# Condensed matter physics seminar series: Marko Znidaric

**F May 24 11am Room 5209**

Marko Znidaric, University of Ljubjana

Organizers: Sarang Gopalakrishnan & Tankut Can

Click here for full series printable PDF.

Filtering by: Seminar

May

24

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F May 24 11am Room 5209**

Marko Znidaric, University of Ljubjana

Organizers: Sarang Gopalakrishnan & Tankut Can

Click here for full series printable PDF.

May

17

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F May 17 11am Room 5209**

David Weld, The University of California at Santa Barbara

Organizers: Sarang Gopalakrishnan & Tankut Can

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May

16

4:15 PM16:15

- Room 6496 at The Graduate Center, CUNY (map)
- Google Calendar ICS

**Kazuo Yamazaki, University of Rochester** **Abstract:** The magnetohydrodynamics system consists of the Navier-Stokes equations forced by Lorentz force, coupled with the Maxwell's equations from electromagnetism. This talk will be relatively expository about the direction of research on stochastic PDE forced by space-time white noise, with a new result on the three-dimensional magnetohydrodynamics system forced by space-time white noise. In short, the fact that the noise is white in not only time but also space forces the solution to become extremely rough in spatial variable, its regularity akin to those of distributions, so that it becomes difficult for the non-linear term to become well-defined in any classical sense because there is no universal agreement on a product of a distribution with another distribution. Our discussion should also include following systems of equations: Kardar-Parisi-Zhang equation, Boussinesq system. The following notions and techniques may also be included in our discussions: Feynman diagrams, local subcriticality, paracontrolled distributions, renormalizations, regularity structures, rough path theory, Wick products, Young's integral.

Part of the Non-Linear Study Group. For more info, see https://www.math.csi.cuny.edu/~mlucia/GCactivities.html

May

9

4:15 PM16:15

- Room 6496 at The Graduate Center, CUNY (map)
- Google Calendar ICS

**Dennis Kriventsov, Rutgers University** **Abstract:** I will discuss an example of a pair of continuous nonnegative subharmonic functions, each vanishing where the other is positive, which have a strictly positive limit for the Alt-Caffarelli-Friedman monotonicity formula at the origin, but for which the origin is not a point of differentiability for the boundary of their supports. Time permitting, I will also discuss some further progress on related problems.This is based on joint work with Mark Allen.

Part of the Non-Linear Study Group. For more info, see https://www.math.csi.cuny.edu/~mlucia/GCactivities.html

May

8

3:00 PM15:00

- Room 5209 at The Graduate Center, CUNY (map)
- Google Calendar ICS

**Bose-Einstein condensation and superfluidity of excitons and polarities in novel two-dimensional nanomaterials**

Oleg Berman, City Tech

May

6

2:00 PM14:00

- The Science Center at the The Graduate Center, CUNY (Rm 4102) (map)
- Google Calendar ICS

** Abstract:**

In the past several years we have developed a comprehensive theory of large scale learning with Deep Neural Networks (DNN), when optimized with Stochastic Gradient Decent (SGD). The theory is built on three theoretical components: (1) rethinking the standard (PAC like) distribution independent worse case generalisation bounds - turning them to problem dependent typical (in the Information Theory sense) bounds that are independent of the model architecture.

(2) The Information Plane theorem: For large scale typical learning the sample-complexity and accuracy tradeoff is characterized by only two numbers: the mutual information that the representation (a layer in the network) maintain on the input patterns, and the mutual information each layer has on the desired output label. The Information Theoretic optimal tradeoff between thees encoder and decoder information values is given by the Information Bottleneck (IB) bound for the rule specific input-output distribution. (3) The layers of the DNN reach this optimal bound via standard SGD training, in high (input & layers) dimension.

In this talk I will briefly review these results and discuss two new surprising outcomes of this theory: (1) The computational benefit of the hidden layers, (2) the emerging understanding of the features encoded by each layers which follows from the convergence to the IB bound.

Based on joint works with Noga Zaslavsky, Ravid Ziv, and Amichai Painsky.

Naftali Tishby is the Ruth & Stan Flinkman Professor in Brain Research at the Hebrew University of Jerusalem, where he is a member of The Benin School of Computer Science and Engineering and The Edmond and Lilly Safra Center for Brain Sciences. Educated as physicist, he has made profound contributions to problems ranging from chemical reaction dynamics to speech recognition, and from natural language processing to the dynamics of real neural networks in the brain. In the late 1980s Tishby and colleagues recast learning in neural networks as a statistical physics problem, and went on to discover that learning in large networks could show phase transitions, as exposure to increasing numbers of examples “cools” the parameters of the network into a range of values that provides qualitatively better performance. Most recently he has emerged as one of the leading figures in efforts to understand the success of deep learning, and this will be the topic of his seminar.

We have set aside two hours, in the hopes of encouraging greater interaction and discussion.

Download the event flier here.

Sponsored by the Initiative for the Theoretical Sciences, and by the CUNY doctoral programs in Physics and Biology.

Supported in part by the Center for the Physics of Biological Function, a joint effort of The Graduate Center and Princeton University

May

3

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F May 3 11am Room 5209**

Paola Cappellaro, The Massachusetts Institute of Technology

Organizers: Sarang Gopalakrishnan & Tankut Can

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Apr

26

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F Apr 26 11am Room 5209**

Philipp Dumitrescu, The Flatiron Institute

Organizers: Sarang Gopalakrishnan & Tankut Can

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Apr

12

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F Apr 12 11am Room 5209**

Arvind Murugan, The University of Chicago

Organizers: Sarang Gopalakrishnan & Tankut Can

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Apr

11

4:15 PM16:15

- Room 6496 at The Graduate Center CUNY (map)
- Google Calendar ICS

**Nonlinear Analysis and PDEs**Goals of these seminars are to discuss techniques that are used nonlinear problems arising in applied mathematics, physics or differential geometry.

These events are sponsored by the Initiative for the Theoretical Sciences. For more information go to https://www.math.csi.cuny.edu/~mlucia/GCactivities.html.

Those participating in the Nonlinear Analysis and PDE seminar may also be interested in the Geometric Analysis Seminar which meets Tuesdays in the same room 6496 starting at 3pm.

Apr

5

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F Apr 5 11am Room 5209**

Marcos Rigol, Pennsylvania State University

Quantum dynamics of interacting many-body systems has become a

unique venue for the realization of novel states of matter. In this talk, we

discuss how it can lead to the generation of time-evolving states that are

eigenstates of emergent local Hamiltonians, not trivially related to the ones

dictating the time evolution. We study geometric quenches in fermionic and

bosonic systems in one-dimensional lattices, and provide examples of

experimentally relevant time-evolving states [1,2] that are either ground

states or highly excited eigenstates of emergent local Hamiltonians [3]. We

also discuss the expansion of Mott insulating domains at finite temperature.

Surprisingly, the melting of the Mott domain is accompanied by an effective

cooling of the system [4]. We explain this phenomenon analytically using the

equilibrium description provided by the emergent local Hamiltonian [4,5].

Part of the Condensed matter physics seminar series

Organizers: Sarang Gopalakrishnan & Tankut Can

Click here for full series printable PDF.

Mar

22

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

Nina Markovic

Organizers: Sarang Gopalakrishnan & Tankut Can

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Feb

15

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F Feb 15 11am Room 5209**

Boris Hanin, Texas A&M University

Organizers: Sarang Gopalakrishnan & Tankut Can

More info:

Boris Hanin is a mathematician work on deep learning and mathematical physics. Before joining the faculty in the Math Department at Texas A&M in 2017, he was an NSF Postdoc in Math at MIT. He is currently a Visiting Scientist at Facebook AI Research in NYC.

“I will present several new results, joint with David Rolnick, about the number of linear regions and the sizes of the boundaries of linear regions in a network N with piecewise linear activations and random weights/biases.

I will discuss a new formula for the average complexity of linear regions that holds even for highly correlated weights and biases, and hence is valid throughout training. It shows, for example, that at initialization, the number of regions along any 1D line grows like the number of neurons in N. In particular, perhaps surprisingly, it is this number is not exponential in the depth of the network.

I will explain the analog of this result for higher input dimension and will report on a number of experiments, which demonstrate empirically that our precise theorems at initialization can be expected to hold qualitatively throughout training.”

Click here for full series printable PDF.

Feb

8

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F Feb 8 11am Room 5209**

Brian Swingle, University of Maryland

Organizers: Sarang Gopalakrishnan & Tankut Can

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Dec

14

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F Dec 14 11am Room 5209**

Alicia Kollar, University of Maryland

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Dec

7

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F Dec 7 11am Room 5209**

Jennifer Cano, Stony Brook University and Flatiron Institute

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Nov

30

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F Nov 30 11am Room 5209**

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Nov

16

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F Nov 16 11am Room 5209**

Ivar Martin, Argonne National Laboratory

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Nov

2

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F Nov 2 11am Room 5209**

Liang Fu, Massachusetts Institute of Technology

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Oct

26

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F Oct 26 11am Room 5209**

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Oct

19

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

Sep

28

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F Sept 28 11am Rm 5209**

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Sep

21

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F Sept 21 11am Room 5209**

Thomas Scaffidi, University of California at Berkeley

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Sep

14

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F Sept. 14 11am Room 5209**

Sriram Ganeshan, City College of New York

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Sep

7

11:00 AM11:00

- Room 5209, The Graduate Center, CUNY (map)
- Google Calendar ICS

**F Sept. 7, 11am in Room 5209**

Andrey Gromov, The University of Chicago

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