Optical Feshbach resonances through a molecular dark state: Efficient manipulation of p-wave resonances in fermionic ¹⁷¹Yb atoms

In a recent experiment by Yamazaki {\it et al.} [Phys.Rev. A {\bf 87} 010704 (R) (2013) ], $p$-wave optical Feshbach resonance in fermionic $^{171}$Yb atoms using purely long-range molecular excited states has been demonstrated. We theoretically show that, if two purely long range excited states of $^{171}$Yb are coupled to the ground-state continuum of scattering states with two lasers, then it is possible to significantly suppress photoassociative atom loss by a dark resonance in the excited states. We present a general theoretical framework for creating a dark state in electronically excited molecular potential for the purpose of increasing the efficiency of an optical Feshbach resonance. This can be accomplished by properly adjusting the relative intensity, phase, polarizations and frequency detunings of two lasers. We present selective numerical results on atom loss spectra, $p$-wave elastic and inelastic scattering cross sections of $^{171}$Yb atoms to illustrate the effects of the molecular dark state on optical Feshbach resonance.