MPQ group: I. Bloch group at MPQ, Quantum Many-Body Systems division, Fermionic quantum gas microscope experiment (Lithium 6)
Interactions between a large ensemble of particles in the degenerate regime often leads to new macroscopic quantum phenomena such as high-temperature superconductivity or fractional quantum Hall states.
However, the exponential scaling of the Hilbert space with the number of constituents makes it impossible to find exact solutions to these problems necessitating to develop both new theoretical and experimental approaches.
Of particular interest is interplay between doping and antiferromagnetism, which is believed to play a fundamental role in high-temperature superconductors. One of the simplest model to address this problem is the Fermi-Hubbard model describing interacting fermions hopping on a lattice. The latter can be realized by trapping a fermionic spin-mixture in optical lattices, offering a complementary route to traditional condensed matter studies to study its debated phase diagram.
Guillaume Salomon is conducting experiments to understand and control strongly correlated fermionic systems using ultracold atoms. In particular, he developed a new technique to study fermionic quantum gases with a local resolution down to the single particle and single spin, called spin-resolved quantum gas microscopy.
He uses it at MPQ to study the doped Fermi-Hubbard model in low dimensions and reveal fundamental phenomena such as spin-charge separation, incommensurate magnetism and magnetic polarons.
Possible applications of research
A better understanding of quantum many-body systems could find applications bridging vastly different fields of research. Examples include the synthesis of new materials with lossless conduction close to room temperature, or decoherence-free quantum information processing and quantum computation.
Collaboration with Harvard
Guillaume Salomon has a fruitful collaboration with the theory group led by Eugene Demler in Harvard, aiming at understanding doped antiferromagnets. They revealed equilibrium signatures of spin-charge separation in Hubbard chains in one dimension and recently experimentally demonstrated the existence of magnetic polarons in the doped two-dimensional Hubbard model. They are currently studying the deconfinement dynamics of spin and charge degrees of freedom after a quench in the Fermi-Hubbard model.