ITR Collaborative Research: Single Spin Measurement for Quantum Information Processing

这是信息技术研究(ITR)的中等奖。量子信息处理和计算提供了从根本上依赖于量子相干现象进行操作的新技术的前景。要想让这类技术取得成功，必须同时开发存储和读取量子信息的方法。该项目将专注于使用电子自旋来存储量子信息。自旋与电荷不同，它与周围环境的相互作用很弱，更好地保持了量子相干。然而，相互作用的同样弱点使得读出单个电子自旋变得困难。这项提议的重点是开发两种不同的方案来检测半导体量子点中的单个自旋。两者都依赖于自旋-电荷转换的读出，在这种转换中，自旋信息被转换为电荷信息。在一种情况下，将使用射频单电子晶体管来检测自旋阻塞，在这种情况下，泡利不相容原理会导致点之间的自旋依赖隧道效应。在另一种情况下，通过非对称量子点的自旋相关的微波激发来完成转换。这两种方案最初将在GaAs量子点中进行演示，然后转移到与现有微电子学更兼容的SiGe量子点中。一个协调的理论部分将专注于消相干时间的计算和设备本身的建模。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。科学教育和外展在培训和开发直接源自研究的课程材料方面都被纳入该项目。%这是信息技术研究(ITR)中等奖项。量子信息处理和计算提供了从根本上依赖于量子力学现象进行操作的新技术的前景。要想让这类技术取得成功，必须同时开发存储和读取量子信息的方法。该项目将专注于利用电子的本征磁性或自旋来存储量子信息。与电荷不同，电子的自旋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，相互作用的同样弱点使自旋的读数变得困难。这项提议的重点是开发两种不同的方案来检测半导体量子点中的单个自旋；两种方案都使用自旋信息的转换来对读出的信息进行充电。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而灵敏的静电计来检测。在另一种情况下，转换将通过非对称量子点的自旋相关微波激发来完成。这两种方案最初都将在砷化镓的点中演示，然后转移到与现有微电子更兼容的硅基方案中。协调的理论研究将对这些设备进行建模，并计算量子信息丢失的时间尺度。这项研究可能有助于开发基于对单个自旋的检测和操纵的新信息技术。科学教育和外展在培训和编写直接源自研究的课程材料方面都纳入了该项目。

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.