Anomalous cooling of the parallel velocity in seeded beams

Parallel Temperatures in Supersonic Beams: Ultra Cooling of Light Atoms seeded in a Heavier Carrier Gas

We have found recently that, in a supersonic expansion of a mixture of two monoatomic gases, the parallel temperatures of the two gases can be very different. This effect is large if the seeded gas is highly diluted and if its atomic mass is considerably smaller than the one of the carrier gas. In the present paper, we present a complete derivation of our theoretical analysis of this effect. Our calculation is a natural extension of the existing theory of supersonic cooling to the case of a gas mixture, in the high dilution limit. Finally, we describe a set of temperature measurements made on …

超声速氦射流捕获与冷却碱金属原子的蒙特卡罗模拟

Monte-Carlo simulations of the capture and cooling of alkali-metal atoms by a supersonic helium jet

本研究通过三维蒙特卡罗模拟并结合量子散射截面，揭示超声速冷氦射流对Li和Rb原子的捕获与冷却机制，且模拟结果与Li荧光实验相符。

Trapping of molecular Oxygen together with Lithium atoms

We demonstrate simultaneous deceleration and trapping of a cold atomic and molecular mixture. This is the first step towards studies of cold atom-molecule collisions at low temperatures as well as application of sympathetic cooling. Both atoms and molecules are cooled in a supersonic expansion and are loaded into a moving magnetic trap which brings them to rest via the Zeeman interaction from an initial velocity of 375 m/s. We use a beam seeded with molecular Oxygen, and entrain it with Lithium atoms by laser ablation prior to deceleration. The deceleration ends with loading of the mixture int…

接近p波Feshbach共振的单组分费米气体中的反常损失行为

Anomalous loss behavior in a single-component Fermi gas close to a $p$-Wave Feshbach resonance

本文扩展级联模型研究单组分费米气体在p波Feshbach共振附近的三体损失，发现弹性与非弹性碰撞速率之比决定损失呈n^3或反常n^2密度依赖，并对应碰撞冷却或非热化稳态演化。

Measuring the temperature and heating rate of a single ion by imaging

We present a technique based on high resolution imaging to measure the absolute temperature and the heating rate of a single ion trapped at the focus of a deep parabolic mirror. We collect the fluorescence light scattered by the ion during laser cooling and image it onto a camera. Accounting for the size of the point-spread function and the magnification of the imaging system, we determine the spatial extent of the ion, from which we infer the mean phonon occupation number in the trap. Repeating such measurements and varying the power or the detuning of the cooling laser, we determine the anom…