IQUIST Seminar: "Quantum Magnetism: The Two-Way Street Between Quantum Materials and Quantum Hardware," Arnab Banerjee, Assistant Professor of Physics and Astronomy, Purdue University

"Quantum Magnetism: The Two-Way Street Between Quantum Materials and Quantum Hardware"

Abstract: Inelastic neutron scattering and transport are poised to provide clean experimental data in quantum magnets. Yet, a grand challenge in quantum materials is that we often do not know a material's microscopic Hamiltonian, that hinders their future applications — most acutely in frustrated, entangled magnets . Quantum computers offer a path forward but carry their own uncertainty: noisy hardware whose outputs must themselves be validated. I will argue that quantum magnetism resolves both problems through a two-way street. Materials with known Hamiltonians serve as ground truth to benchmark quantum hardware; once validated, that hardware can illuminate materials whose Hamiltonians are unknown. We have demonstrated this loop by computing the dynamical structure factor of the spin-1/2 chain KCuF3 and benchmarking it directly against neutron-scattering data, and we have used quantum hardware to simulate spin transport in one-dimensional magnets. I will connect these results to a future roadmap involving spectroscopic and transport data from my own laboratory, including our neutron studies , and outline the path toward observables from light scattering experiments and frustrated Hamiltonians. Magnetism, I will suggest, may be the first genuine application of quantum computing. 

Bio: Arnab Banerjee is an Assistant Professor of Physics and Astronomy at Purdue University, where he leads the Quantum Spin Lab. His group combines synthesis, neutron scattering, millikelvin thermal transport, and quantum-computer simulation in quanutum magnets to provide a overall framework to understand emergent phenomena in them - such as Majorana fermions, non-abelian anyons, ballistic spinons and others - towards future applications. He is an expert in quantum spin liquids, helping establish RuCL3 as a premier Kitaev quantum spin liquid candidate, introducing new triangular-lattice spin liquids in thallium delafossites, and pioneering the benchmarking of quantum computers against real materials. His research is supported by DOE-Basic Energy Sciences, the Army Research Office, NSF Industry-University Cooperative Research Centers, the W. M. Keck Foundation, and the DOE-NQI Quantum Science Center.