IBM announced a revision of its (originally) 2020 quantum computing roadmap, bringing about a renewed focus in quantum computing scaling by doubling down on modularity and quantum-capable networking. In a day and age where delays are the norm, IBM's re-commitment to its quantum computing efforts instills confidence in the company's choice of framework, qubits, and software development, and it lead to the so-called quantum advantage sooner than expected.
IBM's roadmap showcases the benefits of modular scaling. Kookaburra seems to triple the number of interlinked quantum chips, from three chips deployed with Flamingo to Kookaburra's nine. It's clear that IBM still isn't sure where in the qubit count kingdom Flamingo will end up, but it seems to have established 1,386 qubits as the minimum density. Advances in error-correction could prove crucial here, as reducing the number of qubits in active error-correction duties is one surefire way of increasing "useful qubit" counts.
But how is this modularity achieved? IBM has to solve at least three problems. The first includes building systems able to classically communicate with and parallelize operations across multiple QPUs. The company expects its work in this field to bring about improvements in error correction while also accelerating quantum computing workload orchestration.
For that to happen, the company will have to get these QPUs connected and talking amongst themselves. To that end, IBM is developing chip-level couplers that enable short-range inter-chip communications — essentially an MCM (Multi-chip Module) approach to quantum. Much like AMD's rumored approach for its Radeon 7000-series, the aim is to have multiple smaller, easier to manufacture chips working in tandem as seamlessly and abstractedly as possible. Why ignore lessons earned from classical semiconductors?
The third component shifts focus toward full scalability by providing quantum communication links between individual quantum processors. This is the technology that will enable IBM to scale from a single Kookaburra-class chip (with its nine, MCM-like QPUs interlinked) to server-level scaling, by enabling multiple Kookaburra chips to be linked together. It's currently unclear which technologies IBM will be pursuing in this scaling push, but recent advances in quantum photonics place them as likely candidates.
All of these technologies and advancements are necessary if IBM wants to achieve its 2025 goal of packing 4,000+ qubits in a single QPU. The company knows it's in a breakneck race to ship and corner the quantum computing market with its chosen approach to quantum computing, and it has years of ecosystem building behind it. IBM is looking to first integrate its roadmap developments into its IBM Quantum System Two, which will serve as the showcase hardware and testing ground for the new technology.
It remains to be seen if IBM will be able to cross the finish line on the back of its quantum computing technologies. Microsoft is chasing a wholly different path with its search for the famed topological superconductor qubits, as are a number of other companies such as LiteOn, Ampere, Riggeti, and IonQ. And unlike superimposed quantum states, the market only allows for victors or losers.
