EMT/QIS: Quantum Control of Impurity States in a Semiconductor

半导体中杂质态的量子控制--布拉格·戈尔丁和马克·戴克曼密歇根州立大学量子信息是一个新的、快速发展的跨学科研究领域，位于量子物理和信息科学的交界处。它解决了科学和技术中一些最具挑战性的基本问题，同时试图增进我们对量子世界独特属性的理解。在这一领域的预测中，有一种预测是，纯粹基于量子原理的计算机将以指数级的速度加速。如果要利用量子特性来获得质的新能力，就有必要建立表现出长寿命、可控制的量子态的系统。此外，这些设备应该与传统的电子学和光子学兼容。基于半导体中可控杂质态的器件特别有吸引力，因为它们应该是可扩展的，高速运行，并利用现有的半导体技术。本实验和理论研究中所研究的量子系统是基于半导体中的受主，如硅。这些都是替代性的掺杂物，它们的原子性质是众所周知的，而且是不变的。量子比特的两个态是受主的最低轨道态，这是基态被应变和电场分裂的结果。能级之间的距离在几GHz的范围内，每个量子比特由一个门电极单独控制。单量子比特操作可以在短微波脉冲下进行，而双量子比特操作是通过接受者之间的长程偶极相互作用实现的，这使得量子比特-量子比特距离超过100 nm。系统终态的读出是基于对受激子束缚的激子的光散射的量子非破坏光学测量。

Quantum Control of Impurity States in a SemiconductorBrage Golding and Mark DykmanMichigan State UniversityE. Lansing, MI 48824ABSTRACTQuantum information is a new and rapidly developing interdisciplinary area of researchthat resides at the interface between quantum physics and information science. Itaddresses some of the most challenging fundamental problems in science and technologywhile seeking to advance our understanding of the unique properties of the quantumworld. Among the predictions in this field is that of an exponential speedup of computersthat operate on purely quantum principles. If quantum properties are to be exploited forqualitatively new capabilities, it is necessary to build systems that exhibit long-lived,controllable quantum states. In addition, the devices should be compatible withconventional electronics and photonics. The devices based on controlled impurity statesin semiconductors stand out as particularly attractive, since they should be scalable,operate at high speed, and take advantage of existing semiconductor technology.The quantum systems studied in this experimental and theoretical research are based onacceptors in a semiconductor such as silicon. These are substitutional dopants, whoseatomic-like properties are well-known and invariant. The two states of a qubit are thelowest orbital states of the acceptor, a result of splitting of the ground state by strain andelectric field. The distance between the energy levels is in the range of a few GHz andeach qubit is individually controlled by a gate electrode. Single-qubit operations can beperformed with short microwave pulses whereas two-qubit operations are enabled by thelong-range dipolar interaction between the acceptors, which allows the qubit-qubitdistance to be more than 100 nm. The readout of the final state of the system is based onquantum nondemolition optical measurement of light scattering by an exciton bound tothe acceptor.