Harvard-Led Team Achieves Quantum Computing Milestone with DARPA Support



by FARUK IMAMOVIC

Harvard-Led Team Achieves Quantum Computing Milestone with DARPA Support
© Getty Images News/Lukas Schulze

A team of researchers, supported by the United States Defense Advanced Research Projects Agency (DARPA) and led by Harvard University, has made a groundbreaking discovery in quantum computing, developing the first-ever quantum circuit with logical quantum bits (qubits).

This achievement could significantly advance fault-tolerant quantum computing and revolutionize quantum computer processor design.

Revolutionizing Quantum Computing with Rydberg Qubits

The DARPA-funded Optimization with Noisy Intermediate-Scale Quantum devices (ONISQ) program, which began in 2020, sought to outperform classical-only supercomputers in solving complex combinatorial optimization problems.

The Harvard research team, collaborating with MIT, QuEra Computing, Caltech, and Princeton, focused on exploiting the potential of Rydberg qubits. Their major breakthrough involved creating error-correcting logical qubits using arrays of physical Rydberg qubits, a critical component in achieving fault-tolerant quantum computing.

Logical qubits, unlike their error-prone physical counterparts, are error-corrected to maintain their quantum state, enabling them to solve complex problems more efficiently. The team has successfully built quantum circuits with around 48 Rydberg logical qubits, the largest number in existence to date.

The homogeneity and easy manipulation of Rydberg qubits using lasers on a quantum circuit make scaling the number of logical qubits relatively straightforward.

New Paradigms in Quantum Computing and Future Prospects

Dr. Mukund Vengalattore, ONISQ program manager in DARPA’s Defense Sciences Office, highlighted the unique properties of Rydberg qubits: “Rydberg qubits have the beneficial characteristic of being homogenous...

The homogeneity of Rydberg qubits allows them to scale rapidly and also allows them to be manipulated and moved around easily on a quantum circuit”. The research represents a significant departure from the traditional view that millions of physical qubits are necessary for fault-tolerant quantum computing.

With dynamically reconfigurable quantum circuits, the number of logical qubits required to solve complex problems could be far fewer than initially thought. DARPA’s role in fostering collaborations between quantum sensing and quantum information science communities has been instrumental in this discovery.

Vengalattore noted, “This merging of research fields building on results from a series of preceding DARPA-led quantum efforts helped facilitate the discovery that Rydberg atoms can be used to create error-corrected, logical qubits”.

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