November 2021

Date: November 1

Time: 15:30 IST (UTC + 5:30)

Speaker: Wilke van der Schee (CERN )

Title: Non-equilibrium steady state formation in holographic theories

Abstract: In this talk I will present the first holographic simulations of non-equilibrium steady state formation in strongly coupled N=4 SYM theory in 3+1 dimensions [1]. This is achieved by joining together two thermal baths at different temperatures and chemical potentials and comparing the subsequent evolution of the combined system to analytic solutions of the corresponding Riemann problem and to numeric solutions of ideal and viscous hydrodynamics. The time evolution of the energy density that we obtain holographically is consistent with the combination of a shock and a rarefaction wave: A shock wave moves towards the cold bath, and a smooth broadening wave towards the hot bath. Between the two waves emerges a steady state with constant temperature and flow velocity.

Time permitting there will be a somewhat different topic in a similar set-up, where we consider a boundary FRW theory with dynamical gravity [2]. This will give a short introduction to how to have an evolution scheme that allows to evolve far-from-equilibrium strongly coupled matter on a background that evolves according to the Einstein equations.

[1] Christian Ecker, Johanna Erdmenger and WS, Non-equilibrium steady state formation in 3+1 dimensions, 2103.10435 (SciPost Phys)

[2] Christian Ecker, WS, David Mateos and Jorge Casalderrey-Solana, Holographic Evolution with Dynamical Boundary Gravity, 2109.10355

This seminar is a part of the activities of Center for Strings, Gravity and Cosmology of IIT Madras

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Date: November 4

Time: 15:30 IST (UTC + 5:30)

Speaker: Hans Jockers (Univ. of Mainz)

Title: Deformations of JT Gravity

Abstract: In this talk we discuss the duality between JT gravity and the double-scaled matrix model including their respective deformations. This is achieved by relating the thermal partition function to the generating function of topological gravity correlators. We point out some consequences of our findings.

This seminar is a part of the activities of Center for Strings, Gravity and Cosmology and the Center for Quantum Information Theory of Matter and Spacetime of IIT Madras

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Date: November 11

Time: 18:30 IST (UTC + 5:30)

Speaker: Nima Lashkari (Purdue Univ.)

Title: Renormalization and Approximate Error Correction

Abstract: In real-space renormalization group (RG) flow, we integrate out short distance physics, preserving the long-distance correlations. This can be understood as an approximate error correction code. I motivate the connection by a simple example of classical error correction codes in the spin blocking RG of classical systems. In many body quantum systems, I will discuss the quantum error correction properties of the Multi-Scale Renormalization Ansatz (MERA) and its continuous version cMERA. I will comment on the connections with exact RG in continuum field theories.

This seminar is a part of the activities of Center for Quantum Information Theory of Matter and Spacetime of IIT Madras

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Date: November 22

Time: 17:30 IST (UTC + 5:30)

Speaker: Matthias Kaminski (Univ. of Alabama)

Title: Relativistic spin hydrodynamics with torsion

Abstract: After an introduction of the relevant concepts, we are going to discuss recent progress in the construction of relativistic spin hydrodynamics. Using the second law of local thermodynamics and the first-order Palatini formalism, we will formulate relativistic spin hydrodynamics for quantum field theories with Dirac fermions, such as QED and QCD, in a torsionful curved background. Spin density is assumed to relax much slower than other non-hydrodynamic modes in some regimes of experiments. We are going to work in such a regime, and treat spin density as an independent degree of freedom in an extended hydrodynamic description. A new transport coefficient controls the spin relaxation: the rotational viscosity. Lastly, we will outline how holography can significantly contribute to the construction and testing of spin hydrodynamics.

This seminar is a part of the activities of Center for Strings, Gravitation and Cosmology of IIT Madras

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Date: November 25

Time: 17:30 IST (UTC + 5:30)

Speaker: Lata Joshi (Institute for quantum optics and quantum information (IQOQI), Innsbruck)

Title: Proposal to probe many-body quantum chaos with quantum simulators

Abstract: The spectral form factor (SFF), characterizing statistics of energy eigenvalues, is a key diagnostic of many-body quantum chaos. In addition, partial spectral form factors (pSFFs) can be defined which refer to subsystems of the many-body system. They provide unique insights into energy eigenstate statistics of many-body systems. In this talk I will discuss these on the basis of random matrix theory and of the eigenstate thermalization hypothesis. We have proposed a protocol which allows the measurement of SFF and pSFFs in quantum many-body spin models, within the framework of randomized measurements. I will be presenting our measurement scheme which provides a unified testbed to probe many-body quantum chaotic behavior, thermalization and many-body localization in closed quantum systems.

This seminar is a part of the activities of Center for Quantum Information Theory of Spacetime and Matter of IIT Madras

VIDEO: Click here