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Full-Text Articles in Physics
Type-1.5 Superconductivity In Multiband Systems: The Eects Of Interband Couplings, Johan Carlstrom, Egor Babaev, Martin Speight
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 …
Observation Of Thermomechanical Equilibration In The Presence Of A Solid 4he Conduit, M Ray, R Hallock
Observation Of Thermomechanical Equilibration In The Presence Of A Solid 4he Conduit, M Ray, R Hallock
Physics Department Faculty Publication Series
We observe a thermomechanical effect when a chemical-potential difference is created by a temperature difference imposed between two liquid reservoirs connected to each other through Vycor rods in series with solid hcp 4He. By creating a temperature difference, ΔT, between the two reservoirs, we induce a rate-limited growth of a pressure difference between the two reservoirs, ΔP. In equilibrium ΔP vs ΔT is in quantitative agreement with the thermomechanical effect in superfluid helium. These observations confirm that below ∼600 mK a flux-limited flow exists through the solid helium.
Growth Of Solid Hcp 4he Off The Melting Curve, M Ray, R Hallock
Growth Of Solid Hcp 4he Off The Melting Curve, M Ray, R Hallock
Physics Department Faculty Publication Series
We report studies of the growth of solid hcp 4He at pressures higher than the bulk freezing pressure using a cell design that allows us to inject atoms into the solid. Near the melting curve during injection we observe random events during which the pressure recorded in the cell drops abruptly. These events are accompanied by transient increases in the temperature of the cell. We discuss these transients and conclude that they represent the solidification of meta-stable liquid regions and the associated relief of strain in the local solid. We also observe that further from the melting curve the transients …
Elastic Building Blocks For Confined Sheets, R Schroll, Katifori, B Davidovitch
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.
Smooth Cascade Of Wrinkles At The Edge Of A Floating Elastic Film, J Huang, B Davidovitch, C Santangelo, T Russell, N Menon
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 …
A Simple Radionuclide-Driven Single-Ion Source, M Montero Diez, T Daniels, K Kumar, A Pocar, Et. Al.
A Simple Radionuclide-Driven Single-Ion Source, M Montero Diez, T Daniels, K Kumar, A Pocar, Et. Al.
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 …
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
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
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 …
Geometric Symmetries In Superfluid Vortex Dynamics, E Kozik, Boris Svistunov
Geometric Symmetries In Superfluid Vortex Dynamics, E Kozik, Boris Svistunov
Physics Department Faculty Publication Series
Dynamics of quantized vortex lines in a superfluid feature symmetries associated with the geometric character of the complex-valued field, w(z)=x(z)+iy(z), describing the instant shape of the line. Along with a natural set of Noether’s constants of motion, which—apart from their rather specific expressions in terms of w(z)—are nothing but components of the total linear and angular momenta of the fluid, the geometric symmetry brings about crucial consequences for kinetics of distortion waves on the vortex lines, the Kelvin waves. It is the geometric symmetry that renders Kelvin-wave cascade local in the wave-number space. Similar considerations apply to other systems with …
The 17/5 Spectrum Of The Kelvin-Wave Cascade, E Kozik, Boris Svistunov
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.
Minimal Resonances In Annular Non-Euclidean Strips, B Chen, Christian Santangelo
Minimal Resonances In Annular Non-Euclidean Strips, B Chen, Christian Santangelo
Physics Department Faculty Publication Series
Differential growth processes play a prominent role in shaping leaves and biological tissues. Using both analytical and numerical calculations, we consider the shapes of closed, elastic strips which have been subjected to an inhomogeneous pattern of swelling. The stretching and bending energies of a closed strip are frustrated by compatibility constraints between the curvatures and metric of the strip. To analyze this frustration, we study the class of “conical” closed strips with a prescribed metric tensor on their center line. The resulting strip shapes can be classified according to their number of wrinkles and the prescribed pattern of swelling. We …
Classical Phases And Quantum Angles In The Description Of Interfering Bose-Einstein Condensates, Wj Mullin, F Laloe
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 …
Regge Kinematics In Soft Collinear Effective Theory, Jf Donoghue, D Wyler
Regge Kinematics In Soft Collinear Effective Theory, Jf Donoghue, D Wyler
Physics Department Faculty Publication Series
We discuss the kinematics of the particles that make up a Reggeon in field theory, using the terminology of the soft collinear effective theory (SCET). Reggeization sums a series of strongly ordered collinear emissions resulting in an overall Reggeon exchange that falls in the Glauber or Coulomb kinematic region. This is an extremely multiscale problem and appears to fall outside of the usual organizing scheme of SCET.
Gauge Non-Invariance As Tests Of Emergent Gauge Symmetry, John Donoghue, Mohamed M. Anber, Ufuk Aydemir
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.
Beyond Spontaneously Broken Symmetry In Bose-Einstein Condensates, Wj Mullin, F Laloe
Beyond Spontaneously Broken Symmetry In Bose-Einstein Condensates, Wj Mullin, F Laloe
Physics Department Faculty Publication Series
Spontaneous symmetry breaking (SSB) for Bose-Einstein condensates cannot treat phase off-diagonal effects, and thus cannot explain Bell inequality violations. We describe another situation that is beyond a SSB treatment: an experiment where particles from two (possibly macroscopic) condensate sources are used for conjugate measurements of the relative phase and populations. Off-diagonal phase effects are characterized by a “quantum angle” and observed via “population oscillations,” signaling quantum interference of macroscopically distinct states.
Creation Of Noon States By Double Fock-State/Bose-Einstein Condensates, Wj Mullin, F. Laloe
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 …
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
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 …
Comment On "Symmetries And Interaction Coefficients Of Kelvin Waves" [Arxiv:1005.4575] By Lebedev And L'Vov, E Kozik, Boris Svistunov
Comment On "Symmetries And Interaction Coefficients Of Kelvin Waves" [Arxiv:1005.4575] By Lebedev And L'Vov, E Kozik, Boris Svistunov
Physics Department Faculty Publication Series
Dynamics of quantized vortex lines in a superfluid feature symmetries associated with the geometric character of the complex-valued field, w(z)=x(z)+iy(z), describing the instant shape of the line. Along with a natural set of Noether’s constants of motion, which—apart from their rather specific expressions in terms of w(z)—are nothing but components of the total linear and angular momenta of the fluid, the geometric symmetry brings about crucial consequences for kinetics of distortion waves on the vortex lines, the Kelvin waves. It is the geometric symmetry that renders Kelvin-wave cascade local in the wave-number space. Similar considerations apply to other systems with …
Likely Values Of The Higgs Vacuum Expectation Value, Jf Donoghue, K Dutta, A Ross, M Tegmark
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 …
Phenomenology Of The Equivalence Principle With Light Scalars, T Damour, Jf Donoghue
Phenomenology Of The Equivalence Principle With Light Scalars, T Damour, Jf Donoghue
Physics Department Faculty Publication Series
Light scalar particles with couplings of sub-gravitational strength, which can generically be called 'dilatons', can produce violations of the equivalence principle. However, in order to understand experimental sensitivities one must know the coupling of these scalars to atomic systems. We report here on a study of the required couplings. We give a general Lagrangian with five independent dilaton parameters and calculate the 'dilaton charge' of atomic systems for each of these. Two combinations are particularly important. One is due to the variations in the nuclear binding energy, with a sensitivity scaling with the atomic number as A−1/3. The other is …
Equivalence Principle Violations And Couplings Of A Light Dilaton, John Donoghue, Thibault Damour
Equivalence Principle Violations And Couplings Of A Light Dilaton, John Donoghue, Thibault Damour
Physics Department Faculty Publication Series
We consider possible violations of the equivalence principle through the exchange of a light “dilaton-like” scalar field. Using recent work on the quark-mass dependence of nuclear binding, we find that the dilaton-quark-mass coupling induces significant equivalence-principle-violating effects varying like the inverse cubic root of the atomic number—A-1/3. We provide a general parametrization of the scalar couplings, but argue that two parameters are likely to dominate the equivalence-principle phenomenology. We indicate the implications of this framework for comparing the sensitivities of current and planned experimental tests of the equivalence principle.
Type-1.5 Superconducting State From An Intrinsic Proximity Effect In Two-Band Superconductors, Egor Babaev, Johan Carlstrom, Martin Speight
Type-1.5 Superconducting State From An Intrinsic Proximity Effect In Two-Band Superconductors, Egor Babaev, Johan Carlstrom, Martin Speight
Physics Department Faculty Publication Series
We show that in multiband superconductors, even an extremely small interband proximity effect can lead to a qualitative change in the interaction potential between superconducting vortices by producing long-range intervortex attraction. This type of vortex interaction results in an unusual response to low magnetic fields leading to phase separation into domains of two-component Meissner states and vortex droplets.
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
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 …
Type-1.5 Superconductivity In Two-Band Systems, Egor Babaev, Johan Carlstrom
Type-1.5 Superconductivity In Two-Band Systems, Egor Babaev, Johan Carlstrom
Physics Department Faculty Publication Series
In the usual Ginzburg–Landau theory the critical value of Ginzburg–Landau parameter View the MathML source separates regimes of type-I and type-II superconductivity. The latter regime possess thermodynamically stable vortex excitations which interact with each other repulsively and tend to form vortex lattices. It was shown in [5] that this dichotomy in broken in U(1) × U(1) Ginzburg–Landau models which possess a distinct phase with vortex excitations which interact attractively at large length scales and repulsively at shorter distances. Here we discuss the influence of the Josephson coupling and that similar kind of superconductivity can also arise for entirely different reasons …
Worm Algorithm For Problems Of Quantum And Classical Statistics, Nikolai Prokof'ev, Boris Svistunov
Worm Algorithm For Problems Of Quantum And Classical Statistics, Nikolai Prokof'ev, Boris Svistunov
Physics Department Faculty Publication Series
This is a chapter of the multi-author book “Understanding Quantum Phase Transitions,” edited by Lincoln Carr and published by Taylor & Francis. In this chapter, we give a general introduction to the worm algorithm and present important results highlighting the power of the approach.
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
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, …
Criticality In Trapped Atomic Systems, L Pollet, Nikolai Prokof'ev, Boris Svistunov
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.
An Extended Kerr–Schild Ansatz, Benjamin Ett, David Kastor
An Extended Kerr–Schild Ansatz, Benjamin Ett, David Kastor
Physics Department Faculty Publication Series
We present an analysis of the vacuum Einstein equations for a recently proposed extension of the Kerr–Schild ansatz that includes a spacelike vector field as well as the usual Kerr–Schild null vector. We show that many, although not all, of the simplifications that occur in the Kerr–Schild case continue to hold for the extended ansatz. In particular, we find a simple set of sufficient conditions on the vectors such that the vacuum field equations truncate beyond quadratic order in an expansion around a general vacuum background solution. We extend our analysis to the electrovac case with a related ansatz for …