Time: 14:00, May 19 (Friday), 2023

Place: Room 2-412, Building A, IOP-CAS (中科院物理所A楼2段412)

Speaker: Bingtian Ye (Harvard University)

Abstract:

Dynamical universality classes categorize different transport behaviors based upon the relation between the spatial correlation and the evolution time. The most classic examples include the ballistic transport where the distance a particle travels is proportional to time t, and the diffusive transport where the typical travelling distance is proportional to √t. Another slightly more complicated but more intriguing example is the Kardar-Parisi-Zhang (KPZ) universality, which emerges in myriad dynamical phenomena, ranging from directed polymers and traffic models to kinetic roughening. However, all of then known examples were in classical systems until the anomalous transport in the spin-1/2 quantum Heisenberg model is uncovered recently. Even more recent analytical work suggests that all one-dimensional integrable model with non-Abelian symmetries exhibit superdiffusive behaviors, one feature of the KPZ universality. These discoveries have inspired a strong conjecture that all these models fall into the KPZ universality class. Leveraging a novel numerical technique, termed density matrix truncation [1], we investigate a series of such models and provide strong evidence to support the conjecture [2]. Furthermore, we generalize these previous results to show that KPZ transport occurs not only in non-Abelian symmetric integrable models, but also in their periodically-driven and supersymmetric counterparts. Moreover, by analyzing symmetry-breaking perturbations, we observe direct evidence for the purported microscopic mechanism underlying this anomalous transport behavior. On the experimental front, I will present our observation of KPZ behavior in Heisenberg model realized by 87Rb in the optical lattice [3], and a proposal to study higher SU(N) symmetries using alkaline earth atoms.Abstract: Dynamical universality classes categorize different transport behaviors based upon the relation between the spatial correlation and the evolution time. The most classic examples include the ballistic transport where the distance a particle travels is proportional to time t, and the diffusive transport where the typical travelling distance is proportional to √t. Another slightly more complicated but more intriguing example is the Kardar-Parisi-Zhang (KPZ) universality, which emerges in myriad dynamical phenomena, ranging from directed polymers and traffic models to kinetic roughening. However, all of then known examples were in classical systems until the anomalous transport in the spin-1/2 quantum Heisenberg model is uncovered recently. Even more recent analytical work suggests that all one-dimensional integrable model with non-Abelian symmetries exhibit superdiffusive behaviors, one feature of the KPZ universality. These discoveries have inspired a strong conjecture that all these models fall into the KPZ universality class. Leveraging a novel numerical technique, termed density matrix truncation [1], we investigate a series of such models and provide strong evidence to support the conjecture [2]. Furthermore, we generalize these previous results to show that KPZ transport occurs not only in non-Abelian symmetric integrable models, but also in their periodically-driven and supersymmetric counterparts. Moreover, by analyzing symmetry-breaking perturbations, we observe direct evidence for the purported microscopic mechanism underlying this anomalous transport behavior. On the experimental front, I will present our observation of KPZ behavior in Heisenberg model realized by 87Rb in the optical lattice [3], and a proposal to study higher SU(N) symmetries using alkaline earth atoms.

[1] B. Ye*, F. Machado*, C. D. White, R. S. K. Mong, N. Y. Yao, Phys. Rev. Lett. 125, 030601 (2020).

[2] B. Ye*, F. Machado*, J. Kemp*, R. B. Hutson, and N. Y. Yao, Phys. Rev. Lett. 129, 230602 (2022).

[3] D. Wei, A. Rubio-Abadal, B. Ye, F. Machado, J. Kemp, K. Srakaew, S. Hollerith, J. Rui, S. Gopalakrishnan, N. Y. Yao, I. Bloch, J. Zeiher, Science, 376, 716 (2022).

About the speaker:

Bingtian Ye is a physics PhD candidate at Harvard University, advised by Prof. Norman Y. Yao. He received his Bachelor’s degree in physics from Peking University. His research lies at the interface between condensed matter theory and atomic, molecular and optical theory. He is particularly interested in non-equilibrium dynamics of quantum systems.