A Quantum Gas Microscope for Extended Fermi-Hubbard Models
Abstract
Ultracold quantum gases in optical lattices are entering a new era, enabling quantum simulations of relevant condensed matter models in regimes that are extremely difficult or impossible to simulate on classical computers. Recently, experiments in our group realized the long-standing goal of a Fermi-Hubbard antiferromagnet. The Fermi-Hubbard model describes strongly correlated electron systems and is believed to be a minimal model for high temperature d-wave superconductivity, pseudo-gap physics and strange metal behavior. While conceptually simple, the Hubbard model is believed to be numerically intractable in those regimes. Starting from the antiferromagnetic state, we showed that we can enter the pseudogap regime by doping the system, and started to explore the system in this poorly understood phase. Other phases are coming within reach. This experiment can be regarded as a Òspecial purpose quantum computerÓ since it is the massive quantum entanglement that makes it outperform classical computational systems for this task. The recent breakthroughs were enabled by quantum gas microscopy, providing ultimate control of the many-body quantum system on a single particle level. Quantum gas microscopy not only enables us to detect all particles site-resolved with perfect fidelity, but also allows us to generate arbitrary potential landscapes within the lattice. The latter is what enabled us to lower temperatures by a factor of 2-3 to reach long-range antiferromagnetic order. Now that we started to access the low temperature phases of the Òplain vanillaÓ Fermi Hubbard model, it is important to create extended Hubbard models that enable us to explore the influence of additional terms in the Hamiltonian. This will be an essential step for truly having great impact in condensed matter and material research. Real materials are always more complicated than the idealized models. But the clean cold-atom realization enables us to build a bottom up approach. We start with a simple model, which we then extend step by step to explore the effect of additional ingredients. One of the most important additional ingredients found in real matter is interaction beyond the range of a single lattice site, which always exists due to shielded coulomb interaction. Here we propose to convert our Erbium experiment into a quantum-gas-microscope optical-lattice experiment that can realize a Fermi-Hubbard model with beyond on-site interaction. This is achieved through the magnetic dipole-dipole interaction of the Erbium atoms. The upgrade is completely planned out and should be straightforward. We expect to be able to explore many-body systems with dipolar interactions with single site imaging already a few months after purchasing equipment for the upgrade. Studying such models will have large scientific impact, and constitute an important demonstration of a bottom up quantum simulation where starting from a minimal model then other important ingredients are successively added. Currently, only the ultracold atom platform is able to realize such flexibility and quantum performance.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 14, 2019
- Source ID
- W911NF1810182
Entities
People
- Markus Greiner
Organizations
- Army Contracting Command
- Harvard University
- United States Army