Chad Rigetti, the man helping build the UK's first quantum computer

There are some technologies which promise so much, that we return to them time and again, despite myriad failures.

Like serially rebuffed suitors, researchers into nuclear fusion or artificial general intelligence (AGI) keep picking themselves up, hoping that one day, all their dreams will become true.

Sometimes it takes a decade after a particularly big disappointment for optimism to reassert itself, and for investors to forget the unmet deadlines and broken vows of old. But it always happens. The prospect of mastering one of that tiny number of truly world-changing technologies is just too alluring to give up. This time, everyone thinks, things will be different.

So it is with quantum computing. 

Since the late 1970s, scientists have understood that by harnessing the weird-but-true properties of subatomic particles, like electrons, as described by quantum theory, a new breed of computers could be made far more powerful than traditional machines which rely on silicon chips.

In 1981, the celebrated physicist Richard Feynman gave a speech imagining just such a computer. “It's not a Turing machine,” he noted, referring to the definition of “classical” computers set out by Alan Turing in 1936. “But a machine of a different kind.”

Now, after 40 years of trying to make practical reality live up to quantum theory, Britain is getting its first of this different kind of machine. And the man tasked with delivering it is Chad Rigetti.

The UK's first commercial quantum computer

Rigetti is founder of Rigetti computers, which has just been announced as the leader of the £10m, three-year project, co-funded by government and industry, to build the quantum computer in Abingdon, Oxford.

The square-jawed, Canadian-born physicist now based in California, is understandably evangelical about quantum computing’s potential: “I believe it’s an extremely valuable and important technology, to governments and nations around the world”. Its revolutionary power, he says, makes it a “node technology” - an enabler which will unleash dozens of other branches of endeavour.

“The countries that really have leading edge efforts in making quantum computing practical give themselves the seeds of an innovation hub akin to Silicon Valley,” he says. “It's critical to nations that view technology-driven economic development as a core part of their national strategy.”

That certainly seems to chime with the Dominic Cummings agenda. Indeed, announcing the Rigetti deal, Science minister Amanda Solloway declared the government’s ambition “to be the world’s first quantum-ready economy, which could provide UK businesses and industries with billions of pounds worth of opportunities.”

Yet UK government interest in quantum did not arrive with Mr Cummings. Concerted investment has been underway since 2014, with the inception of the National Quantum Technologies Programme. Last summer, combined public and private investment since then reached £1bn - “keeping pace,” the government insisted, “with the US and China”.

Not quite. State funding alone in the US over five years from 2018, is $1.2bn, but that’s without the billions invested by leading companies, notably IBM, Honeywell and Google. And while China’s initial investment in its own National Laboratory for Quantum Information Sciences is just over $1bn, some analysts expect it to hit more than $10bn in the next decade. Worldwide, consultants Qureca estimate $22bn has been committed to quantum research.

That is a significant amount, especially for a technology which has, to put it politely, doubters. “It’s really hard,” Rigetti says of building quantum computers. “And really, really advanced technology, when it’s continually pioneering, I think, will always face a lot of scepticism.”

Hype vs reality

Like a souffle, quantum speculation when overdone is subject to a hope-hype-flop cycle. That can be seen in Rigetti’s valuation at various stages of fundraising in its seven year existence. Its 2014 seed round, according to Pitchbook, valued it at £15m; just three years later investors took stakes which put its worth at £313m. Last month, however, investors acquired 57pc of the company for just £62m,valuing it at just £101m.

Part of the problem, thinks Rigetti, is that while other “deep tech” problems - like AGI - are easily comprehensible if tricky to realise, quantum technology upsets our very perception of reality.

In classical computers, a flow of electrons creates a current which switches transistors, usually made from silicon, on or off. Astonishing advances in engineering means tens of billions of transistors can now be packed onto a single microchip. But each transistor still exists in this state - on or off, one or zero - known as a “bit” (or binary digit), which is the smallest unit of data in a computer.

Quantum computers, on the other hand, rely on qubits, where electrons exist in “superposition” - on or off, or something in between. Not only this, but these qubits can be “entangled” with each other, creating exponential growth in computing power.

Even Einstein was fazed by the weirdness of such phenomena. He called entanglement, which links particles instantly over huge distances, suggesting a faster-than-light connection, “spooky action at a distance”. And one explanation for superposition, where particles exist in multiple states until they are observed, is that multiple states are required for multiple universes - a “multiverse” where multiple realities exist concurrently.

Such boggling concepts, Rigetti admits, are a problem for serious quantum research because “there's still a bit of a view that quantum mechanics is magic versus a rigorous mathematical theory that thoroughly and completely describes how the universe operates. But it's not magical. It works, like Newton's laws work. And we don't find those particularly magical anymore. Though I'm sure at one point, the notion that there is an attractive force between the moon and the Earth did feel quite magical.”

Still, there are many mathematicians unfazed by the complexities who still believe useful quantum computers are not so much magical, as an illusion.

The trouble is that controlling qubits is dauntingly hard. It is not just about the flow of electrons, as in silicon transistors, but their spin. And quantum states are fragile, prone to be knocked-off true by environmental “noise”, and delivering error-laden results. Stabilising qubits, and correcting for errors, are two major challenges.

Whether these can ever be overcome to enable computers powered by chains of millions of entangled qubits is open to question. IBM’s current champion has just 65 qubits, though this week it promised a 1,000 qubit machine by 2023. By the end of the decade it promises to push that to 1 million.

Rigetti says his own company has “built real hardware, real computers, that are true gate model quantum computers” and has progressed to an error-prone if promising state known in the business as “noisy intermediate-scale quantum computing”.

The future, he says, has “an immense possibility to deliver substantial end-user value”. By contrast, an anonymous poster, claiming to be a former “quantum engineer” on the employee review site Glassdoor, describes working at Rigetti as “a very humbling experience in this age of techno hubris.

“Chad,” the post continues, “is quite unhinged and enjoys the privilege of indefinitely suspending reality.”

From Netflix... to the military

The UK consortium which Rigetti leads shows how far there is to go. Its partner Oxford Instruments will supply state of the art refrigeration needed; a start-up called Phasecraft will develop the entirely new kind of algorithms required to put qubits to work; and the University of Edinburgh will be developing ways to test and verify both this new hardware and software.

Standard Chartered Bank is the only industry outsider - it is looking to harness quantum computing to get an edge in finance. But the hope - and Rigetti’s business model - is that countless such companies will ultimately pay to access quantum computing’s power, just as they do today to access cloud computing services run by Amazon, Google, Microsoft and others.

In the near term, which he defines as “three-to-five” years, Rigetti hopes the technology will make dramatic impact in three principal arenas: molecule discovery - which could aid the development of new drugs and new materials - machine learning, and process optimisation for organisations “from Netflix… to the military”.

Each depends on specific advantages that quantum offers over classical computing: subatomic manipulation; uncertainty, and brute computing power respectively.

Last year, in a very specific, abstruse, experiment, Google for the first time claimed its machine, named “Sycamore” had demonstrated “quantum supremacy” by solving a problem in a few seconds which would have taken a classical supercomputer 10,000 years. And last month, the US tech giant used Sycamore to do something far more practical - simulate a chemical reaction.

It all amounts, say IBM, to “an inflection point” for quantum computing, “a milestone that marks our ability to implement error correction and scale up our devices.”

Of course, sceptics will say they have heard it all before. Even Chad Rigetti concedes that, frankly, only seeing will be believing.

“Quantum computing thoroughly tests the laws of quantum physics every time you send an instruction to it. To build computers, you have to completely master that underlying physical theory. And that's what's happening. As we do that, that will lead to a demystification. In the next generation or two, quantum computing will feel much more natural and straightforward.”

In other words the “magic” will be dispelled. Or the illusion will be exposed.