Tristan Shi (University of Washington), QISE Seminar: Ultrafast control of quantum materials with terahertz-frequency light

Abstract

A considerable portion of quantum mechanics’ potency is obscured in thermal equilibrium. Diverse realms rely on creating quantum phases far from equilibrium, such as quantized particles and many-body systems with applications in quantum information processing and storage. Ultrafast terahertz-frequency (THz) laser pulses offer an enticing capability to achieve nonequilibrium phases dictated by collective quantum effects as their timescales are commensurate with nanoscopic dynamics of electrons, spins, lattice ions, etc. In this talk, I will first show that THz-frequency pulses can control the universal photoluminescence blinking in single quantum dots, which remains an ongoing challenge despite decades of research. Then, I will present a nonresonant excitation approach for selective phase controls, exemplified by ferroelectric reversal in LiNbO3 and polymorphic transition in SnSe intertwined with nontrivial band topology. Finally, I will illustrate how the fundamental comprehension of THz-matter interaction can be leveraged to design a nanophotonic device for polarization-sensitive THz imaging.

Tristan Shi is an Assistant Professor in the Department of Chemistry. His lab develops ultrafast terahertz-to-mid-infrared laser technologies to characterize, control, and create non-equilibrium phases with emergent quantum properties on demand. By exploiting strong light–matter interactions at terahertz frequencies in two-dimensional correlated electron systems and quantum emitters, his group explores new routes toward high-speed, robust quantum information storage, processing, and communication.