IBM boasts ‘utility scale’ in quantum chips

• Tech giant claims to have achieved ‘utility scale’ in quantum chips with Heron
• It has developed new ways to connect quantum processors to each other inside quantum machines and then chain the machines together
• It will add new error-correction and enhanced fault-tolerance systems to produce quantum computers by 2033

IBM has unveiled Heron, the latest iteration in its ongoing series of quantum computing processing units (QPUs), at the Quantum Summit 2023, its annual quantum computing conference.

The device has 133 qubits (a qubit being a basic unit of quantum information, the equivalent of a bit in classic computing) – that is six qubits more than its predecessor Eagle. It is the biggest (in terms of qubit count at least) that IBM has yet developed and, thus, the company says, is “the world’s most advanced gate-based, superconducting quantum system”.

Well, perhaps for now. The international race to dominate the global quantum computing market will be an R&D marathon but, as yet, even the leaders of the pack, IBM, Microsoft, Google and Baidu of China, have barely broken a sweat.

A quantum computing chip serves as the processor for quantum computers. It contains quantum bits (qubits) which, thanks to the phenomenon of superposition, can have a value of 0 or 1 or both 0 and 1 simultaneously. This property confers the ability to process algorithms, data and equations massively more rapidly than even the fastest supercomputers based on classical computing architecture and silicon technology.

IBM says that Heron delivers a fivefold improvement in error rates compared to Eagle and has succeeded in achieving “utility scale” whereby, via a collection of tools and its architecture, can easily map problems that would take classical computers years to solve, optimise them to quantum circuits, execute those circuits and then post-process the results, thus enabling high performance with low error rates.

The company has also introduced Quantum System Two, IBM’s first modular quantum computer cluster, powered, in the first instance, by three Heron processors. This is the substructure of IBM’s quantum-centric supercomputing architecture that it will use in production.

Quantum System Two is housed in the US, in a facility in Yorktown Heights, up the Hudson River from New York City. We know little more about it other than it is 15 feet tall and stands quite still for at least 99% of the time – a bit like a giant heron, in fact. It does, though, need cryogenic cooling to operate, which herons do not, given that they spend most of their lives knee-deep in very cold water and are inured to it.

 IBM is at pains to point out that Quantum System Two will feature a total of 399 ‘local’ qubits – the qubit count is important, given that qubit quality and coherence have a profound impact on how quantum computers perform. That’s why, says IBM, it is focusing on maximising the size of quantum circuits. To that end, the company claims that, by the end of next year, each Heron processor will be capable of executing 5,000 operations in a single quantum circuit.

Given that System Two is a modular design for quantum computers yet to come, it is forward compatible with later QPU designs and, it seems, part of the plan is for IBM to concentrate on circuit size in the medium-term future, from now to 2028.

Qubit count isn’t so much a measure of power or computing capability as it is potential. Certainly, the more qubits available the more powerful and capable a quantum system should be – or so says the theory. However, errors propagate very easily, and fault tolerances are low in current systems, which is why some developers are now turning their attention to mitigating such effects rather than simply focusing on providing more and more qubits.

Thus, IBM is seeking ways to increase the number of quantum gates that processors can manage efficiently. That’s because gates, too, are very important indicators of the efficiency of a quantum system: The more gates a processor can implement, the more complex functions can be performed by the system itself. Hence the nascent Blue Jay system that, it is planned and hoped, will be able to execute 1 billion gates across 2,000 qubits per chip by 2033.

Obviously, in a safe somewhere in a secret location, IBM has a list of bird names deemed suitable to be borrowed to identify generations of its quantum processors and machines. We know about Eagle, Flamingo, Starling, Blue Jay and others, but hopefully those that pick the names have seeded out reference to the likes of the passenger pigeon (that went extinct in 1914) and the Dodo (the last one of which was wandering disconsolately around the island of Mauritius in 1662.) Picking one of those names would give quite the wrong message, as would the Ancient Mariner’s albatross...

 - Martyn Warwick, Editor in Chief, TelecomTV