Microwave Lens for Polar Molecules

Abstract

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 TE11m 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.

Diatomic molecules in optical and microwave dipole traps

“…(25) analogs to the sum rules of Eqs. (27) and (28) also exist. However, the squared 3j symbols in these equations will have to be replaced by somewhat more complex double sums involving the coefficients C and C , which normally will not depend on F or M F .…”

“…(7), also with application of the convenient sum rule of Eq. (27). Computed real-and imaginary polarizabilities were obtained for various values ofhω, detuned from the v = 0 → ν = 8 transition frequency.…”

“…For absolute detunings lower than 2 MHz there is a steep rise in the polarizabilities, and small microwave intensities will yield large potential depths. A recent successful experiment on microwave lensing of NH 3 molecules [27] might represent the first important step toward microwave trapping of polar molecules.…”

Decelerating polar molecules using traveling microwave lattices

“…Alternatively, a microwave trap or deceleration in the resonator, which takes advantage of the first-order ac Stark shift associated with low-frequency transitions arising from rotational structure in polar molecules, has been proposed [16,17], and a microwave lens and a prototype decelerator have been experimentally demonstrated [18,19]. A particularly attractive feature of optical field or microwave field is that it can decelerate and trap molecules in their absolute ground state (a strong-field-seeking state), which is immune to inelastic collisional loss for possible further cooling, such as sympathetic or evaporative cooling.…”

“…A particularly attractive feature of optical field or microwave field is that it can decelerate and trap molecules in their absolute ground state (a strong-field-seeking state), which is immune to inelastic collisional loss for possible further cooling, such as sympathetic or evaporative cooling. In the microwave lens experiment [18], a microwave field in a cylindrical resonator is used to transversely focus molecules. When molecules come to low-field regions close to the electric field nodes, they might undergo nonadiabatic transitions which will cause undesired particle loss.…”