Destabilization of dark states and optical spectroscopy in Zeeman-degenerate atomic systems

Abstract

We present a general discussion of the techniques of destabilizing dark states in laser-driven atoms with either a magnetic field or modulated laser polarization. We show that the photon scattering rate is maximized at a particular evolution rate of the dark state. We also find that the atomic resonance curve is significantly broadened when the evolution rate is far from this optimum value. These results are illustrated with detailed examples of destabilizing dark states in some commonlytrapped ions and supported by insights derived from numerical calculations and simple theoretical models.PACS numbers: 32.60.+i 42.50.Hz

Surface-electrode point Paul trap

“…Dark states of the D 3/2 manifold are destabilized by polarization modulation of the 1092-nm light at 10 MHz as described in Ref. [40]. Fluorescence from the ions is collected with a numerical aperture 0.5 lens mounted inside the vacuum chamber and imaged onto a CCD camera (Andor Luca R) and a photomultiplier tube (PMT) (Hamamatsu, H7360-02), the latter achieving an overall detection efficiency (including losses on optics in the imaging system) of 0.6%.…”

Precision measurement of the branching fractions of the5pP1/22state inSrLikforman1, Tugayé2, Guibal3 et al. 2016Phys. Rev. A17180View full textAdd to dashboardCite

“…This configuration prevents the ions from being optically-pumped into a metastable dark state by the repumping laser alone [44]. Laser beams impinging on the ion are switched-on and -off using AOMs in a double-pass geometry driven through RF switches (Mini-Circuits ZYSWA-2-50DR) and then injected in single mode polarization maintaining optical fibers.…”

Continuous all-optical deceleration and single-photon cooling of molecular beams

“…In order to decelerate all of the population in the ground state, it would therefore seem desirable to work on a transition such that these are equal (J = J ) by slowing on a Q-branch transition with π -polarized pulses (a prime denotes the excited state). However, for molecules with integer values of J (such as spin singlets and triplets), Q-branch transitions will have dark states even for pure π polarization [44], and an R-branch transition is desirable instead (J = J − 1). We note here that driving a P -branch transition (J = J + 1, as is done for molecular Doppler cooling) could potentially eliminate the need to repump rotational branching, but would come at the cost of dark ground-state sublevels on the pulsed transition, leading to ground-state molecules that do not get decelerated and velocity, position, and optical phase sensitivity that will likely degrade the population transfer fidelity.…”