Talks

Anomalous Transport in Perturbed Integrable Quantum Spin Chains

The XXZ spin chain, also known as the anisotropic Heisenberg model, is a quintessential system for studying quantum transport, offering a rich array of behaviors in spin dynamics at finite temperatures. In my presentation, I will explore two types of anomalous spin transport phenomena observed in the XXZ model: superdiffusion and subdiffusion. In the first part of my talk, I'll focus on spin superdiffusion. Although it is well-known that the XXZ model displays superdiffusive spin transport at the isotropic point, I will examine the effects of local energy-conserving perturbations on this behavior. Specifically, I will discuss how different symmetries in perturbations that break integrability can impact the spin superdiffusion. In the second part, I'll shift my attention to spin subdiffusion. While the unperturbed XXZ chain doesn't typically show subdiffusion, I will demonstrate how the introduction of a finite linear (Stark) potential can induce this phenomenon. Our results suggest that in the presence of a Stark potential, the XXZ model exhibits fractonic subdiffusion in the thermodynamic limit, effectively contradicting the idea of Stark many-body localization. Interestingly, our numerical studies suggest a crossover from diffusive to subdiffusive behavior, and I'll explain the cross-over scale by examining the dynamics of the dipole moment. In this context, I will show how the dipole moment becomes an emergent conserved quantity, resulting in the fractonic subdiffusion observed in these scenarios. Overall, my presentation will outline the key findings from some of our recent studies, offering insights into the rich and complex behaviors of high temperature spin transport in the XXZ model under various conditions.

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IMPRS Seminar

Colloquium

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QDS

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QDS

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