Spectral features of the tunneling-induced transparency and the Autler-Townes doublet and triplet in a triple quantum dot

Xiao-Qing Luo,Ting Yu,Jun Jing,Zeng-Zhao Li,Wei Xiong,Tie-Fu Li

doi:10.1038/s41598-018-21221-3

Abstract

We theoretically investigate the spectral features of tunneling-induced transparency (TIT) and Autler-Townes (AT) doublet and triplet in a triple-quantum-dot system. By analyzing the eigenenergy spectrum of the system Hamiltonian, we can discriminate TIT and double TIT from AT doublet and triplet, respectively. For the resonant case, the presence of the TIT does not exhibit distinguishable anticrossing in the eigenenergy spectrum in the weak-tunneling regime, while the occurrence of double anticrossings in the strong-tunneling regime shows that the TIT evolves to the AT doublet. For the off-resonance case, the appearance of a new detuning-dependent dip in the absorption spectrum leads to double TIT behavior in the weak-tunneling regime due to no distinguished anticrossing occurring in the eigenenergy spectrum. However, in the strong-tunneling regime, a new detuning-dependent dip in the absorption spectrum results in AT triplet owing to the presence of triple anticrossings in the eigenenergy spectrum. Our results can be applied to quantum measurement and quantum-optics devices in solid systems.

Highlights

Quantum coherence and interference effects can lead to considerably interesting phenomena of quantum optics such as lasing without inversion[1,2], coherent population trapping[3], correlated spontaneous emission[4], and electromagnetically induced transparency (EIT)[5,6,7,8,9]
We have presented a theoretical study of the eigenenergy spectrum and optical absorption properties of a triple-quantum dot (QD) system with four effective energy levels
The results show that, in the case of the electron resonant-tunneling in the triple-QD system, there are degenerate points in the eigenenergy spectrum of the system Hamiltonian

Summary

Introduction

Quantum coherence and interference effects can lead to considerably interesting phenomena of quantum optics such as lasing without inversion[1,2], coherent population trapping[3], correlated spontaneous emission[4], and electromagnetically induced transparency (EIT)[5,6,7,8,9]. As a phenomenon closely related to EIT, Autler-Townes (AT) splitting[10,11] is indicated by a level anticrossing in the eigenenergy spectrum and a transparency window owing to the AT doublet rather than the quantum interference. This phenomenon has been utilized to measure the state of the electromagnetic field[12,13,14], as well as the AT triplet and multiplet spectroscopy[15]. In the strong-tunneling regime, the presence of triple anticrossings in the eigenenergy spectrum reveals the realization of AT triplet in the absorption spectrum, where a new red-shifted (blue-shifted) transparency dip in the absorption spectrum is due to the presence of the blue (red) detuning from the right dot

Methods

Results

Conclusion