Spin Based Quantum Computation Using Photon Mediated Interactions

使用光子介导的相互作用进行基于自旋的量子计算

• 批准号: 1415485
• 负责人: Edo Waks
• 金额: $ 39万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1415485&HistoricalAwards=false
• 关键词: Spin; Based; Quantum; Computation; Using

In a quantum network, information is transmitted and processed using quantum mechanical objects called qubits. This revolutionary computational paradigm enables unprecedented information processing capabilities such as unbreakable cryptographic codes and exponential speedup of computational tasks. To achieve these remarkable capabilities requires the ability to both store qubits and create qubit-qubit interactions over long distances. Trapped spins in solids offer a remarkable system for storing quantum information, but these spins cannot easily interact with each other unless they are in close proximity. Photons provide a promising solution to this problem because they can be transmitted over long distances to create effective interactions between spins that are separated by long distances. However, long distance communication requires photons at optical frequencies while spins usually have resonances in the microwave frequency ranges. Because of this large frequency mismatch, photons typically don't interact with spins. In this project, the group will use optical cavities strongly coupled to a single spin trapped in a quantum dot to solve this problem. Cavities can create a strong effective spin-photon interface by enhancing light-matter interactions. These enhanced interactions open up the possibility for optical frequency photons to couple spins separated by long distances for quantum networks. The group will demonstrate photon mediated spin interactions using quantum dots coupled to optical cavities. Quantum dots are nanoscale structures that behave as artificial atoms. A quantum dot can capture an additional charge that behaves as a trapped spin qubit. By strongly coupling the quantum dot to a cavity, the group will develop a device called a quantum transistor, which forms the basic building block for complex quantum networks. Methods to utilize this device to implement quantum logic operations over long distances will be explored. These results could ultimately enable chip-integrated solid-state quantum devices that form the building blocks for long distance quantum networks. A novel approach to spin-based quantum information processing where photons mediate effective spin-spin interactions will be developed. The fundamental building block for this approach is the spin-photon quantum transistor, which enables a single spin quantum bit (qubit) to apply quantum logic operations on a photon. This spin-photon transistor will be realized using a charged indium arsenide (InAs) quantum dot in a photonic crystal cavity. The charged dot contains an additional electron or hole that provides a spin degree of freedom with long coherence times. By coupling the quantum dot to a photonic crystal cavity, it is possible to attain a strong light-matter interface where the state of the spin modulates the cavity spectrum. This work will attain a better scientific understanding of the system and underlying decoherence mechanisms, and address practical device design and fabrication challenges for creating a scalable quantum architecture. This will provide a unique approach to spin-based quantum information processing that have many important advantages including the ability to couple arbitrary spins, implement gate operations on ultra-fast timescales, and create effective interactions over long distances for quantum networking. Novel devices that could enable quantum information processing in a chip-integrated device that is compact and scalable will be investigated. Major device design and fabrication challenges will be addressed that are crucial for scalable implementation including optimizing light-matter interactions in photonic crystals and aligning quantum dots spatially and spectrally with resonator modes. This could provide a direct pathway for developing highly compact and scalable quantum information processing on a semiconductor chip. This capability would have a revolutionary impact on information technology, enabling exponential faster computation, unconditionally secure communication, and high precision sensors that operate far below the classical noise limit. The devices developed could have major impact in other fields such as opto-electronics, nonlinear optics, and spintronics. In addition to the proposed research effort, the research program will support training of graduate and undergraduate students, and develop an outreach program to create interdisciplinary research opportunities for local high school students.

在量子网络中，使用称为量子比特的量子力学对象来传输和处理信息。 这种革命性的计算范式使前所未有的信息处理能力，如牢不可破的密码和计算任务的指数加速。 为了实现这些非凡的功能，需要能够存储量子位并在长距离上创建量子位-量子位相互作用。 固体中的陷阱自旋为存储量子信息提供了一个了不起的系统，但这些自旋不能轻易相互作用，除非它们非常接近。 光子为这个问题提供了一个很有前途的解决方案，因为它们可以长距离传输，从而在相隔很长距离的自旋之间产生有效的相互作用。 然而，长距离通信需要光学频率的光子，而自旋通常在微波频率范围内具有共振。 由于这种大的频率失配，光子通常不会与自旋相互作用。 在这个项目中，该小组将使用与量子点中捕获的单个自旋强耦合的光学腔来解决这个问题。 腔可以通过增强光与物质的相互作用产生强有效的自旋光子界面。 这些增强的相互作用为光频光子耦合量子网络的长距离自旋提供了可能性。 该小组将使用耦合到光学腔的量子点演示光子介导的自旋相互作用。 量子点是纳米级结构，其行为类似于人造原子。 量子点可以捕获额外的电荷，其表现为被捕获的自旋量子位。 通过将量子点与腔体强耦合，该小组将开发一种称为量子晶体管的设备，它构成了复杂量子网络的基本构建模块。 将探索利用该设备在长距离上实现量子逻辑运算的方法。 这些结果最终可能使芯片集成的固态量子设备成为长距离量子网络的构建模块。 一种新的方法，以自旋为基础的量子信息处理，光子介导有效的自旋-自旋相互作用将被开发。这种方法的基本构建块是自旋光子量子晶体管，它使单个自旋量子位（qubit）能够对光子进行量子逻辑运算。这种自旋光子晶体管将在光子晶体腔中使用带电的砷化铟（InAs）量子点来实现。带电点包含额外的电子或空穴，其提供具有长相干时间的自旋自由度。通过将量子点耦合到光子晶体腔，可以获得强的光-物质界面，其中自旋状态调制腔光谱。这项工作将更好地科学理解系统和底层的退相干机制，并解决实际的器件设计和制造挑战，以创建一个可扩展的量子架构。这将为基于自旋的量子信息处理提供一种独特的方法，该方法具有许多重要的优势，包括能够耦合任意自旋，在超快时间尺度上实现门操作，以及在长距离上为量子网络创建有效的相互作用。将研究能够在紧凑和可扩展的芯片集成器件中实现量子信息处理的新型器件。主要的器件设计和制造的挑战将得到解决，这是至关重要的可扩展的实施，包括优化光子晶体中的光-物质相互作用，并在空间和光谱上与谐振器模式对齐量子点。这可以为在半导体芯片上开发高度紧凑和可扩展的量子信息处理提供直接途径。这种能力将对信息技术产生革命性的影响，使计算速度呈指数级加快，无条件安全通信，以及远低于经典噪声限制的高精度传感器。开发的器件可能会在其他领域产生重大影响，如光电子学，非线性光学和自旋电子学。除了拟议的研究工作，研究计划将支持研究生和本科生的培训，并制定一个推广计划，为当地高中生创造跨学科的研究机会。