Spin correlated interferometry for polarized and unpolarized photons on a beam splitter

Spin interferometry of the 4th order for independent polarized as well as unpolarized photons arriving simultaneously at a beam splitter and exhibiting spin correlation while leaving it, is formulated and discussed in the quantum approach. Beam splitter is recognized as a source of genuine singlet photon states. Also, typical nonclassical beating between photons taking part in the interference of the 4th order is given a polarization dependent explanation.Comment: RevTeX, 19 pages, 1 ps figure, author web page at http://m3k.grad.hr/pavici

Resistive damping implementation as a method to improve controllability in stiff ohmic RF-MEMS switches

This paper presents in detail the entire procedure of calculating the bias resistance of an ohmic RF-MEMS switch, controlled under resistive damping (charge drive technique). In case of a very stiff device, like the North Eastern University switch, the actuation control under resistive damping is the only way to achieve controllability. Due to the short switching time as well as the high actuation voltage, it is not practical to apply a tailored control pulse (voltage drive control technique). Implementing a bias resistor of 33 MΩ in series with the voltage source, the impact velocity of the cantilever has been reduced 80 % (13.2 from 65.9 cm/s), eliminating bouncing and high initial impact force during the pull-down phase. However, this results in an affordable cost of switching time increase from 2.38 to 4.34 μs. During the release phase the amplitude of bouncing has also been reduced 34 % (174 from 255 nm), providing significant improvement in both switching operation phases of the switch. © 2013 Springer-Verlag Berlin Heidelberg

Quantum Communication with Correlated Nonclassical States

Nonclassical correlations between the quadrature-phase amplitudes of two spatially separated optical beams are exploited to realize a two-channel quantum communication experiment with a high degree of immunity to interception. For this scheme, either channel alone can have an arbitrarily small signal-to-noise ratio (SNR) for transmission of a coherent ``message''. However, when the transmitted beams are combined properly upon authorized detection, the encoded message can in principle be recovered with the original SNR of the source. An experimental demonstration has achieved a 3.2 dB improvement in SNR over that possible with correlated classical sources. Extensions of the protocol to improve its security against eavesdropping are discussed.Comment: 8 pages and 4 figures (Figure 1; Figures 2a, 2b; Figure 2

The use of eye tracking glasses in basketball shooting : a systematic review

Sports performance is related to cognitive processes that precede the motor task to be developed. In this way, the coupling between visual information and motor behavior has a major importance in filtering the visual information, necessary to the accomplishment of the motor task to be executed, ignoring ‘accessory’ stimuli. In this field, this essay has the goal of achieving a systematic review about past studies in the context of basketball shooting. We bring to you some evidence that support the applicability and efficiency of Eye Tracking Glasses systems in the analysis of visual attention in basketball shooting, emphasizing the concept of Quiet Eye, interconnected with anxiety and occlusion of vision. The results of the studies demonstrate the importance of the use of Eye Tracking Glasses for the evaluation/intervention in the process of visual attention training related to efficiency in shooting.info:eu-repo/semantics/publishedVersio

Quantum interference of single photons from remote nitrogen-vacancy centers in diamond

We demonstrate quantum interference between indistinguishable photons emitted by two nitrogen-vacancy (NV) centers in distinct diamond samples separated by two meters. Macroscopic solid immersion lenses are used to enhance photon collection efficiency. Quantum interference is verified by measuring a value of the second-order cross-correlation function $g^{(2)}(0) = 0.35 \pm 0.04<0.5$. In addition, optical transition frequencies of two separated NV centers are tuned into resonance with each other by applying external electric fields. Extension of the present approach to generate entanglement of remote solid-state qubits is discussed.Comment: 5 pages, 3 figure

No-cloning theorem and teleportation criteria for quantum continuous variables

We discuss the criteria presently used for evaluating the efficiency of quantum teleportation schemes for continuous variables. Using an argument based upon the difference between 1-to-2 quantum cloning (quantum duplication) and 1-to-infinity cloning (classical measurement), we show that a fidelity value larger than 2/3 is required for successful quantum teleportation of coherent states. This value has not been reached experimentally so far.Comment: 4 pages, 1 figure, submitted to Phys. Rev.

Demonstration of Controllable Temporal Distinguishability in a Three-Photon State

Multi-photon interference is at the heart of the recently proposed linear optical quantum computing scheme and plays an essential role in many protocols in quantum information. Indistinguishability is what leads to the effect of quantum interference. Optical interferometers such as Michaelson interferometer provide a measure for second-order coherence at one-photon level and Hong-Ou-Mandel interferometer was widely employed to describe two-photon entanglement and indistinguishability. However, there is not an effective way for a system of more than two photons. Recently, a new interferometric scheme was proposed to quantify the degree of multi-photon distinguishability. Here we report an experiment to implement the scheme for three-photon case. We are able to generate three photons with different degrees of temporal distinguishability and demonstrate how to characterize them by the visibility of three-photon interference. This method of quantitative description of multi-photon indistinguishability will have practical implications in the implementation of quantum information protocols

Conditional teleportation using optical squeezers and photon counting

We suggest a scheme of using two-mode squeezed vacuum for conditional teleportation of quantum states of optical field. Alice mixes the input state with one of the squeezed modes on another squeezing device and detects the output photon numbers. The result is then communicated to Bob who shifts the photon number of his part accordingly. This is a principally realizable modification of the recent scheme [G.J. Milburn and S.L. Braunstein, Phys. Rev. A 60, 937 (1999)] where measurements of photon number difference and phase sum are considered. We show that for some classes of states this method can yield very high fidelity of teleportation, nevertheless, the success probability may be limited.Comment: 5 pages, 4 figures; notations simplified, more explicit explanatio

Narrowband frequency tunable light source of continuous quadrature entanglement

We report the observation of non-classical quantum correlations of continuous light variables from a novel type of source. It is a frequency non-degenerate optical parametric oscillator below threshold, where signal and idler fields are separated by 740MHz corresponding to two free spectrum ranges of the parametric oscillator cavity. The degree of entanglement observed, - 3.8 dB, is the highest to-date for a narrowband tunable source suitable for atomic quantum memory and other applications in atomic physics. Finally we use the latter to visualize the Einstein-Podolsky-Rosen paradox.Comment: 11 pages, 9 figures, LaTe