Dr. Aranya Bhattacharya
Senior Research Associate (2025-Present)
School of Mathematics,
University of Bristol
Senior Research Associate (2025-Present)
School of Mathematics,
University of Bristol
I am a postdoctoral researcher working on theoretical Physics. My main research interests are quantum gravity, holography and quantum chaos. I try to understand how the quantum version of information is stored in chaotic systems, from simple quantum mechanical ones to the most complicated ones involving black holes, conjectured to be the fastest scramblers of information. While I am also using new ideas and techniques for probing information scrambling and chaos, e.g. entanglement and complexity in most straightforward quantum mechanical systems, the central machinery to apply those ideas systematically within quantum gravity and black hole setups is the famously known holography or AdS/CFT correspondence. This correspondence relates a gravity theory to a quantum field theory (physically closer to quantum mechanical systems) living on the boundary of the gravity theory. I am also interested in exploring the connections between condensed matter and holographic systems through the window of quantum information. The central question in this subfield is how a system thermalises and how to probe ETH (Eigenstate Thermalization Hypothesis). I am using the connections between the autocorrelation function (the overlap between an initial and time-evolved operator) and the poles of the retarded Greens function in thermal settings to relate chaotic properties with the quasinormal ringdown, a procedure through which the information thrown inside a black hole with infalling boundary condition relaxes in a dissipative way. This connection enables one to study signatures of holography within much more tractable setups. If you would like to know more about me and my work, please have a look at my updated CV here, and the details given below.
I, along with my collaborators, have worked on the idea of entanglement and computational complexity in situations where the Page curve is reproduced using the concept of entanglement islands. In [1] (single authored paper in PRD), I studied a multiboundary wormhole model while in [2] and [3], we looked at the evolution of the holographic subregion complexity for evaporating and eternal AdS black holes respectively.
In this program ([4] and [5]), we have developed the notion of operator growth and Krylov complexity for various open quantum systems. Krylov complexity quantifies how an initial state or operator spreads in the corresponding Hilbert space along Hamiltonian time evolution in the Schrödinger or Heisenberg picture respectively. It is related to the spectrum of the Hamiltonian or Liouvillean, and hence acts as a simple but elegant probe of quantum chaos as this spread of operator is known to be fastest for chaotic evolution. One can also figure out different timescales (Scrambling time, Heisenberg time etc.) where this process of spreading of operator goes through major and noticeable changes affecting the overall scaling of the Krylov complexity. We investigate how the notion of chaos changes in the presence of interaction with the environment where the information leaks out to the environment causing a decay of probability in the system degrees of freedom and affecting the notion of chaos.
In this work [6], I, along with a masters student from IISc Bangalore, figured out a way how to quantify chaotic nature of scattering amplitudes. We study the statistics of the poles of several scattering amplitudes with respect to some probe input variable (momenta or scattering angle) and treat them as eigenvalues of a Hamiltonian, which evolves one copy of a thermofield double state non-trivially. Through this method, we study the complexity of several scattering amplitudes and find that the amplitudes for highly excited string states scattering to multiple tachyons show chaotic behaviour typical to the Gaussian Unitary Ensemble (GUE) universality class among the well-known Random matrix universality class. This also indicates the fact that black hole scattering is chaotic since the highly excited string states are conjectured to be dual to black hole microstates due to the string/black hole correspondence by Susskind-Horowitz-Polchinski.
Senior Research Associate in the School of Mathematics, University of Bristol, UK. (September 2025- present)
Adiunkt (Postdoctoral researcher) in Dr. Mario Flory's group in the Theory of Complex Systems department of Jagiellonian University, Krakow, Poland. (September 2023 - August 2025)
Institute of Eminence Postdoctoral Fellow in the Centre for High Energy Physics (CHEP) of the Indian Institute of Science (IISc), Bengaluru. (August 2021 - August 2023)
Graduate Student in the Theory Division of Saha Institute of Nuclear Physics (SINP), Kolkata. (August 2016 - June 2021)
Master of Science (MSc) in Physics from the Indian Institute of Technology Kanpur (IITK). (July 2014 - May 2016)
Bachelor of Science (BSc) Physics Honours from Ramakrishna Mission Vidyamandira (RKMV), Belur Math, Howrah. (July 2011 - May 2014)