Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session A19: Precision Many Body Physics IFocus
|
Hide Abstracts |
Sponsoring Units: DCOMP DAMOP Room: BCEC 156C |
Monday, March 4, 2019 8:00AM - 8:36AM |
A19.00001: Enhanced metrology using quantum-correlated matter Invited Speaker: Ana Maria Rey The best clock in the world has no hands, no pendulum, no digital display. It is made of ultra-cold atoms trapped in a crystal of light. |
Monday, March 4, 2019 8:36AM - 8:48AM |
A19.00002: Algebraic Time Crystallization in a Two-dimensional Superfluid Nikolai Prokof'ev, Boris Svistunov Time crystallization is a hallmark of superfluidity, indicative of the fundamental fact that along with breaking the global U(1) symmetry, superfluids also break time-translation symmetry. While the standard discussion of the time crystallization phenomenon is based on the notion of the global phase and genuine condensate, for the superfluidity to take place in two dimensions an algebraic (topological) order is sufficient. We find that the absence of long-range order in a finite-temperature two-dimensional superfluid translates into in an algebraic time crystallization caused by the temporal phase correlations. The exponent controlling the algebraic decay is a universal function of the superfluid-stiffness-to-temperature ratio; this exponent can be also seen in the power-law singularity of the Fourier spectrum of the AC Josephson current. We elaborate on subtleties involved in defining the phenomenon of time crystallization in both classical-filed and all-quantum cases and propose an experimental protocol in which the broken time translation symmetry--more precisely, temporal correlations of the relative phase, with all possible finite-size, dimensional, and quantum effects included--can be observed without permanently keeping two superfluids in a contact. |
Monday, March 4, 2019 8:48AM - 9:00AM |
A19.00003: Density dependence of the superfluid properties of superclimbing dislocation in solid 4He Anatoly Kuklov, Nikolai Prokof'ev, Boris Svistunov Dislocations with superfluid core [1,2] are the main candidates for the mechanism behind the observation of superflow through solid and the syringe effect [3]. The same features have been confirmed in Refs.[4,5], respectively. One of the unusual features observed in the experiment [4] is the exponentially strong suppression of the flow versus pressure (or crystal density). Our grand canonical ab initio simulations of the superclimbing dislocation by the Worm Algorithm [6] on samples containing about 1430 particles at T=0.25K find that Luttinger parameter K obeys the dependence K=exp (3.4 - 39 n), where n>0 stands for the fractional deviation of the density from the melting value, within the accuracy of 10-15%. Thus, by increasing the density by only about 10% the K-value drops by about two orders of magnitude. This qualitatively agrees with the observation [4]. |
Monday, March 4, 2019 9:00AM - 9:12AM |
A19.00004: Numerical solutions of three-dimensional helium like atoms from the linear combination of their analogue one-dimensional wave functions Faiz Ur Rahman, Yanoar Pribadi Sarwono, Ruiqin Zhang The solutions of Schrödinger wave equations for the ground state of three-dimensional helium atom and its isoelectronic series were obtained from the linear combination of one-dimensional helium-like wave functions. The result shows that the one-dimensional bases along the axes are good choices which facilitate easy numerical integration. The three-dimensional wave function was constructed from the linear combination of the bases and the result was further refined to converge to the exact value using the iteration technique. The resultant ground state energy for the helium atom is with deviation of from the exact value. The method developed is thus demonstrated to be an effective numerical approach to the many-body problem and could be extended to other atomic and molecular systems. |
Monday, March 4, 2019 9:12AM - 9:24AM |
A19.00005: An integrable multi-channel sine-Gordon model with Josephson circuits Ananda Roy, Hubert Saleur Integrable field theories have always fascinated physicists. In particular, those which describe quantum impurity problems have been of much interest to both theorists and experimentalists. A prominent example is the boundary sine-Gordon (bSG) field theory. The latter describes a Luttinger liquid in the presence of an impurity. In this work, we propose an experimentally realizable, multi-channel generalization of the bSG model. We establish the classical and quantum integrability of the model by constructing a corresponding integrable bulk theory. We provide the first nontrivial conserved current of the bulk theory. Subsequently, we postulate the factorized scattering matrix describing the bulk theory and verify it using Bethe Ansatz computation of the ground state energy. Subsequently, we provide the factorized scattering matrix of the boundary field theory. Thermodynamic properties of both the bulk and boundary model are computed using the Thermodynamic Bethe Ansatz. Finally, we propose an experimental realization of the model with superconducting circuits, making use of the robust, tunable and dispersive Josephson nonlinearity. Our proposal can be realized with state-of-the-art system parameters. |
Monday, March 4, 2019 9:24AM - 9:36AM |
A19.00006: Non-Equilibrium Transport in the Kondo Model: Strong and Weak Coupling Adrian Culver, Natan Andrei We present an exact method of calculating the non-equilibrium current driven by a voltage drop across a quantum impurity. The system is described by the two lead Kondo model with non-interacting Fermi-liquid leads. We prepare the system in an initial state consisting of a free Fermi sea in each lead with the voltage drop given as the difference between the two Fermi levels. We quench the system by coupling the impurity to the leads at t=0 and following the time evolution of the wavefunction. In the long time limit, a steady state emerges provided that the size of the system is large compared to the time of evolution (the open system limit). We determine the wavefunction explicitly at any time and show, in particular, that the long time limit satisfies the Lippmann-Schwinger equation with the two Fermi seas serving as the boundary conditions. Using this wavefunction, we obtain an infinite series expression for the current as a function of voltage, either in powers of the antiferromagnetic Kondo coupling constant J or in powers of 1/J. Evaluating the first few terms, we find that a quench to small J reproduces known results while a quench to large J leads to a pre-thermalized regime of maximal conductance with ferromagnetic corrections. |
Monday, March 4, 2019 9:36AM - 9:48AM |
A19.00007: Strong and Weak Field Criticality of Liquid Gas Transition in 2D Max Yarmolinsky, Anatoly Kuklov Finite size scaling (FSS) analysis of the liquid gas criticality is complicated by the absence of any broken symmetry. This, does not allow a straightforward finding of the coexistence line and the critical point -- especially in 2D. The numerical flowgram (NF) method[1] is adapted for a controlled determination of the boundary between weak and strong field critical regions by applying classical Monte Carlo to the square well model. This boundary coincides with the coexistence line of the liquid-gas transition with respect to the leading scaling behavior. The NF method allows measuring the critical indices μ, ν within 1-2% of the total error. Furthermore, the NF allows testing the so called complete scaling theory of the critical point[2] without tuning the system into the coexistence line. This theory predicts linear mixing between the primary scaling operators and pressure. We show that the NF analysis should see corrections to scaling which are stronger than the standard ones of the 2D Ising model. It can also resolve the non analytical correction to the diameter. |
Monday, March 4, 2019 9:48AM - 10:00AM |
A19.00008: Emergent Symmetry U(1) and Tricriticality in a 2D Quantum Clock Model Pranay Patil, Hui Shao, Wenan Guo, Anders W Sandvik We propose a quantum clock model on the square lattice built out of |
Monday, March 4, 2019 10:00AM - 10:12AM |
A19.00009: Symmetry enhanced first-order phase transition in a two-dimensional quantum magnet Bowen Zhao, Anders W Sandvik, Phillip E Weinberg Theoretical descriptions of quantum phase transitions have indicated the existence of critical points with higher symmetries than those of the underlying Hamiltonian. Here we present an example of such an emergent symmetry at a first-order transition, where coexistence of two ordered phases takes the form of higher rotational symmetry in the space of the two order parameters. Using quantum Monte Carlo simulations, we study a two-dimensional (2D) S = 1/2 quantum magnet hosting the antiferromagnetic (AFM) and plaquette-singlet solid (PSS) states recently detected in SrCu2(BO3)2. We observe that the O(3) symmetric AFM order and the Z2 symmetric PSS order form an O(4) vector at the transition. The control parameter (a coupling ratio) rotates the vector from the AFM sector to the PSS sector, with the length of the combined order parameter vector always remaining non-zero. This phenomenon should be observable in SrCu2(BO3)2. |
Monday, March 4, 2019 10:12AM - 10:24AM |
A19.00010: Even-Odd effect of an Spin-S impurity coupled to a quantum critical system Kun Chen, Yashar Komijani, Yuan Huang We discuss an even-odd effect for an impurity with $N$ degenerate internal states immersed in a two-dimensional superfluid--Mott-insulator quantum critical bath, which is described by a spin-$S$ XY Bose Kondo impurity model with $N=2S+1$. Using a dimensionally and momentum-cut-off regularized renrmalization group and an unbiased large-scale Monte Carlo numerical simulations, we establish the phase diagram of an $S=1$ impurity with relevant terms included. We show that the impurity with $N=3$-fold degeneracy is fully screened by the critical bath, which is qualitatively different from the $N=2$ case where the impurity is only partially screened. We then argue that all even-$N$ impurities share the same universal physics as the $N=2$ case, and all odd-$N$ impurities are as the $N=3$ case. We validate our conjuecture with unbiased Monte Carlo simulations up to $N=5$. |
Monday, March 4, 2019 10:24AM - 10:36AM |
A19.00011: Trapping Collapse: Generic weak traps localize an infinite number of repulsive bosons Nikolai Prokof'ev, Kun Chen, Boris Svistunov Weak potential wells (or traps) in one and two dimensions, and the potential wells slightly deeper than the critical ones in three dimensions, feature shallow bound states with localization length much larger than the well radii. We address a simple fundamental question of how many repulsively interacting bosons can be localized by such traps. We find that under rather generic conditions, for both weakly and strongly repulsive particles, in two and three dimensions---but not in one-dimension!---the potential well will trap infinitely many bosons. For example, even hard-core repulsive interactions do not prevent this ``trapping collapse" phenomenon from taking place. A quantum system acquires the phenomenon along with the universal (asymptotically exact) classical-field behavior at large distances, allowing generic description by the Gross-Pitaevskii equation. We also discuss the possibility of having a transition between the infinite and finite number of trapped particles when strong repulsive inter-particle correlations are increased. |
Monday, March 4, 2019 10:36AM - 10:48AM |
A19.00012: Two Temperature Scales in the Triangular Lattice Heisenberg Antiferromagnet Wei Li, Bin-Bin Chen, Lei Chen, Han Li, Dai-Wei Qu, Jan Von Delft, Andreas Weichselbaum The anomalous thermodynamic properties of the paradigmatic frustrated spin-1/2 triangular lattice Heisenberg antiferromagnet (TLH), has remained an open topic of research over decades, both experimentally and theoretically. Here we further the theoretical understanding using the recently developed, powerful exponential tensor renormalization group (XTRG) method on cylinders and stripes in a quasi one-dimensional (1D) setup, as well as a tensor product operator approach directly in 2D. The observed thermal properties of the TLH are in excellent agreement with two recent experimental measurements on the virtually ideal TLH material Ba8CoNb6O24. Remarkably, our numerical simulations reveal two cross-over temperature scales, at Tl /J ~ 0.2 and Th /J ∼ 0.55, with J the Heisenberg exchange coupling, which are also confirmed by a more careful inspection of the experimental data. We propose that in the intermediate temperature range, the gapped roton-like excitations are activated with a strong chiral component and a large contribution to thermal entropies, which thus suppresses the incipient 120 order that emerges for temperatures below Tl. |
Monday, March 4, 2019 10:48AM - 11:00AM |
A19.00013: Some Novel Applications and Interpretations of the Path Integral Formalism Jareth Baca, Ajit Hira, Jose Pacheco, Tommy Cathey, Matilda Fernandez Two importanr considerations which will be addressed in this presentation pertain to extending applications of the Feynman Path Integral Formalism (FPIF) to some important physical problems, and also to the role of this formalism in providing a generally acceptable view of the interpretation of Quantum Mechanics (QM). Of particular interest for our research is the extension of path integral quantiziation geometries other than spherical: namely parabolic, elliptic and hyperbolic geometries. We calculate perturbative expansions of various path integrals of interest, with a view to obtaining Conformal Field Theories (CFTs). We used a Python programming language interface, and Monte Carlo (MC) integrations in our computer codes. Our main results are in the field of plasma Physics, with some applications in fusion and Astrophysics. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700