Eur. Phys. J. B (2016) 89: 40
https://doi.org/10.1140/epjb/e2016-60766-6

Regular Article

AC-field-induced quantum phase transitions in density of states

¹ College of Applied Sciences, Beijing University of Technology, Beijing 100122, P.R. China
² Department of Physics, Tsinghua University, Beijing 100084, P.R. China

^a e-mail: khy@bjut.edu.cn

Received: 22 September 2015
Received in final form: 28 December 2015
Published online: 15 February 2016

Abstract

We investigate the joint effects of the intralead electron interaction and an external alternating gate voltage on the time-averaged local density of states (DOSs) of a quantum dot coupled to two Luttinger-liquid leads in the Kondo regime. A rich dependence of the DOSs on the driving amplitude and intralead interaction is demonstrated. We show that the feature is quite different for different interaction strengths in the presence of the ac field. It is shown that the photon-assisted transport processes cause an additional splitting of the Kondo peak or dip, which exhibits photon-assisted single-channel (1CK) or two-channel Kondo (2CK) physics behavior. The phase transition between photon-assisted 1CK and 2CK physics occurs when the interaction strength is moderately strong. The inelastic channels associated with photon-assisted electron tunneling can dominate electron transport for weak interaction when the ac amplitude is greater than the frequency by one order of magnitude. In the limit of strong interaction the DOSs scale as a power-law behavior which is strongly affected by the ac field.