Photon emission from non-oriented spin systems

Elke Neu, Patrick Appel, Marc Ganzhorn +7 more

We demonstrate the fabrication of single-crystalline diamond nanopillars on a (111)-oriented chemical vapor deposited diamond substrate. This crystal orientation offers optimal coupling of nitrogen-vacancy (NV) center emission to the nanopillar mode and is thus advantageous over previous approaches. We characterize single native NV centers in these nanopillars and find one of the highest reported saturated fluorescence count rates in single crystalline diamond in excess of 106 counts per second. We show that our nano-fabrication procedure conserves the preferential alignment as well as the spin coherence of the NVs in our structures. Our results will enable a new generation of highly sensitive probes for NV magnetometry and pave the way toward photonic crystals with optimal orientation of the NV center's emission dipole.

G. Fehér, J. P. Gordon, Emily Jane Buehler +2 more

Felipe Ortiz Huerta

Willem L. Vos, A. Femius Koenderink, Ivan S. Nikolaev

We study theoretically the spontaneous emission rate of a two-level quantum emitter in any nanophotonic system. We derive a general representation of the rate on the orientation of the transition dipole by only invoking symmetry of the Green function. The rate depends quadratically on orientation and is determined by rates along three principal axes, which greatly simplifies visualization: emission rate surfaces provide insight on how preferred orientations for enhancement (or inhibition) depend on emission frequency and location, as shown for a mirror, a plasmonic sphere, and a photonic band-gap crystal. Moreover, insight is provided on means to ``switch'' the emission rates by actively controlling the orientation of the emitters' transition dipole.

K. S. Mallesh, Swarnamala Sirsi, Mahmoud A A Sbaih +2 more

We classify the pure states of a spin- s system into oriented and non-oriented states. A pure state is said to be non-oriented if it is not an eigenstate of S 2 and S z with respect to any axis of quantization. If it is an eigenstate it is oriented. In this paper, we discuss the notion of spin squeezing in these states. Our analysis shows that the oriented states are not squeezed while non-oriented states exhibit squeezing. We also present a new scheme for the construction of spin- s states using 2 s spinors oriented along different axes. Taking the case of s = 1, we show that `non-oriented' nature and hence squeezing arise from the intrinsic quantum correlations that exist among the spinors in the coupled state.

G. Caimi