Our team aims to develop materials that coherently transfer quantum information between electrical circuits and optical photons.

To achieve this, we must identify and study suitable materials systems that can support both types of excitation. Color centers, atom-like structures in wide-bandgap semiconductors, can serve as an ideal interface between these domains. They have spin excitations whose energies can be tuned anywhere in the microwave frequency range and spin-dependent optical transitions, often in the telecom band.

However, the very properties that make them coherent (localized spin states, small sizes) make them challenging to couple to in both microwave and optical domains. Rare earth ions such as erbium must be embedded in specific host materials to preserve their properties. These materials are not always optimal for patterning into metamaterials or for integration with other systems.

New materials science pathways

Our team studies two materials science pathways to realize coherent electrical-optical coupling via color centers: (1) development of novel color centers and (2) optimized host materials and electrical qubit coupling.

Novel color centers

We will develop new color centers that have advantageous properties compared to existing color centers. The first color centers explored for quantum applications, such as the nitrogen vacancy (NV) center in diamond, were selected for their magnetic sensing properties. For quantum information applications, however, we require color centers with exceptional coherence (tens of microseconds) and low disorder optical transitions (transform limited linewidths).

Optimized host materials

Color centers measure nanometers in size, whereas the natural length scale of a microwave photon measures 1 centimeter. This creates a disappointingly small overlap of energy density. To address this challenge, we will develop materials platforms using theoretical operating protocols to enable significantly improved magnetic, electrical, and acoustic coupling.