Attosecond science, which is the science of generation and application of attosecond light pulses, has become a well-established research field that goes across several traditional areas such as Ultrafast and Nonlinear Optics, Atomic and Molecular Physics, and Condensed Matter Physics. Attosecond pulses have been first produced through the phenomenon of high-order harmonic generation (HHG) in gases. Nowadays, they can also be produced in plasmas produced by high-power lasers, and very recently using free electron lasers. Their duration varies from a few tens to a few hundred attoseconds, while the central photon energy goes from the extreme ultraviolet (XUV) to the X-ray domain. Matter exposed to these ultrashort XUV light pulses ionizes and temporally-confined coherent electron wave packets are created.
The aim of the QPAP project is to perform quantum optics experiments, not with photons as in conventional quantum optics, but with photoelectrons created by absorption of attosecond light pulses. In other words, we aim at developing “attosecond quantum electronics”, quantum electronics not referring here to the physics of few-level systems in a laser medium, but to the quantum behavior of ultrashort electron wavepackets created by the absorption of attosecond light pulses.
This research lies at the crossing between three different areas of atomic, molecular, and optical (AMO) physics: attosecond science, photoionization /dissociation of atoms and molecules, and quantum information. These fields have been largely disconnected in the past. Attosecond science emerged at the beginning of the millennium, with the main emphasis first on the generation of attosecond pulses. Photoionization processes in atoms and molecules have been traditionally studied with synchrotron radiation. Quantum information has preferentially considered simpler systems than electrons in atoms or molecules like photons, ions in a trap, cold atoms, superconducting circuits, etc.
Progress in the performances of the attosecond sources, in particular regarding repetition rate, now enables us to perform photoionization studies of atoms and molecules using the advanced coincidence/three-dimensional momentum techniques developed by scientists for synchrotron radiation experiments. Adding phase information, thanks to interferometric techniques, we hope to be able to follow in time the quantum properties of the created photoelectrons, like coherence and entanglement. In addition, we will study the interaction of matter with a controlled sequence of a few attosecond pulses, with a variable number of pulses and pulse separation, in the presence of a weak and well-characterized dressing field. We will study the properties of the electronic states created by interferences of the electron wavepackets and their temporal evolution.
Our objectives are to characterize and study the quantum coherence of attosecond electron wavepackets, to control quantum interferences of electron wavepackets using a small number of attosecond pulses, and to create and follow in time entangled two-electron attosecond wavepackets.
