Physics Commons^™

Classical Phases And Quantum Angles In The Description Of Interfering Bose-Einstein Condensates, Wj Mullin, F Laloe

Physics Department Faculty Publication Series

The interference of two Bose-Einstein condensates, initially in Fock states, can be described in terms of their relative phase, treated as a random unknown variable. This phase can be understood either as emerging from the measurements or pre-existing to them; in the latter case, the originating states could be phase states with unknown phases, so an average over all their possible values is taken. Both points of view lead to a description of probabilities of results of experiments in terms of a phase angle, which plays the role of a classical variable. Nevertheless, in some situations, this description is not …

Type-1.5 Superconductivity In Multiband Systems: The Eects Of Interband Couplings, Johan Carlstrom, Egor Babaev, Martin Speight

Physics Department Faculty Publication Series

In contrast to single-component superconductors, which are described at the level of Ginzburg- Landau theory by a single parameter and are divided in type-I < 1= p 2 and type-II > 1= p 2 classes, two-component systems in general possesses three fundamental length scales and have been shown to possess a separate \type-1.5" superconducting state1,2. In that state, as a consequence of the extra fundamental length scale, vortices attract one another at long range but repel at shorter ranges, and therefore should form clusters in low magnetic elds. In such clusters one can dene a negative interface energy inside a cluster and at the same there one …

The Beliaev Technique For A Weakly Interacting Bose Gas, B Capogrosso-Sansone, S Giorgini, S Pilati, L. Pollet, N Prokof'ev, B Svistunov, M Troyer

Physics Department Faculty Publication Series

Aiming at simplicity of explicit equations and, at the same time, controllable accuracy of the theory, we present our results for all the thermodynamic quantities and correlation functions for a weakly interacting Bose gas at short-to-intermediate distances obtained within an improved version of Beliaev's diagrammatic technique. With a controllably small (but essentially finite) Bogoliubov's symmetry-breaking term, Beliaev's diagrammatic technique becomes regular in the infrared limit. Up to higher-order terms (for which we present parametric order-of-magnitude estimates), the partition function and entropy of the system formally correspond to those of a non-interacting bosonic (pseudo-)Hamiltonian with a temperature-dependent Bogoliubov-type dispersion relation. Away …

Spectroscopic Analysis Of Tungsten Oxide Thin Films For Sensor Applications, Jose Luis Enriquez Carrejo

Open Access Theses & Dissertations

The objective of this study is targeted toward improving the quality of pure tungsten oxide (WO3) for application to the detection of poisoning gases, especially of H2S. While pure WO3 is a recognized candidate for gas sensing, its characteristics are strongly dependent on the conditions and methods used in its deposition.

Samples of WO3 thin films analyzed in this work were grown on silicon and sapphire substrates using RF magnetron sputtering at a number of different substrate temperatures and Ar:O2 pressure ratios. The properties of the samples were investigated spectroscopically with the goal of determining how variations in the above …

Search For Gravitational-Wave Inspiral Signals Associated With Short Gamma-Ray Bursts During Ligo's Fifth And Virgo's First Science Run, J. Abadie, B. P. Abbott, R. Abbott, T. Accadia, F. Acernese, R. Adhikari, P. Ajith, B. Allen, G. Allen, Shaon Ghosh

Department of Physics and Astronomy Faculty Scholarship and Creative Works

Progenitor scenarios for short gamma-ray bursts (short GRBs) include coalescenses of two neutron stars or a neutron star and black hole, which would necessarily be accompanied by the emission of strong gravitational waves. We present a search for these known gravitational-wave signatures in temporal and directional coincidence with 22 GRBs that had sufficient gravitational-wave data available in multiple instruments during LIGO's fifth science run, S5, and Virgo's first science run, VSR1. We find no statistically significant gravitational-wave candidates within a [ - 5, + 1)s window around the trigger time of any GRB. Using the Wilcoxon-Mann-Whitney U-test, we find no …

Search For Gravitational-Wave Bursts Associated With Gamma-Ray Bursts Using Data From Ligo Science Run 5 And Virgo Science Run 1, B. P. Abbott, R. Abbott, F. Acernese, R. Adhikari, P. Ajith, B. Allen, G. Allen, M. Alshourbagy, R. S. Amin, S. B. Anderson, Rodica Martin

Department of Physics and Astronomy Faculty Scholarship and Creative Works

We present the results of a search for gravitational-wave bursts (GWBs) associated with 137 gamma-ray bursts (GRBs) that were detected by satellite-based gamma-ray experiments during the fifth LIGO science run and first Virgo science run. The data used in this analysis were collected from 2005 November 4 to 2007 October 1, and most of the GRB triggers were from the Swift satellite. The search uses a coherent network analysis method that takes into account the different locations and orientations of the interferometers at the three LIGO-Virgo sites. We find no evidence for GWB signals associated with this sample of GRBs. …

Searches For Gravitational Waves From Known Pulsars With Science Run 5 Ligo Data, B. P. Abbott, R. Abbott, F. Acernese, R. Adhikari, P. Ajith, B. Allen, G. Allen, M. Alshourbagy, R. S. Amin, Rodica Martin

Department of Physics and Astronomy Faculty Scholarship and Creative Works

We present a search for gravitational waves from 116 known millisecond and young pulsars using data from the fifth science run of the LIGO detectors. For this search, ephemerides overlapping the run period were obtained for all pulsars using radio and X-ray observations. We demonstrate an updated search method that allows for small uncertainties in the pulsar phase parameters to be included in the search. We report no signal detection from any of the targets and therefore interpret our results as upper limits on the gravitational wave signal strength. The most interesting limits are those for young pulsars. We present …

Phase Transitions In A Three Dimensional U(1)×U(1) Lattice London Superconductor: Metallic Superfluid And Charge-4e Superconducting States, Egil V. Herland, Egor Babaev, Asle Sudbø

Physics Department Faculty Publication Series

We consider a three dimensional lattice U(1)×U(1) and [U(1)]N superconductors in the London limit with individually conserved condensates. The U(1)×U(1) problem, generically, has two types of intercomponent interactions of different characters. First, the condensates are interacting via a minimal coupling to the same fluctuating gauge field. A second type of coupling is the direct dissipationless drag represented by a local intercomponent current-current coupling term in the free-energy functional. In this work, we present a study of the phase diagram of a U(1)×U(1) superconductor which includes both of these interactions. We study phase transitions and two types of competing paired phases …

A Simple Radionuclide-Driven Single-Ion Source, M Montero Diez, K Twelker, W Fairbank Jr, G Gratta, P Barbeau, K Barry, R Devoe, M Dolinski, M Green, F Leport, A Muller, R Neilson, K O'Sullivan, N Ackerman, B Aharmin, M Auger, C Benitez-Medina, M Breidenbach, A Burenkov, S Cook, T Daniels, K Donato, J Farine, G Giroux, R Gornea, K Graham, C Hagemann, C Hall, K Hall, D Hallman, C Hargrove, S Herrin, A Karelin, L. Kaufman, A Kuchenkov, K Kumar, J Lacey, D Leonard, D Mackay, R Maclellan, B Mong, E Niner, A Odian, A Piepke, A Pocar, C Prescott, K Pushkin, E Rollin, P Rowson, D Sinclair, S Slutsky, V Stekhanov, J Vuilleumier, U Wichoski, J Wodin, L Yang, Y Yen

Physics Department Faculty Publication Series

We describe a source capable of producing single barium ions through nuclear recoils in radioactive decay. The source is fabricated by electroplating 148Gd onto a silicon α-particle detector and vapor depositing a layer of BaF2 over it. 144Sm recoils from the alpha decay of 148Gd are used to dislodge Ba+ ions from the BaF2 layer and emit them in the surrounding environment. The simultaneous detection of an α particle in the substrate detector allows for tagging of the nuclear decay and of the Ba+ emission. The source is simple, durable, and can be manipulated and used in different environments. We …

Gauge Non-Invariance As Tests Of Emergent Gauge Symmetry, John Donoghue, Mohamed M. Anber, Ufuk Aydemir

Physics Department Faculty Publication Series

We motivate the concept of emergent gauge symmetry and discuss ways that this concept can be tested. The key idea is that if a symmetry is emergent, one should look for small violations of this symmetry because the underlying fundamental theory does not contain the symmetry. We describe our recent work implementing this idea in the gravity sector. We also describe the reasons why violations of gauge symmetry may well be linked to violations of Lorentz invariance.

Topological Multicritical Point In The Phase Diagram Of The Toric Code Model And Three-Dimensional Lattice Gauge Higgs Model, I Tupitsyn, A Kitaev, Nikolai Prokof'ev, P.C.E Stamp

Physics Department Faculty Publication Series

We construct a mapping between the two-dimensional toric code model in external magnetic fields, hz and hx, and the three-dimensional classical Ising system with plaquette interactions, which is equivalent to the three-dimensional Z2 gauge Higgs model with anisotropy between the imaginary time and spatial directions. The isotropic limit of the latter model was studied using Monte Carlo simulations on large (up to 603) lattices in order to determine the stability of the topological phase against generic magnetic field perturbations and to resolve fine details of the phase diagram. We find that the topological phase is bounded by second-order transition lines, …

The 17/5 Spectrum Of The Kelvin-Wave Cascade, E Kozik, Boris Svistunov

Physics Department Faculty Publication Series

Direct numeric simulation of the Biot-Savart equation readily resolves the 17/5 spectrum of the Kelvin-wave cascade from the 11/3 spectrum of the non-local (in the wavenumber space) cascade scenario by L’vov and Nazarenko. This result is a clear-cut visualisation of the unphysical nature of the 11/3 solution, which was established earlier on the grounds of symmetry.

Field-Induced Quantum Phase Transitions In The Spin-1/2 Triangular-Lattice Antiferromagnet Cs2cubr4, Nathanael Alexander Fortune, Scott T. Hannahs, Y. Takano, Y. Yoshida, T. Sherline, A. A. Wilson-Muenchow, T. Ono, H. Tanaka

Physics: Faculty Publications

In classical magnetic spin systems, geometric frustration leads to a large number of states of identical energy. We report here evidence from magnetocaloric and related measurements that in Cs2CuBr4 — a geometrically frustrated Heisenberg S= 1/2 triangular antiferromagnet — quantum fluctuations stabilize a series of gapped collinear spin states bounded by first-order transitions at simple increasing fractions of the saturation magnetization for fields directed along the c axis. Only the first of these quantum phase transitions has been theoretically predicted, suggesting that quantum effects continue to dominate at fields much higher than previously considered.

Likely Values Of The Higgs Vacuum Expectation Value, Jf Donoghue, K Dutta, A Ross, M Tegmark

Physics Department Faculty Publication Series

We make an estimate of the likelihood function for the Higgs vacuum expectation value (vev) by imposing anthropic constraints on the existence of atoms while allowing the other parameters of the standard model to also be variable. We argue that the most important extra ingredients are the Yukawa couplings, and for the intrinsic distribution of Yukawa couplings we use the scale-invariant distribution which is favored phenomenologically. The result is successful phenomenologically, favoring values close to the observed vev. We also discuss modifications that can change these conclusions. Our work supports the hypothesis that the anthropic constraints could be the origin …

Creation Of Noon States By Double Fock-State/Bose-Einstein Condensates, Wj Mullin, F. Laloe

Physics Department Faculty Publication Series

NOON states (states of the form |N〉 a |0〉 b +|0〉 a |N〉 b where a and b are single particle states) have been used for predicting violations of hidden-variable theories (Greenberger-Horne-Zeilinger violations) and are valuable in metrology for precision measurements of phase at the Heisenberg limit. We show theoretically how the use of two Fock state/Bose-Einstein condensates as sources in a modified Mach Zender interferometer can lead to the creation of the NOON state in which a and b refer to arms of the interferometer and N is the total number of particles in the two condensates. The modification …

Smooth Cascade Of Wrinkles At The Edge Of A Floating Elastic Film, J Huang, B Davidovitch, C Santangelo, T Russell, N Menon

Physics Department Faculty Publication Series

An ultrathin polymer sheet floating on a fluid forms a periodic pattern of parallel wrinkles when subjected to uniaxial compression. The wave number of the wrinkle pattern increases sharply near the fluid meniscus where the translational symmetry of this one-dimensional corrugated profile is broken. We show that the observed multiscale morphology is controlled by a new “softness” number that quantifies the relative strength of capillary forces at the edge and the rigidity of the bulk pattern. We discover a new elastic cascade by which the wrinkling pattern in the bulk is smoothly matched to the fine structure at the edge …

Elastic Building Blocks For Confined Sheets, R Schroll, Katifori, B Davidovitch

Physics Department Faculty Publication Series

We study the behavior of thin elastic sheets that are bent and strained under the influence of weak, smooth confinement. We show that the emerging shapes exhibit the coexistence of two types of domains that differ in their characteristic stress distributions and energies, and reflect different constraints. A focused-stress patch is subject to a geometric, piecewise-inextensibility constraint, whereas a diffuse-stress region is characterized by a mechanical constraint - the dominance of a single component of the stress tensor. We discuss the implications of our findings for the analysis of elastic sheets that are subject to various types of forcing.

Suppression Of The Critical Temperature For Superfluidity Near The Mott Transition, S Trotzky, L Pollet, F Gerbier, U Schnorrberger, I Bloch, Nikolai Prokof'ev, Boris Svistunov, M Troyer

Physics Department Faculty Publication Series

Ultracold atomic gases in optical lattices have proven to be a controllable, tunable and clean implementation of strongly interacting quantum many-body systems. An essential prospect for such quantum simulators is their ability to map out the phase diagram of fundamental many-body model Hamiltonians. However, the results need to be validated first for representative benchmark problems through state-of-the-art numerical methods of quantum many-body theory. Here we present the first ab initio comparison between experiments and quantum Monte Carlo simulations for strongly interacting Bose gases on a lattice for large systems (up to particles). The comparison enables thermometry for the interacting quantum …

Sharp Transition For Single Polarons In The One-Dimensional Su-Schrieffer-Heeger Model, D Marchand, G De Filippis, V Cataudella, M Berciu, N Nagaosa, Nikolai Prokof'ev, A Mishchenko, P Stamp

Physics Department Faculty Publication Series

We study a single polaron in the Su-Schrieffer-Heeger (SSH) model using four different techniques (three numerical and one analytical). Polarons show a smooth crossover from weak to strong coupling, as a function of the electron-phonon coupling strength λ, in all models where this coupling depends only on phonon momentum q. In the SSH model the coupling also depends on the electron momentum k; we find it has a sharp transition, at a critical coupling strength λc, between states with zero and nonzero momentum of the ground state. All other properties of the polaron are also singular at λ=λc. This result …

Criticality In Trapped Atomic Systems, L Pollet, Nikolai Prokof'ev, Boris Svistunov

Physics Department Faculty Publication Series

We discuss generic limits posed by the trap in atomic systems on the accurate determination of critical parameters for second-order phase transitions, from which we deduce optimal protocols to extract them. We show that under current experimental conditions the in situ density profiles are barely suitable for an accurate study of critical points in the strongly correlated regime. Contrary to recent claims, the proper analysis of time-of-fight images yields critical parameters accurately.