Quantum state engineering

B.2.1 | Laser frequency combs and new frontiers of precision spectroscopy

B.2.2 | Quantum-optical control of cold polar molecules

B.2.3 | Quantum engineering with ultracold fermions

B.2.4 | Decoherence and phase diffusion of the micromaser field

B.2.5 | Multipartite entanglement in quantum optical systems

B.2.6 | Precise laser spectroscopy of antimatter atoms, and metrological determination of the proton-to-electron mass ratio

Controlling microscopic systems at the quantum level will lead to novel applications in information processing (like quantum computing or cryptography), new phases of matter (like Bose-Einstein condensation), or to the most precise tests of the laws of Nature. We will investigate methods to characterise, control, and manipulate quantum systems consisting of photons, atoms, and/or molecules.

First, we will concentrate on how to create arbitrary quantum states of a small number of atoms and/or photons. In particular, we will investigate systems of up to 10 particles and show how to engineer arbitrary entangled states with them. We will characterise the physical properties of those entangled states, as well as their applications in quantum information processing, quantum communication, and precision measurements.

Second, we will study how to control and manipulate the quantum state of large numbers of atoms and/or molecules using external (lasers, electric and/or magnetic) fields. We will develop techniques to trap and cool those systems, and we will analyse and observe novel many-body quantum phenomena. Finally, we will characterise the spectral properties and limits of high-harmonic laser-frequency combs, and we will use them to determine spectroscopic properties of atoms to an unprecedented precision. We will also explore novel spectroscopic techniques and apply them to test fundamental laws of physics.

• Adaptation of laser sources (A.1) to new spectroscopic techniques
• Precision spectroscopy of trapped ions
• New source of cold polar molecules and investigation of ultracold collisions (C.1)
• Creation of diatomic molecules in ground state
• Fermions for precision interferometry
• Characterisation of decoherence in micromasers and micromaser field
• Creation and characterisation of multi-photon entangled states