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Talk 1: Classical dynamics for quantum spin liquids and Talk 2: Bath-engineering magnetic order in quantum spin chains

Abstract for Talk 1:

Dynamical probes and transport experiments are vital in deciphering quantum spin liquids, an exotic phase of matter with proposed applications in fault-tolerant quantum computing. However, experiments on candidate materials are usually performed at finite temperature away from perturbative regimes, evading analytical descriptions. Moreover, numerical simulations on the quantum Hamiltonians often suffer from finite size effects or short time evolution windows. In this talk, I provide an overview of my work involving classical numerical methods, specifically finite temperature Monte Carlo algorithms and Landau-Lifshitz Gilbert equations, to simulate dynamics in frustrated magnets. Using these methods, we offer insights into the finite-temperature crossover behaviour between the spin excitation continuum in a quantum spin liquid and topological magnons in the field-polarized state in various models with large Kitaev interactions.

Abstract for Talk 2:

Dissipative processes can drive different magnetic orders in quantum spin chains. Using a non-perturbative analytic mapping framework, we systematically show how to structure different magnetic orders in spin systems by controlling the locality of the attached baths. Our mapping approach reveals analytically the impact of spin-bath couplings, leading to the suppression of spin splittings, bath-dressing and mixing of spin-spin interactions, and emergence of non-local ferromagnetic interactions between spins coupled to the same bath, which become long-ranged for a global bath. Our general mapping method can be readily applied to a variety of spin models: We demonstrate (i) a bath-induced transition from antiferromagnetic (AFM) to ferromagnetic ordering in a Heisenberg spin chain, (ii) AFM to extended Neel phase ordering within a transverse-field Ising chain with pairwise couplings to baths, and (iii) a quantum phase transition in the fully-connected Ising model. We also demonstrate how the mapping approach can be applied to higher dimensions, larger spin systems, and fermionic systems.

Host: Dvira Segal
Event series  CQIQC SeminarsQO/AMO Seminars