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FullText Articles in Physical Sciences and Mathematics
NarrowBand Search For Gravitational Waves From Known Pulsars Using The Second Ligo Observing Run, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
NarrowBand Search For Gravitational Waves From Known Pulsars Using The Second Ligo Observing Run, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
Isolated spinning neutron stars, asymmetric with respect to their rotation axis, are expected to be sources of continuous gravitational waves. The most sensitive searches for these sources are based on accurate matched filtering techniques that assume the continuous wave to be phase locked with the pulsar beamed emission. While matched filtering maximizes the search sensitivity, a significant signaltonoise ratio loss will happen in the case of a mismatch between the assumed and the true signal phase evolution. Narrowband algorithms allow for a small mismatch in the frequency and spindown values of the pulsar while coherently integrating the entire dataset. In ...
FewBody Dynamics Underlying Postcollision Effects In The Ionization Of H₂ By 75Kev Proton Impact, M. Dhital, S. Bastola, A. Silvus, Don H. Madison, Michael Schulz
FewBody Dynamics Underlying Postcollision Effects In The Ionization Of H₂ By 75Kev Proton Impact, M. Dhital, S. Bastola, A. Silvus, Don H. Madison, Michael Schulz
Physics Faculty Research & Creative Works
We have measured fully differential cross sections (FDCS) for ionization in 75keVp+H2 collisions for ejected electron speeds close to the projectile speed. The data were analyzed in dependence on both the electron emission angle and the projectile scattering angle. Pronounced postcollisional effects between the projectile and the ejected electrons were observed. Significant differences between experiment and theory and between two conceptually very similar theoretical models were found. This shows that in the region of electronprojectile velocitymatching the FDCS is very sensitive to the details of the underlying fewbody dynamics.
Impact Of Anharmonicity On The Vibrational Entropy And Specific Heat Of Uo₂, M. S. Bryan, J. W. L. Pang, B. C. Larson, Aleksandr V. Chernatynskiy, D. L. Abernathy, K. Gofryk, M. E. Manley, For Full List Of Authors, See Publisher's Website.
Impact Of Anharmonicity On The Vibrational Entropy And Specific Heat Of Uo₂, M. S. Bryan, J. W. L. Pang, B. C. Larson, Aleksandr V. Chernatynskiy, D. L. Abernathy, K. Gofryk, M. E. Manley, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
The impact of anharmonicity on the vibrational entropy and heat capacity of UO2 has been investigated from 10 to 1200 K using inelastic neutronscattering measurements of the phonon density of states (PDOS). Small changes in the PDOS are observed from 10 to 295 K, with more noticeable changes appearing in the 750 and 1200K data. The specific heat determined from the PDOS measurements is in agreement with macroscopic specific heat measurements, and the overall impact of nondilation anharmonicity on the specific heat has been shown to be less than 2%. An analysis of the phonon measurements shows that the softening ...
AllSky Search For LongDuration GravitationalWave Transients In The Second Advanced Ligo Observing Run, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
AllSky Search For LongDuration GravitationalWave Transients In The Second Advanced Ligo Observing Run, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
We present the results of a search for longduration gravitationalwave transients in the data from the Advanced LIGO second observation run; we search for gravitationalwave transients of 2500 s duration in the 242048 Hz frequency band with minimal assumptions about signal properties such as waveform morphologies, polarization, sky location or time of occurrence. Signal families covered by these search algorithms include fallback accretion onto neutron stars, broadband chirps from innermost stable circular orbit waves around rotating black holes, eccentric inspiralmergerringdown compact binary coalescence waveforms, and other models. The second observation run totals about 118.3 days of coincident data between ...
Tests Of General Relativity With Gw170817, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Tests Of General Relativity With Gw170817, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
The recent discovery by Advanced LIGO and Advanced Virgo of a gravitational wave signal from a binary neutron star inspiral has enabled tests of general relativity (GR) with this new type of source. This source, for the first time, permits tests of strongfield dynamics of compact binaries in the presence of matter. In this Letter, we place constraints on the dipole radiation and possible deviations from GR in the postNewtonian coefficients that govern the inspiral regime. Bounds on modified dispersion of gravitational waves are obtained; in combination with information from the observed electromagnetic counterpart we can also constrain effects due ...
Transverse Localization Of Transmission Eigenchannels, Hasan Yılmaz, Chia Wei Hsu, Alexey Yamilov, Hui Cao
Transverse Localization Of Transmission Eigenchannels, Hasan Yılmaz, Chia Wei Hsu, Alexey Yamilov, Hui Cao
Physics Faculty Research & Creative Works
Transmission eigenchannels are building blocks of coherent wave transport in diffusive media, and selective excitation of individual eigenchannels can lead to diverse transport behaviour. An essential yet poorly understood property is the transverse spatial profile of each eigenchannel, which is relevant for the associated energy density and critical for coupling light into and out of it. Here, we discover that the transmission eigenchannels of a disordered slab possess exponentially localized incident and outgoing profiles, even in the diffusive regime far from Anderson localization. Such transverse localization arises from a combination of reciprocity, local coupling of spatial modes and nonlocal correlations ...
Triple Differential Cross Sections For ElectronImpact Ionization Of Methane At Intermediate Energy, Esam Ali, Carlos Granados, Ahmad Sakaamini, Don H. Madison
Triple Differential Cross Sections For ElectronImpact Ionization Of Methane At Intermediate Energy, Esam Ali, Carlos Granados, Ahmad Sakaamini, Don H. Madison
Physics Faculty Research & Creative Works
We report an experimental and theoretical investigation of electronimpact single ionization of the highest occupied molecular orbital 1t_{2} and the next highest occupied molecular orbital 2a_{1} states of CH_{4} at an incident electron energy of 250 eV. Triple differential cross sections measured in two different laboratories were compared with results calculated within the molecular 3body distorted wave and generalized Sturmian function theoretical models. For ionization of the 1t_{2} state, the binary peak was observed to have a single maximum near the momentum transfer direction that evolved into a double peak for increasing projectile scattering angles, as ...
LowLatency GravitationalWave Alerts For Multimessenger Astronomy During The Second Advanced Ligo And Virgo Observing Run, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
LowLatency GravitationalWave Alerts For Multimessenger Astronomy During The Second Advanced Ligo And Virgo Observing Run, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
Advanced LIGO's second observing run (O2), conducted from 2016 November 30 to 2017 August 25, combined with Advanced Virgo's first observations in 2017 August, witnessed the birth of gravitationalwave multimessenger astronomy. The first ever gravitationalwave detection from the coalescence of two neutron stars, GW170817, and its gammaray counterpart, GRB 170817A, led to an electromagnetic followup of the event at an unprecedented scale. Several teams from across the world searched for EM/neutrino counterparts to GW170817, paving the way for the discovery of optical, Xray, and radio counterparts. In this article, we describe the online identification of gravitationalwave transients ...
Integer Quantum Hall Transition On A TightBinding Lattice, Martin Puschmann, Philipp Cain, Michael Schreiber, Thomas Vojta
Integer Quantum Hall Transition On A TightBinding Lattice, Martin Puschmann, Philipp Cain, Michael Schreiber, Thomas Vojta
Physics Faculty Research & Creative Works
Even though the integer quantum Hall transition has been investigated for nearly four decades its critical behavior remains a puzzle. The best theoretical and experimental results for the localization length exponent ν differ significantly from each other, casting doubt on our fundamental understanding. While this discrepancy is often attributed to longrange Coulomb interactions, Gruzberg et al. [Phys. Rev. B 95, 125414 (2017)10.1103/PhysRevB.95.125414] recently suggested that the semiclassical ChalkerCoddington model, widely employed in numerical simulations, is incomplete, questioning the established central theoretical results. To shed light on the controversy, we perform a highaccuracy study of the ...
Low Energy Electron And Positron Impact Differential Cross Sections For The Ionization Of Water Molecules In The Coplanar And Perpendicular Kinematics, P. Singh, G. Purohit, C. Champion, D. Sebilleau, Don H. Madison
Low Energy Electron And Positron Impact Differential Cross Sections For The Ionization Of Water Molecules In The Coplanar And Perpendicular Kinematics, P. Singh, G. Purohit, C. Champion, D. Sebilleau, Don H. Madison
Physics Faculty Research & Creative Works
We report here triply differential cross sections (TDCSs) for 81 eV electron and positronimpact ionization of the combined (1b_{1} + 3a_{}1 ) orbitals of the water molecule by using the secondorder distorted wave Born approximation (DWBA2) for ejection electron and positron energies of 5 eV and 10 eV and different momentum transfer conditions. The electronimpact TDCS will be compared with the experimental data measured by Ren et al. [Phys. Rev. A 95, 022701 (2017)] and with the molecular 3body distorted wave (M3DW) approximation results in the scattering plane as well as the perpendicular plane. The DWBA2 results are in better ...
Constraining The PModeGMode Tidal Instability With Gw170817, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Constraining The PModeGMode Tidal Instability With Gw170817, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
We analyze the impact of a proposed tidal instability coupling p modes and g modes within neutron stars on GW170817. This nonresonant instability transfers energy from the orbit of the binary to internal modes of the stars, accelerating the gravitationalwave driven inspiral. We model the impact of this instability on the phasing of the gravitational wave signal using three parameters per star: An overall amplitude, a saturation frequency, and a spectral index. Incorporating these additional parameters, we compute the Bayes factor (ln B^{pg}_{!pg}) comparing our pg model to a standard one. We find that the observed signal is ...
Fractional Brownian Motion In A Finite Interval: Correlations Effect Depletion Or Accretion Zones Of Particles Near Boundaries, T. Guggenberger, G. Pagnini, Thomas Vojta, R. Metzler
Fractional Brownian Motion In A Finite Interval: Correlations Effect Depletion Or Accretion Zones Of Particles Near Boundaries, T. Guggenberger, G. Pagnini, Thomas Vojta, R. Metzler
Physics Faculty Research & Creative Works
Fractional Brownian motion (FBM) is a Gaussian stochastic process with stationary, longtime correlated increments and is frequently used to model anomalous diffusion processes. We study numerically FBM confined to a finite interval with reflecting boundary conditions. The probability density function of this reflected FBM at long times converges to a stationary distribution showing distinct deviations from the fully flat distribution of amplitude 1/L in an interval of length L found for reflected normal Brownian motion. While for superdiffusion, corresponding to a mean squared displacement (MSD) ⟨X^{2}(t)⟩ ≃ t^{α} with 1 < α < 2, the probability density function is lowered in the centre of the interval and rises towards the boundaries, for subdiffusion (0 < α < 1) this behaviour is reversed and the particle density is depleted close to the boundaries. The MSD in these cases at long times converges to a stationary value, which is, remarkably, monotonically increasing with the anomalous diffusion exponent α. Our a priori surprising results may have interesting ...
InfiniteRandomness Fixed Point Of The Quantum SuperconductorMetal Transitions In Amorphous Thin Films, Nicholas A. Lewellyn, Ilana M. Percher, J. J. Nelson, Javier GarciaBarriocanal, Irina Volotsenko, Aviad Frydman, Thomas Vojta, Allen M. Goldman
InfiniteRandomness Fixed Point Of The Quantum SuperconductorMetal Transitions In Amorphous Thin Films, Nicholas A. Lewellyn, Ilana M. Percher, J. J. Nelson, Javier GarciaBarriocanal, Irina Volotsenko, Aviad Frydman, Thomas Vojta, Allen M. Goldman
Physics Faculty Research & Creative Works
The magneticfieldtuned quantum superconductorinsulator transitions of disordered amorphous indium oxide films are a paradigm in the study of quantum phase transitions and exhibit powerlaw scaling behavior. For superconducting indium oxide films with low disorder, such as the ones reported on here, the highfield state appears to be a quantumcorrected metal. Resistance data across the superconductormetal transition in these films are shown here to obey an activated scaling form appropriate to a quantum phase transition controlled by an infiniterandomness fixed point in the universality class of the random transversefield Ising model. Collapse of the fielddependent resistance vs temperature data is obtained ...
Search For Multimessenger Sources Of Gravitational Waves And HighEnergy Neutrinos With Advanced Ligo During Its First Observing Run, Antares, And Icecube, A. Albert, M. André, M. Anghinolfi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Search For Multimessenger Sources Of Gravitational Waves And HighEnergy Neutrinos With Advanced Ligo During Its First Observing Run, Antares, And Icecube, A. Albert, M. André, M. Anghinolfi, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
Astrophysical sources of gravitational waves, such as binary neutron star and black hole mergers or corecollapse supernovae, can drive relativistic outflows, giving rise to nonthermal highenergy emission. Highenergy neutrinos are signatures of such outflows. The detection of gravitational waves and highenergy neutrinos from common sources could help establish the connection between the dynamics of the progenitor and the properties of the outflow. We searched for associated emission of gravitational waves and highenergy neutrinos from astrophysical transients with minimal assumptions using data from Advanced LIGO from its first observing run O1, and data from the Antares and IceCube neutrino observatories from ...
A Fermi GammaRay Burst Monitor Search For Electromagnetic Signals Coincident With GravitationalWave Candidates In Advanced Ligo's First Observing Run, E. Burns, A. Goldstein, C. M. Hui, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
A Fermi GammaRay Burst Monitor Search For Electromagnetic Signals Coincident With GravitationalWave Candidates In Advanced Ligo's First Observing Run, E. Burns, A. Goldstein, C. M. Hui, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
We present a search for prompt gammaray counterparts to compact binary coalescence gravitational wave (GW) candidates from Advanced LIGO's first observing run (O1). As demonstrated by the multimessenger observations of GW170817/GRB 170817A, electromagnetic and GW observations provide complementary information about the astrophysical source, and in the case of weaker candidates, may strengthen the case for an astrophysical origin. Here we investigate lowsignificance GW candidates from the O1 compact binary coalescence searches using the Fermi GammaRay Burst Monitor (GBM), leveraging its all sky and broad energy coverage. Candidates are ranked and compared to background to measure the significance. Those ...
Modelling And Evaluation Of Electrical Resonance Eddy Current For Submillimeter Defect Detection, Yew San Hor, Vinod K. Sivaraja, Yu Zhong, Bui V. Phuong, Christopher Lane
Modelling And Evaluation Of Electrical Resonance Eddy Current For Submillimeter Defect Detection, Yew San Hor, Vinod K. Sivaraja, Yu Zhong, Bui V. Phuong, Christopher Lane
Physics Faculty Research & Creative Works
Eddy current (EC) inspection is used extensively in nondestructive testing (NDT) to detect surfacebreaking defects of engineering components. However, the sensitivity of conventional eddy current inspection has plateaued in recent years. The ability to detect submillimetre defects before it becomes critical would allow engineering components to remain inservice safely for longer. Typically, it is required that higher frequency EC is employed to achieve a suitable sensitivity for detection of such submillimetre defects. However, that would lead to significant electromagnetic noise affecting the sensitivity of the inspection. To overcome this issue, the electricalresonance based eddy current method has been proposed, where ...
Properties Of The Binary Neutron Star Merger Gw170817, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Properties Of The Binary Neutron Star Merger Gw170817, B. P. Abbott, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
On August 17, 2017, the Advanced LIGO and Advanced Virgo gravitationalwave detectors observed a lowmass compact binary inspiral. The initial sky localization of the source of the gravitationalwave signal, GW170817, allowed electromagnetic observatories to identify NGC 4993 as the host galaxy. In this work, we improve initial estimates of the binary's properties, including component masses, spins, and tidal parameters, using the known source location, improved modeling, and recalibrated Virgo data. We extend the range of gravitationalwave frequencies considered down to 23 Hz, compared to 30 Hz in the initial analysis. We also compare results inferred using several signal models ...
Search For SubsolarMass Ultracompact Binaries In Advanced Ligo's First Observing Run, B. P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Search For SubsolarMass Ultracompact Binaries In Advanced Ligo's First Observing Run, B. P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
We present the first Advanced LIGO and Advanced Virgo search for ultracompact binary systems with component masses between 0.2 M_{⊙}1.0 M_{⊙} using data taken between September 12, 2015 and January 19, 2016. We find no viable gravitational wave candidates. Our null result constrains the coalescence rate of monochromatic (delta function) distributions of nonspinning (0.2 M_{⊙}, 0.2 M_{⊙}) ultracompact binaries to be less than 1.0 x 10^{6} Gpc^{3} yr^{1} and the coalescence rate of a similar distribution of (1.0 M_{⊙}, 1.0 M_{⊙}) ultracompact binaries to be less than 1.9 ...
Prospects For Observing And Localizing GravitationalWave Transients With Advanced Ligo, Advanced Virgo And Kagra, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Prospects For Observing And Localizing GravitationalWave Transients With Advanced Ligo, Advanced Virgo And Kagra, Benjamin P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
We present possible observing scenarios for the Advanced LIGO, Advanced Virgo and KAGRA gravitationalwave detectors over the next decade, with the intention of providing information to the astronomy community to facilitate planning for multimessenger astronomy with gravitational waves. We estimate the sensitivity of the network to transient gravitationalwave signals, and study the capability of the network to determine the sky location of the source. We report our findings for gravitationalwave transients, with particular focus on gravitationalwave signals from the inspiral of binary neutron star systems, which are the most promising targets for multimessenger astronomy. The ability to localize the sources ...
Author Correction: Femtosecond Laser Mass Spectrometry And High Harmonic Spectroscopy Of Xylene Isomers (Scientific Reports (2018) Doi: 10.1038/S41598018220559), Abdullah Alharbi, Andrewy E. Boguslavskiy, Dane Austin, Nicolas Thire, D. Wood, P. Hawkins, Felicity Mcgrath, A. S. Johnson, I. LopezQuintas, Bruno Schmidt, Francois Legare, J. P. Marangos, AnhThu Le, Ravi Bhardwaj
Author Correction: Femtosecond Laser Mass Spectrometry And High Harmonic Spectroscopy Of Xylene Isomers (Scientific Reports (2018) Doi: 10.1038/S41598018220559), Abdullah Alharbi, Andrewy E. Boguslavskiy, Dane Austin, Nicolas Thire, D. Wood, P. Hawkins, Felicity Mcgrath, A. S. Johnson, I. LopezQuintas, Bruno Schmidt, Francois Legare, J. P. Marangos, AnhThu Le, Ravi Bhardwaj
Physics Faculty Research & Creative Works
The original version of this Article contained a typographical error in the spelling of the author Nicolas Thiré, which was incorrectly given as Nicholas Thiré. Nicolas Thiré was also incorrectly affiliated with 'Instituto de Química Física Rocasolano, IQFRCSIC, Serrano 119, 28006, Madrid, Spain'. The correct affiliation is listed below.
INRSEMT, Advanced Laser Light Source, 1650 LionelBoulet Bvd, Varennes, J3X1S2, Canada.
This has now been corrected in the PDF and HTML versions of the Article and in the accompanying Supplementary Information file.
Gw170817: Measurements Of Neutron Star Radii And Equation Of State, B. P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Gw170817: Measurements Of Neutron Star Radii And Equation Of State, B. P. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
On 17 August 2017, the LIGO and Virgo observatories made the first direct detection of gravitational waves from the coalescence of a neutron star binary system. The detection of this gravitationalwave signal, GW170817, offers a novel opportunity to directly probe the properties of matter at the extreme conditions found in the interior of these stars. The initial, minimalassumption analysis of the LIGO and Virgo data placed constraints on the tidal effects of the coalescing bodies, which were then translated to constraints on neutron star radii. Here, we expand upon previous analyses by working under the hypothesis that both bodies were ...
RealTime Observation Of Molecular Spinning With Angular HighHarmonic Spectroscopy, Lixin He, Pengfei Lan, AnhThu Le, Baoning Wang, Bincheng Wang, Xiaosong Zhu, Peixiang Lu, C. D. Lin
RealTime Observation Of Molecular Spinning With Angular HighHarmonic Spectroscopy, Lixin He, Pengfei Lan, AnhThu Le, Baoning Wang, Bincheng Wang, Xiaosong Zhu, Peixiang Lu, C. D. Lin
Physics Faculty Research & Creative Works
We demonstrate an angular highharmonic spectroscopy method to probe the spinning dynamics of a molecular rotation wave packet in real time. With the excitation of two timedelayed, polarizationskewed pump pulses, the molecular ensemble is impulsively kicked to rotate unidirectionally, which is subsequently irradiated by another delayed probe pulse for highorder harmonic generation (HHG). The spatiotemporal evolution of the molecular rotation wave packet is visualized from the timedependent angular distributions of the HHG yields and frequency shift measured at various polarization directions and time delays of the probe pulse. The observed frequency shift in HHG is demonstrated to arise from the ...
Electronic Fingerprints Of Cr And V Dopants In The Topological Insulator Sb₂Te₃, Wenhan Zhang, Damien West, Seng Huat Lee, Yunsheng Qiu, CuiZu Chang, Jagadeesh S. Moodera, Yew San Hor, Shengbai Zhang, Weida Wu
Electronic Fingerprints Of Cr And V Dopants In The Topological Insulator Sb₂Te₃, Wenhan Zhang, Damien West, Seng Huat Lee, Yunsheng Qiu, CuiZu Chang, Jagadeesh S. Moodera, Yew San Hor, Shengbai Zhang, Weida Wu
Physics Faculty Research & Creative Works
By combining scanning tunneling microscopy/spectroscopy and firstprinciples calculations, we systematically study the local electronic states of magnetic dopants V and Cr in the topological insulator (TI) Sb_{2}Te_{3}. Spectroscopic imaging shows diverse local defect states between Cr and V, which agree with our firstprinciple calculations. The unique spectroscopic features of V and Cr dopants provide electronic fingerprints for the codoped magnetic TI samples with the enhanced quantum anomalous Hall effect. Our results also facilitate the exploration of the underlying mechanism of the enhanced quantum anomalous Hall temperature in Cr/V codoped TIs.
Gravitational Effects In G Factor Measurements And HighPrecision Spectroscopy: Limits Of Einstein's Equivalence Principle, Ulrich D. Jentschura
Gravitational Effects In G Factor Measurements And HighPrecision Spectroscopy: Limits Of Einstein's Equivalence Principle, Ulrich D. Jentschura
Physics Faculty Research & Creative Works
We study the interplay of general relativity, the equivalence principle, and highprecision experiments involving atomic transitions and gfactor measurements. In particular, we derive a generalized Dirac Hamiltonian, which describes both the gravitational coupling for weak fields and the electromagnetic coupling, e.g., to a central Coulomb field. An approximate form of this Hamiltonian is used to derive the leading gravitational corrections to transition frequencies and g factors. The position dependence of atomic transitions is shown to be compatible with the equivalence principle, up to a very good approximation. The compatibility of gfactor measurements requires a deeper subtle analysis in order ...
Extinction Transitions In Correlated External Noise, Alexander H. O. Wada, Matthew Small, Thomas Vojta
Extinction Transitions In Correlated External Noise, Alexander H. O. Wada, Matthew Small, Thomas Vojta
Physics Faculty Research & Creative Works
We analyze the influence of longrange correlated (colored) external noise on extinction phase transitions in growth and spreading processes. Uncorrelated environmental noise (i.e., temporal disorder) was recently shown to give rise to an unusual infinitenoise critical point [Europhys. Lett. 112, 30002 (2015)EULEEJ0295507510.1209/02955075/112/30002]. It is characterized by enormous density fluctuations that increase without limit at criticality. As a result, a typical population decays much faster than the ensemble average, which is dominated by rare events. Using the logistic evolution equation as an example, we show here that positively correlated (red) environmental noise further enhances these ...
Quantum Critical Behavior Of A ThreeDimensional SuperfluidMott Glass Transition, Jack Crewse, Cameron Lerch, Thomas Vojta
Quantum Critical Behavior Of A ThreeDimensional SuperfluidMott Glass Transition, Jack Crewse, Cameron Lerch, Thomas Vojta
Physics Faculty Research & Creative Works
The superfluid to insulator quantum phase transition of a threedimensional particlehole symmetric system of disordered bosons is studied. To this end, a sitediluted quantum rotor Hamiltonian is mapped onto a classical (3+1)dimensional XY model with columnar disorder and analyzed by means of largescale Monte Carlo simulations. The superfluidMott insulator transition of the clean, undiluted system is in the fourdimensional XY universality class and shows meanfield critical behavior with logarithmic corrections. The clean correlation length exponent ν=1/2 violates the Harris criterion, indicating that disorder must be a relevant perturbation. For nonzero dilutions below the lattice percolation threshold ...
Scanning Tunneling Spectroscopy Investigations Of SuperconductingDoped Topological Insulators: Experimental Pitfalls And Results, Stefan Wilfert, Paolo Sessi, Zhiwei Wang, Henrik Schmidt, M. Carmen MartínezVelarte, Seng Huat Lee, Yew San Hor, Alexander F. Otte, Yoichi Ando, Weida Wu, Matthias Bode
Scanning Tunneling Spectroscopy Investigations Of SuperconductingDoped Topological Insulators: Experimental Pitfalls And Results, Stefan Wilfert, Paolo Sessi, Zhiwei Wang, Henrik Schmidt, M. Carmen MartínezVelarte, Seng Huat Lee, Yew San Hor, Alexander F. Otte, Yoichi Ando, Weida Wu, Matthias Bode
Physics Faculty Research & Creative Works
Recently, the doping of topological insulators has attracted significant interest as a potential route towards topological superconductivity. Because many experimental techniques lack sufficient surface sensitivity, however, definite proof of the coexistence of topological surface states and surface superconductivity is still outstanding. Here we report on highly surface sensitive scanning tunneling microscopy and spectroscopy experiments performed on Tldoped Bi_{2}Te_{3}, a threedimensional topological insulator which becomes superconducting in the bulk at T_{C}=2.3 K. Landau level spectroscopy as well as quasiparticle interference mapping clearly demonstrated the presence of a topological surface state with a Dirac point energy ...
Tuning A RandomField Mechanism In A Frustrated Magnet, Shashikant Singh Kunwar, Arnab Sen, Thomas Vojta, Rajesh Narayanan
Tuning A RandomField Mechanism In A Frustrated Magnet, Shashikant Singh Kunwar, Arnab Sen, Thomas Vojta, Rajesh Narayanan
Physics Faculty Research & Creative Works
We study the influence of spinless impurities on a frustrated magnet featuring a spindensity wave (stripe) phase by means of Monte Carlo simulations. We demonstrate that the interplay between the impurities and an order parameter that breaks a realspace symmetry triggers the emergence of a randomfield mechanism which destroys the stripeordered phase. Importantly, the strength of the emerging random fields can be tuned by the repulsion between the impurity atoms; they vanish for perfect anticorrelations between neighboring impurities. This provides a way of controlling the phase diagram of a manyparticle system. In addition, we also investigate the effects of the ...
Relativistic And Radiative Corrections To The Dynamic Stark Shift: Gauge Invariance And Transition Currents In The Velocity Gauge, Ulrich D. Jentschura, Chandra M. Adhikari
Relativistic And Radiative Corrections To The Dynamic Stark Shift: Gauge Invariance And Transition Currents In The Velocity Gauge, Ulrich D. Jentschura, Chandra M. Adhikari
Physics Faculty Research & Creative Works
We investigate the gauge invariance of the dynamic (ac) Stark shift under "hybrid" gauge transformations from the "length" (E·r ) to the "velocity" (A·p ) gauge. By a "hybrid" gauge transformation, we understand a transformation in which the scalar and vector potentials are modified, but the wave function remains unaltered. The gauge invariance of the leading term is well known, while we here show that gauge invariance under perturbations holds only if one takes into account an additional correction to the transition current, which persists only in the velocity gauge. We find a general expression for this current, and apply ...
Dynamic Effects In Electron Momentum Spectroscopy Of Sulfur Hexafluoride, Xing Wang, Shenyue Xu, Chuangang Ning, O. AlHagan, Pengfei Hu, Yongtao Zhao, Zhongfen Xu, Jingkang Deng, Enliang Wang, Xueguang Ren, Alexander Dorn, Don H. Madison
Dynamic Effects In Electron Momentum Spectroscopy Of Sulfur Hexafluoride, Xing Wang, Shenyue Xu, Chuangang Ning, O. AlHagan, Pengfei Hu, Yongtao Zhao, Zhongfen Xu, Jingkang Deng, Enliang Wang, Xueguang Ren, Alexander Dorn, Don H. Madison
Physics Faculty Research & Creative Works
Electron momentum spectroscopy (EMS) results are presented for the sulfur hexafluoride (SF6) molecule using a highresolution binary (e, 2e) spectrometer at incident energies (Ei) of 600, 1200, and 2400 eV plus the binding energy. The valence orbital momentum profiles were measured with a binding energy resolution of 0.68 eV and angular resolutions of Δθ = ±0.6⁰, ΔΦ = ±0.85⁰. Whereas the two higher incident energies are in the range where normally EMS measurements do not exhibit an impactenergy dependence, the current experimental data display a dynamic dependence on the impact energies. The measured momentum profiles are compared with predictions ...