Long-term operation and performance of cryogenic sapphire oscillators.

Cryogenic sapphire oscillators (CSO) developed at the University of Western Australia (UWA) have now been in operation around the world continuously for many years. Such oscillators, due to their excellent spectral purity are essential for interrogating atomic frequency standards at the limit of quantum projection noise; otherwise aliasing effects will dominate the frequency stability due to the periodic sampling between successive interrogations of the atomic transition. Other applications, which have attracted attention in recent years, include tests on fundamental principles of physics, such as tests of Lorentz invariance.

Raman heterodyne detected electron-nuclear-double-resonance measurements of the nitrogen-vacancy center in diamond.

We report two new applications of the Raman heterodyne detection technique. Raman heterodyne detected electron-nuclear double resonance and a double rf resonance technique are used to obtain the hyperfine structure of the nitrogen-vacancy center in diamond.

Raman heterodyne detection of electron paramagnetic resonance.

We report the detection of an electron paramagnetic resonance signal using Raman heterodyne spectroscopy, a rf -optical double-resonance technique. The signals are associated with the nitrogen-vacancy center in diamond, which has a spin-triplet ground state. A three-line spectrum associated with the nitrogen hyperfine structure is observed for various magnetic field strengths and crystal orientations.