Mr. Thomas Vacheresse Profile

Thomas Vacheresse

at York Univ

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Publications (3)

Proceedings Article | 13 March 2024 Presentation + Paper

Improving the sensitivity grating-echo atom interferometers for measurements of gravity

G. Carlse, J. Randhawa, A. Pouliot, T. Vacheresse, E. Ramos, A. Carew, A. Kumarakrishnan

Proceedings Volume 12912, 129120L (2024) https://doi.org/10.1117/12.3012377

KEYWORDS: Quantum sensors, Quantum gravity sensors, Alkali vapor lasers, Atomic optics, Inertial navigation systems, Vacuum chambers, Vibration, Interferometers, Phase measurement, Reflectivity

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Precision measurements of gravitational acceleration g have far reaching applications in navigation and sensing as well as for tests of general relativity. Grating-echo atom interferometers (AIs) utilize simple setups and distinctive excitation schemes that involve a single excitation laser, and do not require velocity selection. They have demonstrated measurements of gravity precise to 75 parts per billion (ppb) by dropping laser-cooled atomic samples through ~ 1 cm. Here we describe progress toward realizing a cold atom gravimeter using an echo AI designed for drop heights of ~30 cm. The experimental technique involves illuminating the falling sample of laser-cooled rubidium atoms with two standing wave (sw) pulses separated by time t = T. The sw pulses are composed of two traveling-wave components, each having a wave vector of magnitude k = 2π/λ. Momentum state interference produces one-dimensional density gratings with a period λ/2 immediately after each excitation pulse. These gratings dephase due to the velocity distribution of the sample along the sw axis. The AI uses an echo technique to cancel the effect of velocity dephasing and observe a rephased density grating in the vicinity of the echo time τ = 2Τ. The grating contrast and phase are measured by coherently backscattering a traveling wave readout pulse from the sample. The grating phase, measured with respect to a vibrationally stabilized inertial reference frame, scales as 2kgΤ². A drawback of echo AIs is the signal-to-noise ratio, which is limited by the contrast of the grating and systematic effects due the refractive index of the sample. Here, we review improvements to the experimental design and investigate methods of improving the signal-to-noise ratio by optimizing the atom-field coupling. We describe progress toward realizing our goals of increasing the grating contrast and the backscattered signal. The improved contrast is expected to allow the experiment to be carried out at a lower density to reduce corrections due to the refractive index. We discuss a variety of excitation schemes for achieving a target precision of a few ppb.

Proceedings Article | 8 March 2023 Presentation + Paper

Time domain metrology with optical tweezers

G. Carlse, K. Borsos, T. Vacheresse, A. Pouliot, E. Ramos, J. Randhawa, C. Walsh, A. Kumarakrishnan

Proceedings Volume 12447, 124470G (2023) https://doi.org/10.1117/12.2657267

KEYWORDS: Particles, Optical tweezers, Data modeling, CMOS sensors, Time metrology, Metrology, Liquids, Kinematics, Free space optics, Vacuum

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Proceedings Article | 3 March 2022 Presentation + Paper

Accurate determination of an alkali-vapor-inert-gas diffusion coefficient using coherent transient emission from a density grating

Alexander Pouliot, Gehrig Carlse, Thomas Vacheresse, Anantharaman Kumarakrishnan

Proceedings Volume 12016, 120160Q (2022) https://doi.org/10.1117/12.2616878

KEYWORDS: Diffusion, Magnetometers, Rubidium, Magnetism, Optical pumping, Chemical species, Gases, Systems modeling, Signal detection, Nitrogen

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