Anomalous Behavior of Dark States in Quantum Gases of 6Li

Abstract

We create atom-molecule dark states in a degenerate Fermi gas of 6Li in both weakly and strongly interacting regimes using two-photon Raman scattering to couple fermion pairs to bound molecular states in the ground singlet and triplet potential. Near the unitarity point in the BEC-BCS crossover regime, the atom number revival height associated with the dark state abruptly and unexpectedly decreases and remains low for magnetic fields below the Feshbach resonance center at 832.2~G. With a weakly interacting Fermi gas at 0~G we perform precision dark-state spectroscopy of the least-bound vibrational levels of the lowest singlet and triplet potentials. From these spectra, we obtain binding energies of the $v^{\prime \prime }=9$, $N^{\prime \prime }=0$ level of the $a(1^3{\Sigma }_u^{+})$ potential and the $v^{\prime \prime }=38$, $N^{\prime \prime }=0$ level of the $X(1^1{\Sigma }_g^{+})$ potential with absolute uncertainty as low as $20$ kHz. For the triplet potential we resolve the molecular hyperfine structure.

5 pages, 3 figures

References in corpus (7)

• A High Phase-Space-Density Gas of Polar Molecules
• Observation of the Pairing Gap in a Strongly Interacting Fermi Gas
• Molecular Probe of Pairing in the BEC-BCS Crossover
• Ultracold Molecules in the Ro-Vibrational Triplet Ground State
• Atom-molecule dark states in a Bose-Einstein condensate
• Controlling a magnetic Feshbach resonance with laser light
• Pairing-gap, pseudo-gap, and no-gap phases in the radio-frequency spectra of a trapped unitary 6Li gas

Cited by in corpus (1)

• Observation of interference between resonant and detuned STIRAP in the adiabatic creation of ${}^{23}$Na${}^{40}$K molecules