Electron g-factor Engineering in III-V Semiconductors for Quantum Communications

Gate control of spin dynamics in III-V semiconductor quantum dots

We show that the g-factor and the spin-flip time T_{1} of a heterojunction quantum dot is very sensitive to the band-bending interface electric field even in the absence of wave function penetration into the barrier. When this electric field is of the order of 10^{5} V/cm, g and T_{1} show high sensitivity to dot radius and magnetic field arising from the interplay between Rashba and Dresselhaus spin-orbit interactions. This result opens new possibilities for the design of a quantum dot spin quantum computer where g-factor and T_{1} can be engineered by manipulating the spin-orbit coupling thr…

Three-Dimensional Topological Insulators in I-III-VI$_2$ and II-IV-V$_2$ Chalcopyrite Semiconductors

The recent discovery of topological insulators with exotic metallic surface states has garnered great interest in the fields of condensed matter physics and materials science. A number of spectacular quantum phenomena have been predicted when the surface states are under the influence of magnetism and superconductivity, which could open up new opportunities for technological applications in spintronics and quantum computing. To achieve this goal, material realization of topological insulators with desired physical properties is of crucial importance. Based on first-principles calculations, her…

基于时序演化的哈密顿量工程用于半导体量子点中电子自旋的酉控制

Hamiltonian engineering with time-ordered evolution for unitary control of electron spins in semiconductor quantum dots

提出一种用于横向量子点电子自旋可扩展量子计算机的酉控制脉冲设计方法，通过同步控制自旋相互作用推导出通用1-和2-量子比特逻辑门的哈密顿量参数脉冲形式，并推广至多量子比特及受限控制场景。

莫尔半导体中磁性的光学工程与探测

Optical engineering and detection of magnetism in moiré semiconductors

该研究提出莫尔系统中自旋态光学诱导、控制与探测的通用框架，通过拉曼光驱动莫尔过渡金属二硫化物双层实现可调磁相互作用的自旋模型，建立自旋关联与光学信号的联系，为强关联量子系统的光学调控研究铺路。

Engineering two-photon wavefunction and exchange statistics in a semiconductor chip

High-dimensional entangled states of light provide novel possibilities for quantum information, from fundamental tests of quantum mechanics to enhanced computation and communication protocols. In this context, the frequency degree of freedom combines the assets of robustness to propagation and easy handling with standard telecommunication components. Here we use an integrated semiconductor chip to engineer the wavefunction and exchange statistics of frequency-entangled photon pairs directly at the generation stage, without post-manipulation. Tuning the spatial properties of the pump beam allow…

Band engineering in dilute nitride and bismide semiconductor lasers

Highly mismatched semiconductor alloys such as GaNAs and GaBiAs have several novel electronic properties, including a rapid reduction in energy gap with increasing x and also, for GaBiAs, a strong increase in spin orbit- splitting energy with increasing Bi composition. We review here the electronic structure of such alloys and their consequences for ideal lasers. We then describe the substantial progress made in the demonstration of actual GaInNAs telecomm lasers. These have characteristics comparable to conventional InP-based devices. This includes a strong Auger contribution to the threshold…

在III-V族半导体上可控生长稀土掺杂TiO$_{2}$薄膜用于混合量子光子接口

Controlled growth of rare-earth-doped TiO$_{2}$ thin films on III-V semiconductors for hybrid quantum photonic interfaces

本文提出在GaAs和GaSb衬底上通过低温脉冲激光沉积结合砷保护层与缺氧缓冲层，实现Er³⁺掺杂锐钛矿TiO₂(001)外延薄膜的可控生长，为单片集成稀土量子存储器与半导体单光子源、构建可扩展混合量子光子芯片提供了材料平台。

Single-Dirac-Cone topological surface states on pseudo-IV-VI-semimetal/semiconductors: Thallium-based III-V-VI2 Ternary Chalcogenides

We have investigated several classes of strong spin-orbit chalcogenides related to the (Pb,Sn)Te series studied in connection with the Dirac fermion physics in the 1980s. Our first-principle theoretical calculations suggest that ternary chalcogenides TlBiX$_2$ and TlSbX$_2$ (X=Te, Se, S) series harbor small bandgap topological insulators with single Dirac cone on some selective surfaces whereas the isostructural and isoelectronic silver-based AgBiX$_2$ and AgSbX$_2$ (X=Te, Se, S) series do not. We find that several Tl-compounds are in the vicinity of a topological critical point. We identify t…

Control of single photon emitters in semiconductor nanowires by surface acoustic waves

We report on experimental study into the effects of surface acoustic waves on the optical emission of dot-in-a-nanowire heterostructures in III-V material systems. Under direct optical excitation, the excitonic energy levels in III-nitride dot-in-a-nanowire heterostructures oscillate at the acoustic frequency, producing a characteristic splitting of the emission lines in the time-integrated photoluminescence spectra. This acoustically induced periodic tuning of the excitonic transition energies is combined with spectral detection filtering and employed as a tool to regulate the temporal output…