Skip to Content

Desultory D-Wave

D-Wave may not have made a working quantum computer.

D-Wave, a startup in Burnaby, British Columbia, claims to have demonstrated a working prototype of what it says will become the world’s first “commercially viable” quantum computer. But as even its supporters admit, the company has a severe credibility problem in the scientific community (see “Riding D-Wave”). In looking at its claims, I think it’s helpful to ask three questions.

First, what has D-Wave actually built? Second, even if D-Wave has built a quantum computer, is there any realistic possibility of scaling it up to hundreds or thousands of quantum bits (or “qubits”) in a few years–as D-Wave has repeatedly promised it will do, and as would be necessary to solve any practical problems? Finally, if D-Wave has built a scalable device, what problems can it solve more quickly than existing computers can?

Physicists tend to doubt D-Wave’s claims because it has presented no convincing evidence that its current device is quantum-mechanical. As far as any outsider knows, all D-Wave has produced is an extremely expensive and inefficient classical computer with a grand total of 28 bits. By its own admission, D-Wave has not yet demonstrated quantum “entanglement” between even two qubits. (Entanglement is a quantum form of correlation between two or more qubits; all parties agree that it is a non-negotiable requirement for quantum computing.)

Among computer scientists, another source of skepticism is that D-Wave has misled the public about what quantum computers might be able to do if we had them. In particular, D-Wave’s publicity materials talk cavalierly about using its machine to solve what are known as NP-complete problems. These problems (of which the best-known example involves determining the shortest route for a traveling salesman visiting a number of cities) are important because they are common and are thought to be intractable for any computer today. However, almost all computer scientists also believe that these problems cannot be efficiently solved using a quantum computer. We have no good evidence that quantum computers–D-Wave’s or anyone else’s–could find even approximate solutions much faster than a classical computer in cases of practical interest.

Let me be clear: I think that quantum computers are possible in principle, and that D-Wave’s approach might even get us there. I’ve also met people from D‑Wave; I don’t think they’re frauds. But the human capacity for self-deception being what it is, scientists train themselves to look for red flags–and D-Wave is pretty much a red-flag factory.

Scott Aaronson is an assistant professor in MIT’s Department of Electrical Engineering and Computer Science.

Keep Reading

Most Popular

A Roomba recorded a woman on the toilet. How did screenshots end up on Facebook?

Robot vacuum companies say your images are safe, but a sprawling global supply chain for data from our devices creates risk.

A startup says it’s begun releasing particles into the atmosphere, in an effort to tweak the climate

Make Sunsets is already attempting to earn revenue for geoengineering, a move likely to provoke widespread criticism.

10 Breakthrough Technologies 2023

Every year, we pick the 10 technologies that matter the most right now. We look for advances that will have a big impact on our lives and break down why they matter.

These exclusive satellite images show that Saudi Arabia’s sci-fi megacity is well underway

Weirdly, any recent work on The Line doesn’t show up on Google Maps. But we got the images anyway.

Stay connected

Illustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at customer-service@technologyreview.com with a list of newsletters you’d like to receive.