By Ty Burke
In pop culture, quantum physics exists mainly as a convenient plot device to explain the unexplainable. Perhaps the most famous example is the Marvel superhero Ant-Man, who can shrink smaller than an oxygen molecule to enter the quantum realm — even though that would make him smaller than the air he’d need to breathe to survive. It advances the story, even if it doesn’t really make sense. Ant-Man’s abilities are attributed to quantum mechanics, but what does that really mean?
Quantum mechanics won’t help you shrink like Ant-Man, but physics really does get weird at the quantum level. For centuries, a set of physical rules governed the behavior of atoms, the building blocks for all matter in the universe, and enabled the probabilistic prediction of how they interact with each other and with light. In the early 20th century, quantum mechanics emerged as a way to explain observations that did not align with classical physics. At the quantum level, particles can tunnel through energy barriers and spin in both directions at once. It’s enough to make your head spin, but this new physics revolutionized science in ways that continue to reverberate today.

Our ability to understand and control the quantum behavior of electrons in silicon has enabled semiconductors — and a technological revolution in computing that has transformed virtually every aspect of our lives. Our understanding of nuclear spins has enabled us to see the inner workings of the body with magnetic resonance imaging (MRI) machines. Better sensors based on electron spins are on the horizon.
Scientists have only scratched the surface of what quantum technologies can do. As we master how to control individual quantum systems, it will unlock a new quantum revolution, with applications in computing, medicine and energy. UT is already at the forefront of developing the next generation of quantum technologies. Now, the new Texas Quantum Institute (TQI) will unite UT researchers across disciplinary boundaries to forge new frontiers of knowledge and tech.

“TQI brings together researchers with expertise in semiconductor materials, physics and computer science. There are many pockets of quantum research at UT, but there has been no campus-wide organization until now. We only launched in April, and we are already seeing momentum build.”
— Xiuling Li, professor, Chandra Family Department of Electrical and Computer Engineering and co-director, TQI
The tantalizing promise of quantum computing — computers with the ability to solve problems that today’s technologies cannot, and do it much faster — hangs over this well-established but still burgeoning discipline. Despite decades of excitement, companies are still figuring out how to actually get quantum technologies to perform practical application.
TQI can help them do it. UT researchers have expertise in every segment of the ecosystem. One example: Poulami Das is addressing error correction, one of quantum computing’s major hurdles.
Quantum computers could be transformative for applications like machine learning and cryptography, but they are still far too prone to errors, which limits their applications. Quantum computers rely on qubits, the quantum version of the computing bits used by classical computers that store and process information. Qubits can be disrupted by even small amounts of noise, such as radio waves or electromagnetic radiation from the sun. Some researchers have sought to shield quantum computers from as much noise as possible, but quantum errors remain common.


“Quantum error correction is needed to correct errors quickly, so that they do not accumulate to the point where we cannot correct them anymore. For some types of devices, it is necessary to correct errors within a microsecond.”
— Poulami Das, assistant professor, electrical and computer engineering
To do this, Das developed high-performance classical computing hardware that accelerates error correction, automatically adapting its strategy to the complexity of a given error event.
“Error detection algorithms need to be accurate and scalable,” says Das. “We not only need to identify errors for a single qubit, we must be able to do it for hundreds and thousands of program qubits. If you’re not aggressive enough in identifying errors, you’ll get a backlog, and the computer will fail. But if you’re too aggressive, you get false matches and predict errors that won’t actually occur. That can slow down operations too. You need to be right in the sweet spot.”
Computing is only one of the emerging quantum technologies pushing the frontiers of what is possible. David Burghoff envisions a future where quantum sensing technologies are readily available and small enough to fit in the palm of your hand. He makes photonic devices that manipulate particles of light to detect and monitor all kinds of substances. Quantum sensing technologies could identify chemicals that indicate the presence of explosives on a battlefield, or even be used in a kind of breathalyzer device that diagnoses certain types of cancer.


“At longer wavelengths, many molecules have distinct signatures, especially in their gas phases. But the high-sensitivity sensing systems that use these wavelengths tend to be large and have moving parts. By shrinking long-wavelength sensors down to the nanoscale, we could make the technologies much more widely available.”
— David Burghoff, assistant professor, electrical and computer engineering
But for this type of technology to be practical, you need to precisely control the behavior of light at the quantum scale. Existing systems are prone to the loss and dispersion of photons — particles of light — which interferes with the accuracy of these devices. To overcome this challenge, Burghoff is devising ways to use germanium and zinc to make waveguides and resonators — structures on photonics chips — that shepherd particles along the chips more efficiently. This would reduce the loss and dispersion of photons and enable advanced sensing technologies to emerge out of the lab and in to your pocket.
Overcoming hurdles like these will be essential to building revolutionary new quantum technologies, but progress is happening. Just a few years ago, industry was skeptical of quantum technologies, says Xiaoqin (Elaine) Li, a professor of physics and co-director of TQI. But that has changed, with Google, IBM and others building their own quantum computers.

“In some areas of quantum, the U.S. is at risk of losing its leading position, if it hasn’t already. There has been some recognition of that risk, and a lot of new investment in the field. All of these set the stage to establish TQI.”
— Xiaoqin (Elaine) Li, a professor of physics and co-director of TQI
SPECIAL THANKS
The Cockrell School’s Faculty Technology Studio visualized quantum behaviors for this story, including quantum orbitals, quantum tunneling, quantum rotations and QM/MM simulations.