**Sarah Kaiser**, Carlo Bradac, Mattias Johnsson, Matthew van Breugel, Ben Baragiola, Rochelle Martin, Mathieu L. Juan, Gavin Brennen, Thomas Volz

Centers must be *indistinguishable*

- spatial: $V << \lambda^3$
- spectral
- spin manifold

$|J,M\rangle =\sqrt{\frac{(J+M)!(J-M)!}{(2J)!}}\sum_{perm}|\underbrace{111...}_{\text{J+M}}\underbrace{000...}_{\text{J-M}}\rangle$

R H Dicke [doi:10/cbq3mc]

$N$ | # of two-level emitters |
---|---|

$J=\frac{N}{2}$ | total spin for the collective system |

$M\in\{-J,J\}$ | projection of the spin state, J+M excited emitters |

R H Dicke [doi:10/cbq3mc]

$M,~N=3$ | |
---|---|

3/2 | $|111\rangle$ |

1/2 | $|110\rangle+|101\rangle+|011\rangle$ |

-1/2 | $|100\rangle+|010\rangle+|001\rangle$ |

-3/2 | $|000\rangle$ |

- spin–spin coupling
- local phononic environments
- localized charge fields
- lattice stress/strain
- etc.

- Domain Size: max # of cooperating centers
- Initial state of system
- Bright/dark decay rates
- Local dephasing rates

C Bradac

- # of cooperating centers : ✖
- Initial state of system : ➖
- Bright/dark decay rates : ?
- Local dephasing rates : ✔?

B. B Prasanna Venkatesh, M L Juan,

O Romero-Isart [arXiv:1705.07847]

- Ultrafast radiative lifetimes $\approx1\text{ns}$
- Photon correlations consistency check model

- Temperature dependance?
- Other color centers?
- Expand model: Dipole dipole interactions
- Super absorption?