Results for "Holger S. P. Müller"

total 234288took 0.18s
Spectroscopic parameters of phosphine, PH3, in its ground vibrational stateMay 06 2013The ground state rotational spectrum of PH3 has been reanalyzed taking into account recently published very accurate data from sub-Doppler and conventional absorption spectroscopy measurements as well as previous data from the radio-frequency to the far-infrared ... More
Submillimeter spectroscopy of H$_2$C$^{17}$O and a revisit of the rotational spectra of H$_2$C$^{18}$O and H$_2$C$^{16}$OOct 07 2016Mar 12 2019The rotational spectrum of the formaldehyde isotopologue H$_2$C$^{17}$O was investigated between 0.56 and 1.50 THz using a sample of natural isotopic composition. In addition, transition frequencies were determined for H$_2$C$^{18}$O and H$_2$C$^{16}$O ... More
Submillimeter spectroscopy of H$_2$C$^{17}$O and a revisit of the rotational spectra of H$_2$C$^{18}$O and H$_2$C$^{16}$OOct 07 2016The rotational spectrum of the formaldehyde isotopologue H2C(17)O was investigated between 0.56 and 1.50 THz using a sample of natural isotopic composition. In addition, transition frequencies were determined for H2C(18)O and H2C(16)O between 1.37 and ... More
The spectroscopic parameters of sodium cyanide, NaCN (X 1A'), revisitedJan 03 2012The study of the rotational spectrum of NaCN (X 1A') has recently been extended in frequency and in quantum numbers. Difficulties have been encountered in fitting the transition frequencies within experimental uncertainties. Various trial fits traced ... More
Rotational spectra of isotopic species of methyl cyanide, CH3CN, in their ground vibrational states up to terahertz frequenciesOct 16 2009Methyl cyanide is an important trace molecule in star-forming regions. It is one of the more common molecules used to derive kinetic temperatures in such sources. As preparatory work for Herschel, SOFIA, and in particular ALMA we want to improve the rest ... More
Rotational spectra of isotopic species of methyl cyanide, CH$_3$CN, in their ground vibrational states up to terahertz frequenciesOct 16 2009Mar 20 2019Methyl cyanide is an important trace molecule in star-forming regions. It is one of the more common molecules used to derive kinetic temperatures in such sources. As preparatory work for Herschel, SOFIA, and in particular ALMA we want to improve the rest ... More
The CDMS view on molecular data needs of Herschel, SOFIA, and ALMAApr 06 2013The catalog section of the Cologne Database for Molecular Spectroscopy, CDMS, contains mostly rotational transition frequencies, with auxiliary information, of molecules observable in space. The frequency lists are generated mostly from critically evaluated ... More
The Cologne Database for Molecular Spectroscopy, CDMS, in the Virtual Atomic and Molecular Data Centre, VAMDCMar 10 2016The CDMS was founded 1998 to provide in its catalog section line lists of molecular species which may be observed in various astronomical sources using radio astronomy. The line lists contain transition frequencies with qualified accuracies, intensities, ... More
Millimeter and Submillimeter Wave Spectroscopy of PropanalJul 07 2017The rotational spectra of the two stable conformers syn- and gauche-propanal (CH3CH2CHO) were studied in the millimeter and submillimeter wave regions from 75 to 500 GHz with the Cologne (Sub-)Millimeter wave Spectrometer. Furthermore, the first excited ... More
Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)Aug 23 2013The discovery of amino acids in meteorites and the detection of glycine in samples returned from a comet to Earth suggest that the interstellar chemistry is capable of producing such complex organic molecules. Our goal is to investigate the degree of ... More
Terahertz spectroscopy of N$^{18}$O and isotopic invariant fit of several nitric oxide isotopologsDec 16 2014A tunable far-infrared laser sideband spectrometer was used to investigate a nitric oxide sample enriched in 18O between 0.99 and 4.75 THz. Regular, electric dipole transitions were recorded between 0.99 and 2.52 THz, while magnetic dipole transitions ... More
Millimeter and Submillimeter Wave Spectroscopy of PropanalJul 07 2017Mar 13 2019The rotational spectra of the two stable conformers syn- and gauche-propanal (CH$_3$CH$_2$CHO) were studied in the millimeter and submillimeter wave regions from 75 to 500 GHz with the Cologne (Sub-)Millimeter wave Spectrometer. Furthermore, the first ... More
Detection of a branched alkyl molecule in the interstellar medium: iso-propyl cyanideOct 09 2014The largest non-cyclic molecules detected in the interstellar medium (ISM) are organic with a straight-chain carbon backbone. We report an interstellar detection of a branched alkyl molecule, iso-propyl cyanide (i-C3H7CN), with an abundance 0.4 times ... More
ExoMol Line List XXI: Nitric Oxide (NO)May 16 2017Line lists for the ground electronic ground state for six major isotopologues of nitric oxide are presented. The line lists are constructed using empirical energy levels (and line positions) and high-level {\it ab inito} intensities. The energy levels ... More
Rotational spectroscopy, dipole moment and $^{14}$N nuclear hyperfine structure of $iso$-propyl cyanideFeb 28 2011Rotational transitions of $iso$-propyl cyanide, (CH$_3$)$_2$CHCN, also known as $iso$-butyronitrile, were recorded using long-path absorption spectroscopy in selected regions between 37 and 600 GHz. Further measurements were carried out between 6 and ... More
Rotational spectroscopy of isotopic vinyl cyanide, H$_2$C=CH$-$C$\equiv$N, in the laboratory and in spaceJun 12 2008The rotational spectra of singly substituted $^{13}$C and $^{15}$N isotopic species of vinyl cyanide have been studied in natural abundances between 64 and 351 GHz. In combination with previous results, greatly improved spectroscopic parameters have been ... More
Spectroscopic parameters and rest frequencies of isotopic methylidynium, CH+Apr 29 2010Astronomical observations toward Sagittarius B2(M) as well as other sources with APEX have recently suggested that the rest frequency of the J = 1 - 0 transitions of 13CH+ is too low by about 80 MHz. Improved rest frequencies of isotopologs of methylidynium ... More
Deuterated methyl mercaptan (CH$_3$SD): Laboratory rotational spectroscopy and search toward IRAS 16293-2422 BDec 06 2018Mar 12 2019Methyl mercaptan (also known as methanethiol), CH3SH, has been found in the warm and dense parts of high -- as well as low -- mass star-forming regions. The aim of the present study is to obtain accurate spectroscopic parameters of the S-deuterated methyl ... More
Deuterated methyl mercaptan (CH$_3$SD): Laboratory rotational spectroscopy and search toward IRAS 16293-2422 BDec 06 2018Methyl mercaptan (also known as methanethiol), CH3SH, has been found in the warm and dense parts of high -- as well as low -- mass star-forming regions. The aim of the present study is to obtain accurate spectroscopic parameters of the S-deuterated methyl ... More
Spectroscopic line parameters of NO, NO$_2$, and N$_{2}$O for the HITEMP databaseApr 04 2019This work describes the update of NO along with the incorporation of NO$_{2}$ and N$_{2}$O to the HITEMP database. Where appropriate, the HITRAN line lists for the same molecules have also been updated. This work brings the current number of molecules ... More
Rotational spectroscopy as a tool to investigate interactions between vibrational polyads in symmetric top molecules: low-lying states v8 <= 2 of methyl cyanide, CH$_3$CNFeb 24 2015Spectra of methyl cyanide were recorded to analyze interactions in low-lying vibrational states and to construct line lists for radio astronomical observations as well as for infrared spectroscopic investigations of planetary atmospheres. The rotational ... More
Detection of extragalactic argonium, ArH$^+$, toward PKS~1830$-$211Sep 23 2015Argonium has recently been detected as a ubiquitous molecule in our Galaxy. Model calculations indicate that its abundance peaks at molecular fractions in the range of 1E-4 to 1E-3 and that the observed column densities require high values of the cosmic ... More
Revised spectroscopic parameters of SH$^+$ from ALMA and IRAM 30 m observationsSep 05 2014Hydrides represent the first steps of interstellar chemistry. Sulfanylium (SH$^+$), in particular, is a key tracer of energetic processes. We used ALMA and the IRAM 30 m telescope to search for the lowest frequency rotational lines of SH$^+$ toward the ... More
Rotational spectroscopy as a tool to investigate interactions between vibrational polyads in symmetric top molecules: low-lying states $v_8 \le 2$ of methyl cyanide, CH$_3$CNFeb 24 2015Mar 13 2019Spectra of methyl cyanide were recorded to analyze interactions in low-lying vibrational states and to construct line lists for radio astronomical observations as well as for infrared spectroscopic investigations of planetary atmospheres. The rotational ... More
Laboratory spectroscopic study and astronomical detection of vibrationally excited n-propyl cyanideAug 29 2016We performed a spectral line survey called Exploring Molecular Complexity with ALMA (EMoCA) toward Sagittarius~B2(N) between 84.1 and 114.4 GHz with the Atacama Large Millimeter/submillimeter Array (ALMA) in its Cycles 0 and 1. We determined line intensities ... More
Rotational and high-resolution infrared spectrum of HC$_3$N: global ro-vibrational analysis and improved line catalogue for astrophysical observationsNov 23 2017HC$_3$N is an ubiquitous molecule in interstellar environments, from external galaxies, to Galactic interstellar clouds, star forming regions, and planetary atmospheres. Observations of its rotational and vibrational transitions provide important information ... More
Dimethyl ether in its ground state, v=0, and lowest two torsionally excited states, v11=1 and v15=1, in the high-mass star-forming region G327.3-0.6Feb 25 2013The goal of this paper is to determine the respective importance of solid state vs. gas phase reactions for the formation of dimethyl ether. This is done by a detailed analysis of the excitation properties of the ground state and the torsionally excited ... More
The ALMA-PILS survey: The sulphur connection between protostars and comets: IRAS 16293-2422 B and 67P/Churyumov-GerasimenkoFeb 08 2018Feb 21 2018The evolutionary past of our Solar System can be pieced together by comparing analogous low-mass protostars with remnants of our Protosolar Nebula - comets. Sulphur-bearing molecules may be unique tracers of the joint evolution of the volatile and refractory ... More
The ALMA-PILS survey: The sulphur connection between protostars and comets: IRAS 16293-2422 B and 67P/Churyumov-GerasimenkoFeb 08 2018The evolutionary past of our Solar System can be pieced together by comparing analogous low-mass protostars with remnants of our Protosolar Nebula - comets. Sulphur-bearing molecules may be unique tracers of the joint evolution of the volatile and refractory ... More
Towards a Process for Developing Maintenance Tools in AcademiaAug 03 2008Building of tools--from simple prototypes to industrial-strength applications--is a pervasive activity in academic research. When proposing a new technique for software maintenance, effective tool support is typically required to demonstrate the feasibility ... More
Research Challenges in Management and Compliance of Policies on the WebJul 30 2008In this paper we argue that policies are an increasing concern for organizations that are operating a web site. Examples of policies that are relevant in the domain of the web address issues such as privacy of personal data, accessibility for the disabled, ... More
Gravity surveys using a mobile atom interferometerApr 19 2019Mobile gravimetry is important in metrology, navigation, geodesy, and geophysics. Atomic gravimeters could be among the most accurate mobile gravimeters, but are currently constrained by being complex and fragile. Here, we demonstrate a mobile atomic ... More
Molecular Data: Division B / Commission 14 / Working Group Molecular DataOct 29 2015The current report covers the period from the second half of 2011 to late 2014. It is divided into three areas covering rotational, vibrational, and electronic spectroscopy. A signifcant amount of experimental and theoretical work has been accomplished ... More
Division Xii/commission 14/WORKING Group on Molecular DataNov 07 2012The current report covers the period from the second half of 2003 to the first half of 2011, bringing the Working Group's efforts up to date, and is divided into three main sections covering rotational, vibrational, and electronic spectroscopy. Rather ... More
On the existence of curves in K-trivial threefoldsNov 17 1998We give a criterion for a continuous family of curves on a nodal $K$-trivial threefold $X_0$ to contribute geometrically rigid curves to a general smoothing of $X_0$. As an application, we prove the existence of geometrically rigid curves of arbitrary ... More
Waveguide properties of single subwavelength holes demonstrated with radially and azimuthally polarized lightAug 10 2007We investigate the transmission of focused beams through single subwavelength holes in a silver film. We use radially and azimuthally polarized light, respectively, to excite higher order waveguide modes as well as to match the radial symmetry of the ... More
Spatial inhomogeneity and temporal dynamics of a 2D electron gas in interaction with a 2D adatom gasOct 17 2016Sep 13 2017Fundamental interest for 2D electron gas (2DEG) systems has been recently renewed with the advent of 2D materials and their potential high-impact applications in optoelectronics. Here, we investigate a 2DEG created by the electron transfer from a Ag adatom ... More
Spatial in-homogeneity and temporal dynamics of a 2D electron gas in interaction with a 2D adatom gasOct 17 2016Fundamental interest for 2D electron gas (2DEG) systems has been recently renewed with the advent of 2D materials and their potential high-impact applications. Here, we investigate a 2DEG created by the electron transfer from a Ag-2D adatom gas (Ag-2DAG) ... More
Engineered Open Systems and Quantum Simulations with Atoms and IonsMar 29 2012The enormous experimental progress in atomic, molecular and optical (AMO) physics during the last decades allows us nowadays to isolate single, a few or even many-body ensembles of microscopic particles, and to manipulate their quantum properties at a ... More
(1173) Anchises - Thermophysical and Dynamical Studies of a Dynamically Unstable Jovian TrojanApr 06 2012We have performed detailed thermophysical and dynamical modelling of Jovian Trojan (1173) Anchises. Our results reveal a most unusual object. By examining observational data taken by IRAS, Akari and WISE between 11.5 and 60 microns, along with variations ... More
Policy and Legal Challenges of Virtual Worlds and Social Network SitesAug 09 2008This paper addresses policy challenges of complex virtual environments such as virtual worlds, social network sites, and massive multiplayer online games. The complexity of these environments--apparent by the rich user interactions and sophisticated user-generated ... More
Embedded Control System for Mobile Atom InterferometersDec 03 2018Atom interferometers require precise control of digital, analog, and radio frequency signals for effective operation. In this paper, we propose and implement a control system for mobile atom interferometers. The system consists of a microcontroller and ... More
Gravity gradient suppression in spaceborne atomic tests of the equivalence principleDec 06 2016Mar 01 2017The gravity gradient is one of the most serious systematic effects in atomic tests of the equivalence principle (EP). While differential acceleration measurements performed with different atomic species under free fall test the validity of EP, minute ... More
Multi-party authorization and conflict mediation for decentralized configuration management processesMar 19 2019Configuration management in networks with highest security demands must not depend on just one administrator and her device. Otherwise, problems can be caused by mistakes or malicious behavior of this admin, or when her computer got compromised, which ... More
Gravity gradient suppression in spaceborne atomic tests of the equivalence principleDec 06 2016The gravity gradient is one of the most serious systematic effects in atomic tests of the equivalence principle (EP). While differential acceleration measurements performed with different atomic species under free fall test the validity of EP, minute ... More
Test of the isotropy of the speed of light using a continuously rotating optical resonatorAug 15 2005We report on a test of Lorentz invariance performed by comparing the resonance frequencies of one stationary optical resonator and one continuously rotating on a precision air bearing turntable. Special attention is paid to the control of rotation induced ... More
Hyperfine structure in the J = 1-0 transitions of DCO+, DNC, and HN13C: astronomical observations and quantum-chemical calculationsSep 02 2009We have observed the rotational ground-state (J = 1-0) transitions of DCO+, HN13C and DNC with the IRAM 30m telescope toward the dark cloud LDN 1512 which has exceptionally narrow lines permitting hyperfine splitting to be resolved in part. The measured ... More
Verifying quantum superpositions at metre scalesJul 06 2016Jul 15 2016While the existence of quantum superpositions of massive particles over microscopic separations has been established since the birth of quantum mechanics, the maintenance of superposition states over macroscopic separations is a subject of modern experimental ... More
Splitting the Raman beamsplitterMar 24 2018We present an atom interferometry technique in which the beamsplitter is split into two separate operations. A microwave pulse first creates a spin-state superposition, before optical adiabatic passage spatially separates the arms of that superposition. ... More
Measurement of a $^7$Li tune-out wavelength by phase-patterned atom interferometryApr 18 2019Atom interferometers typically use the total populations the interferometer's output ports as the signal, but finer spatial structure can contain useful information. We pattern a matter-wave phase profile onto an atomic sample. An interferometer translates ... More
Linking interstellar and cometary O$_2$: a deep search for $^{16}$O$^{18}$O in the solar-type protostar IRAS 16293--2422May 31 2018Recent measurements carried out at comet 67P/C-G with the ${\it Rosetta}$ probe revealed that molecular oxygen, O$_2$, is the fourth most abundant molecule in comets. Models show that O$_2$ is likely of primordial nature, coming from the interstellar ... More
Ubiquitous argonium (ArH$^+$) in the diffuse interstellar medium -- a molecular tracer of almost purely atomic gasMar 31 2014Apr 14 2014We describe the assignment of a previously unidentified interstellar absorption line to ArH$^+$ and discuss its relevance in the context of hydride absorption in diffuse gas with a low H$_2$ fraction. The column densities along several lines of sight ... More
Wild Pfister forms over Henselian fields, K-theory, and conic division algebrasFeb 17 2010The epicenter of this paper concerns Pfister quadratic forms over a field $F$ with a Henselian discrete valuation. All characteristics are considered but we focus on the most complicated case where the residue field has characteristic 2 but $F$ does not. ... More
New recursions for genus-zero Gromov-Witten invariantsJul 13 2000New relations among the genus-zero Gromov-Witten invariants of a complex projective manifold $X$ are exhibited. When the cohomology of $X$ is generated by divisor classes and classes ``with vanishing one-point invariants,'' the relations determine many-point ... More
Counting curves which move with threefoldsJul 20 1998Nov 03 1998Let X be a (possibly nodal) K-trivial threefold moving in a fixed ambient space P. Suppose X contains a continuous family of curves, all of whose members satisfy certain unobstructedness conditions in P. A formula is given for computing the corresponding ... More
Groups of outer type E6 with trivial Tits algebrasNov 09 2005In two 1966 papers, Jacques Tits gave a construction of exceptional Lie algebras (hence implicitly exceptional algebraic groups) and a classification of possible indexes of simple algebraic groups. For the special case of his construction that gives groups ... More
Outer automorphisms of algebraic groups and a Skolem-Noether theorem for Albert algebrasAug 24 2015The question of existence of outer automorphisms of a simple algebraic group $G$ arises naturally both when working with the Galois cohomology of $G$ and as an example of the algebro-geometric problem of determining which connected components of the automorphism ... More
Hyperfine Structure in H^{13}CO^{+} and ^{13}CO: measurement, analysis, and consequences for the study of dark cloudsMar 02 2004The magnetic moment of the ^{13}C nucleus is shown to provide a potentially useful tool for analysing quiescent cold molecular clouds. We report discovery of hyperfine structure in the H^{13}CO^{+}(1-0) transition. The doublet splitting is observed to ... More
Radial distributions of sub-populations in the globular cluster M15: a more centrally concentrated primordial populationMar 02 2015We examine the radial distributions of stellar populations in the globular cluster (GC) M15, using HST/WFC3 photometry of red giants in the nitrogen-sensitive F343N-F555W color. Surprisingly, we find that giants with "primordial" composition (i.e., N ... More
Effective dynamics in Hamiltonian systems with mixed phase spaceMar 29 2005An adequate characterization of the dynamics of Hamiltonian systems at physically relevant scales has been largely lacking. Here we investigate this fundamental problem and we show that the finite-scale Hamiltonian dynamics is governed by effective dynamical ... More
Renormalization flow of Yang-Mills propagatorsAug 06 2004Nov 09 2004We study Landau-gauge Yang-Mills theory by means of a nonperturbative vertex expansion of the quantum effective action. Using an exact renormalization group equation, we compute the fully dressed gluon and ghost propagators to lowest nontrivial order ... More
Return interval distribution of extreme events and long term memoryMar 12 2008The distribution of recurrence times or return intervals between extreme events is important to characterize and understand the behavior of physical systems and phenomena in many disciplines. It is well known that many physical processes in nature and ... More
Magnetically-driven electronic phase separation in the semimetallic ferromagnet EuB$_6$Apr 27 2012From measurements of fluctuation spectroscopy and weak nonlinear transport on the semimetallic ferromagnet EuB$_6$ we find direct evidence for magnetically-driven electronic phase separation consistent with the picture of percolation of magnetic polarons ... More
Increased complexity in interstellar chemistry: Detection and chemical modeling of ethyl formate and n-propyl cyanide in Sgr B2(N)Feb 26 2009In recent years, organic molecules of increasing complexity have been found toward the prolific Galactic center source Sagittarius B2. We wish to explore the degree of complexity that the interstellar chemistry can reach in star-forming regions. We carried ... More
Laboratory spectroscopy of 1,2-propanediol at millimeter and submillimeter wavelengthsAug 22 2014Ethanediol is one of the largest complex organic molecules detected in space thus far. It has been found in different types of molecular clouds. The two propanediol isomers are the next larger diols. Hence, they are viable candidates to be searched for ... More
The Solar Electron and Proton Telescope aboard STEREO -- understanding proton spectraJan 29 2018The Solar Electron and Proton Telescope (SEPT) aboard the Solar Terrestrial Relations Observatory (STEREO) is designed to provide the three-dimensional distribution of energetic electrons and protons with good energy and time resolution. Each SEPT instrument ... More
Laboratory spectroscopic study of the $^{15}$N isotopomers of cyanamide, H$_2$NCN, and a search for them toward IRAS 16293$-$2422 BJan 02 2019Cyanamide is one of the few interstellar molecules containing two chemically different N atoms. It was detected recently toward the solar-type protostar IRAS 16293-2422 B together with H$_2$N$^{13}$CN and HDNCN in the course of the Atacama Large Millemeter/submillimeter ... More
Coupled quasimonopoles in chiral magnetsMar 29 2019Magnetic singularities, also known as magnetic monopoles or Bloch points, represent intriguingphenomena in nanomagnetism. We show that a pair of coupled Bloch points may appear as alocalized, stable state in cubic chiral magnets. Detailed analysis is ... More
Investigation of the unidirectional spin heat conveyer effect in a 200nm thin Yttrium Iron Garnet filmFeb 04 2016We have investigated the unidirectional spin wave heat conveyer effect in sub-micron thick yttrium iron garnet (YIG) films using lock-in thermography (LIT). Although the effect is small in thin layers this technique allows us to observe asymmetric heat ... More
An experimental investigation on the high density transition of the Scrape-off Layer transport in ASDEX UpgradeJul 14 2014A multidiagnostic approach, utilizing Langmuir probes in the midplane, X-point and divertor walls, along with Lithium beam and infrared measurements is employed to evaluate the evolution of the Scrape-off Layer (SOL) of ASDEX Upgrade across the L-mode ... More
Numerical Bianchi I solutions in semi-classical gravitationApr 28 2006Aug 15 2006It is believed that soon after the Planck era, spacetime should have a semi-classical nature. In this context we consider quantum fields propagating in a classical gravitational field and study the backreaction of these fields, using the expected value ... More
Domain wall dynamics in a single CrO$_2$ grainJan 26 2011Recently we have reported on the magnetization dynamics of a single CrO$_2$ grain studied by micro Hall magnetometry (P. Das \textit{et al.}, Appl. Phys. Lett. \textbf{97} 042507, 2010). For the external magnetic field applied along the grain's easy magnetization ... More
Ultrafast Local Magnetization and Demagnetization in Heusler AlloysMar 17 2016With the goal of pushing Spintronic devices towards faster and faster timescales, we demonstrate, using ab-intio time-dependent density functional theory simulations of bulk Heusler compounds subject to ultrashort intense laser pulses, that the local ... More
PAMOP: Petascale Atomic, Molecular and Optical Collision CalculationsJan 14 2015Petaflop architectures are currently being utilized efficiently to perform large scale computations in Atomic, Molecular and Optical Collisions. We solve the Schr\"odinger or Dirac equation for the appropriate collision problem using the R-matrix or R-matrix ... More
Butterfly hysteresis loop at non-zero bias field in antiferromagnetic molecular rings: cooling by adiabatic magnetizationOct 14 2002At low temperatures, the magnetization of the molecular ferric wheel NaFe$_6$ exhibits a step at a critical field $B_c$ due to a field-induced level-crossing. By means of high-field torque magnetometry we observed a hysteretic behavior at the level-crossing ... More
Resummation and the semiclassical theory of spectral statisticsAug 17 2007We address the question as to why, in the semiclassical limit, classically chaotic systems generically exhibit universal quantum spectral statistics coincident with those of Random Matrix Theory. To do so, we use a semiclassical resummation formalism ... More
CCH in prestellar coresAug 08 2009We study the abundance of CCH in prestellar cores both because of its role in the chemistry and because it is a potential probe of the magnetic field. We also consider the non-LTE behaviour of the N=1-0 and N=2-1 transitions of CCH and improve current ... More
Exact Demonstration of Magnetization Pleateaus and First Order Dimer-Néel Phase Transitions in a Modified Shastry-Sutherland Model for SrCu$_2$(BO$_3$)$_2$Oct 12 1999We study a generalized Shastry-Sutherland model for the material SrCu$_2$(BO$_3$)$_2$. Along a line in the parameter space, we can show rigorously that the model has a first order phase transition between Dimerized and N\'eel-ordered ground states. Furthermore, ... More
Exploring Molecular Complexity with ALMA (EMoCA): Deuterated complex organic molecules in Sagittarius B2(N2)Nov 18 2015Deuteration is a powerful tracer of the history of the cold prestellar phase in star forming regions. Apart from methanol, little is known about deuterium fractionation of complex organic molecules in the interstellar medium, especially in high mass star ... More
Anisotropic electrical resistivity of LaFeAsO: evidence for electronic nematicityAug 07 2012Oct 17 2012Single crystals of LaFeAsO were successfully grown out of KI flux. Temperature dependent electrical resistivity was measured with current flow along the basal plane, \rho_perpend(T), as well as with current flow along the crystallographic c-axis, \rho_parallel(T), ... More
Phonon-assisted robust and deterministic two-photon biexciton preparation in a quantum dotAug 29 2014We investigate both experimentally and theoretically a simple yet more robust and flexible alternative to Rabi oscillation-type biexciton preparation protocols traditionally used for semiconductor quantum dots. The quantum dot is excited by a strong laser ... More
Antiskyrmions stabilized at interfaces by anisotropic Dzyaloshinskii-Moriya interactionFeb 24 2017May 01 2017Chiral magnets are an emerging class of topological matter harbouring localized and topologically protected vortex-like magnetic textures called skyrmions, which are currently under intense scrutiny as a new entity for information storage and processing. ... More
Symmetry-protected topological phases in lattice gauge theories: topological QED$_2$Apr 27 2018Jan 08 2019The interplay of symmetry, topology, and many-body effects in the classification of possible phases of matter poses a formidable challenge that is attracting great attention in condensed-matter physics. Such many-body effects are typically induced by ... More
Performance of a First-Level Muon Trigger with High Momentum Resolution Based on the ATLAS MDT Chambers for HL-LHCNov 30 2015Highly selective first-level triggers are essential to exploit the full physics potential of the ATLAS experiment at High-Luminosity LHC (HL-LHC). The concept for a new muon trigger stage using the precision monitored drift tube (MDT) chambers to significantly ... More
Continuous 40 GW/cm$^2$ laser intensity in a near-concentric optical cavityOct 26 2016Oct 29 2016Manipulating free-space electron wave functions with laser fields can bring about new electron-optical elements for transmission electron microscopy. In particular, a Zernike phase plate would enable high-contrast imaging of soft matter, leading to new ... More
Sisyphus Cooling of LithiumAug 08 2013Mar 20 2014Laser cooling to sub-Doppler temperatures by optical molasses is thought to be inhibited in atoms with unresolved, near-degenerate hyperfine structure in the excited state. We demonstrate that such cooling is possible in one to three dimensions, not only ... More
Multiaxis atom interferometry with a single diode laser and a pyramidal magneto-optical trapJul 27 2017Feb 11 2018Atom interferometry has become one of the most powerful technologies for precision measurements. To develop simple, precise, and versatile atom interferometers for inertial sensing, we demonstrate an atom interferometer measuring acceleration, rotation, ... More
Large-scale structure formation for power spectra with broken scale invarianceJul 11 1995Jul 13 1995We have simulated the formation of large-scale structure arising from COBE-normalized spectra computed by convolving a primordial double-inflation perturbation spectrum with the CDM transfer function. Due to the broken scale invariance ('BSI') characterizing ... More
Ferroelectric properties of charge-ordered alpha-(BEDT-TTF)2I3Jul 01 2014Jun 19 2015A detailed investigation of the out-of-plane electrical properties of charge-ordered alpha-(BEDT-TTF)2I3 provides clear evidence for ferroelectricity. Similar to multiferroic alpha-(BEDT-TTF)2Cu[N(CN)2]Cl, the polar order in this material is ascribed ... More
Continuous 40 GW/cm$^2$ laser intensity in a near-concentric optical cavityOct 26 2016Dec 13 2016Manipulating free-space electron wave functions with laser fields can bring about new electron-optical elements for transmission electron microscopy. In particular, a Zernike phase plate would enable high-contrast imaging of soft matter, leading to new ... More
Laser Interferometers as Dark Matter DetectorsMay 03 2016While global cosmological and local galactic abundance of dark matter is well established, its identity, physical size and composition remain a mystery. In this paper, we analyze an important question of dark matter detectability through its gravitational ... More
Atom interferometry in an optical cavitySep 25 2014We propose and demonstrate a new scheme for atom interferometry, using light pulses inside an optical cavity as matter wave beamsplitters. The cavity provides power enhancement, spatial filtering, and a precise beam geometry, enabling new techniques such ... More
High-resolution atom interferometers with suppressed diffraction phasesOct 30 2014Jun 02 2015We experimentally and theoretically study the diffraction phase of large-momentum transfer beam splitters in atom interferometers based on Bragg diffraction. We null the diffraction phase and increase the sensitivity of the interferometer by combining ... More
Offset Simultaneous Conjugate Atom InterferometersJan 11 2019Correlating the signals from simultaneous atom interferometers has enabled some of the most precise determinations of fundamental constants. Here, we show that multiple interferometers with strategically chosen initial conditions ("offset simultaneous ... More
Controlling the Multiport Nature of Bragg Diffraction in Atom InterferometrySep 20 2016Bragg diffraction has been used in atom interferometers because it allows signal enhancement through multiphoton momentum transfer and suppression of systematics by not changing the internal state of atoms. Its multi-port nature, however, can lead to ... More
Lithium recoil measurement without a subrecoil sampleOct 24 2016Oct 26 2016We report both the first atom interferometer with a low-mass, laser-cooled atom (lithium-7) and the first simultaneous conjugate Ramsey-Bord\'e interferometers with an atomic ensemble not cooled or selected to subrecoil speeds. Above the recoil temperature, ... More
Chameleon Dark Energy and Atom InterferometryMar 21 2016Atom interferometry experiments are searching for evidence of chameleon scalar fields with ever-increasing precision. As experiments become more precise, so too must theoretical predictions. Previous work has made numerous approximations to simplify the ... More
Measurement of the fine-structure constant as a test of the Standard ModelDec 10 2018Dec 12 2018Measurements of the fine-structure constant alpha require methods from across subfields and are thus powerful tests of the consistency of theory and experiment in physics. Using the recoil frequency of cesium-133 atoms in a matter-wave interferometer, ... More
Detection of amino acetonitrile in Sgr B2(N)Jan 21 2008Mar 04 2008Amino acids are building blocks of proteins and therefore key ingredients for the origin of life. The simplest amino acid, glycine, has long been searched for in the interstellar medium but has not been unambiguously detected so far. Since the search ... More
Lithium recoil measurement without a subrecoil sampleOct 24 2016We report both the first atom interferometer with a low-mass, laser-cooled atom (lithium-7) and the first simultaneous conjugate Ramsey-Bord\'e interferometers with an atomic ensemble not cooled or selected to subrecoil speeds. Above the recoil temperature, ... More