Buffer-gas-induced collision shift for theSr88S1

Abstract

Precision saturation spectroscopy of the 88 Sr 1 S0 − 3 P1 is performed in a vapor cell filled with various rare gas including He, Ne, Ar, and Xe. By continuously calibrating the absolute frequency of the probe laser, buffer gas induced collision shifts of ∼kHz are detected with gas pressure of 1-20 mTorr. Helium gave the largest fractional shift of 1.6 × 10 −9 Torr −1 . Comparing with a simple impact calculation and a Doppler-limited experiment of Holtgrave and Wolf [Phys. Rev. A 72, 012711 (2005)], our results show larger broadening and smaller shifting coefficient, indicating effective atomic loss due to velocity changing collisions. The applicability of the result to the 1 S0 − 3 P0 optical lattice clock transition is also discussed.

Coherent forward broadening in cold atom clouds

“…Collective long-range interactions have shown their import in many phenomena such as coherent forward scattering [2,3], the collective Lamb shift [4], fault-tolerant quantum computation [5], laser cooling [6], and homogeneous line-broadening [7]. The study of collective effects and their role in transition lines is of particular importance for the implementation of highly accurate atomic clocks [8][9][10][11][12], where achieving narrow resonance lines is essential. As the quest for extremely accurate atomic clocks progresses, an understanding of the plethora of physical processes in cold atomic gasses, such as density dependent line-broadening [8], will need to be understood using models that extend the classical theories of line-broadening, since these models mainly rely on local interactions [13][14][15].…”