Anisotropic interactions in an ultracold Dysprosium gas

• Applicant: Professor Dr. Tilman Pfau
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2016 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 258183570

Our ab-initio understanding of macroscopic quantum phenomena like superconductivity, superfluidity or quantum magnetism relies on microscopic theoretical models which involve interacting constituents like electrons, holes, atoms or quasiparticles. Strong interactions often result in strong quantum correlations which sometimes render theoretical models intractable, but e.g. allow for new states of matter in the presence of topological order and robust ground state degeneracy. Experimentally, the microscopic understanding at the level of individual particles is often inaccessible, and only averaged or macroscopic quantities/observables are probed. Quantum gas microscopes for two-dimensional arrangements of ultracold atoms have led to a new paradigm in the field as they allow to detect spatial configurations particle by particle and therefore grant access to the microscopic (quantum-) correlations. Here we propose to implement a spatial-, energy- and spin-resolved quantum gas microscope for the most magnetic atom, Dysprosium, which allows for both fermionic and bosonic ensembles with proven control over long and short range interactions. To maximize the effect of the nearest-neighbour interaction due to the dipole-dipole interaction we will use a near UV lattice at around 360 nm. With this the nearest-neighbour interactions will be enhanced by a factor of six compared to previous experiments. To be able to image single atoms on the UV lattice, the microscope will be based on an energy-dependent shelving technique using a long-lived electronic state as well as a state-of-the-art magnetic field control. Using the shelving technique the so called "super-resolution" limit of microscopy can be reached, which provides a significant improvement over the Abbe limit. This it is done for example in biology using stochastic optical reconstruction microscopy (STORM) or more recently in cold atoms using atomic localisation through a dark state. This atom-by-atom-approach will be used to unravel the microscopic nature of various macroscopic quantum phenomena: new phases of matter with strong nearest-neighbour interactions, e.g. Haldane chain or stripe phase in 2D, and quantum magnetism in lattice spin models. It is not clear whether short-range correlations exist in the recently discovered quantum droplets, but with our proposed experimental tool we will be able to freeze the droplets in the UV lattice and then measure the macroscopic correlations and therefore challenge the existing theory. The microscopic analysis will test theoretical models and bridge the gap between emergent macroscopic quantum phenomena and their underlying microscopic ingredients

• DFG Programme: Research Units
• Subproject of: FOR 2247: From few to many-body physics with dipolar quantum gases