Victor Gondret
Post-Doctoral researcher Institut d'Optique, Université Paris-Saclay.
I am a post-doctoral researcher in the Quantum Atom Optics team at the Laboratoire Charles Fabry, Institut d’Optique Graduate School, Université Paris-Saclay. My research focuses on the entanglement of massive particles, probing coherence with atom interferometry.
The experimental setup on which I work is a ultra-cold atom machine that cool down metastable helium atoms to Bose-Einstein condensation (BEC). Since metastable helium atoms have a really high internal energy, it is possible to detect them with micro-channels plate (MCPs). This means that we can detect the arrival time of individual atoms as well as its impact position on the detector. Combined with time-of-flight measurements that give access to the in-trap momentum distribution, helium is a really nice species to study correlations.
In this illustration, every data point corresponds to the velocity of an individual atom. The experimental setup involved two colliding Bose-Einstein Condensates (BECs), resulting in the formation of a halo comprised of entangled particles. Each point on the spherical surface is entangled with its counterpart on the opposite side. The regions with the highest density at the top and bottom of the sphere represent the locations of the two BECs.
We also perform atomic interferometry using laser light to perform Bragg diffraction. This makes possible to study the coherence between two massive wavepackets and therefore to probe entanglement and non-classical effects.
news
| Jul 2025 |
ArXiv release of our observation of entanglement in a cold atom analog of preheating!We have released a new observation on arXiv . In it, we excite parametrically collective excitations  in a Bose-Einstein condensate, which mimics parametric amplification of particle in preheating, the stage after cosmic inflation  . This is done by changing periodically the effective 1D coupling constant of the elongated cloud, which parametrically produce pairwise opposite momentum quasiparticles  . As the initial temperature of the gas is very low, the exponential growth of the excitation number is largely triggered by vacuum fluctuations, resulting in an entangled state, which we observe  . Have a look at it!
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| Jun 2025 |
Our pulse shaping paper is published in Phys. Rev. A!
 ! I summarize the key results in this post but to have all the detail, you should have a look at it  .
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| May 2025 |
Invited seminar at HeidelbergI’ve just returned from Heidelberg University  , where I had the pleasure of visiting Prof. Markus Oberthaler and his fantastic team for two days. It was a great opportunity to present my PhD work and to discuss future research directions and collaborations  . A heartfelt thank you to everyone for the warm welcome and inspiring discussions  !
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