Diffraction of a CW atom laser in the Raman-Nath regime

TL;DR

This paper demonstrates the diffraction of a continuous-wave atom laser in the Raman-Nath regime, a key step towards continuous atom interferometry that can improve measurement bandwidth and reduce aliasing effects.

Contribution

The work shows the first experimental realization of atom laser diffraction in the Raman-Nath regime, enabling continuous interferometry with potential for high-bandwidth measurements.

Findings

Atom laser diffracts into up to 9th order with momenta of ±18 ħk.

Diffraction results match numerical simulations.

Continuous atom laser outcoupling lasts up to 400 ms.

Abstract

Atom interferometry is the most successful technique for precision metrology. However, current interferometers using ultracold atoms allows one to probe the interference pattern only momentarily and has finite duty cycle, resulting in an aliasing effect and a low-bandwidth measurement -- also known as Dick effect. Interferometry with a continuous-wave atom laser shows promise in overcoming these limitations due a continuous monitoring of the interference pattern. In this work, we demonstrate a key step towards such an interferometry by demonstrating a diffraction of an `atom laser' in the Raman-Nath regime. We outcouple a continuous beam of coherent atoms from a reservoir of $^{87}$Rb Bose-Einstein condensate (BEC) upto 400 ms. The `atom laser' interacts with a grating formed by a standing wave of a far detuned laser light. The atom laser diffracts into several orders going up to 9$^{th}$ order or up to momenta of $\pm 18\ \hbar k$. We have characterized the diffraction of atom laser for different conditions and the results match with numerical simulations. Such atom laser will allow for construction of an atom-interferometer to probe physics phenomenon continuously up to a time of the order of few hundred millisecond.