Researchers at the University of Waterloo in Canada have achieved a breakthrough in quantum entanglement by directly entangling three photons for the first time. The team, working with detectors developed by the National Institute of Standards and Technology (NIST), generated entangled photon triplets at a rate of 660 per hour.
Entanglement is a key feature of quantum mechanics where particles become linked in such a way that the state of one particle determines the state of the others. This breakthrough could have significant implications for quantum computing, quantum communications, and fundamental physics experiments.
The researchers used a process called cascaded down-conversion to generate the entangled triplets. They started with a blue photon that was polarized both vertically and horizontally, then sent it through a special crystal to create two entangled red daughter photons. One of these was then sent through another crystal to generate two near-infrared granddaughter photons entangled with the second daughter photon.
The NIST detectors were crucial to the success of the experiment, as they were able to detect and measure individual photons at telecom wavelengths with high efficiency. The team also demonstrated the quality and value of the triplets by testing local realism and measuring one of each of a succession of triplets to show they could herald or announce the presence of the remaining entangled pairs.
This work could pave the way for more complex quantum systems and may eventually lead to the generation of four or more entangled photons with improvements in conversion efficiency.
Keywords: Entanglement, Photon, Polarization, Quantum States, Superconducting
