Atoms in confined media
Atoms in ultra-diluted vapors constitute the ideal physical system to carry out Quantum Physics experiments. Thanks to its low density, the interaction between atoms is negligible, and the system behaves like a set of isolated and identical quantum systems. The interaction with this atomic system can be carried out relatively easily through electromagnetic fields, usually optical. These fields allow both modifying the states of the system and measuring them, using various spectroscopic techniques. This atomic system is easily obtained in airtight containers. At room temperature, atoms move at thermal speeds, reducing interaction times to micro-seconds due to the confinement imposed by the container, and introducing very important frequency shifts due to the Doppler effect. These effects, which strongly limit the resolution of the measurements, can be substantially attenuated with specific spectroscopic techniques, or directly by reducing the velocities through optical cooling.
In the past we investigated situations of extreme confinement, such as those obtained in a fine cell with micro-metric dimensions, which imposes confinement in one dimension (1D) [Fai07][Len09][Fai10]. This situation becomes very relevant when you want to miniaturize devices such as atomic clocks, magentometers, etc.
Recently, we investigated various 2D and 3D confinement situations for atomic vapor, as described below.
Rydberg atoms
Rydberg states are electronic states of hydrogenoid (alkaline) atoms with very high energy. This implies that the excited electron is very close to the ionization threshold, or equivalently, that the electron has a very large average distance to the nucleus. This distance can be thousands of times greater than that of the electron in its lowest energy state, so the atom “fats” thousands of times when excited. This gives these states one of their most outstanding properties: their extremely high capacity to interact with external electromagnetic fields. This is due to its very high electrical and magnetic polarizability, which is multiplied by a factor of ten million. This makes these quantum states very interesting, because it allows them to interact strongly with other atoms at “macroscopic” distances that can be measured in microns. Thus, atoms in Rydberg states are ideal for generating collective quantum states, usually called super-atoms, studying coherent collective phenomena such as super-radiance, or the opposite phenomenon, sub-radiance, or constructing simulators of collective processes. such as superconductivity, or quantum processors. Another very important property of the Rydberg states is that their average natural life is very long, and in some particular cases they can “live” for seconds.
In the FCA group we began our research with Rydberg atoms a few years ago. Currently we seek to create in the laboratory, a paradigmatic system of Physics: an atom coupled to a resonant macroscopic system. In this configuration, the quantum system (atom) finds its evolution determined by the properties of the macroscopic (classical) resonant system, and of course, by the magnitude of the coupling.
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