Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session C19: Precision Many Body Physics IIIFocus

Hide Abstracts 
Sponsoring Units: DCOMP DCMP Chair: Evgeny Kozik, Kings Coll Room: BCEC 156C 
Monday, March 4, 2019 2:30PM  3:06PM 
C19.00001: Quantum Monte Carlo Study of Strongly Interacting Fermi Gases in Two Dimensions: BCSBEC Crossover, Spinorbit Coupling, and Dynamical Response Functions Invited Speaker: Hao Shi We describe recent advances in 
Monday, March 4, 2019 3:06PM  3:18PM 
C19.00002: "Quasielectrons in Lattice Moore–Read Models" Sourav Manna, Julia Wildeboer, Anne E. B. Nielsen Anyons are fractionally charged quasiparticles which are neither fermions nor bosons. Anyons exhibit fractional statistics and important for topological quantum computation. Anyonic Moore–Read states provides a well explored description for the insertion of quasiholes in the continuum. However, quasielectron insertion creates a singularity in the continuum state which further complicates the problem. In this work we show that the singularity problem can be avoided by placing quasielectrons in fractional quantum Hall lattice systems. We construct Moore–Read Pfaffian states for filling fraction 5/2 and incorporate quasiholes and quasielectrons. We investigate density profile, charge, size and braiding properties of the anyons by means of a Metropolis Monte Carlo simulation. Further we derive a few body parent Hamiltonian for the states. Additionally we investigate density profile, charge and shape of the anyons in the Kapit–Mueller model by employing an exact diagonalization technique. We compare our results for the analytical states with the anyons in the Kapit–Mueller model. 
Monday, March 4, 2019 3:18PM  3:30PM 
C19.00003: Dispersion Relation of the GMP Mode in the Nematic Phase of Fractional Quantum Hall States Umang Mehta, Dam Thanh Son We compute the dispersion relation for the GMP mode of the fractional quantum Hall effect in the nematic phase for Jain sequences at large N using Golkar, Nguyen, Roberts and Son's 'higherspin theory' for magnetorotons. The dispersion relation is computed to all orders in the momentum expansion and is valid wherever the momentum expansion holds. It captures the magnetoroton minimum at finite momentum in the regime where the momentum expansion still holds. 
Monday, March 4, 2019 3:30PM  3:42PM 
C19.00004: Interacting Chern insulators: Diagrammatics well beyond the lowest order Igor Tupitsyn, Nikolai Prokof'ev We study phase diagram of the interacting spin1/2 Haldane model with chiral phase φ=π/2 at halffilling. Both onsite and longrange Coulomb repulsive interactions (HaldaneHubbardCoulomb model) are considered. The problem with onsite interaction U alone was addressed in the past by a variety of approximate and finite size methods that produced results in disagreement with each other both quantitatively and qualitatively. Conventional Quantum Monte Carlo methods, capable of dealing with "reasonable" system sizes, are ineffective here due to the fermionic sign problem. We employ the Diagrammatic Monte Carlo (DiagMC) technique to (i) accurately locate topologically nontrivial phases in the (△,U)plane (△ is the inversion symmetry breaking onsite energy) and (ii) demonstrate the strong effect of typically discarded in theoretical considerations longrange part of the Coulomb interaction. The DiagMC technique is not subject to the conventional fermionic sign problem and allows one to deal with arbitrary shape of interaction potential in an approximations free manner. Final results with controlled accuracy are obtained by computing vertex corrections from higherorder diagrams until convergence is reached. 
Monday, March 4, 2019 3:42PM  3:54PM 
C19.00005: Critical torus spectrum of the GrossNeveuYukawa field theory Michael Schuler, Stephan Heßelmann, Seth Whitsitt, Thomas C Lang, Stefan Wessel, Andreas Läuchli We compute the lowenergy critical torus spectrum of the GrossNeveuYukawa universality class, which features N=4 component Dirac spinors that spontaneously break a Z_{2} chiral symmetry, in D=(2+1) dimensions. A possible lattice realization of such Dirac fermions is provided by the interacting tV model of spinless fermions on the honeycomb lattice. We use a combination of Exact Diagonalization and Quantum Monte Carlo simulations to compute the energy spectrum on finitesize clusters with periodic boundaries, and perform an extrapolation to the thermodynamic limit. We show that the interaction between the spinor field and the scalar orderparameter field strongly influences the torus spectrum at the critical point, and propose the critical spectrum as a universal fingerprint of the critical GrossNeveuYukawa field theory. Moreover, we estimate the renormalization of the Fermi velocity in the Dirac phase from the interaction induced corrections to the energy spectrum, and extrapolate the observed linear renormalization up to the critical point. Finally, we contrast the Fermi velocity renormalization in the spinless tV model with the situation in the spinful Hubbard model. 
Monday, March 4, 2019 3:54PM  4:06PM 
C19.00006: Unconventional pairing symmetry of interacting Dirac fermions on a πflux lattice Huaiming Guo The pairing symmetry of interacting Dirac fermions on the πflux lattice is studied with the determinant quantum Monte Carlo and numerical linkedcluster expansion methods. The s* (i.e., extended s) and dwave pairing symmetries, which are distinct in the conventional square lattice, are degenerate under the Landau gauge. We demonstrate that the dominant pairing channel at strong interactions is an unconventional ds*wave phase consisting of alternating stripes of s* and dwave phases. A complementary meanfield analysis shows that while the s* and dwave symmetries individually have nodes in the energy spectrum, the ds* channel is fully gapped. The results represent a new realization of pairing in Dirac systems, connected to the problem of chiral dwave pairing on the honeycomb lattice, which might be more readily accessed by coldatom experiments. 
Monday, March 4, 2019 4:06PM  4:18PM 
C19.00007: ABSTRACT WITHDRAWN

Monday, March 4, 2019 4:18PM  4:30PM 
C19.00008: Universal Fermisurface anisotropy renormalization for interacting Dirac fermions with longrange interactions Shaffique Adam, Jia Ning Leaw, Ho Kin Y Tang, Maxim Trushin, Fakher Assaad, Sankar Das Sarma Recent evidence suggest an intriguing universal relationship between the Fermi surface anisotropy of the noninteracting parent twodimensional electron gas and the strongly correlated composite Fermi liquid formed in a strong magnetic field close to halffilling. Inspired by these observations, we explore more generally the question of anisotropy renormalization in interacting 2D Fermi systems. Using a recently developed [1] nonperturbative and numericallyexact projective quantum Monte Carlo simulation as well as other numerical and analytic techniques, only for Dirac fermions with longrange Coulomb interactions do we find a universal squareroot decrease of the Fermisurface anisotropy [2]. Our proposed universality can be tested in several anisotropic Dirac materials including graphene, topological insulators and organic conductors. 
Monday, March 4, 2019 4:30PM  4:42PM 
C19.00009: Energy scales and quasiparticle behavior of fermions in the normal state of flatband systems Pramod Kumar, Vanhala Tuomas, Sebastiano Peotta, Paivi Torma We explore the energy scales and quasiparticle behavior in the paramagnetic normal state of the repulsive Hubbard model on the Lieb lattice. The special geometry of the Lieb lattice, a facecentered 2D square lattice, has a flat dispersion, which leads to various novel electronic phases with the inclusion of manybody interactions [1, 2]. Singularity in the density of states can lead to the breakdown of quasiparticle behavior at finite temperature. The interplay of the singularity and the interaction determine the energy scale to observe such nonFermi liquid behavior. We address this using dynamical mean field theory (DMFT), a very wellestablished methodology for correlated manybody systems. We have used continuoustime quantum Monte Carlo (CTQMC), an exact impurity solver, within DMFT. We also comment on particlehole mapping between attractive and repulsive Hubbard model with a unitary transformation and the corresponding electronic properties. 
Monday, March 4, 2019 4:42PM  4:54PM 
C19.00010: Bosonic Crystalline Symmetry Protected Topological Phases beyond the Group Cohomology Proposal Hao Song, Zhaoxi Xiong, ShengJie Huang It is demonstrated by explicit construction that the intricate links among shortrangeentangled (SRE) states across different dimensions have a vivid embodiment in the realm of symmetry protected topological (SPT) phases with crystalline symmetry. We systematically study threedimensional bosonic topological phases protected by any space group symmetry G. We prove that these phases are classified by H_{φ}^{5}(G;Z)×H_{φ}^{1}(G;Z), where φ indicates g∈G acting on Z as multiplying φ(g)=±1 depending on whether orientation is preserved by g or not. The factor H_{φ}^{5}(G;Z)=H_{Borel,φ}^{4}(G;U(1)), known as the group cohomology proposal for classifying bosonic SPT phases, corresponds to only the phases presented by some SRE 2skeleton without presence of E_{8} state or its multiples (i.e., twodimensional chiral bosonic phases characterized by quantized thermal Hall effect). The extra factor H_{φ}^{1}(G;Z) describes inequivalent E_{8} state configurations and be easily read off directly from the international (HermannMauguin) symbol for G. Moreover, our result supports the Generalized Cohomology Hypothesis in the case of crystalline symmetries. 
Follow Us 
Engage
Become an APS Member 
My APS
Renew Membership 
Information for 
About APSThe American Physical Society (APS) is a nonprofit 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 207403844
(301) 2093200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 5914000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 200452001
(202) 6628700