Making a Quantum Leap Forward

Capable of faster and more complex computing than a traditional computer, quantum computing is poised to quickly take machine learning and artificial intelligence to the next level. 

New work at the University of Pittsburgh blends physics with computer engineering to accelerate quantum computing capabilities while taking inspiration from something more familiar: a tree. The work recently received a $300,000 New Initiative Grant from the Charles E. Kaufman Foundation.

“One of the challenges of quantum computers is that the interactions tend to be noisy—there isn’t 100 percent fidelity,” said Alex K. Jones, professor of electrical and computer engineering at Pitt, who is leading this project. “The state changes create noise over time, so from input to output, it’s a race against decoherence, the loss of information. We’re working to create better gates so that the time for each operation is shorter, resulting in better error correction and higher fidelity.”

Qubits are the basic unit of information in quantum computing. Where binary code in computer science uses bits, either 1s or 0s, qubits function together in a system, like atoms, and can be entangled with other qubits. That means anything done to one qubit happens to the entangled ones, as well. 

These properties make them much more powerful than bits—and much more complicated to work with.

To push quantum computing toward its full potential, Jones is partnering with Michael Hatridge, associate professor of physics at Pitt. They realized that in order to optimize the way these qubits talk to one another, the classic lattice structures used in IBM and Google’s quantum computers were limiting. 

Instead, they are arranging the qubits in the shape of a tree, a methodology from classical parallel computer networks. 

Jones and Hatridge are using a device called a SNAIL that allows them to create interactions between qubits as if they form elements, like “leaves,” on a tree, building a rich interaction space. In order for leaves on different “branches” to communicate, they must connect through the “trunk” of the tree, reaching out to their destination. With this SNAIL device, five or six qubits can interact with each other at the same time, opening the door for researchers to scale up this tree or other flexible approaches. 

For instance, the team has proposed a “Corral” topology unique to both physics and computer science in a paper that will appear at the February 2023 High-performance Computer Architecture (HPCA) Conference in Montreal..

“We realized the tree structure and these novel structures like the Corral made it easier to move data around and opened richer computational space,” said Jones. “With this award from the Kaufman Foundation, we are looking at the interaction between qubits  within individual modules. What can we learn about these nodes, and how do we pick the best computational interactions among them to advance the power of quantum computing so that each qubit can accomplish more than before?”

Noting that this is only the first of several in-depth collaborations in this area, Jones added,

“We’ve only just scratched the surface.”

The New Initiative Grants “encourage investigators with strong research records to establish interdisciplinary collaborations requiring expertise beyond that of any single researcher and take a novel approach to the topic in question,” according to the Pittsburgh Foundation’s news release. This is the 11th time a Pitt researcher has received this grant.

For the Last Decade, the Pittsburgh Quantum Institute Has Been Moving Quantum Computing Forward

Today, Pittsburgh is a hub of education and research in quantum science and engineering, anchored by the powerhouse institutions of the University of Pittsburgh and Carnegie Mellon University. But our place at the national forefront of quantum science didn’t happen overnight. According to Adam Leibovich, director of the Pittsburgh Quantum Institute (PQI), the seed for the region’s success in the field was planted about a decade ago.

“Ten years ago, Jeremy Levy, PQI’s founding director, saw the opportunity to bring people together to foster more cooperation and generate more research,” says Leibovich, who is also a Professor in the Kenneth P. Dietrich School of Arts and Sciences’ Department of Physics and Astronomy and the school’s Associate Dean for Research and Faculty Development. “As a result, he started PQI, which is one of the earliest regional collaborations in the country.

Today, PQI has more than 100 faculty members from Pitt, CMU, and Duquesne with appointments in physics, chemistry, engineering, computer science, business, and philosophy of science. Among those members are Pitt’s Michael Hatridge, associate professor from the Dietrich School, and Alex Jones, professor from the Swanson School of Engineering.

Michael is one of the brightest young stars in quantum computing,” says Leibovich. “He created a novel modular qubit system which can be put together to assemble a larger quantum computer. One of the focus areas of study now is how to string qubits together. Most operations involve two qubits interacting with each other. The interaction of two qubits that are spatially separated is a question of architecture. And Michael and Alex are working on ways to connect qubits that will enhance the efficiency of their interaction.

In addition to the partnership between Hatridge and Jones, there are several other cross- and interdisciplinary quantum initiatives happening at Pitt. Just this fall, two new undergraduate academic programs launched: Physics and Quantum Computing is a major offered jointly by the Dietrich School and the School of Computing and Information (SCI), and Quantum Information Science is an interdisciplinary certificate offered jointly by the Dietrich School, SCI, and the Swanson School.

Says Leibovich, “A decade ago, Pittsburgh and Pitt were part of a very forward-thinking effort to generate new knowledge, create new partnerships, and advance research in quantum science and engineering. Today, those goals of innovation, collaboration, and education still drive us. And I’m excited about the progress and possibilities that lie ahead.