We discuss a method to follow step-by-step time evolution of atomic and molecular systems based on QED (Quantum Electrodynamics). Our strategy includes expanding the electron field operator by localized wavepackets to define creation and annihilation operators and following the time evolution using the equations of motion of the field operator in the Heisenberg picture. We first derive a time evolution equation for the excitation operator, the product of two creation or annihilation operators, which is necessary for constructing operators of physical quantities such as the electronic charge density operator. We then describe our approximation methods to obtain time differential equations of the electronic density matrix, which is defined as the expectation value of the excitation operator. By solving the equations numerically, we show "electron-positron oscillations", the fluctuations originated from virtual electron-positron pair creations and annihilations, appear in the charge density of a hydrogen atom and molecule. We also show that the period of the electron-positron oscillations becomes shorter by including the self-energy process, in which the electron emits a photon and then absorbs it again, and it can be interpreted as the increase in the electron mass due to the self-energy.
Genuine Molecular Effects in Bound-State Quantum Electrodynamics
Philipps–Universität Marburg（马尔堡菲利普斯大学）；Helmholtz Institut Mainz（美因茨亥姆霍兹研究所）；Johannes Gutenberg-Universität Mainz（美因茨约翰内斯·古腾堡大学）；GSI Helmholtzzentrum für Schwerionenforschung GmbH（GSI亥姆霍兹重离子研究中心）；Instituto de Modelado e Innovación Tecnológica (UNNE-CONICET)（建模与技术创新研究所（UNNE-CONICET））；Universidad Nacional del Nordeste（东北国立大学）；Van Swinderen Institute for Particle Physics and Gravity, University of Groningen（格罗宁根大学范·斯温德伦粒子物理与引力研究所）；University of Groningen（格罗宁根大学）；Narodowe Centrum Badań Jądrowych (NCBJ)（国家核研究中心（NCBJ））
Nonrelativistic quantum electrodynamic approach to polarizabilities of light atoms
我们发展了一个计算量子电动力学效应对光原子系统极化率影响的场量子化方案。该方案基于Pachucki的长波量子电动力学理论[Phys. Rev. A \textbf{69}，052502（2004）]，其将非相对论量子电动力学理论与Power-Zienau变换相结合。利用该方案导出了外电磁场效应，包括电多极极化率和磁多极极化率及其相对论修正和辐射修正。由于宇称对称性，库仑横光子贡献为零。
Approaching meV level for transition energies in the radium monofluoride molecule RaF and radium cation Ra$^+$ by including quantum-electrodynamics effects
本文报道了一氟化镭分子$^{226}$ RaF和镭阳离子$^{226}$ Ra $^+$跃迁能的高精度理论预测。考虑过渡$X~^2Σ_{1/2} \to A~^2Π_{1/2}$在RaF是这个分子的主要特征之一，并可用于激光冷却RaF的电子电偶极矩的后续测量。对于分子和原子的预测，我们超越了狄拉克-库仑哈密顿和治疗高阶电子关联效应内的耦合集群理论，包括四倍和更高的振幅。量子电动力学（QED）的影响包括非微扰使用的模型QED运营商，现在实施的分子。结果表明，在分子和原子计算中包含QED效应是解决Dirac-Coulomb-Breit哈密顿量和实验中获得的理论值之间的差异的关键因素。与实验值的剩余偏差在几个meV之内。这比通常被认为是理论分子物理学中的指导线的“化学精度”（1 kcal/mol=43 meV）好一个数量级以上。
Molecular production in two-component atomic Fermi gases
我们提供了一个实用的方法，通过线性向下扫描的费什巴赫共振在简并费米气体含有两个原子的自旋态的非相干混合物的分子生产。我们表明，原子的关联效率是由朗道-齐纳参数，除了气体的密度。我们的方法的微观二元跃迁概率的成对求和导致一个直观的解释所观察到的饱和的分子生产和恢复所有的原子损失曲线的C. A. Regal等人[Nature（London）427，47（2003）]以及K.E. Strecker等人[Phys. Rev. Lett. 91，080406（2003）]，没有可调参数。
Tunable Molecular Interactions Near an Atomic Feshbach Resonance: Stability and Collapse of a Molecular Bose-Einstein Condensate
Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China（中国科学院微观电磁尺度物理科学研究国家中心和中国科学技术大学物理学院）；Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China（上海量子科学研究中心和中国科学院量子信息与量子物理学卓越创新中心，中国科学技术大学）；Hefei National Laboratory, University of Science and Technology of China（中国科学技术大学合肥国家实验室）；Department of Physics and James Franck Institute, University of Chicago（芝加哥大学物理系和詹姆斯·弗兰克研究所）；E. L. Ginzton Laboratory and Department of Applied Physics, Stanford University（斯坦福大学E.L.金茨顿实验室和应用物理系）；Department of Physics and Hong Kong Institute of Quantum Science and Technology, The University of Hong Kong（香港大学物理系和香港量子科学与技术研究所）；Enrico Fermi Institute, University of Chicago（芝加哥大学恩里科·费米研究所）
