Ground state EIT cooling of $^{171}$Yb$^+$ ion

TL;DR

This paper proposes a ground state cooling scheme for $^{171}$Yb$^+$ ions using EIT with a polychromatic laser field, enabling deep cooling without magnetic fields, which benefits precision frequency standards.

Contribution

The work introduces a magnetic-field-free EIT cooling method for $^{171}$Yb$^+$ ions that achieves ground state cooling and reduces Zeeman shifts.

Findings

Deep cooling to the motional ground state achieved.

No magnetic field required for cooling process.

Significant suppression of quadratic Zeeman shifts.

Abstract

The work propose a scheme of deep laser cooling of $^{171}$Yb$^{+}$. The cooling is based on the effect of electromagnetically induced transparency (EIT) in a polychromatic field with three frequency components are resonant to optical transitions of the $^2S_{1/2} \to \, ^2P_{1/2}$ line. The deep cooling down to the ground motional state in a trap allows for a significant suppression of the second order Doppler shift in frequency standards. Moreover, there is no need to use a magnetic field, which is required for Doppler cooling of $^{171}$Yb$^{+}$ in a field with two-frequency component. The cooling without use of magnetic field is important for deep suppression of quadratic Zeeman shifts of clock transitions from uncontrolled residual magnetic fields.