Loss-tolerant hybrid measurement test of CHSH inequality with weakly amplified N00N states

Although our understanding of Bell's theorem and experimental techniques to test it have improved over the last 40 years, thus far all Bell tests have suffered at least from the detection or the locality loophole. Most photonic Bell tests rely on inefficient discrete-outcome measurements, often provided by photon counting detection. One possible way to close the detection loophole in photonic Bell tests is to involve efficient continuous-variable measurements instead, such as homodyne detection. Here, we propose a test of the Clauser-Horne-Shimony-Holt (CHSH) inequality that applies photon counting and homodyne detection on weakly amplified two-photon N00N states. The scheme suggested is remarkably robust against experimental imperfections and suits the limits of current technology. As amplified quantum states are considered, our work also contributes to the exploration of entangled macroscopic quantum systems. Further, it may constitute an alternative platform for a loophole-free Bell test, which is also important for quantum-technological applications.Comment: 9 pages, 3 figure

Witnessing Entanglement with Second-Order Interference and Stokes Parameters

We propose to use Stokes parameter as an entanglement witness for correlated EPR mixed states of light. Such states can be generated with a beam splitter acting on two mixed squeezed states of light. Stokes witness operators are closely related to the Hanbury-Brown and Twiss interference and can be used to test entanglement in balanced homodyne experiments involving fluctuations of quantum quadratures of the electric field.Comment: 10 pages, 2 figur

Perfect excitation of a matter qubit by a single photon in free space

We propose a scheme for perfect excitation of a single two-level atom by a single photon in free space. The photon state has to match the time reversed photon state originating from spontaneous decay of a two-level system. We discuss its experimental preparation. The state is characterized by a particular asymmetric exponentially-shaped temporal profile. Any deviations from this ideal state limit the maximum absorption. Although perfect excitation requires an infinite amount of time we demonstrate that there is a class of initial one-photon quantum states which can achieve almost perfect absorption even for a finite interaction time. Our results pave the way for realizing perfect coupling between flying and stationary qubits in free space thus opening a possibility for building scalable quantum networks.Comment: 4 pages, 2 figure

Single-photon single-ion interaction in free space configuration in front of a parabolic mirror

The efficient interaction between single photons and single matter objects in free space is of key importance for quantum technologies. An experimental setup for testing this possibility involves single two-level ion trapped at the focus of a parabolic metallic mirror. We study the conditions for the setup, under which the assumption about the free-space mode structure of the radiation field in the vicinity of the atom is justified. In our analysis we apply vectorial properties of light by including polarization degree of freedom. We look for possible changes in the spontaneous emission rate of the atom resulting from the presence of the parabolic boundary conditions.Comment: 10 pages, 2 figures; Open Syst. Inf. Dyn. 19 (2012

The effect of contrasting selected graphical elements of a web page on information retrieval time

As online presence plays an increasingly important role in corporate success, the high usability of a company’s website becomes one of its most valuable assets. The time required to reach the needed information, which plays a key role among the many factors that influence a website’s usability, depends to a significant degree on the site’s design. The perception of the visual aspects of design is in turn influenced by various so-called “visual means”. This term encompasses a range of methods, procedures or techniques of using elements of graphical design to achieve the desired effect, which should be applied according not only to the informational content of the site, but also to the designer’s overall vision, i.e. the graphical layout of the site. Therefore, it can be said that a usable website design is largely dependent on the site’s composition, understood as maintaining the appropriate relations between its form and content. One of methods for increasing the visibility of a given graphical element is highlighting its distinctness, difference from other elements. This method is called contrasting. This article presents the methodology and a discussion of the results of original research into the impact of contrasting chosen text elements on the home page of a website on the time needed by a user to reach the information "privileged" by such a procedure