Nonergodic states in aperiodic quantum chains

• Grant number: 25/20171-1
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: February 01, 2026
• End date: January 31, 2028
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Eric de Castro e Andrade
• Grantee: Gaurav Khairnar
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 22/15453-0 - Correlated quantum materials, AP.TEM

Abstract

Interacting many-body systems exhibit a wide range of fascinating phenomena in equilibrium: emergence of collective behavior, symmetry-breaking phase transitions, quasiparticle excitations, and more. When driven out of equilibrium, one expects even richer dynamics. If an isolated many-body system fully explores its large Hilbert space, it undergoes thermalization, a behavior known as quantum ergodicity. It is therefore natural to ask under what conditions a general interacting system can evade ergodicity. One well-established route involves the presence of localized states, which give rise to the celebrated phenomenon of many-body localization. More recently, a new class of weak ergodicity-breaking mechanisms has been discovered in Rydberg atom experiments, where persistent revivals occur depending on the choice of initial state. While most initial conditions lead to rapid relaxation, specific ones give rise to nonergodic dynamics, an effect referred to as quantum many-body scarring.In this project, we aim to explore such routes to ergodicity breaking in spin chains with deterministic aperiodic ingredients generated by substitution rules, where geometric fluctuations can be systematically controlled. (AU)