Collaborative Research: PM: CeNTREX, A Search for Nuclear Time-Reversal Symmetry Violation with Quantum-State-Controlled TlF Molecules

合作研究：PM：CeNTREX，利用量子态控制的 TlF 分子寻找核时间反转对称性破坏

• 批准号: 2110405
• 负责人: Jonathan Engel
• 金额: $ 21.96万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2110405&HistoricalAwards=false
• 关键词: Collaborative; Research; PM; CeNTREX; Search

Fundamental symmetries are at the heart of our understanding of the physical world. In particular, small-scale violations of the time-reversal (T) symmetry are necessary to explain the observed predominance of matter over antimatter, one of the most fundamental problems in modern science. New T-violating physics is likely to be mediated by particles with large masses that exceed the current reach of high-energy accelerators. This experiment will carry out a high-precision search for the nuclear Schiff moment, a charge separation in the thallium (Tl) nucleus, that would signal T-violation. Detecting a Schiff moment with a sensitivity exceeding the best current limit would provide clear evidence for physics beyond the Standard Model, while a null measurement would set a stringent constraint on theories that include sources of T violation, and potentially identify the technical goals for future particle accelerators. Experimental molecular quantum science and theoretical nuclear physics will be combined here in a new collaboration using table-top experiments and state-of-the-art calculations. The Tl Schiff moment will be measured using thallium fluoride (TlF) polar molecules that are aligned with an applied electric field in a long interaction region. The presence of a Schiff moment will be manifested by a precession of the Tl magnetic moment (spin) about the applied field. This project will broadly impact technology and education. Graduate and undergraduate students will be actively involved in research, acquiring hands-on skills that are highly valued in academia, industry, and national labs. The results of this work are expected to have a strong appeal to the media and members of the public, and will be widely disseminated.This project applies the techniques of molecular quantum science to a measurement of time-reversal symmetry (T) violation, as part of the Cold Molecule Nuclear Time Reversal Experiment (CeNTREX). The investigators seek to improve upon previous measurements of T violation in atomic nuclei by nearly two orders of magnitude in terms of sensitivity to fundamental parameters. This level of precision will help address grand challenges such as the observed matter-antimatter asymmetry in the universe. The investigators will use a beam of cold TlF molecules in order to combine the intrinsically high sensitivity of Tl to the T-violating nuclear Schiff moment, the large effective electric field at the Tl nucleus within strongly polarized molecules, and state-of-the-art techniques for controlling individual molecular quantum states including optical cycling for laser cooling and high-fidelity detection. In parallel, they will address the theoretical question of interpreting the measurement by developing modern methods of nuclear physics to accurately calculate the dependence of the Schiff moment on the underlying nucleon-nucleon interactions and to quantify its uncertainty. This measurement will have intellectual synergy with other ongoing T violation searches; complementary experiments can identify the source of an observed symmetry violation via their different sensitivities to fundamental parameters. This project is also complementary to the Large Hadron Collider (LHC) which is poised to detect new high-energy particles and potentially identify the nature of their T-violating interactions. The measurement supported by the current award relies on long-lived coherent superpositions of molecular quantum states, and will make an impact on quantum sensing with molecules via the meticulous quantum state control of TlF, ultrahigh-precision spectroscopy including internal co-magnetometry, and radiation pressure forces applied to novel systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

基本对称性是我们理解物理世界的核心。特别是，对时间反转(T)对称性的小规模破坏对于解释观察到的物质对反物质的优势是必要的，这是现代科学中最基本的问题之一。新的违反T的物理很可能是由大质量的粒子中介的，这些粒子超过了目前高能加速器的覆盖范围。这项实验将对核希夫矩进行高精度搜索，希夫矩是铊(TL)核中的一种电荷分离，它将发出T破坏的信号。检测灵敏度超过最佳电流极限的希夫矩将为超越标准模型的物理提供明确的证据，而零测量将对包括T违规源的理论设置严格的限制，并可能确定未来粒子加速器的技术目标。实验分子量子科学和理论核物理将在这里结合在一起，利用桌面实验和最先进的计算进行新的合作。热释光希夫矩将用在长相互作用区中与外加电场排列的TLF极性分子来测量。希夫矩的存在将通过TL磁矩(自旋)围绕外加磁场的进动来表示。该项目将对技术和教育产生广泛影响。研究生和本科生将积极参与研究，获得学术界、工业界和国家实验室高度重视的动手技能。这项工作的结果有望对媒体和公众产生强烈的吸引力，并将被广泛传播。该项目应用分子量子科学技术来测量时间反转对称性(T)破坏，作为冷分子核时间反转实验(CENTREX)的一部分。研究人员试图在对基本参数的敏感性方面，将原子核中T破坏的测量结果提高近两个数量级。这种水平的精度将有助于解决重大挑战，例如观测到的宇宙中物质-反物质的不对称性。研究人员将使用一束冷的TLF分子束，以结合TL对违反T的核Schiff矩(强极化分子内TL核的巨大有效电场)的内在高灵敏度，以及控制单个分子量子态的最先进技术，包括用于激光冷却和高保真检测的光学循环。同时，他们将通过发展现代核物理方法，准确计算希夫矩对基本核子-核子相互作用的依赖，并量化其不确定性，来解决解释测量的理论问题。这种测量将与其他正在进行的T破坏搜索具有智力上的协同作用；互补性实验可以通过它们对基本参数的不同敏感性来识别观察到的对称破坏的来源。该项目也是对大型强子对撞机(LHC)的补充，大型强子对撞机准备探测新的高能粒子，并可能识别它们违反T的相互作用的性质。目前的奖项支持的测量依赖于分子量子态的长期相干叠加，并将通过TLF的精细量子态控制、包括内部共磁学在内的超高精度光谱以及应用于新系统的辐射压力力来影响分子的量子传感。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。