ITR Collaborative Research: Single Spin Measurement for Quantum Information Processing

这是一个信息技术研究（ITR）中等奖。 量子信息处理和计算提供了新技术的前景，这些新技术的操作基本上依赖于量子相干现象。 为了使这种技术获得成功，必须开发存储和阅读量子信息的方法。 该项目将专注于使用电子自旋来存储量子信息。 与电荷不同，自旋与周围环境的相互作用很弱，可以更好地保持量子相干性。 然而，同样的相互作用的弱点使得读出单个电子自旋变得困难。 该提案的重点是发展两种不同的方案，用于检测半导体量子点中的单个自旋。 两者都依赖于通过自旋-电荷转换的读出，其中自旋信息被转换为电荷信息。 在一种情况下，自旋封锁，其中泡利不相容原理导致点之间的自旋相关隧穿，将使用射频单电子晶体管检测。 另一种是通过自旋相关的微波激发非对称量子点来实现转导。 这两种方案最初都将在GaAs量子点中进行演示，然后转移到SiGe量子点中，这将与现有的微电子产品更加兼容。 一个协调的理论部分将集中在计算退相干时间和设备本身的建模。 这项研究有助于开发基于检测和操纵单个自旋的新信息技术。 科学教育和推广活动在培训和直接来自研究的课程材料的开发方面都被纳入了该项目。这是一个信息技术研究（ITR）中等奖。 量子信息处理和计算提供了新技术的前景，这些新技术的操作基本上依赖于量子力学现象。 为了使这种技术获得成功，必须开发存储和阅读量子信息的方法。 该项目将重点关注使用电子的内在磁性或自旋来存储量子信息。 电子的自旋与其电荷不同，与周围环境的相互作用很弱，因此量子信息不太容易丢失。 然而，同样的相互作用的弱点，使自旋的读出变得困难。 该提案的重点是发展两种不同的方案，用于检测半导体量子点中的单个自旋;两者都使用自旋信息转换为电荷信息进行读出。 在一种情况下，一对量子点之间的自旋相关电子转移将使用一种称为单电子晶体管的快速灵敏的静电计来检测。 另一种是通过非对称量子点的自旋相关微波激发来实现转换。 这两种方案最初都将在砷化镓点上进行演示，然后转移到与现有微电子产品更兼容的硅基点上。 协调的理论研究将对设备进行建模，并计算量子信息丢失的时间尺度。 这项研究可以帮助开发基于检测和操纵单个自旋的新信息技术。 在培训和直接从研究中产生的课程材料的编制方面，科学教育和推广都被纳入了该项目。

This is an Information Technology Research (ITR) medium award. Quantum information processing and computing offer the prospect of new technologies that rely fundamentally on quantum coherent phenomena for their operation. For such technologies to be successful, means of storing and reading out quantum information must both be developed. This project will focus on using the electronic spin to store quantum information. Spin, unlike charge, interacts weakly with its surroundings and better maintains quantum coherence. The same weakness of interaction, however, makes readout of individual electronic spins difficult. This proposal focuses on development of two different schemes for detection of individual spins in semiconductor quantum dots. Both rely on readout by means of spin-charge transduction, in which spin information is converted to charge information. In one case, spin blockade, in which the Pauli exclusion principle causes spin-dependent tunneling between dots, will be detected using a radio-frequency single-electron transistor. In the other, transduction will be accomplished by spin-dependent microwave excitation of an asymmetric quantum dot. Both schemes will initially be demonstrated in GaAs quantum dots, and later transferred to SiGe dots, which will be more compatible with existing microelectronics. A coordinated theoretical component will focus on calculations of decoherence times and on modeling of the devices themselves. This research could help in development of new information technologies based on detection and manipulation of individual spins. Science education and outreach are integrated into the project both in terms of training and in the development of curricular materials flowing directly out of the research.%%%This is an Information Technology Research (ITR) medium award. Quantum information processing and computing offer the prospect of new technologies that rely on fundamentally quantum mechanical phenomena for their operation. For such technologies to be successful, means of storing and reading out quantum information must both be developed. This project will focus on using the intrinsic magnetism, or spin, of an electron to store quantum information. The spin of an electron, unlike its electrical charge, interacts weakly with its surroundings, so that the quantum information is less easily lost. The same weakness of interaction, however, makes readout of the spin difficult. This proposal focuses on development of two different schemes for detection of individual spins in semiconductor quantum dots; both use conversion of spin information to charge information for readout. In one case spin-dependent electron transfer between a pair of quantum dots will be detected using a fast and sensitive electrometer called a single-electron transistor. In the other, conversion will be accomplished by spin-dependent microwave excitation of an asymmetric quantum dot. Both schemes will initially be demonstrated in gallium arsenide dots, and later transferred to silicon-based ones that will be more compatible with existing microelectronics. Coordinated theoretical research will model the devices and calculate the time scales on which quantum information is lost. This research could help develop new information technologies based on detection and manipulation of individual spins. Science education and outreach are integrated into the project both in terms of training and in the development of curricular materials flowing directly out of the research.