arXiv subjects

Gregory W. Hoth

Publications and source records attributed to Gregory W. Hoth.

4 recordsLinked to original sources

arXiv2024

High-Performance Silicon Photonic Single-Sideband Modulators for Cold Atom Interferometry

The most complicated and challenging system within a light-pulse atom interferometer (LPAI) is the laser system, which controls the frequencies and intensities of multiple laser beams over time to configure quantum gravity and inertial sensors. The main function of an LPAI laser system is to perform cold-atom generation, state-preparation, state-selective detection and to generate coherent two-photon process for the light-pulse sequence. Substantial miniaturization and ruggedization of the laser system can be achieved by bringing most key functions of the laser system onto photonic integrated circuit (PIC). We demonstrate a high-performance silicon photonic suppressed-carrier single-sideband (SC-SSB) modulator at 1560 nm, which can dynamically frequency shift within the LPAI. With independent RF-channel control, we study the imbalances in both the optical and RF phases/amplitudes to reach 30 dB carrier-suppression, unprecedented 47.8 dB sideband-suppression at peak conversion-efficiency: -6.846 dB (20.7 %). Using a silicon photonic SSB-modulator, we demonstrate cold-atom generation, state-selective detection, and atom interferometer fringes to estimate gravitational acceleration, $g \approx 9.77 \pm 0.01 \,\rm{m/s^2}$, in a Rubidium ($^{87}$Rb) atom system.

physics.optics↗

arXiv2021

A passively pumped vacuum package sustaining cold atoms for more than 200 days

Compact cold-atom sensors depend on vacuum technology. One of the major limitations to miniaturizing these sensors are the active pumps -- typically ion pumps -- required to sustain the low pressure needed for laser cooling. Although passively pumped chambers have been proposed as a solution to this problem, technical challenges have prevented successful operation at the levels needed for cold-atom experiments. We present the first demonstration of a vacuum package successfully independent of ion pumps for more than a week; our vacuum package is capable of sustaining a cloud of cold atoms in a magneto-optical trap (MOT) for greater than 200 days using only non-evaporable getters and a rubidium dispenser. Measurements of the MOT lifetime indicate the package maintains a pressure of better than $2\times10^{-7}$ Torr. This result will significantly impact the development of compact atomic sensors, including those sensitive to magnetic fields, where the absence of an ion pump will be advantageous.

physics.atom-ph↗

arXiv2020

Cold-atom clock based on a diffractive optic

Clocks based on cold atoms offer unbeatable accuracy and long-term stability, but their use in portable quantum technologies is hampered by a large physical footprint. Here, we use the compact optical layout of a grating magneto-optical trap (gMOT) for a precise frequency reference. The gMOT collects $10^7$ $^{87}$Rb atoms, which are subsequently cooled to $20\,μ$K in optical molasses. We optically probe the microwave atomic ground-state splitting using lin$\perp$lin polarised coherent population trapping and a Raman-Ramsey sequence. With ballistic drop distances of only $0.5\,$mm, the measured short-term fractional frequency stability is $2 \times 10 ^{-11} /\sqrtτ$.

physics.atom-ph↗

arXiv2018

Multi-axis atom interferometer gyroscope with a single source of atoms

Using the technique of point source atom interferometry, we characterize the sensitivity of a multi-axis gyroscope based on free-space Raman interrogation of a single source of cold atoms in a glass vacuum cell. The instrument simultaneously measures the acceleration in the direction of the Raman laser beams and the component of the rotation vector in the plane perpendicular to that direction. We characterize the sensitivities for the magnitude and direction of the rotation vector measurement, which are 0.033 $^{\circ}/\mathrm{s}$ and 0.27 $^{\circ}$ with one second averaging time, respectively. The sensitivity could be improved by increasing the Raman interrogation time, allowing the cold-atom cloud to expand further, correcting the fluctuations in the initial cloud shape, and reducing sources of technical noise. The unique ability of the PSI technique to measure the rotation vector in a plane may permit applications of atom interferometry such as tracking the precession of a rotation vector and gyrocompassing.

physics.atom-ph↗