Kwiat receives two additional STTR grants to commercialize quantum optics technology, total of $4.8M in last five years

The research group of Paul Kwiat, physics professor in The Grainger College of Engineering at the University of Illinois Urbana-Champaign, has received two Small Business Technology Transfer (STTR) grants to develop commercially viable quantum light sources. These are the 23rd and 24th such grants this group has received in the last five years from STTR programs, representing a total of $4.8 million in funding.

“STTRs are competitive, multi-phase programs with relatively few projects accepted for first phase 1, the proof-of-concept project; then, of those, only around 25% typically mature to phase 2 projects focused on research and development, potentially leading to a marketable technology,” Kwiat said. “The fact that our group has received nearly 20 such grants, all for quantum optics-related technologies, shows that we’re doing something right.”

For the current awards, Kwiat’s group has partnered with the small business Physical Sciences, Inc. to develop reliable, efficient sources of entangled photons that carry the quantum information needed for communications and networking applications. The core of their technology is a strategy for obtaining multiple entangled photons at once.

The first project has the goal of creating entangled pairs of photons with different energies — one suitable for propagation through an optical fiber, the other for free-space communication links — enabling hybrid networking. The second aims to efficiently generate quantum states with a large number of photons, up to five at a time, which are known to have theoretical advantages for quantum sensing, a task that has proven elusive until now.

“At the present time, most quantum communication operations and protocols are built around having two entangled photons, but the possibilities start to grow when we start to build protocols for three, four, five or more entangled photons,” Kwiat said. “Part of the reason such protocols are underdeveloped is that simultaneously having more than two entangled photons is exceedingly difficult. We’re trying to change that.”

In many cases, entangled photon creation is a probabilistic process, meaning that it must be repeated many times until the desired outcome occurs. The creation of two pairs of entangled photons is a relatively uncommon event in such processes, so the simultaneous creation of three or more becomes even rarer.

Physical Sciences and Kwiat’s group are exploring the possibility of preparing many-photon states by storing generated photons in an optical “buffer” until the total desired number is attained.

“Imagine a group of friends is meeting at an airport,” Kwiat said. “There’s a certain probability that each friend will arrive in any given hour, but the probability of two or more friends arriving in the same hour becomes very small. You have two choices: you can wait around until everyone

happens to show up all at once, or you can have the friends wait in the airport lounge as they arrive until everyone is there. Clearly, the second option is preferable, and that’s basically what we’re trying to do on the quantum scale.”

The main technological challenges are signaling that a photon has entered the buffer and keeping it there until all desired photons are present. Kwiat’s group has solved the first problem by using “heralding photons” that indicate the presence of another photon without disturbing its quantum state. The second requires special hardware, ultra-low-loss reflectors that “trap” the photons until they’re all available.

Kwiat’s group has received 14 Phase 1 grants and 10 Phase 2 grants through STTR programs sponsored by NASA, the National Science Foundation, the U.S. Department of Energy and the Air Force Office of Scientific Research.

Paul G Kwiat is an Illinois Grainger Engineering professor of physics in the Department of Physics. He is also affiliated with the Department of Electrical and Computer Engineering, the Materials Research Laboratory and the Illinois Quantum Information Science and Technology Center. He holds the John Bardeen Chair in Physics and Electrical Engineering appointment.