4/8/2021 Quantum Matter Seminar
2021-04-08 13:00 - 14:30 (America/New_York)

4/14/2021 Quantum Matter Seminar
2021-04-14 10:30 - 12:00

4/15/2021 Quantum Matter in Mathematics Seminar
2021-04-15 10:30 - 12:00

4/21/2021 Quantum Matter Seminar
2021-04-21 10:30 - 12:00 | Virtual

4/22/2021 Quantum Matter Seminar
2021-04-22 10:30 - 12:00 | Virtual

4/28/2021 Quantum Matter Seminar
2021-04-28 13:00 - 14:30

4/29/2021 Quantum Matter Seminar
2021-04-29 10:30 - 12:00

5/5/2021 Quantum Matter Seminar
2021-05-05 20:00 - 21:30

5/6/2021 Quantum Matter Seminar
2021-05-06 10:30 - 12:00

5/13/2021 Quantum Matter Seminar
2021-05-13 10:30 - 12:00

5/20/2021 Quantum Matter Seminar
2021-05-18 10:30 - 12:00

5/19/2021 Quantum Matter Seminar
2021-05-19 10:30 - 12:00

6/3/2021 Quantum Matter Seminar
2021-05-26 10:30 - 12:00

6/2/2021 Quantum Matter Seminar
2021-06-02 10:30 - 12:00

6/9/2021 Quantum Matter Seminar
2021-06-09 10:30 - 12:00

6/10/2021 Quantum Matter Seminar
2021-06-10 10:30 - 12:00

6/16/2021 Quantum Matter Seminar
2021-06-16 10:30 - 12:00

6/17/2021 Quantum Matter Seminar
2021-06-17 10:30 - 12:00

7/7/2021 Quantum Matter Seminar
2021-07-07 10:30 - 12:00 | Virtual

7/8/2021 Quantum Matter Seminar
2021-07-08 20:00 - 21:30

7/14/2021 Quantum Matter Seminar
2021-07-14 11:30 - 12:00

Hybrid Fracton Orders
2021-07-15 10:30 - 12:30 | Virtual
Nathanan Tantivasadakarn (Harvard)
Video
Title: Hybrid Fracton Orders
Abstract: I will introduce a family of gapped quantum phases that exhibit the phenomenology of both conventional three-dimensional topological orders and fracton orders called “Hybrid Fracton Orders”. First, I will present the simplest example of such an order: the “Hybrid X-cube” model, where excitations can be labeled identically to those of the Z2 toric code tensored with the Z2 X-cube model, but exhibit fusion and braiding properties between the two sets of excitations. Next, I will provide a general construction of hybrid fracton orders which inputs a finite group G and an abelian normal subgroup N and produces an exactly solvable model. Such order can host non-abelian fracton excitations when G is non-abelian. Furthermore, the mobilities of a general excitation is dictated by the choice of N, from which by varying, one can view as “interpolating” between a pure 3D topological order and a pure fracton order.
Based on 2102.09555 and 2106.03842

7/21/2021 Quantum Matter Seminar
2021-07-21 10:30 - 12:00

7/22/2021 Quantum Matter Seminar
2021-07-22 08:00 - 09:30

The nu=5/2 enigma: Recent insights from theory and experiment
2021-07-29 10:30 - 12:00 | Virtual
peaker: Ady Stern & David Mross (Weizmann)
Speaker: Ady Stern & David Mross (Weizmann
Title: The nu=5/2 enigma: Recent insights from theory and experiment
Abstract: Non-Abelian phases of matter have long inspired quantum physicists across various disciplines. The strongest experimental evidence of such a phase arises in quantum Hall systems at the filling factor 5/2 but conflicts with decades of numerical works. We will briefly introduce the 5/2 plateau and explain some of the key obstacles to identifying its topological order. We will then describe recent experimental and theoretical progress, including a proposal for resolving the 5/2 enigma based on electrical conductance measurements.

Naturalness and muon anomalous magnetic moment
2021-09-01 18:31 - 19:31 | Virtual
Title: Naturalness and muon anomalous magnetic moment
Abstract: We study a model for explaining the apparent deviation of the muon anomalous magnetic moment, (g-2), from the Standard Model expectation. There are no new scalars and hence no new hierarchy puzzles beyond those associated with the Standard model Higgs; the only new particles that are relevant for (g-2) are vector-like singlet and doublet leptons. Interestingly, this simple model provides a calculable example violating the Wilsonian notion of naturalness: despite the absence of any symmetries prohibiting its generation, the coefficient of the naively leading dimension-six operator for (g−2) vanishes at one-loop. While effective field theorists interpret this either as a surprising UV cancellation of power divergences, or as a delicate cancellation between matching UV and calculable IR corrections to (g−2) from parametrically separated scales, there is a simple explanation in the full theory: the loop integrand is a total derivative of a function vanishing in both the deep UV and IR. The leading contribution to (g−2) arises from dimension-eight operators, and thus the required masses of new fermions are lower than naively expected, with a sizable portion of parameter space already covered by direct searches at the LHC. All of the the viable parameter can be probed by the LHC and planned future colliders.

Exotic quantum matter: From lattice gauge theory to hyperbolic lattices
2021-09-02 18:34 - 19:34 | Virtual
Title: Exotic quantum matter: From lattice gauge theory to hyperbolic lattices
Abstract: This talk, in two parts, will discuss two (unrelated) instances of exotic quantum matter. In the first part, I will discuss quantum critical points describing possible transitions out of the Dirac spin liquid, towards either symmetry-breaking phases or topologically ordered spin liquids. I will also comment on the role of instanton zero modes for symmetry breaking in parton gauge theories. In the second part, I will propose an extension of Bloch band theory to hyperbolic lattices, such as those recently realized in circuit QED experiments, based on ideas from algebraic geometry and Riemann surface theory.

Cornering the universal shape of fluctuations and entanglement
2021-09-08 18:37 - 19:37 | Virtual
Title: Cornering the universal shape of fluctuations and entanglement
Abstract: Understanding the fluctuations of observables is one of the main goals in physics. We investigate such fluctuations when a subregion of the full system can be observed, focusing on geometries with corners. We report that the dependence on the opening angle is super-universal: up to a numerical prefactor, this function does not depend on anything, provided the system under study is uniform, isotropic, and correlations do not decay too slowly. The prefactor contains important physical information: we show in particular that it gives access to the long-wavelength limit of the structure factor. We illustrate our findings with several examples: classical fluids, fractional quantum Hall (FQH) states, scale invariant quantum critical theories, and metals. Finally, we discuss connections with the entanglement entropy, including new results for Laughlin FQH states.
Ref: arXiv:2102.06223

Quantum gravity from quantum matter
2021-09-09 18:38 - 19:38 | Virtual
Title: Quantum gravity from quantum matter
Abstract: We present a model of quantum gravity in which dimension, topology and geometry of spacetime are collective dynamical variables that describe the pattern of entanglement of underlying quantum matter. As spacetimes with arbitrary dimensions can emerge, the gauge symmetry is generalized to a group that includes diffeomorphisms in general dimensions. The gauge symmetry obeys a first-class constraint operator algebra, and is reduced to a generalized hypersurface deformation algebra in states that exhibit classical spacetimes. In the semi-classical limit, we find a saddle-point solution that describes a series of (3+1)-dimensional de Sitter-like spacetimes with the Lorentzian signature bridged by Euclidean spaces in between.

More Exact Results in Gauge Theories: Confinement and Chiral Symmetry Breaking
2021-09-10 18:44 - 19:44 | Virtual
Title: More Exact Results in Gauge Theories: Confinement and Chiral Symmetry Breaking
Abstract: In this follow-up to Hitoshi Murayama’s talk “Some Exact Results in QCD-like and Chiral Gauge Theories”, I present a detailed analysis of the phases of $SO(N_c)$ gauge theory.
Starting with supersymmetric $SO(N_c)$ with $N_F$ flavors, we extrapolate to the non-supersymmetric limit using anomaly-mediated supersymmetry breaking (AMSB). Interestingly, the abelian Coulomb and free magnetic phases do not survive supersymmetry breaking and collapse to a confining phase. This provided one of the first demonstrations of true confinement with chiral symmetry breaking in a non-SUSY theory.
