arXiv subjects

Jack Roth

Publications and source records attributed to Jack Roth.

5 recordsLinked to original sources

arXiv2026

Magic Velocity Selection in Atom Interferometry

Velocity-selective Raman transitions are widely used in atom interferometers to prepare atomic ensembles with narrowly defined momentum distributions. However, differential light shifts between atomic energy levels generate velocity distributions that are correlated with the Raman beam intensity, and therefore with the position of the atoms within the laser beam. We show that these spatially inhomogeneous velocity distributions interact with detuning-dependent systematic effects in a Bragg diffraction-based simultaneous conjugate Ramsey-Bord\'e interferometer. These interactions can induce systematic phase shifts of order 10 milliradians in the interferometer phase. We further identify a "magic" detuning for velocity selection and show that operating at this detuning suppresses the systematic phase shift. Magic velocity selection eliminates systematic errors arising from correlations between atom velocity and position, facilitating high-resolution atom interferometry experiments targeting sub-part-per-billion accuracy.

physics.atom-ph↗

arXiv2026

Serrodyne Matterwave Optics

Bragg diffraction for atom interferometry conventionally requires two laser frequencies whose difference makes the two-photon transition resonant. We show that this frequency difference can instead be generated by serrodyne modulation, allowing Bragg pulses to be driven with a single-frequency laser. The serrodyne modulation is performed using an acousto-optic modulator driven with a phase-modulated RF drive, and generated kilohertz-scale frequency shifts on top of the AOM carrier frequency. While in general serrodyne modulation generates strong unwanted frequency components, we find conditions so that the Bragg diffraction pulses, and atom interferometers constructed from them, are robust to these imperfections, opening the door to the development of ultra compact, single frequency Bragg diffraction based atom interferometers with serrodyne modulation implemented by a position modulated retroreflection mirror.

physics.atom-ph↗

arXiv2026

A fast and accurate method for simulating Bragg atom interferometers

Atom interferometers are used in a variety of applications, from measuring gravity and gravity gradients in the field to performing tests of fundamental physics in the lab. One method of increasing interferometer sensitivity is to produce a larger momentum difference between interferometer arms through the use of large momentum transfer methods, such as Bragg diffraction. However, Bragg diffraction introduces systematic effects in the accumulated interferometer phase that are challenging to characterize. A Bragg atom interferometer is described by the one-dimensional time-dependent Schr\"odinger equation (1D-TDSE). In this paper we show that for the case of Bragg diffraction the 1D-TDSE partial differential equation can be separated into several systems of ordinary differential equations, allowing for the use of adaptive step size Runge-Kutta methods. We compare the convergence of this method to the split-step and Crank-Nicolson methods, and present a method for further computational speed-ups using a lookup table.

physics.atom-ph↗

arXiv2025

Linewidth narrowing and wideband frequency modulation of a DBR laser

We present a scheme to phase-lock a 240 mW, 852 nm distributed Bragg reflector (DBR) laser to a fixed-frequency narrow-linewidth laser with a rapidly tunable frequency offset near 9 GHz. The phase-lock is accomplished by electronic feedback on the beatnote between the two lasers. The frequency offset can be swept 200 MHz in 300 us, limited by the feedback loop bandwidth, allowing for its use in complex cooling and state preparation schemes needed in atomic physics experiments. Additionally, we find that the phase-lock reduces the linewidth of the DBR laser below its natural linewidth of ~400 kHz to ~100 kHz.

physics.atom-ph↗

arXiv2022

Offset Lock with 440 GHz Range using Electro-Optic Modulation

Offset locking is a popular method for stabilizing laser frequency, which is crucial to many physics experiments. Wide range offset locks are desirable, as they increase the span of usable frequencies in an experiment. Here, we experimentally realize a wide-range offset lock using a beat-note setup combined with electro-optic phase modulation. By using frequency down-conversion of the beat note and locking to sidebands generated by electro-optic modulation, we achieve an offset range of $\pm$ 220.1 GHz with offset frequency fluctuations under 0.1 Hz, enabling an optical heterodyne offset lock with the largest known range of any such lock. The relative simplicity of our setup provides a compelling method for locking at offsets in the hundreds of GHz range.

physics.optics↗