Hi! I’m Kabir, a physics PhD student at the University of Geneva working with Romain Vasseur. At leading order, I am interested in all things at the interface of quantum information, statistical mechanics, and field theory. My PhD research focuses on many-body physics relevant to quantum simulators, using field theory and statistical mechanics to understand universal measurement-related phenomena both in and out of equilibrium. Have a look at my papers below to learn more.
Outside of physics, I like to play chess, brew coffee with more care than necessary, and stay physically active to counteract a (theoretical) physicist’s chair-bound life.
Stowe (2023)
News
We resolved a long-standing puzzle about a peculiar phase transition in the Ising universality class. Here’s our pre-print!
Our work on post-selected criticality in MIPTs and Random Tensor Networks is published in PRL!
Our work on measurement-altered criticality is out on arxiv!
Delivered tutorial sessions in QLANDS 2026 on stat-mech of random circuits. My first time around Paris!
Attended the ALPS 3 school on generalized symmetries!
The work on MIE in CFTs has been published in PRL!
Older news
Our work on studying post-selected criticality in MIPTs is out on arXiv!
We understand a replica phase transition that occurs in the Ising universality class, uncovering interesting universal properties of the Born distribution via its Shannon entropy and altered-correlations.
We show that post-selection changes the universality class of measurement-induced phase transitions to those of the entanglement transition in random tensor networks.
We develop a statistical-mechanics description of measurement-induced transitions in random quantum circuits with time-reversal symmetry.
Abstract
Time-reversal (TR) symmetry is crucial for understanding a wide range of physical phenomena, and plays a key role in constraining fundamental particle interactions and in classifying phases of quantum matter. In this work, we introduce an ensemble of random quantum circuits that are representative of the dynamics of generic TR-invariant many-body quantum systems. We derive a general statistical mechanics model describing entanglement, many-body quantum chaos, and quantum information dynamics in such TR-invariant circuits. As an example of application of our formalism, we study the universal properties of measurement-induced phase transitions in monitored TR-invariant systems, with measurements performed in a TR-invariant basis. We find that TR invariance of the unitary part of the dynamics does not affect the universality class, unless measurement outcomes are postselected to satisfy the global TR invariance of each quantum trajectory. We confirm these predictions numerically and find, for both generic and Clifford-based evolutions, critical exponents in the case of “strong,” i.e., global TR invariance where each quantum trajectory is TR invariant.
We express gravity-induced decoherence in terms of spacetime curvature, separating tidal effects from non-inertial kinematics.
Abstract
There has been considerable interest over the past years in investigating the role of gravity in quantum phenomenon such as entanglement and decoherence. In particular, gravitational time dilation is believed to decohere superpositions of center of mass of composite quantum systems. Since true effects of gravity are encoded in the curvature of spacetime, the universality of such decoherence must be characterized through components of Riemann tensor Rabcd, with a clear separation from non-inertial kinematic effects. We obtain the reduced density matrix of a composite system in a generic curved spacetime and express the decoherence time scale explicitly in terms of curvature. The decoherence in an inertial frame is caused by tidal acceleration. We also analyze the effects of self-gravity and show that the coupling of gravitational interaction with external curvature can not be captured by the replacement m→m+Hint/c2.
