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Register a new userTrapping molecules on a chip in traveling potential wells
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A microstructured array of over 1200 electrodes on a substrate has been configured to generate an array of local minima of electric field strength with a periodicity of $120 mu$m about $25 mu$m above the substrate. By applying sinusoidally varying potentials to the electrodes, these minima can be made to move smoothly along the array. Polar molecules in low field seeking quantum states can be trapped in these traveling potential wells. This is experimentally demonstrated by transporting metastable CO molecules in 30 mK deep wells that move at constant velocities above the substrate.
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We present experiments on decelerating and trapping ammonia molecules using a combination of a Stark decelerator and a traveling wave decelerator. In the traveling wave decelerator a moving potential is created by a series of ring-shaped electrodes to which oscillating high voltages are applied. By lowering the frequency of the applied voltages, the molecules confined in the moving trap are decelerated and brought to a standstill. As the molecules are confined in a true 3D well, this new kind of deceleration has practically no losses, resulting in a great improvement on the usual Stark deceleration techniques. The necessary voltages are generated by amplifying the output of an arbitrary wave generator using fast HV-amplifiers, giving us great control over the trapped molecules. We illustrate this by experiments in which we adiabatically cool trapped NH3 and ND3 molecules and resonantly excite their motion.
We have recently demonstrated static trapping of ammonia isotopologues in a decelerator that consists of a series of ring-shaped electrodes to which oscillating high voltages are applied [Quintero-P{e}rez et al., Phys. Rev. Lett. 110, 133003 (2013)]. In this paper we provide further details on this traveling wave decelerator and present new experimental data that illustrate the control over molecules that it offers. We analyze the performance of our setup under different deceleration conditions and demonstrate phase-space manipulation of the trapped molecular sample.
In the last years, it was demonstrated that neutral molecules can be loaded on a microchip directly from a supersonic beam. The molecules are confined in microscopic traps that can be moved smoothly over the surface of the chip. Once the molecules are trapped, they can be decelerated to a standstill, for instance, or pumped into selected quantum states by laser light or microwaves. Molecules are detected on the chip by time-resolved spatial imaging, which allows for the study of the distribution in the phase space of the molecular ensemble.
Polar molecules in selected quantum states can be guided, decelerated, and trapped using electric fields created by microstructured electrodes on a chip. Here we explore how transitions between two of these quantum states can be induced while the molecules are on the chip. We use CO (a 3-Pi(1), v=0) molecules, prepared in the J=1 rotational level, and induce the J=2 <-- J=1 rotational transition with narrow-band sub-THz (mm-wave) radiation. First, the mm-wave source is characterized using CO molecules in a freely propagating molecular beam, and both Rabi cycling and rapid adiabatic passage are examined. Then, we demonstrate that the mm-wave radiation can be coupled to CO molecules that are less than 50 micron above the chip. Finally, CO molecules are guided in the J=1 level to the center of the chip where they are pumped to the J=2 level, recaptured, and guided off the chip.
Recently, a decelerator for neutral polar molecules has been presented that operates on the basis of macroscopic, three-dimensional, traveling electrostatic traps (Osterwalder et al., Phys. Rev. A 81, 051401 (2010)). In the present paper, a complete description of this decelerator is given, with emphasis on the electronics and the mechanical design. Experimental results showing the transverse velocity distributions of guided molecules are shown and compared to trajectory simulations. An assessment of non-adiabatic losses is made by comparing the deceleration signals from 13-CO with those from 12-CO and with simulated signals.
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