Matter-wave cavity gravimeter

Hong Yuan Ling

William M. Brown

Karol Gietka, Farokh Mivehvar, Helmut Ritsch

We propose a novel type of composite light-matter interferometer based on a supersolidlike phase of a driven Bose-Einstein condensate coupled to a pair of degenerate counterpropagating electromagnetic modes of an optical ring cavity. The supersolidlike condensate under the influence of the gravity drags the cavity optical potential with itself, thereby changing the relative phase of the two cavity electromagnetic fields. Monitoring the phase evolution of the cavity output fields thus allows for a nondestructive measurement of the gravitational acceleration. We show that the sensitivity of the proposed gravimeter exhibits Heisenberg-like scaling with respect to the atom number. As the relative phase of the cavity fields is insensitive to photon losses, the gravimeter is robust against these deleterious effects. For state-of-the-art experimental parameters, the relative sensitivity Δg/g of such a gravimeter could be of the order of 10^{-10}-10^{-8} for a condensate of a half a million atoms and interrogation time of the order of a few seconds.

Philippe Bouyer

The remarkable success of atom coherent manipulation techniques has motivated competitive research and development in precision metrology. Matter-wave inertial sensors – accelerometers, gyrometers, gravimeters – based on these techniques are all at the forefront of their respective measurement classes. Atom inertial sensors provide nowadays about the best accelerometers and gravimeters and allow, for instance, to make the most precise monitoring of gravity. New concepts of matter-wave interferometry can also be used to study the low frequency variations of the strain tensor of space-time and gravitation. For instance, the MIGA instrument, which is currently built in the underground laboratory in Rustrel, France will allow the monitoring of the evolution of the gravitational field at unprecedented sensitivity, which will be exploited both for geophysical studies and for Gravitational Waves (GWs) observations. This present will present the status of this instrument.

William M. Brown

Lucas Borges

The work developed in this thesis investigate the dynamics of ultracold atoms trapped in a ring cavity and undergoing Bloch oscillations due to the influence of a one-dimensional vertical optical lattice and of the gravitational force.In this configuration, the atoms collectively scatter light from the pump into the copropagating cavity mode, which then leads to a self-consistent grating of the matter: this mechanism was coined collective atomic recoil lasing (CARL).Such interaction between atomic motion and cavity modes provides a possible continuous and non-destructive method to monitor the Bloch oscillations dynamics, which could be implemented in atomic gravimeters.This dissertation investigates the fundamental problem of dissipation effects due to spontaneous emission of the atoms, which is responsible for a suppression of the Bloch oscillations signatures on the light modes.We also study a possible solution for this issue by including a third atomic level in the configuration to explore a probable dissipation reduction due to the phenomenon of electromagnetically induced transparency (EIT).