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Interferometry and optics for atoms (OIA)

> Composition of the team

> Publications and communications

> Thesis

 

Atomic diffraction through a nano-grating


 

1) Group members:
Permanent: Gabriel Dutier, Quentin Bouton, Nathalie Fabre, Francisco Perales, Martial Ducloy.

PhD students: Julien Lecoffre, Ayoub Hadi et Matthieu Bruneau (co-supervision with University of Leibniz - Hanovre/Germany)

 

 

2) Research context:

An atom in front of a surface is one of the simplest and fundamental problem in physics. Yet, it allows testing quantum electrodynamics, while providing platforms for the nanotechnologies and quantum technologies. In particular, the presence of electromagnetic quantum fluctuations (associated to the zero-point energy in quantum mechanics) leads to a force between an atom and a surface (macroscopic body). This force is called the Casimir-Polder (C.P) force.
 

Every polarizable object in nature is subjected to the C.P force. This force prevails at the nanoscopic scale, entailing its strong connections with many domains, from nanotechnology to physical chemistry. The basic understanding of this force is crucial for probing novel physics involving an atom and a material at a small relative distance.
 

In this context, we have built slow atomic beam interacting with a nanograting (grating featuring nanoscale dimensions: 100 nm width slits, 200 nm period and 100 nm thickness for instance). The nanogratings are developed and manufactured by the team itself within the RENATECH framework at “Institut d’Electronique de Microelectronique et de Nanotechnologie” (IEMN, Lille). Passing through the nanograting, the atoms interact with the slits within the C.P interaction for atom-surface distance up to 50 nm.

 

3) Experiment:

Our unique experimental set-up uses a laser-cooled Argon source in the 43P2 metastable state to create a slow atomic beam with velocity ranging from 10 m/s and 50 m/s [1]. The atoms in the beam interact with the nanograting within the C.P force. The metastable Argon atoms are then detected with an efficient time-position detection at the single atom level with microchannel plates (Figure 1). The atomic wave packet phase shift induced by the atom-surface interaction modifies the interference pattern. The diffraction spectrum is here dominated by the C.P interaction due to the large interaction time allowed by the slow velocities (the phase being proportional to the interaction time in the nanograting). It leads to a highly sensitive measurements of the C.P force (see Figure 2).

 

Figure 1

Figure 1: Sketch of the experiment. Neutral Argon atoms interact with a nanograting within the C.P potential. This interaction with the nanograting leads to a diffraction pattern. Information related to the C.P potential are extracted from the analysis of the interference pattern.
 

 

Figure 2
 

Figure 2: Experimental diffraction spectrum of metastable argon through a nanograting at 26 m/s (in blue). The angle θ is the diffraction angle. In red, theoretical curve without considering the C.P interaction.The difference between the blue and red curve underlines how strongly the diffraction spectrum is dominated by the C.P interaction.

 


 

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Figure 3: This video shows single Argon atoms arriving on the microchannel plates detector during an experimental acquisition. As more and more atoms reach the detector, the full interference pattern becomes more and more visible!

 

 

With our approach, we could recently discriminate for the first time the retarded and the non-retarded regime for atom-distance smaller than 51 nm [2]. However, the quality with the theoretical model is around 5-10 % (state-of-the-art value). In order to achieve an in-depth understanding of the C.P interaction, we are developing tools to improve this value. For example, we are collaborating with the University of Leibniz in Hanover (Germany) to solve the exact potential with the Schrödinger equation. Besides, we plan to use deep learning network trained to accurately reconstruct the diffraction pattern. This method is well suited to extract parameters from high dimensional data. The short-term objective is to realize a C.P measurement at the percent level. In this context, we propose a M2 internship (see here).
 

These results will allow us in the future to implement new strategies to control the C.P interaction. Besides, new constraints on a possible non-Newtonian gravitational interaction could be established using 36Ar isotope with comparison to 40Ar spectra [3].
 


 

4) Group Picture:

Picture of Team
September 2022. Left picture, from left to right: Francisco Perales, Charles Garcion,
Quentin Bouton, Julien Lecoffre, Gabriel Dutier and Nathalie Fabre. Right picture: Martial Ducloy.


 

5) Internship proposal:


We are always looking for prospective PhD students, postdocs or interns to join our group. Do not hesitate to contact one of the staff members. We are looking forward to hearing from you!

This year, we offer an M2 internship! See here


 


6) Contact:
Gabriel Dutier, Quentin Bouton, Nathalie Fabre

 



7) Former members:
- Charles Garcion (thesis 2019-2022)
- Ilias Boutaleb (2023, M1, Sorbonne université)
- Hajra Ghulam (2022, M1, Université de Paris)
- Fabio D’ORTOLI-GALERNEAU (2022, L3, ENS)
- Baazia Elmehdi (2022, Ingénierie en Instrumentation, Institut Sup Gallilée)
- Hanane Bricha Tazi (thesis 2016-2019)
- Franck Correia (thesis 2015-2018)
- Mehdi Hamamda (2012-2015)
- Thierry Taillandier-Loize (thesis 2011-2014)

 



8) References:
[1] T. Taillandier-Loize, S. A Aljunid, F. Correia, N. Fabre, F. Perales, J.M Tualle, J.Baudon, M. Ducloy and G. Dutier, A simple velocity-tunable pulsed atomic source of slow metastable argon, J. Phys. D: Appl. Phys, 49, 13, 135503, (2016).
[2] C. Garcion, N. Fabre, H. Bricha, F. Perales, S. Scheel, M. Ducloy, and G. Dutier, Intermediate-Range Casimir-Polder Interaction Probed by High-Order Slow Atom Diffraction, Phys. Rev. Lett. 127, 170402 (2021).
[3] R. Onofrio, Casimir forces and non-Newtonian gravitation, New J. Phys. 8 237 (2006). 9) Some picture of the experiment:

 

Final Picture

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