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Quantum computation using optical control of electron spins in quantum dots

利用量子点中电子自旋的光学控制进行量子计算

基本信息

批准号：
14076201
负责人：
MUTO Shunichi
金额：
$ 12.61万
依托单位：
Hokkaido Universigy
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2005
项目状态：
已结题

项目摘要

An electron spin in a quantum dot is one of important candidates to be used for future large scale quantum computing. We have already proposed a set of universal quantum gates using photon-assisted tunneling and its coulomb blockade. In this project, we have done various experimental studies on the feasibility of this proposal. Also, the quantum computing is required to be connected to the photonic quantum infromation processing. Therefore we proposed a scheme to cunvert a photon qubit and an electron spin qubit and experimentally evaluated this proposal.Before experiments, we did computer simulation of our universal gates and found that the experimental demonstration of the CNOT gateis possible ifthe coheraice of an electron spin is largo-than 100 ps.Then, we developed a measurem ent technology based on the four-wave-mixing FWM to detarmine the electron spin coherence. We applied this to the spin relaxation measurements of electrons in a quantum well for which the pump -probe technique is established. The result of the new method, i.e. spin-diffracted FWM gave the same result as the pump -probe, indicating the validity of the method. We then, applied this to the ensemble of InAlAs/AlGaAs quantum dots and found that the longest coherence of these dots is as long as 7 ns. This value is much longer than those in the conventional method using streak-camera and indicates that the measurements of resonant excitation and dedection such as ours are necessary for precise determination of spin coherence instead of the non-resonant measurements such as those using streak-camers.We also proposed a new qubit conversion scheme using the nuclear field to realize the degenerate electron levels and energy-split hole levels in a quantum dot. By exerimentally realizing the nuclear field by optically orienting the electron spins in an InAlAs/AlGaAs quantum dot, we found that we can realize the band structure for a qubit conversion between a photon and an dectron spin.

量子点中的电子自旋是未来大规模量子计算的重要候选对象之一。我们已经提出了一套利用光子辅助隧穿及其库仑阻塞的通用量子门。在本项目中，我们对这一建议的可行性进行了各种实验研究。量子计算还需要与光子量子信息处理相结合。为此，我们提出了一种将光子量子比特和电子自旋量子比特相互转换的方案，并对该方案进行了实验验证.在实验之前，我们对我们的通用门进行了计算机模拟，发现只要电子自旋的相干性大于100 ps，就可以实现CNOT门的实验验证.我们发展了一种基于四波混频四波混频的电子自旋相干性测量技术。我们将其应用于量子阱中电子的自旋弛豫测量，并建立了泵浦-探测技术。新方法，即自旋衍射四波混频法的结果与泵浦探测法的结果一致，表明了该方法的有效性。然后，我们将其应用于InAlAs/AlGaAs量子点的系综，发现这些量子点的最长相干性长达7 ns。该值比传统的条纹照相机方法中的值长得多，这表明我们所采用的共振激发和探测方法代替条纹照相机等非共振测量方法是精确测定自旋相干性所必需的.我们还提出了一种新的利用核场实现简并电子能级和能量的量子比特转换方案.在量子点中分裂空穴能级。通过在InAlAs/AlGaAs量子点中对电子自旋进行光学取向来实验性地实现核场，我们发现可以实现光子与自旋之间量子比特转换的能带结构。

项目成果

期刊论文数量（178）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Photon Antibunching Observed from an InAlAs Single Quantum Dot

从 InAlAs 单量子点观察到的光子反聚束

DOI：
发表时间：
2005
期刊：
Jpn. J. Appl. Phys. Express Lett Vol. 44, No.25
影响因子：
0
作者：
S. Kimura;H. Kumano;M. Endo;I. Suemune;T. Yokoi;H. Sasakura;S. Adachi;S. Muto;H. Z. Song;S. Hirose;and T. Usuki
通讯作者：
and T. Usuki

Quantum gates based on electron spins of triple quantum dot

基于三量子点电子自旋的量子门