Sound controls

Using light and sound to control noise in quantum devices

Have you ever wondered why your credit score is what it is? Do you have private information stored in the cloud that you want to keep? Have you thought about investing in cryptocurrency? Worried about cyber warfare?

If you answered yes to any of these questions, quantum computing is playing a role in your life – or at least it will when its use becomes practical enough to power the systems that govern our daily lives.

This is where the work of Ryan Behunin comes in.

Behunin, an assistant professor of applied physics and materials science and a researcher at NAU’s Center for Materials Interfaces in Research & Applications (¡MIRA!), explores fundamental questions about the interplay of light, sound, and matter. His latest research project, “Controlling Noise in Quantum Devices with Light and Sound”, was funded by an NSF CAREER grant of nearly $500,000, which supports early-career professors in their groundbreaking research.

This work targets the challenges of realizing practical quantum computers by helping the building blocks of quantum computers, called “qubits,” work better. This is essential because quantum computers have the potential to solve some problems that cannot be solved using traditional computing technology. The challenge is that currently the technology is too vulnerable to environmental disturbances that corrupt the information stored in quantum computers – too noisy, so to speak – to achieve its full potential.

Behunin’s goal is to quiet this noise.

“Theoretically, quantum physics can enable powerful new computers that achieve massive exponential speedups over traditional forms of computation, enabling computations that are currently unsolvable” said Behunin. “In practice, however, the very quantum features that enable these remarkable properties are quickly erased by a process called decoherence, not unlike how a plucked guitar string eventually relaxes.”

As a result, decoherence limits the lifetime of quantum states, posing challenges for practical quantum technologies. This project will show how decoherence can be controlled by manipulating sound waves.

“Noise” in quantum mechanics works much like static electricity on the radio, making it hard to “hear” the signal. The most problematic source of noise for many quantum devices comes from two-level tunneling states, or TLS. They’re not well understood, but they’re everywhere, and physicists have yet to find an effective way to quiet TLS. This research will take advantage of the strong interaction between TLS and sound waves to develop new techniques that control and reduce this source of noise.

The answers Behunin seeks have implications for cybersecurity, advanced manufacturing, and areas such as drug development; faster and more accessible quantum computing could mean faster and more affordable creation of drugs or other organic materials.

“We can take a big step towards practical quantum technology if we can show how noise can be controlled and reduced in quantum devices,” said Behunin.

This project will also focus on providing research opportunities for students from populations historically underrepresented in the field of physics, including women and minority groups. In addition to its innovative research, the mission of ¡MIRA! is to increase diversity in these areas. Recruiting students to labs like Behunin’s is a big part of that mission, as is outreach to K-12 students to get them excited about STEM research long before they enter college. ‘university. That’s why part of this project includes Behunin teaching a free mini-class on quantum physics at Tynkertopia, a non-profit STEAM center located in the Sunnyside neighborhood of Flagstaff.

“Scientifically, we’re trying to answer deep questions about materials science, namely, what is TLS and how can we get rid of it?” said Behunin. “With respect to diversity, this project aims to engage communities that are underrepresented in science. The goal is to increase access and exposure to quantum science in our underserved communities. »