Laser Cooling of 171Yb+ Ion in Polychromatic Light Field

Abstract

Standard methods of laser cooling ¹⁷¹Yb⁺ in a radiofrequency trap involve the use of coherent optical fields resonant to the optical transition of the ²S_1/2 → ²P_1/2 line, as well as a magnetic field that is used to destroy the coherent population trapping (CPT) appeared at the ²S_1/2(F = 1) level. Further precision measurements with use of the clock transitions (quadrupole ²S_1/2(F = 0) → ²D_3/2(F = 2) and octupole ²S_1/2(F = 0) → ²F_7/2(F = 2)) require significant suppression and control of residual magnetic fields. In this work, we investigate in detail an alternative method of laser cooling ¹⁷¹Yb⁺ with use of polychromatic fields, which allows completely eliminate the use of a magnetic field in the ion cooling process and thus suppress Zeeman quadratic shift associated with uncontrolled residual magnetic fields.