Lu clock comparison at the 10 level via correlation spectroscopy.

The extreme precision of optical atomic clocks has led to an anticipated redefinition of the second by the International System of Units. Furthermore, accuracies pushing the boundary of 1 part in 10 and beyond will enable new applications, such as in geodesy and tests of fundamental physics. The to optical transition in Lu has exceptionally low sensitivity to external perturbations, making it suitable for practical clock implementations with inaccuracy at or below 10.

Erratum: Realization of the Dicke Model Using Cavity-Assisted Raman Transitions [Phys. Rev. Lett. 113, 020408 (2014)].

This corrects the article DOI: 10.1103/PhysRevLett.113.

Realization of the Dicke model using cavity-assisted Raman transitions.

We realize an open version of the Dicke model by coupling two hyperfine ground states using two cavity-assisted Raman transitions. The interaction due to only one of the couplings is described by the Tavis-Cummings model and we observe a normal mode splitting in the transmission around the dispersively shifted cavity. With both couplings present the dynamics are described by the Dicke model and we measure the onset of superradiant scattering into the cavity above a critical coupling strength.