Researchers create first programmable logic quantum processor

Researchers at Harvard University have achieved a major milestone in their quest for stable, scalable quantum computing, an ultra-high-speed technology that will enable game-changing advances in fields as diverse as medicine, science and finance.

The team, led by Mikhail Lukin, the Joshua and Beth Friedman University Professor of Physics and co-director of the Harvard Quantum Initiative, created the first programmable logical quantum processor capable of encoding up to 48 logical qubits and Perform hundreds of quantum calculations. Logic gate operation, a huge improvement over previous efforts.

Published in naturethis work was conducted in collaboration with Marcus Greiner, the George Wasmer Leverett Professor of Physics; colleagues at MIT; and QuEra Computer, a Boston company based on technology from the Harvard lab .

The system is the first demonstration of large-scale algorithm execution on an error-correcting quantum computer, heralding the emergence of early fault-tolerant or reliable uninterrupted quantum computing.

Lukin described the achievement as akin to a possible turning point in the early days of artificial intelligence: The long-theorized ideas of quantum error correction and tolerance are starting to bear fruit.

“I think this is one of those moments where it’s clear that something very special is about to happen,” Lukin said. “While there are still challenges ahead, we expect this new development to significantly accelerate progress toward large-scale, useful quantum computers.” “

Dennis Caldwell of the National Science Foundation agrees.

“This breakthrough is a masterpiece of quantum engineering and design,” said Caldwell, acting assistant director of the Directorate for Mathematical and Physical Sciences, which operates through the National Science Foundation’s Physics Frontier Center and Quantum Leap Challenge Institute programs. Support this research. “The team not only accelerates the development of quantum information processing using neutral atoms, but also opens new doors to explore large-scale logical qubit devices, which could bring transformative benefits to science and society at large.”

It’s a long and complicated road.

In quantum computing, a quantum bit, or “qubit,” is a unit of information, just like a binary bit in classical computing. For more than two decades, physicists and engineers have shown the world that quantum computing can, in principle, create physical qubits by manipulating quantum particles (atoms, ions or photons).

But successfully exploiting the strangeness of quantum mechanics for computation is more complicated than simply accumulating enough qubits, because qubits are inherently unstable and prone to collapse from their quantum states.

The real currency in this field is so-called logical qubits: redundant, error-corrected bundles of physical qubits that can store information used in quantum algorithms. Creating logical qubits as controllable units like classical bits has been a fundamental obstacle in the field, and it is widely believed that the technology cannot truly take off unless quantum computers can operate reliably on logical qubits.

The best computing systems to date have demonstrated one or two logical qubits, and a quantum gate operation, similar to a unit of programmed code between them.

The Harvard team’s breakthrough builds on years of research into a quantum computing architecture pioneered in Lukin’s lab called the Neutral Atom Array. It is currently being commercialized by QuEra, which recently signed a licensing agreement with Harvard University’s Office of Technology Development for a patent portfolio based on the innovative technology developed by Lukin’s team.

The key component of the system is an ultracold, levitated block of rubidium atoms within which the system’s physical qubits can move and connect into pairs or become “entangled” during calculations.

Entangled pairs of atoms form gates, which are units of computing power. Previously, the team demonstrated low error rates in entanglement operations, proving the reliability of the neutral atom array system.

Using a logical quantum processor, researchers have now demonstrated parallel, multiplexed control of entire blocks of logical qubits using lasers. The result is more efficient and scalable than having to control a single physical qubit.

“We are trying to mark a shift in the field to start testing algorithms with error-correcting qubits rather than physical qubits, and to build a foundation for larger “The device paved the way.” student in the lab of Dr. Lu Jin.

The team continues to work on demonstrating more types of operations on the 48 logical qubits and configuring its system to run continuously rather than manually looping as it does now.

This article was provided by the Harvard Gazette, the official newspaper of Harvard University. For more university news, visit Harvard.edu.