A. D. Ludlow

Compact, thermal-noise-limited optical cavity for diode laser stabilization at 1×10 −15

We demonstrate phase and frequency stabilization of a diode laser at the thermal noise limit of a passive optical cavity. The system is compact and exploits a cavity design that reduces vibration sensitivity. The subhertz laser is characterized by comparison with a second independent system with similar fractional frequency stability (1x10(-15) at 1 s). The laser is further characterized by resolving a 2 Hz wide, ultranarrow optical clock transition in ultracold strontium.

Simple and compact Hz-level linewidth laser system via improved mounting configuration of a reference cavity

We report a simple, robust 1-Hz linewidth laser system enabled by an improved mounting strategy for optical reference cavities used for laser frequency stabilization.

Strontium optical lattice clock: 10 −16 uncertainty

We report on the improved characterization and operation of an optical frequency standard based on nuclear-spin-polarized, ultracold neutral strontium confined in a one dimensional optical lattice. We implement a remote optical carrier phase link between JILA and NIST Boulder campus, permitting high precision evaluation of the Sr system with other optical standards. Frequency measurement against a free-space Ca standard enables determination of systematic shifts of the Sr standard at or below 1 x 10-16 fractional uncertainty. We observe a density-dependent shift of the clock transition and its dependence on excited state fraction, with a zero crossing of the shift. We perform a 50-hour-long absolute frequency measurement of the strontium transition referenced to the NIST-F1 Cs fountain standard. This yields a value for the Sr clock transition frequency with a fractional uncertainty of 8.6 x 10-16, limited by the H-maser and Cs standards used. This represents our fifth, and the most accurate, measurement of the 87Sr clock frequency.

Strontium optical lattice clock with high accuracy and stability

Techniques of modern quantum optics allows for the preparation of atoms in well controlled quantum states ideal for precision measurements and tests of fundamental laws of physics. We report on our recent progress with a highly stable and accurate optical atomic clock based on ultracold fermionic 87Sr atoms confined in a one dimensional optical lattice. Currently, we have carried out a detailed evaluation of our clock at the 10-16 level and can report stability at 2 times 10-15 level at one second. At typical operating parameters for the clock we observe evidence of a density dependent clock shift. Operating the clock at a particular excitation ratio of ground state and excited clock state we observe a shift consistent with zero.

10 W average power frequency comb with sub-mHz relative linewidths from an Yb:fiber system

We present a fully phase-stabilized frequency comb with 10 W average power and 136 MHz repetition rate produced by a Yb:fiber system. Direct comparison with an octave-spanning Ti:sapphire comb yields record-low sub-mHz relative linewidths for frequency combs.

Sr Optical Clock with High Stability and Accuracy

We report on our recent evaluations of stability and accuracy of the JILA Sr optical lattice clock. We discuss precision tools for the lattice clock, including a stabilized clock laser with sub-Hz linewidth, fs-comb based technology allowing accurate clock comparison in both the microwave and optical domains, and clock transfer over optical fiber in an urban environment. High resolution spectroscopy (Q > 2 × 10) of lattice-confined, spin-polarized strontium atoms is used for both a high-performance optical clock and atomic structure measurement. Using a Ca optical standard for comparison, the overall systematic uncertainty of the Sr clock is reduced to < 2 × 10.

Strontium Optical Lattice Clock at JILA

Results from the JILA optical lattice clock are presented. We report on our development of precision tools for the lattice clock, including a stabilized clock laser with sub-Hz linewidth, fs-comb based technology allowing accurate clock comparison in both the microwave and optical domains, and clock transfer over optical fiber in an urban environment. High resolution spectroscopy (Q > 2 times 1014) of lattice confined strontium atoms is used for both a high-performance optical clock and atomic structure measurements. The current accuracy and stability of the lattice clock are also discussed.

High Spectral Resolution and Accuracy Studies for a Sr Optical Lattice Clock

The authors report recent progress on an optical lattice clock based on the ¹So-³Po transition of ⁸⁷Sr. Improvement of the spectral resolution allows measurement of the magnetically-induced frequency shift with an uncertainty below 10^-15. The high line quality factor is expected to yield complete evaluation of systematic effects at that same level in the near future

Laser stabilization of the local oscillator for an optical atomic clock

This paper demonstrates an ultrastable diode laser system for an optical atomic clock. This laser exploits a novel mounting configuration and is limited by the thermal noise of the cavity to which it is locked. Our measurements show the reality of Hz-level linewidth measurements between lasers of different colors located in different rooms.

Phase coherent manipulation of light: from precision spectroscopy to extreme nonlinear optics

Phase control of wide-bandwidth optical frequency combs enables amazing capabilities in optical frequency measurement and synthesis, optical atomic clocks, united time-frequency spectroscopy, coherent pulse synthesis and manipulation, and deterministic studies in sub-cycle physics.