Quantum Defects and Narrowband Emitters Could Deliver High-Capacity Optical Disc Storage

Researchers from Argonne National Laboratory and the University of Chicago have come up with a shot in the arm for optical storage like CD-ROMs — blending classical physical and quantum modeling to dramatically increase how much data can be stored on each disc.

"We worked out the basic physics behind how the transfer of energy between defects could underlie an incredibly efficient optical storage method," explains Giulia Galli, Liew Family Professor at the University of Chicago, Argonne senior scientist, and co-corresponding author of the work. "This research illustrates the importance of exploring first-principles and quantum mechanical theories to illuminate new, emerging technologies."

Traditional optical discs store data in a way that is read back by a laser shining on their surface — which means the density of data stored is limited by the wavelength of said laser, with the diffraction limit of light putting a hard upper bound on just how much information a disc can hold. The team's solution: wavelength multiplexing, achieved by embedded rare-earth emitters in the disc.

To prove the concept, the team developed models of a theoretical future optical disc material with embedded narrowband rare-earth emitters — atoms that absorb light and re-emit it at specific wavelengths. This re-emitted light can then be captured by a quantum defect — the breakthrough that could lead to high-density optical storage in the future.

"We wanted to develop the necessary theory to predict how energy transfer between emitters and defects work," explains Swarnabha Chattaraj, a postdoctoral research fellow at Argonne and first and co-corresponding author on the work. "That theory then allowed us to figure out the design rules for potentially developing new optical memories. To start applying this to developing optical memory, we still need to answer additional basic questions about how long this excited state remains and how we read out the data. But understanding this near-field energy transfer process is a huge first step."

The team's work, funded by the Department of Energy's Office of Science, has been published in the journal Physical Review Research under open-access terms.