Quantum devices can potentially revolutionize countless aspects of our lives. At first, scientists require a fast, efficient source of the entangled pairs of photons such systems use to transmit and manipulate information.
Recently, scientists from the Stevens Institute of Technology have successfully created a fast, efficient source of photons’ entangled pairs. They have come up with a chip-based photon source 100 times more efficient than previously possible and also brought massive quantum device integration within reach.
Scientists created photon pairs by trapping light in carefully sculpted nanoscale microcavities; as light circulates in the cavity, its photons resonate and split into entangled pairs. But, here is the twist: Currently, such systems are incredibly inefficient, requiring a torrent of incoming laser light comprising hundreds of millions of photons before a single entangled photon pair will grudgingly drip out at the other end.
By developing a new chip-based photon source that’s 100 times more efficient than any previous device, scientists were able to create tens of millions of entangled photon pairs per second from a single microwatt-powered laser beam.
Yuping Huang, Gallagher associate professor of physics and director of the Center for Quantum Science and Engineering, said, “This is a huge milestone for quantum communications.”
In collaboration with Stevens graduate students Zhaohui Ma and Jiayang Chen, Huang built on his laboratory’s previous research to carve extremely high-quality microcavities into lithium niobate crystal flakes. The racetrack-shaped cavities internally reflect photons with very little energy loss, enabling light to circulate longer and interact with greater efficiency.
By fine-tuning additional factors such as temperature, the team created an unprecedentedly bright source of entangled photon pairs. During experiments, this allowed photon pairs to be produced in far more significant quantities for a given amount of incoming light, dramatically reducing the energy needed to power quantum components.
Scientists are now working on ways to refine their process further. They say they expect soon to attain the real Holy Grail of quantum optics: a system that can turn a single incoming photon into an entangled pair of outgoing photons, with virtually no waste energy along the way.
Chen said, “It’s achievable. At this point, we need incremental improvements.”
- Ultrabright quantum photon sources on-chip, Physical Review Letters (2020). arxiv.org/abs/2010.04242