Observation of unitary p-wave interactions between fermions in an optical lattice
Date
2022-05-27Author
Venu, Vijin
Xu, Peihang
Mamaev, Mikhail
Corapi, Frank
Bilitewski, Thomas
D'Incao, Jose P.
Fujiwara, Cora J.
Rey, Ana Maria
Thywissen, Joseph H.
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Exchange-antisymmetric pair wavefunctions in fermionic systems can give rise to unconventional superconductors and superfluids with non-trivial transport properties. The realisation of these states in controllable quantum systems, such as ultracold gases, could enable new types of quantum simulations, topological quantum gates, and exotic few-body states. However, p-wave and other antisymmetric interactions are weak in naturally occurring systems, and their enhancement via Feshbach resonances in ultracold systems has been limited by three-body loss. In this work, we create isolated pairs of spin-polarised fermionic atoms in a multi-orbital three-dimensional optical lattice. We spectroscopically measure elastic p-wave inter- action energies of strongly interacting pairs of atoms near a magnetic Feshbach resonance, and find pair lifetimes to be up to fifty times larger than in free space. We demonstrate that on-site inter- action strengths can be widely tuned by the magnetic field and confinement strength, but collapse onto a universal single-parameter curve when rescaled by the harmonic energy and length scales of a single lattice site. Since three-body processes are absent within our approach, we are able to observe elastic unitary p-wave interactions for the first time. We take the first steps towards coherent temporal control via Rabi oscillations between free-atom and interacting-pair states. All experimental observations are compared both to an exact solution for two harmonically confined atoms interacting via a p-wave pseudopotential, and to numerical solutions using an ab-initio interaction potential. The understanding and control of on-site p-wave interactions provides a necessary component for the assembly of multi-orbital lattice models, and a starting point for investigations of how to protect such a system from three-body recombination even in the presence of weak tunnelling, for instance using Pauli blocking and lattice engineering. This combination will open a path for the exploration of new states of matter and many-body phenomena enabled by elastic p-wave interactions.
Citation
Venu, V., Xu, P., Mamaev, M., Corapi, F., Bilitewski, T., D'Incao, J.P., Fujiwara, C.J., Rey, A.M., Thywissen, J.H. (2022). Observation of unitary p-wave interactions between fermions in an optical lattice. Nature, 613, 262-267. https://doi.org/10.48550/arxiv.2205.13506