Periodic Reporting for period 4 - LaGaTYb (Exploring lattice gauge theories with fermionic Ytterbium atoms)
Berichtszeitraum: 2023-08-01 bis 2024-10-31
Our project aims at performing quantum simulation experiments with ultracold fermionic atoms in optical lattices, which will allow us to study phenomena related to high-energy physics using table-top experiments. Quantum effects play a large role in many areas of physics, ranging from condensed matter to particle physics. Unfortunately, understanding the complex interplay between many interacting quantum particles is generally beyond what can be computed using state-of-the-art numerical techniques. In order to gain additional insights the complexity of the problem is typically reduced by identifying the main microscopic features of the system, which are responsible for the observed phenomena. A good example is the so-called Fermi-Hubbard model – a famous condensed-matter model, that has only two main parameters: tunneling or motion of fermions in a periodic potential and on-site interactions between them. However, despite having only two parameters the model is too complex to be solved exactly. This underlines the complexity of quantum many-body systems and the challenges we face, when trying to understand them. On the other hand, this also highlights their unique potential for future technological applications. Quantum simulation offers an alternative approach to solve complex many-body problems. The idea goes back to Richard Feynman, who proposed to use a well-controlled quantum mechanical system to simulate the behavior of interest. In our experiments we build such devices using ultracold atoms in optical lattices. The main apparatus consists of a vacuum chamber in which the atoms are cooled and trapped using laser beams. In the final configuration the interfering laser beams form a crystal-like array of potential minima, where the atoms are trapped and between which they can tunnel in order to move in the lattice. This resembles the motion of electrons in an ion crystal and allows us to study fundamental phenomena in condensed matter and statistical physics. The main goal of this project is to go beyond that and establish a new platform that combines periodic optical lattices with precise local control in order to access more exotic phenomena from high-energy physics. By the completion of the project, we have successfully developed the essential tools required for the hybrid lattice-tweezer quantum simulator. This includes the realization of a tweezer array, precise measurements of tune-out wavelengths, and the development of a ground-state cooling scheme based on the ultra-narrow optical clock transition. When combined with quantum gas microscopy, this progress will pave the way for studies of lattice gauge theories, which are central to a large variety of research areas including high-energy physics.
We have successfully finished setting up the main infrastructure and the main experimental setup. Central to the experimental apparatus is an UHV vacuum chamber with a science cell that is fully made of glass for high-resolution imaging. First, atoms leaving a commercial oven enter a Zeeman slower region to reduce their longitudinal velocity. In a second stage die atomic beam is collimated by a 2D magneto-optical trap which further redirects the atomic beam towards the science chamber. Here, the atoms are cooled in a magneto-optical trap on the intercombination line at 556nm before loading them into a 3D clock-magic optical lattice. In oder to cool the atoms to the absolute ground state on each lattice site, we employ sideband cooling on the ultranarrow optical clock transition (publication in preparation). Using this scheme we reach final temperatures without any discernible thermal excitation along both horizontal lattice axes. A key ingredient for the novel hybrid lattice-tweezer quantum simulator is local state-dependent control. To this end, we have realized optical tweezer arrays and performed precise measurements of the ground- and excited-state tune-out wavelength, which resulted in one peer-reviewed publication (Phys. Rev. A 108, 053325 (2023)) and one preprint (arXiv:2412.14163). In parallel, we have devised a scheme for the realization of lattice gauge theories based on our experimental platform (PRX Quantum 4, 020330 (2023)). Moreover, we have presented our scientific results at numerous conferences and workshops, most notably at interdisciplinary ones at the interface of quantum simulation and high-energy physics (June 2022: ECT workshop, Trento; July 2022: ICAP2022, Toronto; Nov 2022: QMEL2022, Mainz; April 23: Toward Quantum Advantage in High Energy Physics, Garching near Munich; June 23: ICOLS 2023, Estes Park; Feb 24: ICTP workshop, Trieste; Sept 24: QuantHEP conference, Munich).
We are developing a novel approach which will enable extremely fast cycle times for quantum simulation experiments combined with unprecedented control over local tunnelings, which can even be controlled in a state-dependent manner. This technique is based on the optical clock transition available in Yb atoms. We anticipate that after the successful completion of the experimental apparatus, novel entangling gates and high-fidelity large-scale quantum simulation of lattice gauge theories will be possible. This is a stepping stone towards studying phenomena related to high-energy physics using table-top experiments.