Quantum Circuit’s ‘Lego-Block-Like Approach’ Could Be Key to Quantum Computing

(TechnologyReview) All manner of equipment, from super-accurate lasers to supercooled refrigerators, is needed to harness the exotic forces of quantum mechanics for the task of processing data. The big challenge facing the nascent industry is to create machines that can be scaled up both reliably and relatively cheaply. Generating and managing the quantum bits, or qubits, that carry information in the computers is difficult. The most common response has been to create quantum computers with as many qubits as possible on a single chip. The problem is, the error rates are extreme.
Robert Schoelkopf, a professor at Yale, thinks there’s a better way forward. Instead of trying to cram ever more qubits onto a single chip, Quantum Circuits, a startup he cofounded in 2017, is developing what amount to mini quantum machines. The idea of bolting together smaller quantum building blocks to create bigger computers has been around for years, but it’s never quite caught on.
Quantum Circuits’ approach is very different from that standard. The core of its system is a small aluminum module containing superconducting circuits that are made on silicon or sapphire chips. Each module contains what amounts to five to 10 qubits. The company uses quantum teleportation to network these modules together.
Schoelkopf says there are several reasons that networking modules together is better than cramming as many qubits as possible onto a single chip. Quantum Circuits’ modular machines will still need some of the same gear as rival ones, including the supercooling refrigerators and monitoring gear.
Author Martin Giles suggested a comparison to Lego blocks Quantum Circuit’s approach. Schoelkopf was initially a little wary but then became quite enthusiastic. “In general, every complex device I know,” he said, “is based on having the equivalent of Lego blocks, and you define the interfaces and how they fit together …[Lego bricks] are really cheap. They can be mass-produced. And they always plug together the right way.”