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

基本的对称性是我们理解物理世界的核心。特别是，时间反转(T)对称的小尺度破坏对于解释所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的物理学很可能是由大质量粒子介导的，这些粒子的质量超过了目前高能加速器的范围。这个实验将对核希夫矩进行高精度的搜索，希夫矩是铊（Tl）核中的电荷分离，它将标志着t违反。以超过最佳电流极限的灵敏度检测希夫矩将为超越标准模型的物理学提供明确的证据，而零测量将对包括T违逆源在内的理论设置严格的约束，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学将在这里结合在一个新的合作使用桌面实验和最先进的计算。将使用氟化铊（TlF）极性分子来测量Tl希夫矩，这些分子在长相互作用区域内与外加电场对齐。希夫矩的存在将表现为Tl磁矩（自旋）绕外加磁场的进动。这个项目将对科技和教育产生广泛影响。研究生和本科生将积极参与研究，获得在学术界、工业界和国家实验室高度重视的动手技能。这项工作的结果预计将对新闻媒介和公众产生强烈的吸引力，并将得到广泛传播。本项目将分子量子科学技术应用于时间反转对称(T)违逆的测量，作为冷分子核时间反转实验（CeNTREX）的一部分。在对基本参数的敏感性方面，研究人员试图改进以前对原子核T违逆的测量，提高近两个数量级。这种精确度将有助于解决诸如观测到的宇宙中物质-反物质不对称等重大挑战。研究人员将使用冷TlF分子束，以结合Tl对违反t的核希夫矩的固有高灵敏度，强极化分子内Tl核的大有效电场，以及控制单个分子量子态的最先进技术，包括用于激光冷却的光循环和高保真检测。同时，他们将通过发展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效应；互补实验可以通过它们对基本参数的不同灵敏度来识别观测到的对称性破坏的来源。这个项目也是对大型强子对撞机（LHC）的补充，LHC准备探测新的高能粒子，并可能确定它们违反t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的细致量子态控制、包括内部共磁计在内的超高精度光谱以及应用于新系统的辐射压力力，对分子的量子传感产生影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.