Directional optical switching and transistor functionality using optical parametric oscillation in a spinor polariton fluid

Over the past decade, spontaneously emerging patterns in the density of polaritons in semiconductor microcavities were found to be a promising candidate for all-optical switching. But recent approaches were mostly restricted to scalar fields, did not benefit from the polariton's unique spin-dependent properties, and utilized switching based on hexagon far-field patterns with 60{\deg} beam switching (i.e. in the far field the beam propagation direction is switched by 60{\deg}). Since hexagon far-field patterns are challenging, we present here an approach for a linearly polarized spinor field, that allows for a transistor-like (e.g., crucial for cascadability) orthogonal beam switching, i.e. in the far field the beam is switched by 90{\deg}. We show that switching specifications such as amplification and speed can be adjusted using only optical means

RELBET 4.0 user's guide

This manual describes the operation and use of RELBET 4.0 implemented on the Hewlett Packard model 9000. The RELBET System is an integrated collection of computer programs which support the analysis and post-flight reconstruction of vehicle to vehicle relative trajectories of two on-orbit free-flying vehicles: the Space Shuttle Orbiter and some other free-flyer. The manual serves both as a reference and as a training guide. Appendices provide experienced users with details and full explanations of program usage. The body of the manual introduces new users to the system by leading them through a step by step example of a typical production. This should equip the new user both to execute a typical production process and to understand the most significant variables in that process

Slope Stability Evaluation for an Existing Steep Cut in Weathered Volcanics, Hong Kong

This case study concerns an investigation of a major existing soil slope. It is a 60m (197 ft) high cutting slope, at 40 degrees to 60 degrees to the horizontal, exhibiting a considerably greater degree of stability than was obtained by a series of geotechnical investigations and analyses. The common practice of correlation between widely spaced borings is shown to be inappropriate at this site because of the highly variable ground conditions. Rather, the comprehensive geological comprehensive engineering investigation carried out has enabled a detailed appreciation of the distribution and nature of weathered materials at the site. Transitional materials with soil-like appearance and weak rock properties have been identified. Based on this information, slope stability evaluation was carried out with more realistic results and with greater confidence

Nonet Symmetry and Two-Body Decays of Charmed Mesons

The decay of charmed mesons into pseudoscalar (P) and vector (V) mesons is studied in the context of nonet symmetry. We have found that it is badly broken in the PP channels and in the P sector of the PV channels as expected from the non-ideal mixing of the \eta and the \eta'. In the VV channels, it is also found that nonet symmetry does not describe the data well. We have found that this discrepancy cannot be attributed entirely to SU(3) breaking at the usual level of 20--30%. At least one, or both, of nonet and SU(3) symmetry must be very badly broken. The possibility of resolving the problem in the future is also discussed.Comment: 9 pages, UTAPHY-HEP-

Prospects for detection of Υ(1D)→Υ(1S)ππ\Upsilon(1D) \to \Upsilon(1S) \pi \pi via Υ(3S)→Υ(1D)+X\Upsilon(3S) \to \Upsilon(1D) + X

At least one state in the first family of D-wave $b \bar b$ quarkonium levels has been discovered near the predicted mass of 10.16 GeV/$c^2$. This state is probably the one with J=2. This state and the ones with J=1 and J=3 may contribute a detectable amount to the decay $\Upsilon(1D) \to \Upsilon(1S) \pi \pi$, depending on the partial widths for these decays for which predictions vary considerably. The prospects for detection of the chain $\Upsilon(3S) \to \Upsilon(1D) + X \to \Upsilon \pi \pi + X$ are discussed.Comment: 4 pages, LaTeX, 1 figure, to be published in Phys. Rev. D, comment added after Eq. (2

A Field Test Study on under Water Vacuum Preloading Method

Vacuum preloading technique incorporating prefabricated vertical drains is one of the most widely used ground improvement methods in the world for improving the engineering properties of soft clays. Although many successful on-shore cases on application of the technique have been reported, the effectiveness of applying the technique under water has not yet been investigated. Moreover, many technical and operation factors, that are playing important roles in vacuum consolidation, are also not yet fully understood. To study the feasibility of under water vacuum preloading, a large-scale field test was conducted. A 50 m by 50 m geo-membrane was laid under water in an 80 m wide by 100 m long pond. The geo-membrane was custom made with drainage outlet pipes to release the trapped air bubbles during the placement under water. Prefabricated vertical drains were installed on an equilateral triangular grid at a spacing of 1.2 m to a depth of 7 m. Internal drainage pipes were provided in the sand cushion layers to provide a passage for the prefabricated vertical drains with the external vacuum pumps. Instruments such as piezometers, vacuum sensors, inclinometers, settlement plates and extensometers were installed to monitor the performance of the system. An automatic and remote wireless monitoring system was installed for data collection because of difficult access. Vane shear tests and cone penetration tests were conducted before and after vacuum preloading to determine the effectiveness of the operation. This paper documents the constructions of the field test and reports the major observations from the monitored readings. The operation has demonstrated that under water vacuum preloading is feasible and that with proper design and construction procedure, a very tight seal can be provided by the geo-membrane separating the water and the underlying prefabricated vertical drains through out the test. The monitored results demonstrate that the stiffness and strength of the soft clay can be improved effectively

Conditional q-Entropies and Quantum Separability: A Numerical Exploration

We revisit the relationship between quantum separability and the sign of the relative q-entropies of composite quantum systems. The q-entropies depend on the density matrix eigenvalues p_i through the quantity omega_q = sum_i p_i^q. Renyi's and Tsallis' measures constitute particular instances of these entropies. We perform a systematic numerical survey of the space of mixed states of two-qubit systems in order to determine, as a function of the degree of mixture, and for different values of the entropic parameter q, the volume in state space occupied by those states characterized by positive values of the relative entropy. Similar calculations are performed for qubit-qutrit systems and for composite systems described by Hilbert spaces of larger dimensionality. We pay particular attention to the limit case q --> infinity. Our numerical results indicate that, as the dimensionalities of both subsystems increase, composite quantum systems tend, as far as their relative q-entropies are concerned, to behave in a classical way

Remote state preparation and teleportation in phase space

Continuous variable remote state preparation and teleportation are analyzed using Wigner functions in phase space. We suggest a remote squeezed state preparation scheme between two parties sharing an entangled twin beam, where homodyne detection on one beam is used as a conditional source of squeezing for the other beam. The scheme works also with noisy measurements, and provide squeezing if the homodyne quantum efficiency is larger than 50%. Phase space approach is shown to provide a convenient framework to describe teleportation as a generalized conditional measurement, and to evaluate relevant degrading effects, such the finite amount of entanglement, the losses along the line, and the nonunit quantum efficiency at the sender location.Comment: 2 figures, revised version to appear in J.Opt.