QUROPE Quantum Information Processing and Communication in Europe

Testing QED and gravity interactions with an ultracold atomic quantum sensor

The aim of our project is to realize precise measurements of atom surface interactions, in order to test QED and gravity related interactions. We expect to test predictions of underlying theories at distances of order of a µm, and push limits on possible deviations from them. The sensitivity of our atom interferometer sensor will allow improving current limits on tests of gravity at short distances, with a new technique, completely different from “classical” experiments that use macroscopic bodies.

In our experiment, ultracold atoms are trapped in a vertical lattice, and an atom interferometer is used to measure the force experienced by the atoms. The interferometer is created by putting the atoms in a quantum superposition of wavepackets localized in two neighboring wells thanks to laser pulses, and letting them evolve, before recombining them. The phase difference accumulated by the two partial wavepackets, proportional to the energy difference between the wells, reveals among over quantities, the atom-surface interaction, when the atoms are located close to the surface of a mirror. We have already made the demonstration of the extreme sensitivity of this sensor, by measuring gravity acceleration with 100 ng resolution, so far away from the surface of the mirror.

The experimental setup has recently being upgraded to accommodate a dielectric mirror under vacuum. The work will focus on the transport of the atoms with a Bloch elevator, the control of the final atoms position, thanks to lattice site resolved selection in a superlattice, and the realization of interferometer measurements in the vicinity of the surface of this mirror. These measurements will be compared with theoretical expectations, based on a precise calculation of the Casimir Polder potential. This comparison will allow for constraining the maximum amplitude of eventual new forces. At the shortest distances we aim at exploring (at about a µm distance), we plan to perform differential measurements between the two Rb isotopes (87 and 85), in order to cancel the influence of Casimir Polder interactions that are too large to be calculated with a low enough uncertainty. 

Start date : as soon as possible

Duration : 3 year for the PhD, 1 year for the postdoc

Required:

• Master Degree in Physics for the PhD position / PhD in Physics for the postdoc

• fluency in English, oral and written

Expected for the student and required for the postdoc:

• some relevant experience in cold atoms physics   

Contact Dr Franck Pereira dos Santos (franck [dot] pereira [at] obspm [dot] fr) directly by email. Include CV. Apply immediately.

https://syrte.obspm.fr/spip/science/iaci/