Method for synthesizing high quality copper oxide crystals for quantum photonics

Copper oxidation generally means tarnished surfaces and corroded electronic components. But the compound Cu_twoOr, or cuprous oxide, it is a promising material for quantum photonics, optoelectronics, and renewable energy technologies. Now, a team of researchers has found a way to synthesize high-quality copper oxide microcrystals.

Researchers from the KTH Royal Institute of Technology report that they have developed a scalable production method for cuprous oxide (Cu_twoO) crystals of micrometric size. The Solid State Physics Institute, Graz University of Technology, Austria, and the Laboratoire d’Optique Appliquée Ecole Polytechnique, Palaiseau, France also participated in the study.

“The unique properties of Cu_twoOr it may lead to new schemes for solid-state light quantum information processing that are difficult to do with other materials, “says Stephan Steinhauer, a researcher at the Quantum Nano Photonics group at KTH.

“This work paves the way for the widespread use of Cu_twoOr in optoelectronics and for the development of new device technologies. “

To synthesize the crystals, a thin film of copper is heated to high temperatures under vacuum. In their study, which was published in Communications Materials, KTH researchers took this method and identified the growth parameters to achieve Cu_twoOr microcrystals with excellent quality of optical material.

The process is compatible with standard silicon manufacturing techniques and allows the possibility of photonic circuit integration.

“Most of the quantum optics experiments with this material have been done with geological samples found in mines, for example, the Tsumeb mine in Namibia,” says Steinhauer. “Our synthesis method is associated with very low cost manufacturing, suitable for mass production and does not require gases or chemicals that are toxic or harmful to the environment.”

He says the work lays the foundation for realization of solid-state Rydberg excitation-based quantum technologies, which are excited quantum states with a high primary quantum number.

These excitations can interact with photonic integrated circuits, aiming to generate on-chip and light manipulation at the single-photon level, he says. “Exciting challenges lie ahead in translating previously developed quantum information processing and quantum detection schemes for Rydberg atoms into the solid state environment of a semiconductor crystal at the micron or nanometric scale.”