Emergent s-wave interactions between identical fermions in quasi-one-dimensional geometries

Abstract

Orbital degrees of freedom play an essential role in metals, semiconductors, and strongly confined electronic systems. Experiments with ultracold atoms have used highly anisotropic confinement to explore low-dimensional physics, but typically eliminate orbital degrees of freedom by preparing motional ground states in strongly confined directions. Here we prepare multi-band systems of spin-polarized fermionic potassium (${}^{40}$K) in the quasi-one-dimensional (q1D) regime and quantify the strength of atom-atom correlations using radio-frequency spectroscopy. The activation of orbital degrees of freedom leads to a new phenomenon: a low-energy scattering channel that has even particle-exchange parity along the q1D axis, as if the underlying interactions were s-wave. This emergent exchange symmetry is enabled by orbital singlet wave functions in the strongly confined directions, which also confer high-momentum components to low-energy q1D collisions. We measure both the q1D odd-wave and even-wave "contact" parameters for the first time, and compare them to theoretical predictions of one-dimensional many-body models. The strength and spatial symmetry of interactions are tuned by a p-wave Feshbach resonance and by transverse confinement strength. Near resonance, the even-wave contact approaches its theoretical unitary value, whereas the maximum observed odd-wave contact remains several orders of magnitude below its unitary limit. Low-energy scattering channels of multi-orbital systems, such as those found here, may provide new routes for the exploration of universal many-body phenomena.

v2: revised manuscript

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Cited by in corpus (8)

• Spin incoherent liquid and interaction-driven criticality in 1D Hubbard model
• Emergent $s$-wave interactions in orbitally active quasi-two-dimensional Fermi gases
• Temperature dependence of $p$-wave contacts in a harmonically trapped Fermi gas
• Cooper pairing and tripling in one-dimensional spinless fermions with attractive two- and three-body forces
• Radio-Frequency Spectroscopy and the Dimensional Crossover in Interacting Spin-Polarized Fermi Gases
• Hybridization of the amplitude mode in a confined fermionic superfluid
• Efficient shortcuts-to-adiabaticity for loading an ultracold Fermi gas into higher orbital bands of one-dimensional optical lattice
• Mass-imbalance effect on the cluster formation in a one-dimensional Fermi gas with coexistent $s$- and $p$-wave interactions