RF spectroscopy in a resonant RF-dressed trap

We study the spectroscopy of atoms dressed by a resonant radiofrequency (RF) field inside an inhomogeneous magnetic field and confined in the resulting adiabatic potential. The spectroscopic probe is a second, weak, RF field. The observed line shape is related to the temperature of the trapped cloud. We demonstrate evaporative cooling of the RF-dressed atoms by sweeping the frequency of the second RF field around the Rabi frequency of the dressing field.Comment: 7 figures, 8 pages; to appear in J. Phys.

Recent developments in trapping and manipulation of atoms with adiabatic potentials

A combination of static and oscillating magnetic fields can be used to ‘dress’ atoms with radio-frequency (RF), or microwave, radiation. The spatial variation of these fields can be used to create an enormous variety of traps for ultra-cold atoms and quantum gases. This article reviews the type and character of these adiabatic traps and the applications which include atom interferometry and the study of low-dimensional quantum systems. We introduce the main concepts of magnetic traps leading to adiabatic dressed traps. The concept of adiabaticity is discussed in the context of the Landau–Zener model. The first bubble trap experiment is reviewed together with the method used for loading it. Experiments based on atom chips show the production of double wells and ring traps. Dressed atom traps can be evaporatively cooled with an additional RF field, and a weak RF field can be used to probe the spectroscopy of the adiabatic potentials. Several approaches to ring traps formed from adiabatic potentials are discussed, including those based on atom chips, time-averaged adiabatic potentials and induction methods. Several proposals for adiabatic lattices with dressed atoms are also reviewed

Quadrupole and hybrid traps

<p><strong>Figure 4.</strong> Quadrupole and hybrid traps. (a) Quadrupole trap (<em>T</em>_avg = 375 μK). (b) Hybrid trap (<em>T</em>_avg = 500 μK).</p> <p><strong>Abstract</strong></p> <p>We report the rapid accelerated thermalization of potassium (³⁹K) atoms loaded in a magnetic trap, in the presence of a single dipole trap beam. More than an order of magnitude reduction in the thermalization time, to less than a second, is observed with the focused off-resonant beam occupying only 0.01% of the volume of the magnetic trap. A new method for testing for thermalization of relatively hot clouds is devised. The cold atoms are loaded from a magneto-optical trap (MOT) of ³⁹K that has gone through a compressed MOT and sub-Doppler cooling stage. The atoms are prepared in the magnetically stretched |<em>F</em> = 2, <em>m_F</em> = 2〉 state prior to loading into the hybrid trap. We also report a direct loading of ³⁹K atoms, prepared in the state |<em>F</em> = 1〉, into a single beam dipole trap.</p

Values of various parameters during the C-MOT stage

<p><b>Table 1.</b> Values of various parameters during the C-MOT stage. δ_<em>C</em>, δ_<em>R</em> are the cooling and repump detuning, <em>I_C</em>, <em>I_R</em> and <em>I_S</em> are the cooling, repump and the saturation intensity respectively.</p> <p><strong>Abstract</strong></p> <p>We report the rapid accelerated thermalization of potassium (³⁹K) atoms loaded in a magnetic trap, in the presence of a single dipole trap beam. More than an order of magnitude reduction in the thermalization time, to less than a second, is observed with the focused off-resonant beam occupying only 0.01% of the volume of the magnetic trap. A new method for testing for thermalization of relatively hot clouds is devised. The cold atoms are loaded from a magneto-optical trap (MOT) of ³⁹K that has gone through a compressed MOT and sub-Doppler cooling stage. The atoms are prepared in the magnetically stretched |<em>F</em> = 2, <em>m_F</em> = 2〉 state prior to loading into the hybrid trap. We also report a direct loading of ³⁹K atoms, prepared in the state |<em>F</em> = 1〉, into a single beam dipole trap.</p

(a) Thermal relaxation in a hybrid trap, (b), (c) and (d) shows the thermal relaxation in magnetic trap after the dipole trap has been kept on for 1 s, 500 ms and 200 ms respectively, (e) shows the thermal relaxation in the magnetic quadrupole trap only

<p><strong>Figure 2.</strong> (a) Thermal relaxation in a hybrid trap, (b), (c) and (d) shows the thermal relaxation in magnetic trap after the dipole trap has been kept on for 1 s, 500 ms and 200 ms respectively, (e) shows the thermal relaxation in the magnetic quadrupole trap only.</p> <p><strong>Abstract</strong></p> <p>We report the rapid accelerated thermalization of potassium (³⁹K) atoms loaded in a magnetic trap, in the presence of a single dipole trap beam. More than an order of magnitude reduction in the thermalization time, to less than a second, is observed with the focused off-resonant beam occupying only 0.01% of the volume of the magnetic trap. A new method for testing for thermalization of relatively hot clouds is devised. The cold atoms are loaded from a magneto-optical trap (MOT) of ³⁹K that has gone through a compressed MOT and sub-Doppler cooling stage. The atoms are prepared in the magnetically stretched |<em>F</em> = 2, <em>m_F</em> = 2〉 state prior to loading into the hybrid trap. We also report a direct loading of ³⁹K atoms, prepared in the state |<em>F</em> = 1〉, into a single beam dipole trap.</p

The aspect ratio <em>W_x</em>/<em>W_y</em>, of the atomic cloud for various expansion times after releasing from the quadrupole magnetic trap and hybrid trap with a holding time of 2 s

<p><strong>Figure 1.</strong> The aspect ratio <em>W_x</em>/<em>W_y</em>, of the atomic cloud for various expansion times after releasing from the quadrupole magnetic trap and hybrid trap with a holding time of 2 s. <em>W_x</em> and <em>W_y</em> are the cloud size along the <em>x</em>- and <em>y</em>-axis respectively.</p> <p><strong>Abstract</strong></p> <p>We report the rapid accelerated thermalization of potassium (³⁹K) atoms loaded in a magnetic trap, in the presence of a single dipole trap beam. More than an order of magnitude reduction in the thermalization time, to less than a second, is observed with the focused off-resonant beam occupying only 0.01% of the volume of the magnetic trap. A new method for testing for thermalization of relatively hot clouds is devised. The cold atoms are loaded from a magneto-optical trap (MOT) of ³⁹K that has gone through a compressed MOT and sub-Doppler cooling stage. The atoms are prepared in the magnetically stretched |<em>F</em> = 2, <em>m_F</em> = 2〉 state prior to loading into the hybrid trap. We also report a direct loading of ³⁹K atoms, prepared in the state |<em>F</em> = 1〉, into a single beam dipole trap.</p

Values of various parameters during the sub-Doppler cooling stage

<p><b>Table 2.</b> Values of various parameters during the sub-Doppler cooling stage.</p> <p><strong>Abstract</strong></p> <p>We report the rapid accelerated thermalization of potassium (³⁹K) atoms loaded in a magnetic trap, in the presence of a single dipole trap beam. More than an order of magnitude reduction in the thermalization time, to less than a second, is observed with the focused off-resonant beam occupying only 0.01% of the volume of the magnetic trap. A new method for testing for thermalization of relatively hot clouds is devised. The cold atoms are loaded from a magneto-optical trap (MOT) of ³⁹K that has gone through a compressed MOT and sub-Doppler cooling stage. The atoms are prepared in the magnetically stretched |<em>F</em> = 2, <em>m_F</em> = 2〉 state prior to loading into the hybrid trap. We also report a direct loading of ³⁹K atoms, prepared in the state |<em>F</em> = 1〉, into a single beam dipole trap.</p