IBM adopts heavy-hex lattice for quantum computing

One of the pioneers of modern quantum computing is making a major architectural change. IBM is moving all of its IBM Quantum computing devices to the heavy-hex lattice topology, which promises a reduction in error rates, allowing quantum systems to overcome one of the key challenges keeping them from maximizing their potential.

As of August 8, all IBM Quantum systems will be based on this architecture, which represents the fourth iteration in the company’s quantum computing topology. Heavy-hex lattice also is the basis for IBM’s new Quantum System One Falcon and Hummingbird quantum processor architectures in use in systems in Germany and Japan. IBM announced the move in a blog post this week.

In a heavy-hex lattice architecture, “each unit cell of the lattice consists of a hexagonal arrangement of qubits, with an additional qubit on each edge,” the post stated. It’s scalable, which will help IBM meet its stated goal of advancing from 127 qubits in quantum computing systems this year to 1,000 qubits in 2023.

But, perhaps even more significant is the promise of reduced error rates in the new architecture. Accuracy of quantum computations has been cited by sector experts as a major hurdle to the advancement of quantum computers and their ability to overtake classical computers in solving many practical problems. IBM itself said as much in a paper published in September 2020 on the viability of heavy-hex lattice.

IBM described the heavy-hex topology as “a product of co-design between experiment, theory, and applications, that is scalable and offers reduced error-rates while affording the opportunity to explore error correcting codes. Based on lessons learned from earlier systems, the heavy-hex topology represents a slight reduction in qubit connectivity from previous generation systems, but, crucially, minimizes both qubit frequency collisions and spectator qubit errors that are detrimental to real-world quantum application performance.”

IBM last month delivered a Quantum System One to German research group Fraunhofer-Gesellschaft, a move which marked the first deployment of an IBM quantum computer outside of a U.S. data center. The company followed up with a deployment in Japan, and soon will have one located at the Cleveland Clinic, based on a partnership announced earlier this year.

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