Electron Spin Dynamics on the Surface of Superfluid Helium

非技术摘要电子是所有原子的基本成分，正是它们相互作用的各种形式，在很大程度上导致了我们在周围世界中看到的广泛的材料性质。除了带负电荷外，每个电子都像极弱的条形磁铁。对于单个电子，其弱磁点的方向由量子力学描述，这允许电子自旋(自旋是描述电子弱磁场的另一个术语)被用作量子比特，或量子比特，用于量子信息处理。当一组电子开始时，它们的所有自旋都指向某个方向，并且打开指向不同方向的大的外部磁场，电子的磁场围绕外部磁场的方向旋转。自旋相干性是衡量电子自旋不改变其自转速度的精确度。长自旋相干对于量子模拟和量子计算是可取的，并已被预测用于液氦表面的电子。这个实验项目的目的是首次测量这些电子的自旋相干性，并了解限制它们相干性的物理过程。测量和理解这些过程是构建使用单个电子的磁矩作为其比特的量子计算机的关键一步。量子计算是未来高科技产业和国家安全的重要研究领域。该项目将支持一名博士后的继续教育，并部分支持一名博士生以及本科生研究人员的参与，他们致力于基础物理及其应用于新技术机会之间的工作。这位同事和学生将学习如何使用现代纳米科学研究的最先进工具，这已被证明是对学术界和高科技行业的职业生涯的极好培训。技术摘要本项目将使用电子自旋共振(ESR)来测量超流氦表面电子的自旋驰豫和相干。计算和间接的实验证据表明，这些电子的自旋相干性很长，即使它们是移动的，但驰豫和相干性时间从未被直接测量过。早期的ESR实验因无法对自旋进行热化而受阻，但已经设计出了有望实现快速自旋热化的设备。具有长相干性的移动电子将是特别有价值的量子比特，因为在某些架构中，移动量子比特的能力可以将量子纠错的开销减少两个或更多个数量级。这项研究将由一名博士后研究员和一名博士生和非全日制本科生提供部分支持。这些同事和学生将学习纳米制造、低温技术、高灵敏度微波测量和量子信息。这些技能需要足智多谋和对细节的关注，事实证明，这些技能对学术界、国家实验室和高科技行业的科学职业生涯是极好的培训。

Nontechnical AbstractElectrons are a fundamental constituent of all atoms, and it is the tremendous variety of forms their interactions can take which is largely responsible for the wide range of material properties we see in the world around us. In addition to having a negative electric charge, every electron also acts like an extremely weak bar magnet. For an individual electron, the direction that its weak magnet points is described by quantum mechanics, which allows the electron spin ('spin' is another term for describing the weak magnetic field of an electron) to be used as a quantum bit, or 'qubit', for quantum information processing. When a group of electrons are started with all their spins pointing in some direction, and a large external magnetic field pointing in a different direction is turned on, the magnetic field of the electrons rotates around the direction of the external field. The spin coherence is a measure of how accurately the electrons' spins do not change their rotation rate. Long spin coherence is desirable for quantum simulation and quantum computing and has been predicted for electrons on the surface of liquid helium. This experimental project is aimed at making the first measurements of the spin coherence of these electrons, and understanding the physical processes which limit their coherence. Measuring and understanding these processes are a key step towards constructing a quantum computer that uses the magnetic moments of individual electrons as its bits. Quantum computing is an important research area for future high technology industries and national security. This project will support the continuing education of a Postdoctoral Fellow, and partially support a Ph.D. student, together with the participation of undergraduate researchers, working at the boundary between fundamental physics and its applications to new technological opportunities. The Fellow and students will learn how to use the most advanced tools of modern nanoscience research, which has proven to be excellent training for careers in both academia and high technology industries.Technical AbstractThis project will use Electron Spin Resonance (ESR) to measure the spin relaxation and coherence of electrons on the surface of superfluid helium. Calculations and indirect experimental evidence suggest that the spin coherence of these electrons is long, even when they are mobile, but the relaxation and coherence times have never been directly measured. Earlier ESR experiments were stymied by an inability to thermalize the spins, but devices have been designed which are expected to enable rapid spin thermalization. Mobile electrons with long coherence will be particularly valuable quantum bits, or qubits, since the ability to move qubits can reduce the overhead for quantum error correction by two or more orders of magnitude in some architectures. This research will be performed by a Postdoctoral Fellow with partial support of a Ph.D. student and part-time undergraduate students. The Fellow and students will learn nanofabrication, low-temperature techniques, high-sensitivity microwave measurements and quantum information. These skills, requiring resourcefulness and attention to detail have proven themselves to be excellent training for scientific careers in academia, national labs, and high technology industries.