Storage and Adiabatic Cooling of Polar Molecules in a Microstructured Trap

Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, D-85748 Garching, Germany.
Physical Review Letters (Impact Factor: 7.51). 12/2011; 107(26):263003. DOI: 10.1103/PhysRevLett.107.263003
Source: PubMed


We present a versatile electric trap for the exploration of a wide range of quantum phenomena in the interaction between polar molecules. The trap combines tunable fields, homogeneous over most of the trap volume, with steep gradient fields at the trap boundary. An initial sample of up to 10(8), CH(3)F molecules is trapped for as long as 60 s, with a 1/e storage time of 12 s. Adiabatic cooling down to 120 mK is achieved by slowly expanding the trap volume. The trap combines all ingredients for opto-electrical cooling, which, together with the extraordinarily long storage times, brings field-controlled quantum-mechanical collision and reaction experiments within reach.

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    ABSTRACT: We discuss laser dressed dipolar and Van der Waals interactions between atoms and polar molecules, so that a cold atomic gas with laser admixed Rydberg levels acts as a designed reservoir for both elastic and inelastic collisional processes. The elastic scattering channel is characterized by large elastic scattering cross sections and repulsive shields to protect from close encounter collisions. In addition, we discuss a dissipative (inelastic) collision where a spontaneously emitted photon carries away (kinetic) energy of the collision partners, thus providing a significant energy loss in a single collision. This leads to the scenario of rapid thermalization and cooling of a molecule in the mK down to the \mu K regime by cold atoms.
    Full-text · Article · Dec 2011 · Physical Review Letters
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    ABSTRACT: Polar molecules have a rich internal structure and long-range dipole-dipole interactions, making them useful for quantum-controlled applications and fundamental investigations. Their potential fully unfolds at ultracold temperatures, where various effects are predicted in many-body physics, quantum information science, ultracold chemistry and physics beyond the standard model. Whereas a wide range of methods to produce cold molecular ensembles have been developed, the cooling of polyatomic molecules (that is, with three or more atoms) to ultracold temperatures has seemed intractable. Here we report the experimental realization of optoelectrical cooling, a recently proposed cooling and accumulation method for polar molecules. Its key attribute is the removal of a large fraction of a molecule's kinetic energy in each cycle of the cooling sequence via a Sisyphus effect, allowing cooling with only a few repetitions of the dissipative decay process. We demonstrate the potential of optoelectrical cooling by reducing the temperature of about one million CH(3)F molecules by a factor of 13.5, with the phase-space density increased by a factor of 29 (or a factor of 70 discounting trap losses). In contrast to other cooling mechanisms, our scheme proceeds in a trap, cools in all three dimensions and should work for a large variety of polar molecules. With no fundamental temperature limit anticipated down to the photon-recoil temperature in the nanokelvin range, we expect our method to be able to produce ultracold polyatomic molecules. The low temperatures, large molecule numbers and long trapping times of up to 27 seconds should allow an interaction-dominated regime to be attained, enabling collision studies and investigation of evaporative cooling towards a Bose-Einstein condensate of polyatomic molecules.
    Preview · Article · Nov 2012 · Nature
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    ABSTRACT: Die Kühlung von Atomen bis hin zum ultrakalten Bose‐Einstein‐Kondensat ist seit Jahren Stand der Technik. Für Moleküle, insbesondere solche mit mehr als zwei Atomen, ist es bislang jedoch nicht gelungen, in diesen Temperaturbereich vorzustoßen. Die in unserer Gruppe am Max‐Planck‐Institut für Quantenoptik entwickelte optoelektrische Sisyphus‐Kühlung birgt erstmals das Potenzial, ultrakalte Moleküle zu produzieren.
    No preview · Article · Mar 2013 · Physik in unserer Zeit
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