arXiv subjects

Ashby P. Hilton

Publications and source records attributed to Ashby P. Hilton.

6 recordsLinked to original sources

arXiv2026

A Portable Dual-Color Two-Photon Rubidium Optical Frequency Standard

Portable atomic clocks are essential in a wide variety of applications, most notably in the operation of global navigation satellite systems. Existing portable atomic clocks utilizing microwave-based interrogation schemes are now routinely eclipsed by the next generation of atomic frequency standards based on optical interrogation. While optical frequency standards demonstrate greatly improved frequency stability, they have only recently reached a level of technical maturity required to demonstrate this improved performance outside of well curated laboratory environments. Here, we demonstrate a fully autonomous and portable optical frequency standard based on an efficient dual-color excitation of the $5S_{1/2}\rightarrow5D_{5/2}$ two-photon transition in $^{87}$Rb. The standard utilizes a combination of robust, highly developed commercial-off-the-shelf telecommunications technologies and a fully integrated portable optical frequency comb, providing the optical and microwave outputs vital for interfacing with existing electronic systems and infrastructure. The system demonstrates a fractional frequency stability of $1.9\times10^{-13}$ at 1s of integration time, reaching $3.5\times10^{-15}$ at 8000s of integration time without the need for drift removal. This portable demonstrator unit marks a significant achievement in the development of Rb optical atomic frequency standards, and for the deployment of optical atomic frequency standards outside of the laboratory.

physics.atom-ph↗

arXiv2025

Demonstration of a simple and compact ytterbium magneto-optical trap

We present a low Size, Weight and Power (SWaP), low-complexity, ytterbium magneto-optical trap (MOT). We demonstrate trapping of $1.4 \times 10^6$ $^{171}$Yb atoms on the $|{^1S_0}, F = 1/2\rangle \leftrightarrow |{^1P_1}, F' = 3/2\rangle$ transition directly from a hot thermal beam. We explore the effect of trap detuning and oven temperature on trap number, density, loading rate and sample temperature. The low SWaP and low-complexity design presents a realistic pathway towards portable ytterbium MOTs, allowing cold atom ytterbium systems to escape the confines of the laboratory and perform precision measurements in field environments.

physics.atom-ph↗

arXiv2019

Light-shift spectroscopy of optically trapped atomic ensembles

We develop a method for extracting the physical parameters of interest for a dipole trapped cold atomic ensemble. This technique uses the spatially dependent ac-Stark shift of the trap itself to project the atomic distribution onto a light-shift broadened transmission spectrum. We develop a model that connects the atomic distribution with the expected transmission spectrum. We then demonstrate the utility of the technique by deriving the temperature, trap depth, lifetime, and trapped atom number from data that was taken in a single shot experimental measurement.

physics.atom-ph↗

arXiv2019

Heterodyne fiber interferometer for frequency-noise reduction and rapid wide-band tunability of a conventional laser source

Self-heterodyne fiber interferometers have been shown to be capable of stabilizing lasers to ultra-narrow linewidths and present an excellent alternative to high finesse cavities for frequency stabilization. In addition to suppressing frequency noise, these devices are highly tunable, and can be manipulated to produce high speed frequency sweeps over the entire range of the laser. We present an analytic approach for choosing a delay-line length for both optimal noise suppression and highest in-loop frequency sweep rate. Using this model we have implemented a fiber-based active Michelson interferometer as a frequency discriminator for a conventional diode laser and demonstrated a linewidth of 700 Hz over millisecond timescales. We also demonstrate a frequency scan rate of 1 THz/s and independently measure the maximum deviation in frequency from the linear sweep to be 100 kHz, predominantly limited by acoustic resonances in the apparatus.

physics.optics↗

arXiv2018

Dual-colour magic-wavelength trap for suppression of light shifts in atoms

We present an optical approach to compensating for spatially varying ac-Stark shifts that appear on atomic ensembles subject to strong optical control or trapping fields. The introduction of an additional weak light field produces an intentional perturbation between atomic states that is tuned to suppress the influence of the strong field. The compensation field suppresses sensitivity in one of the transition frequencies of the trapped atoms to both the atomic distribution and motion. We demonstrate this technique in a cold rubidium ensemble and show a reduction in inhomogeneous broadening in the trap. This two-colour approach emulates the magic trapping approach that is used in modern atomic lattice clocks but provides greater flexibility in choice of atomic species, probe transition, and trap wavelength.

physics.atom-ph↗

arXiv2018

High-efficiency cold-atom transport into a waveguide trap

We have developed and characterized an atom-guiding technique that loads $3\times10^6$ cold rubidium atoms into hollow-core optical fibre, an order-of-magnitude larger than previously reported results. This result was possible because it was guided by a physically realistic simulation that could provide the specifications for loading efficiencies of 3% and a peak optical depth of 600. The simulation further showed that the demonstrated loading efficiency is limited solely by the geometric overlap of the atom cloud and the optical guide beam, and is thus open to further improvement with experimental modification. The experimental arrangement allows observation of the real-time effects of light-assisted cold atom collisions and background gas collisions by tracking the dynamics of the cold atom cloud as it falls into the fibre. The combination of these observations, and physical understanding from the simulation, allows estimation of the limits to loading cold atoms into hollow-core fibres.

physics.atom-ph↗