Nuclear T-violation searches using ultracold atoms and molecules

宇宙物质-反物质不对称性的起源是基础物理学中最深层次的悬而未决的问题之一。这种不对称性被认为是由极高能量尺度下发生的微观时间反转对称性破坏(T破坏)引起的。虽然这样的能量目前超出了对撞机的能力范围，但原子核可以充当这一新物理学的“天线”，通过精确测量它们的核对称性来揭示线索。通过使用在超低温下(在微开尔文制度下)保持的激光冷却和俘获的原子和分子，核T破坏的测量可以获得对新物理的极高灵敏度。这些测量也得益于使用八极形变的核，如225Ra，它们对核T破坏具有很大的本征敏感性。由于电子对原子核施加了很大的电场，将原子核结合到极性分子中甚至进一步增强了可测量的物理效应。这里描述的研究计划旨在通过利用所有这些因素来开发世界领先的核T破坏实验。它将利用原子和分子物理学的许多最新技术。该计划将(A)使用被捕获在可重新配置的光钳阵列中的激光冷却原子：被捕获的原子可以实现更高精度的测量，而镊子阵列中的原子可以被置于纠缠态，以利用量子关联提高测量的精度。该计划还将(B)研究含有八极变形核的极性分子的使用，这种核可以在极低的温度下由激光冷却的原子组装而成：超冷分子组装提供了一条生产捕获分子的既定途径。这三种成分的结合--八极变形的原子核、极性分子和光学陷阱阵列中的量子纠缠--将为实验开辟一条道路，与最先进的技术相比，T破坏的敏感度将提高1000倍以上。这项研究计划将利用原子物理和量子信息科学领域的最新发展，并将其应用于一项特定的基础物理任务：以前所未有的灵敏度测量核T-破坏。这将是世界上第一个这样的项目。这将使我的团队能够吸引优秀的学生和博士后，并产生一批在精密亚原子物理最新技术方面接受过独特培训的熟练人才。该研究计划旨在发现基本的科学真理，但它处于高科技前沿的地位也肯定会带来技术衍生产品。该研究计划还将对原子物理和量子信息科学产生实质性的科学反作用，产生推动亚原子物理发展的新想法。

The origin of the matter-antimatter asymmetry of the universe is one of the deepest open questions in fundamental physics. This asymmetry is believed to arise from microscopic time-reversal symmetry violation (T-violation) occuring at extremely high energy scales. Although such energies are beyond the present reach of colliders, atomic nuclei can act as "antennas" for this new physics, revealing clues through precision measurements of their nuclear symmetries. Measurements of nuclear T-violation can achieve extremely high sensitivity to new physics by using laser-cooled and trapped atoms and molecules held at ultracold temperatures (in the micro-kelvin regime). The measurements also benefit by using octupole-deformed nuclei such as 225Ra, which have a large intrinsic sensitivity to nuclear T-violation. Incorporating the nuclei within a polar molecule enhances the measurable physics effects even further, due to the large electric fields applied to the nuclei by the electrons. The research program described here aims to develop a world-leading nuclear T-violation experiment by taking advantage of all of these factors. It will leverage many of the latest techniques from atomic and molecular physics. This program will (a) use laser-cooled atoms trapped in a reconfigurable array of optical tweezers: trapped atoms lead to higher precision measurements, and atoms in tweezer arrays can be placed in entangled states to boost the precision of measurements using quantum correlations. The program will also (b) investigate the use of polar molecules containing octupole-deformed nuclei, which can be  assembled from laser-cooled atoms at extremely low temperatures: ultracold molecular assembly offers an established path towards production of trapped molecules,. The combination of these three ingredients -- octupole-deformed nucleus, polar molecule and quantum entanglement in an optical trap array -- will open a path to experiments with more than thousand-fold higher sensitivity to T-violation compared to the state of the art. This research program will take advantage of the latest developments in the fields of atomic physics and quantum information science, and apply them to a specific fundamental physics task: measuring nuclear T-violation with unprecedented sensitivity. This program will be the first of its kind in the world. It will enable my group to attract excellent students and postdocs, and generate a cohort of skilled personnel with unique training in the latest techniques of precision subatomic physics. The research program aims to discover fundamental scientific truths, but its position at the high-technology frontier also makes it certain that it will lead to technological spin-offs. The program of research will also have a substantial scientific back-action on atomic physics and quantum information science, generating new ideas to advance subatomic physics.