Magnetic trapping and Zeeman relaxation of imidogen (NH X-triplet-Sigma)

Magnetic trapping and coherent control of laser-cooled molecules

We demonstrate coherent microwave control of the rotational, hyperfine and Zeeman states of ultracold CaF molecules, and the magnetic trapping of these molecules in a single, selectable quantum state. We trap about $5\times 10^{3}$ molecules for 2 s at a temperature of 65(11) $μ$K and a density of $1.2 \times 10^{5}$ cm$^{-3}$. We measure the state-specific loss rate due to collisions with background helium.

Trap-induced ac Zeeman shift of the thorium-229 nuclear clock frequency

We examine the effect of a parasitic rf magnetic field, attributed to ion trapping, on the highly anticipated nuclear clock based on $^{229}$Th$^{3+}$ [C. J. Campbell et al., Phys. Rev. Lett. 108, 120802 (2012)]. The rf magnetic field induces an ac Zeeman shift to the clock frequency. As we demonstrate, this shift threatens to be the dominant systematic frequency shift for the clock, exceeding other systematic frequency shifts and the projected systematic uncertainty of the clock by orders of magnitude. We propose practical means to suppress or eliminate this shift.

Magneto-electrostatic trapping of ground state OH molecules

We report the magnetic confinement of neutral, ground state hydroxyl radicals (OH) at a density of $\sim3\times10^{3}$ cm$^{-3}$ and temperature of $\sim$30 mK. An adjustable electric field of sufficient magnitude to polarize the OH is superimposed on the trap in either a quadrupole or homogenous field geometry. The OH is confined by an overall potential established via molecular state mixing induced by the combined electric and magnetic fields acting on the molecule's electric dipole and magnetic dipole moments, respectively. An effective molecular Hamiltonian including Stark and Zeeman terms…

Electromagnetically induced absorption in magneto-optically trapped atoms

Electromagnetically induced absorption (EIA) was observed on a sample of $% ^{85}Rb$ in a magneto-optical trap using low intensity cw copropagating pump and probe optical fields. At moderate trapping field intensity, the EIA spectrum is determined by the Zeeman effect produced on the atomic ground-state by the trapping quadrupolar magnetic field. The use of EIA spectroscopy for the magnetic field mapping of cold atomic samples is illustrated.

固态氩中铥的晶体场与塞曼效应

Crystal Fields and Zeeman Effect for Thulium in Solid Argon

研究植入固态氩中铥原子的晶体场和塞曼效应，发现1140 nm跃迁因晶体场和超精细耦合分裂，强选择规则使该跃迁变为磁-电跃迁，mT磁场下可分辨塞曼位移，实现全光学直流磁场检测。

Fictitious magnetic field gradients in optical microtraps as an experimental tool for interrogating and manipulating cold atoms

Optical microtraps provide a strong spatial confinement for laser-cooled atoms. They can, e.g., be realized with strongly focused trapping light beams or the optical near fields of nano-scale waveguides and photonic nanostructures. Atoms in such traps often experience strongly spatially varying AC Stark shifts which are proportional to the magnetic quantum number of the respective energy level. These inhomogeneous fictitious magnetic fields can cause a displacement of the trapping potential that depends on the Zeeman state. Hitherto, this effect was mainly perceived as detrimental. However, it…

Atomic dynamics in evaporative cooling of trapped alkali atoms in strong magnetic fields

We investigate how the nonlinearity of the Zeeman shift for strong magnetic fields affects the dynamics of rf field induced evaporative cooling in magnetic traps. We demonstrate for the 87-Rb and 23-Na F=2 trapping states with wave packet simulations how the cooling stops when the rf field frequency goes below a certain limit (for the 85-Rb F=2 trapping state the problem does not appear). We examine the applicability of semiclassical models for the strong field case as an extension of our previous work [Phys. Rev. A 58, 3983 (1998)]. Our results verify many of the aspects observed in a recent …

State-dependent potentials in a nanofiber-based two-color trap for cold atoms

We analyze the ac Stark shift of a cesium atom interacting with far-off-resonance guided light fields in the nanofiber-based two-color optical dipole trap realized by Vetsch \textit{et al.} [Phys. Rev. Lett. \textbf{104}, 203603, (2010)]. Particular emphasis is given to the fictitious magnetic field produced by the vector polarizability of the atom in conjunction with the ellipticity of the polarization of the trapping fields. Taking into account the ac Stark shift, the atomic hyperfine interaction, and a magnetic interaction, we solve the stationary Schrödinger equation at a fixed point in sp…

A Moving-Trap Zeeman Decelerator

We present a moving-trap Zeeman decelerator (MTZD) for use in molecular beam manipulation and magnetic-trapping experiments of paramagnetic atoms and molecules. The 0.49 m MTZD consists of a combination of a 2D magnetic quadrupole guide and deceleration coils, which together produce an array of 3D magnetic traps. The design is based on that of Trimeche et al. with significant modifications. The 2D quadrupole is driven by fast rising and falling square pulses of current (up to 700 A) of arbitrary lengths of time. The traps can be made to move at velocities from ca. 370 m/s down to zero, which i…

在强非均匀磁场中囚禁离子激光冷却的实验实现

Experimental implementation of laser cooling of trapped ions in strongly inhomogeneous magnetic fields

本文展示了在强非均匀磁场中对分段线性 Paul 阱中囚禁的 $^{40}$Ca$^+$ 离子实现高效多普勒激光冷却，并利用塞曼效应位置依赖性绘制磁场图，为混合囚禁冷离子与中性分子实验及量子科学研究奠定基础。

Properties of the ground $^3$F$_2$ state and the excited $^3$P$_0$ state of atomic thorium in cold collisions with $^3$He

We measure inelastic collisional cross sections for the ground $^3$F$_2$ state and the excited $^3$P$_0$ state of atomic thorium in cold collisions with $^3$He. We determine for Th ($^3$F$_2$) at 800 mK the ratio $γ\approx 500$ of the momentum-transfer to Zeeman relaxation cross sections for collisions with $^3$He. For Th ($^3$P$_0$), we study electronic inelastic processes and find no quenching even after $10^6$ collisions. We also determine the radiative lifetime of Th ($^3$P$_0$) to be $τ> 130$ ms. This great stability of the metastable state opens up the possibility for further study, incl…

自然丰度费米子钾的亚多普勒激光冷却与磁囚禁

Sub-Doppler laser cooling and magnetic trapping of natural-abundance fermionic potassium

本文利用天然丰度钾源在单腔室中实现了 $^{40}$K 的亚多普勒冷却与磁囚禁，获得了 $3\ imes10^5$ 个约 10~\ extmu K 的原子，并展示了不同条件下的磁阱寿命，证明未富集钾可用于优化含 $^{40}$K 实验装置并延长富集源寿命。