Abstract
A microstructured array of 1254 electrodes on a substrate has been configured to generate an array of local minima of electric field strength with a periodicity of 120 μm about 25 μm 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. Recently, we experimentally demonstrated this by transporting metastable CO molecules at constant velocities above the substrate (Meek et al 2008 Phys. Rev. Lett. 100 153003). Here, we outline and experimentally demonstrate how this microstructured array can be used to decelerate polar molecules directly from a molecular beam. For this, the sinusoidally varying potentials need to be switched on when the molecules arrive above the chip, their frequency needs to be chirped down in time and they need to be switched off before the molecules leave the chip again. Deceleration of metastable CO molecules from an initial velocity of 360 m s-1 to a final velocity as low as 240 m s-1 is demonstrated in the 15–35 mK deep potential wells above the 5 cm long array of electrodes. This corresponds to a deceleration of almost 105 g, and about 85 cm-1 of kinetic energy is removed from the metastable CO molecules in this process.
Highlights
A microstructured array of 1254 electrodes on a substrate has been configured to generate an array of local minima of electric field strength with a periodicity of 120 μm about 25 μm above the substrate
It was already mentioned in the previous section that the waveforms are switched on at the time when molecules moving with an initial velocity of 360 m s−1 have just arrived on the decelerator
The resulting timeof-flight spectrum shows a broad background on top of which there is an intense, narrow peak centered at 0.83 ms, i.e. at the time it takes to travel with a constant velocity of 360 m s−1 over the full 29.8 cm distance from the excitation zone to the detector
Summary
A microstructured array of 1254 electrodes on a substrate has been configured to generate an array of local minima of electric field strength with a periodicity of 120 μm about 25 μm above the substrate. Deceleration of metastable CO molecules from an initial velocity of 360 m s−1 to a final velocity as low as 240 m s−1 is demonstrated in the 15–35 mK deep potential wells above the 5 cm long array of electrodes. When two dipolar fields with different length scales and opposite directions are superimposed, a minimum of the electric field strength is created This minimum is located at the point where the long-range dipole that dominates far from the surface is canceled by the short-range dipole that dominates close to the surface. Such a minimum of the electric field strength presents a trap for polar molecules in a low-field seeking quantum state. With the electrode design used in the present study, an array of electric field minima is created above the surface, as shown in figure 1
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