A question we often hear from non-experts is “what do you actually do at work”. Here are a few things.
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Atomic Physics
We use cold atoms as a pristine, highly controllable medium to manipulate quantum light. With laser beams and magnetic coils, we can trap a cloud of Rubidium atoms, bring them inside the optical cavity where our experiments are performed, shape the atomic cloud to the desired size and density, cool the atoms to make them stay nearly still during the experiment, and drive them to the desired states.
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Cavity Quantum Electrodynamics
In free space, photons can go anywhere. In an optical cavity, they can only go in a well-defined set of modes: they become easier to catch and they have more chances to interact with the atoms that we put inside (in fact, they bind to the atoms so strongly that they form quasi-particles called polaritons). By changing the shape of the cavity, one can modify the “landscape” seen by the photons, making it curved or flat depending on the experiment to be performed.
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Optical Wavefront Shaping
We use spatial light modulators and digital micro-mirror devices to form beams with specific shapes required for our experiments. Wavefront shaping techniques also allow us to use a multimode optical fiber, which strongly randomizes the transmitted light, as an optical system for manipulating and imaging cold atoms.
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Ultra-High Vacuum
Experiments involving cold atoms must be performed under ultra-high vacuum. In our case, the pressure is one trillion (1e-12) times smaller than the atmospheric one: reaching it in a chamber full of coils, optics, electrodes, piezo-electrics, insulators and mechanics requires very careful design and assembly.
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Lasers & Optics
We use tens of laser beams dynamically controlled in intensity and frequency to manipulate, probe and image our atoms and to stabilize our optical resonators. Their powers reach several watts and their wavelengths range from the blue to the infrared. We stabilize their frequencies to ten parts per trillion, reaching linewidths of a few kHz.
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Electronics & Programming
The relevant physical timescales in our experiments range from seconds down to nanoseconds, so electronics and computers are everywhere. We dynamically control over a hundred of analog, digital and RF channels and we acquire many signals from photon counters, cameras and photodiodes. Most of our electronics are now digital, programmed in VHDL, Verilog, C, Python or Labview.
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Mechanics
We put a special effort in the design of our in-vacuum mechanics, which were carefully machined in our workshop, to satisfy many contradictory requirements. They must be stiff and simple in order to avoid vibrations and reach a good vacuum, yet allow plenty of optical access and be reconfigurable between different experiments without opening the vacuum chamber.
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