Ashish SHUKLA

 

Post Doctoral Fellow

Research group: String Theory 

Personal website

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Research interests :

I am primarily working on the AdS/CFT correspondence and its applications to the study of strongly coupled quantum many-body systems. The dynamics of such systems near thermal equilibrium is captured by relativistic hydrodynamics, which provides an effective macroscopic description of the system in terms of fluid variables, such as the local temperature, fluid velocity etc. The evolution of these variables is governed by the conservation equations for the system, such as the conservation of the energy-momentum tensor. The power of the formalism rests in the idea that near thermal equilibrium, the conserved currents of the system can be expressed in an expansion in terms of the fluid variables and their derivatives, which leads to immense simplification for an otherwise complex problem. The various state-dependent coefficients that enter this derivative expansion, called transport parameters, capture physical properties of the system. Examples of these transport parameters include the shear and bulk viscosities, conductivity etc. My research has focused on studying transport parameters for charged relativistic fluids that appear at the second order in the derivative expansion, in the static limit. I am also interested in studying fluctuations in relativistic fluids, caused by the underlying thermal noise, using the Schwinger-Keldysh closed time-path formalism. 

I am also working on the connections between quantum information and gravity. My research here focuses on studying quantum information aspects of field theories with a holographic dual. The duality enables us to extract various interesting properties of the quantum system, such as the entanglement entropy, by performing computations in the dual gravitational description.

I am also interested in the physics of black holes, as well as theoretical cosmology. My PhD thesis focused on deriving constraints on the correlation functions of inflationary perturbations in single field models of cosmological inflation. The constraints follow from the underlying spacetime reparametrization invariance of general relativity. They take the form of Ward identities, relating n-point correlation functions of inflationary perturbations to n+1-point correlation functions, on taking appropriate limits under the action of suitable operators. Since the Ward identities follow from underlying symmetries of the system, they provide robust model-independent checks on various single field models of inflation.

Thesis:

"Symmetry constraints in single field models of inflation." Department of Theoretical Physics, Tata Institute of Fundamental Research, Mumbai, India. Supervisor: Prof. Sandip Trivedi. PhD defended on October 31, 2018. Link to the thesis: please click here.

Publications:

A complete list of my publications can be found at the Inspire HEP website: please click here.

 

Address CPHT, Ecole Polytechnique, 91128 Palaiseau cedex, France
Phone 33 (0) 1 69 33 42 71
Contact firstname.lastname@polytechnique.edu
Office Aile zéro, pièce 1026

 

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