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Can You See the Quantum Light? Icarus Quantum Creates Entangled Photons
John Himes
December 9, 2023
Impressed by today’s networks? That’s nothing compared to what’s coming next.
Icarus Quantum, a startup based out of Boulder, Colorado, is building quantum networking technology for quantum teleportation. This tech builds on top of the networks we already have to teleport quantum states by sending classical signals.
You may be wondering, “What’s the big deal?” Information already moves so fast—in the case of fiber-optic cables, it moves at the speed of light. But the incentive for quantum networking isn’t efficiency.
It unlocks new possibilities. A quantum internet could connect quantum computers (QCs) together and create an explosive effect that’s analogous to the networking of the first classical computers and the paradigm shift that is the internet.
But that’s not the near-term vision for Icarus Quantum. Their technology’s first use case will be adding an overlay to today’s networks—bolstering cybersecurity by generating encryption keys to establish a secure wired connection between two devices.
From scientist to CEO
Dr. Poolad Imany, the company’s founder and CEO, has been working to make this a reality for the past 10 years. He first learned about quantum optics while studying electrical engineering at Purdue University, and since then he’s devoted his life’s work to uncovering the mysteries of quantum mechanics and putting that knowledge to work.
During his time as a postdoctoral associate at the National Institute of Standards and Technology (NIST) in the Quantum Nanophotonics Group, Dr. Imany had his breakthrough moment.
His group has worked on quantum dot (QD) technology for 30 years, looking for a way to deterministically generate pairs of entangled photons. Dr. Imany was running an experiment that involved exciting the QDs with perfectly aligned lasers, but it was impossible to know exactly what frequency would lead to the desired results.
So there he was, sitting in the lab, counting photons, expecting nothing, and getting nothing for months. “Then suddenly we saw exactly the sign we were looking for,” recounts Dr. Imany. “It took another six months to know that we could fully replicate the results on demand. Then we moved forward.”
In January 2022, Dr. Imany launched Icarus Quantum. He soon brought on Dr. Shuo Sun, a physicist at the University of Colorado (CU) Boulder.
They knew they had a breakthrough technology. Now they just had to commercialize it.
The near-term solution: Quantum data encryption
“This is it!” exclaimed Dr. Imany when he realized that the immediate and practical application of his technology is improving information security for today’s networks.
Unlike a lot of quantum technology, the benefits aren’t theoretical or contingent on future developments—organizations want a better security posture, and they want it now.
“Quantum networks will be essential no matter what, regardless of whether quantum computing becomes mainstream,” says Dr. Imany.
Here’s how it works.
Icarus’s technology first creates a pair of entangled photons, meaning that whatever happens to one of them will happen to the other, no matter where they are. They distribute the photons to the two entities that need a secure connection, then both parties measure the photon’s polarization.
This lets them make sure that their photons are still entangled. Remember, measurement causes disturbance in quantum particles; looking at either of the photons will disentangle them. So if the network along which they’re traveling is compromised, the eavesdropper will leave fingerprints. The photons won’t be entangled.
Both sides measure the polarization and share those measurements. If they’re the exact same, then they know their photons are entangled and their line is secure.
This means they can now generate a unique encryption key with subsequent entangled photons. When they measure the encrypted photons, they can be certain that both sides are taking the same measurement. The end result is a fresh key that provides an ironclad encrypted connection over an existing network.
Better encryption standards are always useful, but it’s particularly important as quantum computers threaten to break today’s most advanced encryption. The search for post-quantum cryptography is as much a national security concern as it is a priority for businesses that store and transmit sensitive data, like banks and healthcare companies.
“We trust today’s cryptography because it hasn’t been broken yet,” explains Dr. Imany. “But there’s no way of proving that it’s unbreakable. Quantum networking is the only way to be certain that we haven’t been compromised.”
While enhancing cybersecurity is the company’s immediate path to commercialization, Icarus Quantum sees it as a stepping stone for a grander vision.
They understand how their technology could enable hybrid computing, which combines classical and quantum computers to leverage the strengths of each. A quantum network could hand information off from one to the other.
The real endgame, which Dr. Imany calls “the holy grail,” is networking multiple QCs together to create a quantum internet. “The capabilities explode exponentially,” he says. While traditional computers scale linearly as we add more bits to the system, QCs scale by orders of magnitude as we add more qubits.
The problem with this scalability is creating a single QC with enough qubits to reach a threshold where it can solve the intractable optimization problems that aren’t possible to solve with today’s most advanced supercomputers. By networking QCs together, engineers may be able to access greater qubit counts than ever before to reach those goals.
How to create a quantum network with quantum dots
At the heart of Icarus Quantum’s innovation are semiconductor quantum dots (QDs), the technology whose creators won a Nobel Prize in 2023. These “artificial atoms” behave similarly to atoms, despite being relatively much larger—a dozen nanometers across rather than about 0.1 nanometer.
The basic premise involves using a laser to excite them, raising the electrons to a high energy state. When they decay, the electrons fall back to the base level and release light as a result. In this case, they release a pair of entangled photons.
The QDs may be semiconductors, but they’re actually not made out of silicon.
To make their QDs, Icarus uses a process called molecular-beam epitaxy. They start with a wafer of gallium arsenide crystal—called a crystal because it has one repeating shape—and then they shoot indium arsenide at it.
The indium arsenide crystals sit on top of the gallium arsenide and bond, growing the crystal. But, since the lattice constant of indium arsenide is larger, it creates strain. The end result is islands—quantum dots—that are 10–20 nanometers in diameter.
“These are scalable integrated platforms,” says Dr. Imany, describing the process they use to dice them into chips after patterning them with nanofabrication.
The final product is an “encapsulated chip with a laser in a cryostat” that sits at around 4 kelvins. That’s -452 degrees Fahrenheit—cold, but still not as cold as the dilution refrigerators that are used in superconducting quantum computers. Those devices approach absolute zero, or 0 kelvin.
“Advances in cryostat technology have been a huge gain for our technology,” explains Dr. Imany. “They’re getting smaller and more efficient.” This is a great example of how the commercial progress of one technology can unlock commercial viability for another.
A similar enabler is the chip-scale lasers they’re building at NIST. These microscopic optics are a key component of Icarus Quantum’s technology, and by integrating them directly onto the chip, they’re able to create a complete package that they hope will allow turnkey operation for their customers.
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Technological advantages and challenges
The reason Dr. Imany and Dr. Sun chose QDs to begin with is that they saw the potential for a reliable source of high-quality entangled photons.
Previous entangled photon generators were probabilistic, with a maximum success rate of 1% at every attempt. This number plummets even further when multiple sources are interfaced together for long-range and multi-node quantum networks.
The company’s technology is maximized for efficiency—it can generate quantum light more than 70% of the time, a number that’s only limited by fabrication imperfections. Previous entanglement generators were probabilistic, with only about 1% success in generating entangled photons.
The company’s QDs are able to generate billions of entangled photons per second.
Then there’s the quality component, which refers to how entangled the photons are on a scale of 0 to 1. At 1, they’re totally entangled—whatever happens to one happens to the other. 0 refers to anti-entanglement, which leads to opposite results. For instance, if one photon’s polarization is horizontal, its anti-entangled partner has vertical polarization. In the middle, at 0.5, is not entangled at all.
They’re after high-fidelity output that creates entanglement ratings that are as close to 1 as possible. The team has had initial results that point toward reliably making highly entangled photons.
Another challenge they’ve had to work through is capturing the photons themselves. They shoot out at all angles, so the scientists needed a way to direct them. Enter the optical cavity, which acts as a funnel for individual photons.
“Our main challenge right now is to improve the optical cavities and integrate them with our QDs without degradation to the other parts of the system that we’ve perfected,” says Dr. Imany.
It’s an understatement to say there’s a lot of engineering that goes into perfecting a system of this much complexity. Between the optics, the materials, the electronics, and even the software components, developing this technology to the point where it’s ready to go to market will require continued dedication and support.
Luckily for them, they’re in the right spot at the right time.
Colorado Tech Spotlight: From metaphor to literal photons
“Colorado will be the unquestionable leader of quantum tech in the US,” says Dr. Imany.
Icarus Quantum is part of a thriving quantum startup community, giving them the opportunity to make frequent contact with other innovators so they can share their expertise and learn from each others’ mistakes.
As a postdoc at NIST and a professor at CU Boulder, respectively, Dr. Imany and Dr. Sun continue to collaborate with their institutional colleagues and make use of the resources that are available to them.
For instance, the federal CHIPS act appropriates billions of dollars for onshoring high-tech manufacturing, some of which has already gone to NIST. “This is an open entity that benefits everyone,” explains Dr. Imany. “Investments there are felt throughout the Colorado tech community.”
The capable workforce is another main draw of the local ecosystem. Between the other quantum companies, including leaders like Infleqtion, Quantinuum, and Atom Computing, alongside public institutions like JILA, the CU system, and CU Boulder’s top-rated physics program, there are more people here that are up to the challenge of engineering quantum technology than virtually anywhere else.
Icarus Quantum works with grad students and appreciates how people come from around the globe to advance quantum tech. “Not a lot of people leave after they come here,” Dr. Imany says, smiling.
Another piece of the puzzle is partnership with the public sector. Of course, since Icarus Quantum has developed a dual-use technology with massive cybersecurity implications, the Department of Defense bankrolls much of their research and development. Icarus Quantum has received funding from the Air Force and the Space Force, both of which have a major footprint in Colorado.
Their work with the Space Force is of particular note. “Leveraging satellite nodes, we are supercharging quantum communications to stretch entanglement across continents,” writes Dr. Imany in the announcement. “Our on-demand and high-quality entanglement generations will revolutionize data security and sensing via satellites.”
Icarus Quantum is proud to call Colorado home, and they’re thankful that the state government cares so much about fostering innovation.
For instance, the Colorado Office of Economic Development and International Trade offers an advanced industries early-stage capital and retention grant that provides funding of up to $250,000 for developing and commercializing cutting-edge tech. This is one of many programs.
Everyone knows that we get 300 days of sunshine here in Colorado. Photons must think this is a great place to be. We definitely can’t blame them.
About the Colorado Tech Spotlight
The Colorado Tech Spotlight highlights local innovations and the stories behind them. The series explores how the Colorado tech ecosystem creates an environment that promotes technological progress.
It is produced by Dynamic Tech Media and written by John Himes.
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