A direct measurement method of quantum relaxation time

Peng Zhang; Haoqi Tang; Chuanchuan Gu; Hong Wang; Guangfu Luo; Yalin Lu; X-D Xiang

doi:10.1093/nsr/nwaa242

A direct measurement method of quantum relaxation time

Natl Sci Rev. 2020 Sep 18;8(4):nwaa242. doi: 10.1093/nsr/nwaa242. eCollection 2021 Apr.

Authors

Peng Zhang¹, Haoqi Tang¹, Chuanchuan Gu¹, Hong Wang², Guangfu Luo¹, Yalin Lu³, X-D Xiang¹

Affiliations

¹ Department of Materials Science and Engineering & Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China.
² Materials Genome Initiative Center and School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
³ Synergetic Innovation Center of Quantum Information and Quantum Physics & Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, China.

Abstract

The quantum relaxation time of electrons in condensed matters is an important physical property, but its direct measurement has been elusive for a century. Here, we report a breakthrough that allows direct determination of quantum relaxation time at zero and non-zero frequencies using optical measurement. Through dielectric loss function, we connect bound electron effects to the physical parameters of plasma resonance and find an extra term of quantum relaxation time from inelastic scattering between bound electrons and conduction electrons at non-zero frequencies. We demonstrate here that the frequency-dependent inelastic polarization effect of bound electrons is the dominant contribution to quantum relaxation time of conduction electrons at optical frequencies, and the elastic polarization effect of bound electrons also dramatically changes the plasma resonance frequency through effective screening to charge carriers.

Keywords: dielectric loss function; plasma resonance; quantum relaxation time.