View Abstract Sign in for premium content
Abstract:
Optical clocks constitute the state of the art in precision timekeeping. Research groups now reach 10^-18 level instability and accuracy in multiple optical clock platforms, including ion clocks and optical lattice clocks with neutral atoms, improving on current microwave clocks by orders of magnitude. These clocks are predominantly laboratory scale metrology experiments in controlled environments. We are developing a strontium optical lattice clock based on foundry compatible integrated photonics to improve upon the scalability and SWaP-C overhead of standard laboratory scale optical clocks. Our novel alignment-free “metasurface (MS) magneto-optical trap (MOT)” atom-photonic interface includes twelve metasurface optics fabricated on two silica wafers outside of our vacuum chamber. The MS optics are illuminated directly with modes from commercial optical fiber. The resulting 6 pairs of counter-propagating MOT beams form a unique geometry to cool strontium from a hot atom beam for both of the MOT transitions required for loading the atoms into an optical lattice. We demonstrate laser cooling and trapping of all four naturally occurring strontium species in our broadline MS MOT, including MOTs with 8x10^6 88Sr atoms and 3x10^5 87Sr atoms, atom numbers commensurate with optical clock operation. We stabilize our lasers’ frequencies by offset phase locking to supercontinuum generated with a commercial frequency comb fiber coupled to tantala waveguides. Through optical nonlinearities and dispersion engineering, the tantala waveguides extend the frequency comb spectrum to each of the desired wavelengths from 922 nm to 689 nm, achieving optical beat notes with the reference optical mode of up to 45 dB SNR. We further report on our progress in demonstrating narrowline cooling of strontium, loading the cooled atoms into an optical lattice, and realizing an optical clock. Our alignment free MS MOT infrastructure and tanala supercontinuum offer a scalable solution and significant simplification in the optical infrastructure required for optical lattice clocks.