Events

Quantum simulation is one of the pillars of Quantum Revolution 2.0. Its essence is to simulate a complicated and hard-to-control quantum system using a simple and controllable one. Ultracold atoms and ions, due to their unprecedented controllability, have become an important platform for quantum simulation. In this talk, I will introduce two recent works in collaboration with my experimental colleagues at Rice. The first work concerns the simulation of electron transfer — an important issue relevant to many biochemical processes and material science — using trapped ions; and the second concerns the simulation of spin-charge separation — a unique phenomenon in one dimensional quantum many-body system — using two-component ultracold Fermi gas. These two works clearly demonstrated the advantages of performing quantum simulation using cold atoms and ions. I will also discuss some future directions based on these works.

The roles of quantum effects in biological systems have long fascinated biophysicists. Meanwhile, proteins undergo sophisticated motions in space and time, which are believed to ultimately govern the biological function and activities of the proteins. Quasi-elastic neutron scattering (QENS) provides exceptional tools for studying the dynamics of proteins in the time range of picosecond to nanosecond at the molecular level. In this talk, based on our recent work on various biological systems studied by QENS and other techniques, such as inelastic neutron scattering (INS), small angle neutron scattering (SANS), and neutron spin echo (NSE), I will discuss the possibility of using neutron scattering techniques to reveal the quantum mechanical effects, such as tunneling effect in the dynamics of proteins and connect them with protein activities or functions.

An essential feature of topological crystalline states (TCSs), which are short-range-entanged topological states protected by crystalline symmetries, is they generally have high-order gapless boundary states, such as one-dimensional hinge states and zero-dimensional corner states on a two-dimensional surface. Therefore, such TCSs are also called high-order topological states. In this work, we design a systematic method to compute possible high-order boundary states of a TCS for all possible surface geometries. We show that the location of surface gapless region, dubbed the anomaly pattern, can be symmetrically and continuously deformed without changing the topologically-protected gapless states, and such deformation defines a homotopy equivalence between anomaly patterns. The list of equivalent classes of anomaly patterns are completely determined by the point-group symmetry, and it is universal for all types of TCSs, including bosonic, free-fermion and interacting-fermion states. We also describe how to compute the anomaly pattern of a bulk topological state, for all types of TCSs.