Continuous wave detector has wide frequency range

Portable battery-operated detector indicates the presence of steady state signals exceeding a predetermined value over a wide frequency range by the closure of output relay contacts. It was designed to monitor electronic equipment used in the Saturn 2 program

Time-Resolved Ultraviolet Observations of the Globular Cluster X-ray Source in NGC 6624: The Shortest Known Period Binary System

Using the Faint Object Spectrograph (FOS) aboard the Hubble Space Telescope, we have obtained the first time-resolved spectra of the King et al. ultraviolet-bright counterpart to the 11-minute binary X-ray source in the core of the globular cluster NGC 6624. This object cannot be readily observed in the visible, even from HST, due to a much brighter star superposed <0.1'' distant. Our FOS data show a highly statistically significant UV flux modulation with a period of 11.46+-0.04 min, very similar to the 685 sec period of the known X-ray modulation, definitively confirming the association between the King et al. UV counterpart and the intense X-ray source. The UV amplitude is very large compared with the observed X-ray oscillations: X-ray variations are generally reported as 2-3% peak-to-peak, whereas our data show an amplitude of about 16% in the 126-251 nm range. A model for the system by Arons & King predicts periodic UV fluctuations in this shortest-known period binary system, due to the cyclically changing aspect of the X-ray heated face of the secondary star (perhaps a very low mass helium degenerate). However, prior to our observations, this predicted modulation has not been detected. Employing the Arons & King formalism, which invokes a number of different physical assumptions, we infer a system orbital inclination 35deg<i<50 deg. Amongst the three best-studied UV/optical counterparts to the intense globular cluster X-ray sources, two are now thought to consist of exotic double-degenerate ultrashort period binary systems.Comment: 10 pages including 2 figures in Latex (AASTeX 4.0). Accepted for publication in vol. 482 (1997 June 10 issue) of The Astrophysical Journal (Letters

Specific heat of the ideal gas obeying the generalized exclusion statistics

We calculate the specific heat of the ideal gas obeying the generalized exclusion statistics (GES) in the continuum model and the tight binding model numerically. In the continuum model of 3-d space, the specific heat increases with statistical parameter at low temperature whereas it decreases with statistical parameter at high temperature. We find that the critical temperature normalized by $\mu_f$ (Fermi energy) is 0.290. The specific heat of 2-d space was known to be independent of $g$ in the continuum model, but it varies with $g$ drastically in the tight-binding model. From its unique behavior, identification of GES particles will be possible from the specific heat.Comment: 14 pages, 9 figures, to be published in Eur. Phys. J. B, References and figures added, typos corrected, one section removed and two sections merge

A Search for the Optical Counterpart of the Luminous X-ray Source in NGC 6652

We examine images of the field of X1832-330, the luminous (Lx ~ 10^36 erg/s) X-ray burst source near the center of the globular cluster NGC 6652, in order to identify the optical counterpart for further study. U and B ground-based images allow us to set a limit M_B > 3.5 for the counterpart at the time of those observations, provided that the color is (U-B)_0 ~ -1, similar to the sources known in other clusters. Archival Hubble Space Telescope observations survey most but not all of the 1 sigma X-ray error circle, and allow us to set limits M_B > 5.9 and M_B > 5.2 in the WF/PC and WFPC2 regions, respectively. In the WF/PC images we do weakly detect a faint object with UV-excess, but it is located 11.7'' from the ROSAT X-ray position. This considerable (2.3 sigma) discrepancy in position suggests that this candidate be treated with caution, but it remains the only reasonable one advanced thus far. We measure for this star m_439 = 20.2 +- 0.2, (m_336 - m_439) = -0.5 +- 0.2, and estimate M_B = 5.5, (U-B)_0 = -0.9, similar to other known optical counterparts. If this candidate is not the identification, our limits imply that the true counterpart, not yet identified, is probably the optically-faintest cluster source yet known, or alternatively that it did not show significant UV excess at the time of these observations. Finally, we assess the outlook for the identification of the remaining luminous globular cluster X-ray sources.Comment: 15 pages including 5 figures and no tables. Accepted for publication in The Astronomical Journal; to appear in Volume 116, September 1998. A preprint with full resolution figures may be downloaded from http://www.astro.washington.edu/deutsch/pubs

Adiabatic Quantum Computation in Open Systems

We analyze the performance of adiabatic quantum computation (AQC) under the effect of decoherence. To this end, we introduce an inherently open-systems approach, based on a recent generalization of the adiabatic approximation. In contrast to closed systems, we show that a system may initially be in an adiabatic regime, but then undergo a transition to a regime where adiabaticity breaks down. As a consequence, the success of AQC depends sensitively on the competition between various pertinent rates, giving rise to optimality criteria.Comment: v2: 4 pages, 1 figure. Published versio

Calculating the relative entropy of entanglement

We extend Vedral and Plenio's theorem (theorem 3 in Phys. Rev. A 57, 1619) to a more general case, and obtain the relative entropy of entanglement for a class of mixed states, this result can also follow from Rains' theorem 9 in Phys. Rev. A 60, 179.Comment: 2 pages, RevTex, an important reference adde

Multipartite pure-state entanglement and the generalized GHZ states

We show that not all 4-party pure states are GHZ reducible (i.e., can be generated reversibly from a combination of 2-, 3- and 4-party maximally entangled states by local quantum operations and classical communication asymptotically) through an example, we also present some properties of the relative entropy of entanglement for those 3-party pure states that are GHZ reducible, and then we relate these properties to the additivity of the relative entropy of entanglement.Comment: 7 pages, Revtex, type error correcte

Fiber-Cavity-Based Optomechanical Device

We describe an optomechanical device consisting of a fiber-based optical cavity containing a silicon nitiride membrane. In comparison with typical free-space cavities, the fiber-cavity's small mode size (10 {\mu}m waist, 80 {\mu}m length) allows the use of smaller, lighter membranes and increases the cavity-membrane linear coupling to 3 GHz/nm and quadratic coupling to 20 GHz/nm^2. This device is also intrinsically fiber-coupled and uses glass ferrules for passive alignment. These improvements will greatly simplify the use of optomechanical systems, particularly in cryogenic settings. At room temperature, we expect these devices to be able to detect the shot noise of radiation pressure.Comment: 4 pages, 3 figures; the following article has been submitted to Applied Physics Letter

Daubechies Wavelets for Linear Scaling Density Functional Theory

We demonstrate that Daubechies wavelets can be used to construct a minimal set of optimized localized contracted basis functions in which the Kohn-Sham orbitals can be represented with an arbitrarily high, controllable precision. Ground state energies and the forces acting on the ions can be calculated in this basis with the same accuracy as if they were calculated directly in a Daubechies wavelets basis, provided that the amplitude of these contracted basis functions is sufficiently small on the surface of the localization region, which is guaranteed by the optimization procedure described in this work. This approach reduces the computational costs of DFT calculations, and can be combined with sparse matrix algebra to obtain linear scaling with respect to the number of electrons in the system. Calculations on systems of 10,000 atoms or more thus become feasible in a systematic basis set with moderate computational resources. Further computational savings can be achieved by exploiting the similarity of the contracted basis functions for closely related environments, e.g. in geometry optimizations or combined calculations of neutral and charged systems

Magnetic Domain Patterns Depending on the Sweeping Rate of Magnetic Fields

The domain patterns in a thin ferromagnetic film are investigated in both experiments and numerical simulations. Magnetic domain patterns under a zero field are usually observed after an external magnetic field is removed. It is demonstrated that the characteristics of the domain patterns depend on the decreasing rate of the external field, although it can also depend on other factors. Our numerical simulations and experiments show the following properties of domain patterns: a sea-island structure appears when the field decreases rapidly from the saturating field to the zero field, while a labyrinth structure is observed for a slowly decreasing field. The mechanism of the dependence on the field sweeping rate is discussed in terms of the concepts of crystallization.Comment: 4 pages, 3 figure