We have assembled the experimental setup for laser cooling and trapping of calcium atoms in a magneto-optical trap. As a part of this setup on air-cooled Zeeman slower for calcium atomic beam was developed. By using the atomic beam we recorded the resonance of fluorescence. The spectral width of the resonance 58.6 MHz is comparable with the natural width of cooling transition 4 s 21 S 0 −4 s 4 p 1 P 1 .
We have assembled the experimental setup for laser cooling and trapping of calcium atoms in a magneto-optical trap. As a part of this setup on air-cooled Zeeman slower for calcium atomic beam was developed. By using the atomic beam we recorded the resonance of fluorescence. The spectral width of the resonance 58.6 MHz is comparable with the natural width of cooling transition 4 s 21 S 0 −4 s 4 p 1 P 1 .
We report on a system for atomic beam deceleration and magneto-optical trapping of calcium atoms that uses the 1S0–1P1 transition, in which a single laser is used to trap and slow the atoms. The slower laser beam is focused near the magneto-optical trap’s center, which has a waist size much smaller than the atomic cloud such that its influence on the trapped atoms is greatly reduced. We also investigate the theoretical possibility of cooling by use of a two-photon (4s2)1S0–(4s5s)1S0 transition. Excitation near resonance with the 1P1 level results in an equilibrium temperature seven times smaller than the Doppler limit of the 1S0–1P1 transition.
We report the construction and characterization of an experimental setup for producing a cold gas of 40Ca atoms and excite them to high Rydberg states with a resonant three-photon-excitation scheme. The apparatus comprises four stages, each designed in-house. An oven heated to ∼500∘C generates an atomic beam that is collimated by a capillary stack. The beam is sent into a passive, permanent-magnet-based Zeeman slower that reduces the atomic velocity to 30 m/s. The slow atoms are captured in a magneto-optical trap (MOT) and cooled to 1.0(3) mK with a trapping time of 16(2) ms. Ground-state atoms in the cold gas are excited to high Rydberg states via resonant excitation through the intermediate 4s4p1P1 and 4s4d1D2 states. The MOT is operated at the center of an electrode stack, which serves to apply continuous and pulsed electric fields and field-ionize the Rydberg atoms for detection. We benchmark our MOT against previous implementations and find its performance consistent with state-of-the-art results in terms of temperature and trapping lifetime. Finally, we demonstrate Rydberg spectroscopy of calcium, confirming the system's suitability for ultracold Rydberg physics experiments.
We present a compact apparatus for laser cooling and trapping of atomic calcium. The set-up consisting of a Zeeman-slowed thermal beam and a magneto-optical trap (MOT) has potential use for studying optical lattices, optical clocks, sensitive trace analysis, ultra-cold collisions and the feasibility of achieving quantum degeneracy in an alkaline earth element. Construction of the apparatus is described as well as the characterization of the trap in terms of atom number and lifetime. The lifetime results are compared with a rate equation model for the system.
We describe a new system for laser cooling and trapping of neutral Calcium atoms employing the ¹S0 -¹ P1 resonant transition at 423 nm. An on-axis magneto-optical trap (MOT) is loaded from a Zeeman decelerated atomic beam. When a single laser is used, in order to avoid perturbation of the trap by the deceleration laser beam, this one has been tightly focused near the MOT center, with a waist size much smaller than the atomic cloud. In order to test the efficiency of this novel technique, we have then employed a second, independent decelerating laser, with a profile mode matched to the atomic beam. For an oven temperature of 580±C this system can load 1.2 (2) x 10(7) atoms in 16 (1) ms. By the spatial extension of the atomic cloud the one dimension rms velocity was estimated to be 136 (12) cm/s, corresponding to a temperature of 9 (2) mK. The variation of the number of trapped atoms as a function of laser detuning and intensity, trap magnetic field gradient and oven temperature is analyzed. Spatial structures of the trapped atoms, like stable rings created by vortex forces, have been observed. This is the first time that these structures, already observed in alkali-metal elements, are reported in MOTs of alkaline-earth elements.
We explore an efficient method for preparing large samples of ultracold calcium atoms. An optimized conventional (Doppler-limited) magneto-optical trap collects atoms from a Zeeman cooled atomic beam using a strong dipole transition within the singlet system. This transition is not completely closed thus yielding an intense flux of atoms into the metastable triplet state 3P2. A second magneto-optical trap sharing the same magnetic-field gradient is superimposed which captures and further cools the metastables using the narrow-band infrared transition ${}^{3}{\stackrel{\ensuremath{\rightarrow}}{{P}_{2}}}^{3}{D}_{3}.$ In our present experiment we were able to prepare $3\ifmmode\times\else\texttimes\fi{}{10}^{8}$ atoms at temperatures below 20 microkelvin within 250 ms. Minor technical improvements of our setup promise to yield above 1010 atoms at submicrokelvin temperatures within 1 s.
The advent of the laser opened the way to the development of powerful methods for producing and manipulating cold atomic gases. To set the stage we describe a typical experiment, which is shown schematically in Fig. 4.1. A beam of sodium atoms emerges from an oven at a temperature of about 600 K, corresponding to a speed of about 800 m s −1 , and is then passed through a so-called Zeeman slower, in which the velocity of the atoms is reduced to about 30 m s −1 , corresponding to a temperature of about 1 K. In the Zeeman slower, a laser beam propagates in the direction opposite that of the atomic beam, and the radiation force produced by absorption of photons retards the atoms. Due to the Doppler effect, the frequency of the atomic transition in the laboratory frame is not generally constant, since the atomic velocity varies. However, by applying an inhomogeneous magnetic field designed so that the Doppler and Zeeman effects cancel, the frequency of the transition in the rest frame of the atom may be held fixed. On emerging from the Zeeman slower the atoms are slow enough to be captured by a magneto-optical trap (MOT), where they are further cooled by interactions with laser light to temperatures of order 100 μK. Another way of compensating for the changing Doppler shift is to increase the laser frequency in time, which is referred to as ‘chirping’.