Charles Santori Abstract

Optical Manipulation of Nitrogen-Vacancy Centers in Diamond

 Charles Santori - HP Labs

The nitrogen-vacancy (NV) center in diamond has recently attracted much interest as a potential solid-state quantum bit (qubit) because of its long-lived electronic and nuclear spin coherence combined with optical addressability. These capabilities have enabled an impressive set of experiments by several groups demonstrating coherent control of single electron spins, coupling to nearby impurity electron spins, and controlled coupling to nuclear spins. So far, all of these experiments have involved single NV centers interacting with a local environment. For most potential applications we can imagine, we need a way to connect many spatially distant NV centers together. Given the optical capabilities of the NV cneter, one of the most promising ways to realize the required coherent communication may be through a photonic network.

This talk will describe HP Labs’ ongoing research towards realizing such a network in diamond. First, I will describe low-temperature spectroscopy of both ensembles and single NV centers in low-nitrogen diamond to clarify the excited-state structure and available optical transitions. These experiments include a demonstration of coherent population trapping without a magnetic field. This result was surprising given the previous theoretical understanding of the excited-state level structure, and subsequent theoretical work suggests that non-spin-conserving and cycling transitions can exist simultaneously, allowing for both optical spin manipulation and readout. Presently, we are focused on developing microcavity and waveguide structures in diamond with the goal of enabling efficient transfer of quantum states between electron spins and photons, and to allow efficient transmission of photons across a diamond chip. I will show some early results, and also describe some of the difficulties involved in realizing high-quality optical devices in this unusual material system without sacrificing the properties of NV centers.