LAMP-SEMINAR

QUANTUM SOLIDS THAT FLOW: HIGGS-LIKE MODES AND NONLINEAR DEFECTS IN ULTRACOLD SUPERSOLIDS

Speaker: KOUSHIK MUKHERJEE (The University of Electro-Communications, Tokyo, Japan)

Date and time
Venue
Library Block Lecture Hall

Abstract

Supersolidity is a highly counterintuitive phenomenon in which a system spontaneously breaks translational symmetry, resembling a solid, while maintaining the frictionless flow of a superfluid. While the concept of supersolidity has been extensively studied and debated in the context of helium, ultracold atoms have emerged as a promising alternative platform. In this presentation, I will discuss the physical mechanisms underlying the formation of the supersolid state in a trapped Bose-Einstein condensate of magnetic atoms. I will then describe the collective excitation spectra across the superfluid-supersolid phase transition, where Higgs-like amplitude excitations coexist with sound modes. I will also explain how a supersolid in a toroidal geometry can serve as an ideal platform for the clean study of Higgs-like modes. In particular, I will show how this geometry gives rise to isolated Higgs modes and, subsequently, massive Higgs quasiparticles. Finally, I will discuss rotation-driven supersolidity and the emergence of re-entrant phases arising from the interplay between vortex and crystalline order in a supersolid

Short Biography
Koushik Mukherjee is currently a JSPS Postdoctoral Researcher at the University of Electro-Communications, Tokyo. Prior to this, he was a postdoctoral researcher at Lund University, Sweden, for more than three and a half years. He obtained his PhD from the Indian Institute of Technology Kharagpur, where he also completed his master’s degree. During his PhD, he spent nearly two years at the University of Hamburg being funded a DAAD fellowship. His research interests lie at the intersection of theoretical atomic, molecular, and optical physics and quantum optics. His work focuses on supersolidity, phase-ordering kinetics, and the quantum extension of classical fluid instabilities to correlated few- and many-body systems, particularly in ultracold atomic gases