When & Where

The CTP Lunch Club meets every Friday at noon in the Cosman seminar room, 6C-442 (provided that there are sufficient speakers). A light lunch will be provided begining at 11:50am (usually pizza, however some other options may be explored).

The seminars are designed for graduate students and should be accessible to all students. First year students are particularly encouraged to attend so that they may learn about research being performed in the CTP. The goal is learning, and to encourage participation, the seminars will be for students only.

Email notification of the club will be sent to the ctp-all, ctp-postdocs and ctp-students email lists as appropriate. If you wish to speak, or have suggestions about speakers and/or possible workshop topics, please contact the organizers, Ethan Dyer at edyer_at_mit[dot]edu, and Mark Mezei at mezei_at_mit[dot]edu.

• February 18
Irene Bredberg

From Navier-Stokes To Einstein

We show by explicit construction that for every solution of the incompressible Navier-Stokes equation in $p+1$ dimensions, there is a uniquely associated "dual" solution of the vacuum Einstein equations in $p+2$ dimensions. The dual geometry has an intrinsically flat timelike boundary segment $Σc$ whose extrinsic curvature is given by the stress tensor of the Navier-Stokes fluid. We consider a "near-horizon" limit in which $Σc$ becomes highly accelerated. The near-horizon expansion in gravity is shown to be mathematically equivalent to the hydrodynamic expansion in fluid dynamics, and the Einstein equation reduces to the incompressible Navier-Stokes equation. For $p=2$, we show that the full dual geometry is algebraically special Petrov type II. The construction is a mathematically precise realization of suggestions of a holographic duality relating fluids and horizons which began with the membrane paradigm in the 70's and resurfaced recently in studies of the AdS/CFT correspondence.

Faculty and postdocs welcome.

• February 25
Dionysis Anninos

Some words on the de Sitter entropy, holography

We review some of the prominent ideas about de Sitter thermodynamics and the possibility of holography in de Sitter or de Sitter like spaces.

For students and postdocs only.

• March 4
Clay Cordova

An Introduction to Integrable Systems in Physics

I will give an simple introduction to integrable systems, with examples ranging from classical mechanics to quantum field theory.

Faculty and postdocs welcome.

• March 11
Kurt Hinterbichler

Galileons

Galileons are scalar field theories that possess some curious properties and have attracted a lot of interest lately. They arose from studies of the four-dimensional effective actions of higher-dimensional brane-world models such as DGP, but have since taken on a life of their own. Their properties include a small number of free parameters, and quantum behavior which is much better than for typical scalars. For these reasons, they promise to find uses in well-behaved modifications of gravity, more constrained and better motivated theories of inflation, and possibly even the hierarchy problem.

Faculty and postdocs welcome.

• April 1
Brian Tiburzi

The Fermion Sign Problem at Finite Density, and the Large Nc Limit

The study of QCD at finite baryon density is severely hampered by the so-called sign problem. As a result, we have no known first principles approach to study nuclear matter, or neutron stars from QCD. On the surface, the large Nc limit does not seem to simplify matters. In this limit, however, one can exploit dualities that exist between strongly coupled gauge theories. I will focus on some rather novel "strong-strong dualities" that have recently been discovered at finite density. These dualities relate strongly coupled theories plagued by a sign problem, to strongly coupled theories free of sign problems. As a result, such dualities give deeper insight into the nature of the sign problem and possibly provide a way to simulate QCD at finite density in the large Nc limit.

• April 8
Yusuke Nishida

Liberating Efimov physics from three dimensions

When two particles attract via a resonant short-range interaction, three particles always form an infinite tower of bound states characterized by a discrete scaling symmetry. This phenomenon is called as the Efimov effect. Keywords regarding the Efimov effect are universality, scale invariance, quantum anomaly, and renormalization group limit cycle. I will explain how these keywords appear in its understanding and discuss its observation in ultracold atom experiments. Then I will discuss how the Efimov physics, which has been considered to exist only in three dimensions, can be liberated from three dimensions and introduce experiments toward such directions.

• April 22
Sam Ocko

Topological quantum codes from (hopefully) physically realistic Hamiltonians

One possible route to the realization of a scalable quantum computer is to protect quantum information through storing it the degenerate ground states of a topologically ordered Hamiltonian. While many topologically ordered Hamiltonians are known, they all come from many-particle interactions or effectively have many-particle interactions. I use "gadget particles" to give an exactly solvable system with only two-particle interactions.

Faculty and Postdocs Welcome

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