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We here report on the experimental realization of a microwave decelerator for neutral polar molecules, suitable for decelerating and focusing molecules in high-field-seeking states. The multi-stage decelerator consists of a cylindrical microwave cavity oscillating on the TE 11n mode, with n=12 electric field maxima along the symmetry axis. By switching the microwave field on and off at the appropriate times, a beam of state-selected ammonia molecules with an incident mean velocity of 25 m/s is guided while being spatially focussed in the transverse direction and bunched in the forward direction. Deceleration from 20.0 m/s to 16.9 m/s and acceleration from 20.0 m/s to 22.7 m/s is demonstrated.
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Recently a number of diatomic and polyatomics molecules has been identified as a prospective systems for Doppler/Sisyphus cooling. Doppler/Sisyphus cooling allows to decrease the kinetic energy of molecules down to microkelvin temperatures with high efficiency and then capture them to molecular traps, including magneto-optical trap. Trapped molecules can be used for creation of molecular fountains and/or performing controlled chemical reactions, high-precision spectra measurements and a multitude of other applications. Polyatomic molecules with heavy nuclei present considerable interest for the search for new physics outside of Standard Model and other applications including cold chemistry, photochemistry, quantum informatics etc. Herein we would like to attract attention to radium monohydroxide molecule (RaOH) which is on the one hand an amenable object for laser cooling and on the other hand provides extensive possibilities for searching for P-odd and P,T-odd effects. At the moment RaOH is the heaviest polyatomic molecule proposed for direct cooling with lasers.
We here report on the implementation of a microwave lens for neutral polar molecules suitable to focus molecules both in low-field-seeking and in high-field-seeking states. By using the TE_11m modes of a 12 cm long cylindrically symmetric microwave resonator, Stark-decelerated ammonia molecules are transversally confined. We investigate the focusing properties of this microwave lens as a function of the molecules velocity, the detuning of the microwave frequency from the molecular resonance frequency, and the microwave power. Such a microwave lens can be seen as a first important step towards further microwave devices, such as decelerators and traps.
We explore coherent multi-photon processes in $^{87}$Rb$^{133}$Cs molecules using 3-level lambda and ladder configurations of rotational and hyperfine states, and discuss their relevance to future applications in quantum computation and quantum simulation. In the lambda configuration, we demonstrate the driving of population between two hyperfine levels of the rotational ground state via a two-photon Raman transition. Such pairs of states may be used in the future as a quantum memory, and we measure a Ramsey coherence time for a superposition of these states of 58(9) ms. In the ladder configuration, we show that we can generate and coherently populate microwave dressed states via the observation of an Autler-Townes doublet. We demonstrate that we can control the strength of this dressing by varying the intensity of the microwave coupling field. Finally, we perform spectroscopy of the rotational states of $^{87}$Rb$^{133}$Cs up to $N=6$, highlighting the potential of ultracold molecules for quantum simulation in synthetic dimensions. By fitting the measured transition frequencies we determine a new value of the centrifugal distortion coefficient $D_v=htimes207.3(2)~$Hz.
We provide a theory of the deflection of polar and non-polar rotating molecules by inhomogeneous static electric field. Rainbow-like features in the angular distribution of the scattered molecules are analyzed in detail. Furthermore, we demonstrate that one may efficiently control the deflection process with the help of short and strong femtosecond laser pulses. In particular the deflection process may by turned-off by a proper excitation, and the angular dispersion of the deflected molecules can be substantially reduced. We study the problem both classically and quantum mechanically, taking into account the effects of strong deflecting field on the molecular rotations. In both treatments we arrive at the same conclusions. The suggested control scheme paves the way for many applications involving molecular focusing, guiding, and trapping by inhomogeneous fields.
We study interaction of generic asymmetric molecules with a pair of strong time-delayed short laser pulses with crossed linear polarizations. We show that such an excitation not only provides unidirectional rotation of the most polarizable molecular axis, but also induces a directed torque along this axis, which results in the transient orientation of the molecules. The asymmetric molecules are chiral in nature and different molecular enantiomers experience the orienting action in opposite directions causing out-of-phase oscillation of their dipole moments. The resulting microwave radiation was recently suggested to be used for analysis/discrimination of chiral molecular mixtures. We reveal the mechanism behind this laser induced orientation effect, show that it is classical in nature, and envision further applications of light with skewed polarization.
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