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，小规模违反时间反转（T）对称性对于解释所观察到的物质相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 T 违反物理学很可能是由质量超过当前高能加速器所能达到的大质量粒子介导的。 该实验将对核希夫矩（铊 (Tl) 核中的电荷分离）进行高精度搜索，这将发出 T 违规信号。 检测灵敏度超过最佳电流限制的席夫矩将为超出标准模型的物理学提供清晰的证据，而零测量将对包括 T 违规来源在内的理论设置严格的约束，并有可能确定未来粒子的技术目标加速器。 实验分子量子科学和理论核物理学将在这里通过桌面实验和最先进的计算进行新的合作。 Tl 希夫矩将使用氟化铊 (TlF) 极性分子进行测量，这些分子与长相互作用区域中的外加电场对齐。 希夫矩的存在将通过 T1 磁矩（自旋）围绕所施加的场的进动来证明。 该项目将广泛影响技术和教育。 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实践技能。 这项工作的成果预计将对媒体和公众产生强烈的吸引力，并将得到广泛传播。该项目将分子量子科学技术应用于时间反演对称性（T）破坏的测量，如冷分子核时间反转实验（CeNTREX）的一部分。 研究人员寻求将原子核中 T 破坏的先前测量结果在对基本参数的敏感性方面提高近两个数量级。 这种精度水平将有助于解决重大挑战，例如观测到的宇宙中物质与反物质的不对称性。 研究人员将使用一束冷 TlF 分子，以便将 Tl 对 T 破坏核席夫矩的固有高灵敏度、强极化分子内 Tl 核处的大有效电场以及最新状态结合起来。用于控制单个分子量子态的艺术技术，包括用于激光冷却和高保真检测的光学循环。 与此同时，他们将通过开发现代核物理方法来解决解释测量的理论问题，以准确计算希夫矩对潜在核子-核子相互作用的依赖性并量化其不确定性。 该测量将与其他正在进行的 T 违规搜索产生智力协同作用；互补实验可以通过对基本参数的不同敏感性来识别观察到的对称性破坏的来源。 该项目也是对大型强子对撞机 (LHC) 的补充，后者旨在探测新的高能粒子，并有可能确定其 T 破坏相互作用的性质。 当前奖项支持的测量依赖于分子量子态的长寿命相干叠加，并将通过 TlF 的精细量子态控制、超高精度光谱（包括内部共磁测量和辐射）对分子量子传感产生影响该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。