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Colloquium

The colloquium is currently held at 4:30 PM on Tuesdays in Harriman 137. Cookies, tea and coffee are served from 4:15 PM outside the lecture hall.

Colloquium committee:Marivi Fernandez-Serra (Chair), Will Farr, Dmitri Kharzeev, Rouven Essig and Giacinto Piacquadio

Archive of colloquia from 1999 to the present


Spring 2023 Colloquia
Date Speaker Title & Abstract

Feb 7

Alyson Brooks

Rutgers

What is the Matter with Dwarf Galaxies?


The large-scale structure of our Universe is well described by a model in which matter is predominantly Cold Dark Matter (CDM). While CDM was initially thought to have trouble reproducing the small scales of our Universe (dwarf galaxies and the central regions of galaxies like the Milky Way), it has generally become accepted in the last decade that a proper treatment of the gas and stars (baryonic matter) can alleviate those tensions. However, the models of energetic "feedback" from stars that have solved some of the tensions in CDM are now running into trouble solving new problems, specifically the "diversity of rotation curves" problem. In this talk, I will highlight the successes and troubles of current baryonic models, and discuss whether self-interacting dark matter (SIDM) might be a better model to explain observations.

Feb 14

Phil Phillips

UIUC

Beyond BCS: An Exact Model for Superconductivity and Mottness


The Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity described all superconductors until the 1986 discovery of the high-temperature counterpart in the cuprate ceramic materials. This discovery has challenged conventional wisdom as these materials are well known to violate the basic tenets of the Landau Fermi liquid theory of metals, crucial to the BCS solution. Precisely what should be used to replace Landau's theory remains an open question. The natural question arises: What is the simplest model for a non-Fermi liquid that yields tractable results. Our work builds[1] on an overlooked symmetry that is broken in the normal state of generic models for the cuprates and hence serves as a fixed point. A surprise is that this fixed point also exhibits Cooper's instability[2,3]. However, the resultant superconducting state differs drastically[3] from that of the standard BCS theory. For example the famous Hebel-Slichter peak is absent and the elementary excitations are no longer linear combinations of particles and holes but rather are superpositions of composite excitations. Our analysis here points a way forward in computing the superconducting properties of strongly correlated electron matter.

[1] E. Huang, G. La Nave, P. Phillips, Nat. Phys., 18, pages 511–516 (2022).
[2] PWP, L. Yeo, E. Huang, Nature Physics, 16, 1175-1180 (2020).
[3] J. Zhao, L. Yeo, E. Huang, PWP, PRB, Phys. Rev. B 105, 184509 (2022).

Feb 21

Zoe Yan

Princeton

Microscopy of quantum correlations in an ultracold molecular gas


Ultracold molecules are a promising platform for quantum simulation of spin physics due to their long-range interactions and large set of internal states. To understand the complex many-body states that emerge in these systems, both in and out of equilibrium, new experimental techniques are needed to probe molecule correlations in the strongly interacting regime.

We study the site-resolved dynamics of spin correlations in a gas of ultracold NaRb molecules in a 2D optical lattice. The molecules realize a quantum XY model with long-range interactions. Using a site-resolved Ramsey interferometric technique, we detect oscillations in nearest- and next-nearest-neighbor correlations due to spin interactions. Furthermore, we apply a periodic external microwave field to engineer XXZ spin Hamiltonians with tunable anisotropies. The correlations are measured by dissociating the molecules and detecting the corresponding Rb atoms with single-site resolution using a quantum gas microscope. The techniques presented here open new doors for probing quantum correlations in complex many-body systems of ultracold molecules.

Feb 28

Feliciano Giustino

UT Austin

TBA.

Mar 7

TBA.

TBA.

Mar 14

--

Spring Break.

Mar 21

TBA.

TBA.

Mar 28

TBA.

TBA.

Apr 4

Elena D'onghia

University of Wisconsin

TBA.

Apr 11

TBA.

TBA.

Apr 18

Chris Ashall

Virginia Tech

TBA.

Apr 25

Xu Du

Stony Brook University

TBA.

May 2

Matthew Dawber

Stony Brook University

Graduate colloquium.


Archived Colloquium Schedules