Is There a Quantum Advantage? Daniel Grier Joins CSE to Prove That There Is.

Mar 23, 2023
New CSE Assistant Professor Daniel Grier

By Kimberley Clementi

Quantum computing is to classical computing what Ant-Man is to The Avengers: a diminutive team member with a sizeable advantage performing certain tasks. At least that’s what Daniel Grier, a new assistant professor in the Computer Science and Engineering and Mathematics departments at UC San Diego, aims to prove with his research.

“I work on quantum complexity theory, which tries to understand the capabilities of quantum computers and how they compare to their classical counterparts,” said Grier.

Grier is referring to the inherent hierarchy of computational problems. Quantum complexity theory delineates between problems that can be solved efficiently by classical computers and those that require quantum computers.

According to Grier, early comparisons suggest that quantum computers outperform classical computers in particular calculations. However, most proofs are predicated on a number of conjectures. Grier hopes his research on near-term quantum computing paradigms will get us closer to a definitive proof of quantum advantage.

“One key goal of my research is to mathematically prove that there are certain problems that are easy for a quantum computer, and yet no classical device could possibly solve them,” said Grier.

Grier contends that solidifying the mathematical foundation for a computation model based on qubits, or quantum bits, is important because quantum mechanics is notoriously subtle. Some problems that seem to require quantum computers might actually have clever classical algorithms.  In contrast, Grier’s research could help physicists and engineers build devices that are certifiably using quantum mechanics for the purposes of computation.

“When I started as a graduate student, quantum computing was still pretty theoretical,” said Grier. “It feels somewhat surreal to be living in a world where quantum computers are actually being built and phrases like ‘quantum computing start-up’ are common.”

Despite the burgeoning connection between quantum computing research and industry, Grier’s focus remains theoretical. That’s what initially drew him to UC San Diego; the university has strong theory groups in both CSE and Mathematics. Grier looks forward to working with students in both departments and expanding the community of researchers focused on quantum computation.

Prior to joining UC San Diego, Grier was a postdoc at the Institute for Quantum Computing at the University of Waterloo. He completed his PhD in computer science at the Massachusetts Institute of Technology, where he was awarded a National Science Foundation Graduate Research Fellowship.