A Paley-Wiener theorem for reductive symmetric spaces

Let X = G/H be a reductive symmetric space and K a maximal compact subgroup of G. The image under the Fourier transform of the space of K-finite compactly supported smooth functions on X is characterized.Comment: 31 pages, published versio

Paley-Wiener spaces for real reductive Lie groups

We show that Arthur's Paley-Wiener theorem for K-finite compactly supported smooth functions on a real reductive Lie group G of the Harish-Chandra class can be deduced from the Paley-Wiener theorem we established in the more general setting of a reductive symmetric space. In addition, we formulate an extension of Arthur's theorem to K-finite compactly supported generalized functions (distributions) on G and show that this result follows from the analogous result for reductive symmetric spaces as well.Comment: Latex2e, 28 pages, change of definition of space P^* on p. 17 + minor correction

Development of a unique laboratory standard indium gallium arsenide detector for the 500 to 1700 micron spectral region, phase 2

In the course of this work, 5 mm diameter InGaAs pin detectors were produced which met or exceeded all of the goals of the program. The best results achieved were: shunt resistance of over 300 K ohms; rise time of less than 300 ns; contact resistance of less than 20 ohms; quantum efficiency of over 50 percent in the 0.5 to 1.7 micron range; and devices were maintained and operated at 125 C without deterioration for over 100 hours. In order to achieve the goals of this program, several major technological advances were realized, among them: successful design, construction and operation of a hydride VPE reactor capable of growing epitaxial layers on 2 inch diameter InP substrates with a capacity of over 8 wafers per day; wafer processing was upgraded to handle 2 inch wafers; a double layer Si3N4/SiO2 antireflection coating which enhances response over the 0.5 to 1.7 micron range was developed; a method for anisotropic, precisely controlled CH4/H2 plasma etching for enhancement of response at short wavelengths was developed; and electronic and optical testing methods were developed to allow full characterization of detectors with size and spectral response characteristics. On the basis of the work and results achieved in this program, it is concluded that large size, high shunt resistance, high quantum efficiency InGaAs pin detectors are not only feasible but also manufacturable on industrial scale. This device spans a significant portion of visible and near infrared spectral range and it will allow a single detector to be used for the 0.5 to 1.7 micron spectral region, rather than the presently used silicon (for 0.5 to 1.1 microns) and germanium (0.8 to 1.7 microns)

Experimental Demonstration of a Synthetic Lorentz Force by Using Radiation Pressure

Synthetic magnetism in cold atomic gases opened the doors to many exciting novel physical systems and phenomena. Ubiquitous are the methods used for the creation of synthetic magnetic fields. They include rapidly rotating Bose-Einstein condensates employing the analogy between the Coriolis and the Lorentz force, and laser-atom interactions employing the analogy between the Berry phase and the Aharonov-Bohm phase. Interestingly, radiation pressure - being one of the most common forces induced by light - has not yet been used for synthetic magnetism. We experimentally demonstrate a synthetic Lorentz force, based on the radiation pressure and the Doppler effect, by observing the centre-of-mass motion of a cold atomic cloud. The force is perpendicular to the velocity of the cold atomic cloud, and zero for the cloud at rest. Our novel concept is straightforward to implement in a large volume, for a broad range of velocities, and can be extended to different geometries.Comment: are welcom

Photon number states generated from a continuous-wave light source

Conditional preparation of photon number states from a continuous-wave nondegenerate optical parametric oscillator is investigated. We derive the phase space Wigner function for the output state conditioned on photo detection events that are not necessarily simultaneous, and we maximize its overlap with the desired photon number state by choosing the optimal temporal output state mode function. We present a detailed numerical analysis for the case of two-photon state generation from a parametric oscillator driven with an arbitrary intensity below threshold, and in the low intensity limit, we present a formalism that yields the optimal output state mode function and fidelity for higher photon number states.Comment: 8 pages, 7 figures, v2: shortened versio

Structural Insights into Heterodimerization and Catalysis of the Human Cis- prenyltransferase “NgBR/DHDDS” Complex

Cis-prenyltransferses (cis-PTases) constitute a family of enzymes involved in the synthesis of isoprenoid lipids required for various biological functions across all domains of life. The eukaryotic cis-PTase catalyzes the rate-limiting step in the synthesis of dolichyl phosphate, an indispensable glycosyl carrier lipid required for protein glycosylation in the lumen of endoplasmic reticulum. Based on enzyme composition, cis-PTases can be either homomeric or heteromeric enzymes. The human cis-PTase possesses a heteromeric configuration consisting of the two evolutionary related subunits: NgBR (dehydrodolichyl diphosphate synthase accessory subunit, first identified as a Nogo-B receptor) and DHDDS (dehydrodolichyl diphosphate synthase catalytic subunit). Recently, several mutations in both subunits have been reported to associate with various human diseases, collectively known as congenital disorders of glycosylation (CDG), including severe CDG type I, developmental and epileptic encephalopathy, and autosomal recessive retinitis pigmentosa. In addition, mutations on the NgBR subunit have been recently reported in patients suffering from early onset of Parkinson’s disease (EOPD). Despite its crucial role in the protein glycosylation process, the molecular mechanism of heteromeric cis-PTases remains poorly understood due to lack of structural-functional studies on these enzymes, in contrast to homodimeric cis-PTases which have been extensively studied. Therefore, in this dissertation, I illustrate the first crystal structure of a heteromeric, human cis-PTase NgBR/DHDDS complex solved at 2.3 Å. The structure revealed novel features that were not previously observed in homodimeric enzymes, including a new dimeric interface formed by a unique C-terminus in DHDDS and a novel N-terminal segment in DHDDS serving as a membrane sensor for lipid activation. In addition, the structure elucidated the molecular details associated with substrate binding, catalysis, and disease-causing mutations. Finally, the structure provided novel insights into the mechanism of product chain elongation, an interesting yet one of the most enigmatic topics on prenyl chain elongating enzymes. In summary, the crystal structure advances our understanding of the molecular mechanism of heteromeric cis-PTase enzymes

Manipulation of the graphene surface potential by ion irradiation

We show that the work function of exfoliated single layer graphene can be modified by irradiation with swift (E_{kin}=92 MeV) heavy ions under glancing angles of incidence. Upon ion impact individual surface tracks are created in graphene on SiC. Due to the very localized energy deposition characteristic for ions in this energy range, the surface area which is structurally altered is limited to ~ 0.01 mum^2 per track. Kelvin probe force microscopy reveals that those surface tracks consist of electronically modified material and that a few tracks suffice to shift the surface potential of the whole single layer flake by ~ 400 meV. Thus, the irradiation turns the initially n-doped graphene into p-doped graphene with a hole density of 8.5 x 10^{12} holes/cm^2. This doping effect persists even after heating the irradiated samples to 500{\deg}C. Therefore, this charge transfer is not due to adsorbates but must instead be attributed to implanted atoms. The method presented here opens up a new way to efficiently manipulate the charge carrier concentration of graphene.Comment: 6 pages, 4 figure

Synthetic Lorentz force in classical atomic gases via Doppler effect and radiation pressure

We theoretically predict a novel type of synthetic Lorentz force for classical (cold) atomic gases, which is based on the Doppler effect and radiation pressure. A fairly uniform and strong force can be constructed for gases in macroscopic volumes of several cubic millimeters and more. This opens the possibility to mimic classical charged gases in magnetic fields, such as those in a tokamak, in cold atom experiments.Comment: are welcom

Detecting swift heavy ion irradiation effects with graphene

In this paper we show how single layer graphene can be utilized to study swift heavy ion (SHI) modifications on various substrates. The samples were prepared by mechanical exfoliation of bulk graphite onto SrTiO$_3$, NaCl and Si(111), respectively. SHI irradiations were performed under glancing angles of incidence and the samples were analysed by means of atomic force microscopy in ambient conditions. We show that graphene can be used to check whether the irradiation was successful or not, to determine the nominal ion fluence and to locally mark SHI impacts. In case of samples prepared in situ, graphene is shown to be able to catch material which would otherwise escape from the surface.Comment: 10 pages, 3 figure