pages, two-colum

Expression profiling of cyclin B1 and D1 in cervical carcinoma

Aim: Cyclins are a family of regulatory proteins that play a key role in controlling the cell cycle. Abnormalities of cell cycle regulators, including cyclins and cyclin dependent kinases, have been reported in various malignant tumors. This study was undertaken to quantitatively detect cyclin B1 and D1 in cervical cancer. Methods: A quantitative real-time reverse transcription polymerase chain reaction and Western blot assay were used to analyze the expression of cyclin B1/D1 mRNA and proteins, respectively, in fresh invasive cervical cancer (n = 41) and normal cervical tissues (n = 10). Results: There was significantly greater cyclin B1 expression in invasive cervical cancer than in normal cervical tissue (P = 0.019). However, cyclin D1 expression was not significantly different. A Western blot assay yielded similar results. Conclusion: Our results were consistent with the concept that up-regulation of cyclin B1 expression occurred in cervical cancer and an aberrant expression of cyclin B1 might play an important role in cervical carcinogenesis.Цель: циклины представляют собой семейство регуляторных белков, контролирующих клеточный цикл. Наличие функциональных и структурных нарушений регуляторов клеточного цикла (циклинов и циклинзависимых киназ) было отмечено в клетках различных злокачественных новообразований. Целью данного исследования было проведение количественного определения циклинов B1 и D1 в клетках рака шейки матки. Методы: определение уровня экспрессии циклинов B1/D1 (mRNA и белков соответственно) в свежеполученных клетках инвазивного рака шейки матки (n = 41) и нормальной ткани шейки матки (n = 10) проводили методами RT-PCR в режиме реального времени и Вестерн-блот анализа. Результаты: отмечен более высокий уровень экспрессии гена циклина В1 в клетках инвазивного рака шейки матки, чем в клетках нормальной ткани (P = 0,019). Не выявлены значительные различия в уровне экспрессии гена циклина D1. При Вестерн-блот анализе получены аналогичные результаты. Выводы: результаты исследования подтверждают концепцию об активации экспрессии циклина В1 при раке шейки матки. Аберрантная экспрессия циклина В1 может играть важную роль при злокачественной трансформации эпителия шейки матки

Synchronization and resonance in a driven system of coupled oscillators

We study the noise effects in a driven system of globally coupled oscillators, with particular attention to the interplay between driving and noise. The self-consistency equation for the order parameter, which measures the collective synchronization of the system, is derived; it is found that the total order parameter decreases monotonically with noise, indicating overall suppression of synchronization. Still, for large coupling strengths, there exists an optimal noise level at which the periodic (ac) component of the order parameter reaches its maximum. The response of the phase velocity is also examined and found to display resonance behavior.Comment: 17 pages, 3 figure

Interferometric Bell-state preparation using femtosecond-pulse-pumped Spontaneous Parametric Down-Conversion

We present theoretical and experimental study of preparing maximally entangled two-photon polarization states, or Bell states, using femtosecond pulse pumped spontaneous parametric down-conversion (SPDC). First, we show how the inherent distinguishability in femtosecond pulse pumped type-II SPDC can be removed by using an interferometric technique without spectral and amplitude post-selection. We then analyze the recently introduced Bell state preparation scheme using type-I SPDC. Theoretically, both methods offer the same results, however, type-I SPDC provides experimentally superior methods of preparing Bell states in femtosecond pulse pumped SPDC. Such a pulsed source of highly entangled photon pairs is useful in quantum communications, quantum cryptography, quantum teleportation, etc.Comment: 11 pages, two-column format, to appear in PR

Performance of the CREAM calorimeter in accelerator beam test

The CREAM calorimeter, designed to measure the spectra of cosmic-ray nuclei from under 1 TeV to 1000 TeV, is a 20 radiation length (X0) deep sampling calorimeter. The calorimeter is comprised of 20 layers of tungsten interleaved with 20 layers of scintillating fiber ribbons, and is preceded by a pair of graphite interaction targets providing about 0.42 proton interaction lengths (\lambda int). The calorimeter was placed in one of CERN's SPS accelerator beams for calibration and testing. Beams of 150 GeV electrons were used for calibration, and a variety of electron, proton, and nuclear fragment beams were used to test the simulation model of the detector. In this paper we discuss the performance of the calorimeter in the electron beam and compare electron beam data with simulation results.The CREAM calorimeter, designed to measure the spectra of cosmic-ray nuclei from under 1 TeV to 1000 TeV, is a 20 radiation length (X0) deep sampling calorimeter. The calorimeter is comprised of 20 layers of tungsten interleaved with 20 layers of scintillating fiber ribbons, and is preceded by a pair of graphite interaction targets providing about 0.42 proton interaction lengths (\lambda int). The calorimeter was placed in one of CERN's SPS accelerator beams for calibration and testing. Beams of 150 GeV electrons were used for calibration, and a variety of electron, proton, and nuclear fragment beams were used to test the simulation model of the detector. In this paper we discuss the performance of the calorimeter in the electron beam and compare electron beam data with simulation results