PHYSICS SEMINAR
Date and Time: Thursday, 19 May, 11 am
Venue: Lecture Hall 1
Some implications of Quantum Null Energy Condition for AdS_3/CFT_2
Pratik Roy
IIT Madras.
19-05-22

---

Abstract

Quantum Null Energy Condition (QNEC) places lower bounds on the expectation value of the energy-momentum tensor of a non-gravitational theory in terms of null derivatives of the entanglement entropy. We develop a technique to study QNEC in quenches in CFT2 states which are holographically dual to Banados geometries. For transitions between BTZ geometries, we find that an increase in both entropy and temperature, as required by classical thermodynamics, is necessary but not sufficient to not violate QNEC. We determine lower and upper bounds on the increase of entropy (temperature) for a fixed increase in temperature (entropy). Our results provide explicit instances of quantum lower and upper bounds on irreversible entropy production whose existence has been established in the literature on quantum thermodynamics. Our techniques also allow significant generalization of earlier results regarding the evolution of holographic entanglement entropy after quenches. This will be based on arXiv:2109.09914 (published in PRL).

If time permits, I will discuss how our methods yield a refined version of the Landauer principle, which bounds the minimum irreversible entropy production needed to delete encoded quantum information. We can further show that sudden deletion is impossible under certain conditions, thus circumventing some no-go theorems forbidding self-correcting quantum memory in lower dimensions. This will be based on arXiv:2202.00022.