We use ultracold atoms as quantum simulators for many-body phenomena and as quantum sensors, in particular for fundamental physics.
Quantum Simulation - More is different
We are studying many-body phenomena at the interface between quantum optics and solid-state physics. Following a statement by P.W. Anderson, "More is Different", genuine many-body phenomena are emergent phenomena that only appear when many particles come together, typical examples being superfluidity or magnetism.
Quantum Sensors
The humble atom is nature's most powerful quantum sensor, and its unparalleled precision is harnessed in atomic clocks to literally define our time. A new and upcoming development are plans to exploit large-scale atom interferometers, where baselines can range from 10m to km- and larger scales, that will offer unprecedented sensitivity to detect gravitational waves in the mid-frequency range, search for ultra-light dark matter, and hunt for unknown physics.
We are part of the AION collaboration that is developing a new experimental platform to perform interferometry with ultracold strontium atoms.
Tools
Ultracold atoms
We are working with several atomic species, namely Rubidium, Potassium (bosonic & fermionic) and Strontium, each providing different complementary capabilities. Potassium and Potassium-Rubidium mixtures host a range of well-characterised Feshbach resonances and enable tuneable quantum gases and mixtures, while Strontium provides an ultra-narrow clock transition that enables atomic clocks and precision interferometry.
We develop and use novel optical trapping geometries ranging from novel optical lattices over cooling and transport traps to arrays of microtraps and optical tweezers.
Ultracold Atoms in optical lattices
We study many-body phenomena using ultracold atoms, that is Bose-Einstein condensates and degenerate Fermi gases, which we load into optical lattices. These periodic (or quasiperiodic) optical potentials are analogous to the electrostatic potential felt by electrons in a conventional solid. Thereby, we effectively build a quantum simulator for condensed matter physics, where we can study many-body physics in a very clean and precisely controlled system and have all the tools from quantum optics at our disposal.
Many-body Dynamics
In particular, we can follow the dynamics of the system in real time and observe its non-equilibrium dynamics, which is typically an even richer problem than the equilibrium states.
In addition, the underlying quantum optics toolbox with its various fast modulation techniques enables us to synthesize genuinely new many-body systems using Floquet engineering and to thereby create novel effects.
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Strongly-correlated systems
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Topological systems
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Band-structure engineering
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Out-of-equilibrium dynamics
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Quantum quenches
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Disordered Systems / Many-body localization