Concepts in a quantum synchronization setup

[Danny Boy]

In a https://jila.colorado.edu/thompson/sites/default/files/pdf/PhysRevLett.113.154101_0.pdf on quantum synchronization, they introduce the setup given in the attached 'Fig1.png'. I would like confirm a few concepts regarding this setup. The setup is described in the following way:

The general setup is shown schematically in Fig.1. Two
ensembles, each containing $N$ two-level atoms with excited
state $|e \rangle$ and ground state $| g \rangle$, are collectively coupled to a
high-quality optical cavity. The transition frequencies of the
atoms in ensembles $A$ and $B$ are detuned from the cavity
resonance by $δ/2$ and $−δ/2$, respectively. This could
be achieved by spatially separating the ensembles and
applying an inhomogeneous magnetic field to induce a
differential Zeeman shift. The atoms in both ensembles are
pumped incoherently to the excited state, as could be
realized by driving a transition to a third state that rapidly
decays to $|e\rangle$.

Questions:

• We set the ensembles frequency transitions to $δ/2$ and $−δ/2$ respectively. Do we then model this as individual dipoles oscillating at those frequencies in their respective ensembles?
• Is the sequence of the setup to first put all the particles in a spin up state and then initiate the respective detuned oscillations? Is this what the image is showing?

 

[azntoon]

Are the "high-quality optical cavity" and the "inhomogeneous magnetic field" both necessary components in order to drive the respective detuned oscillations?Yes, you can model the ensembles as individual dipoles oscillating at the respective frequencies.Yes, the sequence of the setup is to first put the particles in a spin-up state and then initiate the respective detuned oscillations. This is what the image is showing.Yes, the high-quality optical cavity and the inhomogeneous magnetic field are both necessary components in order to drive the respective detuned oscillations.