اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدMeasurement of collisions between laser cooled cesium atoms and trapped cesium ions
98
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We report the measurement of collision rate coefficient for collisions between ultracold Cs atoms and low energy Cs+ ions. The experiments are performed in a hybrid trap consisting of a magneto-optical trap (MOT) for Cs atoms and a Paul trap for Cs+ ions. The ion-atom collisions impart kinetic energy to the ultracold Cs atoms resulting in their escape from the shallow MOT and, therefore, in a reduction in the number of Cs atoms in the MOT. By monitoring, using fluorescence measurements, the Cs atom number and the MOT loading dynamics and then fitting the data to a rate equation model, the ion-atom collision rate is derived. The Cs-Cs+ collision rate coefficient $9.3(pm0.4)(pm1.2)(pm3.5) times 10^{-14}$ m$^{3}$s$^{-1}$, measured for an ion distribution with most probable collision energy of 95 meV ($approx k_{B}.1100$ K), is in fair agreement with theoretical calculations. As an intermediate step, we also determine the photoionization cross section of Cs $6P_{3/2}$ atoms at 473 nm wavelength to be $2.28 (pm 0.33) times 10^{-21}$ m$^{2}$.
قيم البحث
اقرأ أيضاً
We study the peformances of Raman velocimetry applied to laser-cooled, spin-polarized, cesium atoms. Atoms are optically pumped into the F=4, m=0 ground-state Zeeman sublevel, which is insensitive to magnetic perturbations. High resolution Raman stim
ulated spectroscopy is shown to produce Fourier-limited lines, allowing, in realistic experimental conditions, atomic velocity selection to one-fiftieth of a recoil velocity.
We present first indications of sympathetic cooling between two neutral, optically trapped atomic species. Lithium and cesium atoms are simultaneously stored in an optical dipole trap formed by the focus of a CO$_2$ laser, and allowed to interact for
a given period of time. The temperature of the lithium gas is found to decrease when in thermal contact with cold cesium. The timescale of thermalization yields an estimate for the Li-Cs cross-section.
We demonstrate a prototype of a Focused Ion Beam machine based on the ionization of a laser-cooled cesium beam adapted for imaging and modifying different surfaces in the few-tens nanometer range. Efficient atomic ionization is obtained by laser prom
oting ground-state atoms into a target excited Rydberg state, then field-ionizing them in an electric field gradient. The method allows obtaining ion currents up to 130 pA. Comparison with the standard direct photo-ionization of the atomic beam shows, in our conditions, a 40-times larger ion yield. Preliminary imaging results at ion energies in the 1-5 keV range are obtained with a resolution around 40 nm, in the present version of the prototype. Our ion beam is expected to be extremely monochromatic, with an energy spread of the order of 1 eV, offering great prospects for lithography, imaging and surface analysis.
We consider the feasibility of observing a trap-induced resonance [Stock et al., Phys. Rev. Lett. 91, 183201 (2003)] for the case of two 133Cs atoms, trapped in separated wells of a polarization-gradient optical lattice, and interacting through a mul
tichannel scattering process. Due to the anomalously large scattering length of cesium dimers, a strong coupling can occur between vibrational states of the trap and a weakly bound molecular state that is made resonant by the ac-Stark shift of the lattice. We calculate the energy spectrum of the two-atom system as a function of the distance between two potential wells by connecting the solutions of the Schroedinger equation for the short-range molecular potential to that of the long-range trap in a self-consistent manner. The short-range potential is treated through a multichannel pseudopotential, parametrized by the K matrix, calculated numerically for atoms in free space in a close-coupling approximation. This captures both the bound molecular spectrum as well as the energy-dependent scattering for all partial waves. We establish realistic operating conditions under which the trap-induced resonance could be observed and show that this strong and coherent interaction could be used as a basis for high-fidelity two-qubit quantum logic operations.
We demonstrate a double-trap system well suited to study cold collisions between trapped ions and trapped atoms. Using Yb$^+$ ions confined in a Paul trap and Yb atoms in a magneto-optical trap, we investigate charge-exchange collisions of several is
otopes for collision energies down to 400 neV (5 mK). The measured rate coefficient of $6 times 10^{-10}$ cm$^{3}$s$^{-1}$, constant over four orders of magnitude in collision energy, is in good agreement with that derived from a semiclassical Langevin model for an atomic polarizability of 143 a.u.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
