Optical frequency analysis on dark state of a single trapped ion

Abstract

We demonstrate an optical frequency analysis method using the Fourier transform of detection times of fluorescence photons emitted from a single trapped 40 Ca + ion. The response of the detected photon rate to the relative laser frequency deviations is recorded within the slope of a dark resonance formed in the lambda-type energy level scheme corresponding to two optical dipole transitions. This approach enhances the sensitivity to the small frequency deviations and does so with reciprocal dependence on the fluorescence rate. The employed lasers are phase locked to an optical frequency comb, which allows for precise calibration of optical frequency analysis by deterministic modulation of the analyzed laser beam with respect to the reference beam. The attainable high signal-to-noise ratios of up to a MHz range of modulation deviations and up to a hundred kHz modulation frequencies promise the applicability of the presented results in a broad range of optical spectroscopic applications.

A frequency comb stabilized Ti:Sa laser as a self-reference for ion-trap experiments with a 40Ca+ ion

“…We measured the variation of the fluorescence photons with the frequency of the 397 nm laser beam, scanned across resonance, and we conclude that both schemes are suitable when the Doppler cooling experiment is run under the optimal attainable conditions. This stabilization scheme opens the possibility to use the optical frequency comb as the reference in more complex scenarios involving many laser sources, 35 as it happens when the laser-cooled 40 Ca + ion is stored in a Penning trap located in a magnetic field of 7 T, 20 where up to eight more diode lasers are required for Doppler cooling. Furthermore, under minor modifications in the comb setup, this can be simultaneously used to measure accurately the frequency of the quadrupole transition 2 S 1/2 ↔ 2 D 5/2 in 40 Ca + .…”

Optical cavity for ultra-narrow linewidth laser system

“…The high-finesse optical resonators play an irreplaceable role in the spectral-narrowing and frequency stabilisation of lasers. They allow reducing of laser linewidth to a sub-Hz level [1], which opens the way for the realisation of optical clocks [2], ultra-stable references based on frequency combs [3] and laser spectroscopy systems with unprecedented resolution. The resonator described in this work was developed in a collaboration between ISI CAS (optical design, resonator's shield chamber, optical setup for the laser locking) and the TOPTEC (optical design, development and assembly of the resonator).…”