How Quantum Computing Works

BY PETER CHAMPELLI AND ISABELLE BOUSQUETTE

MICROSOFT,

International Business Machines, Alphabet’s Google and a host of other tech companies are in a race to disrupt the nature of computing.

Collectively in the U.S., these companies have spent hundreds of millions in the past few years to develop a new type of computer– known as a quantum computer– that leverages the principles of quantum physics to solve problems far beyond the capabilities of today’s best supercomputers.

And the companies say they could do it in the next two to five years.

When this point is reached, some problems that would take a traditional computer more than trillions of years to solve could take a quantum computer mere minutes, changing business as usual for industries involved with financial trading, shipping logistics, pharmaceuticals, scientific discovery, data encryption, insurance, internet delivery and more.

But building a quantum computer large enough to perform meaningful calculations is more complicated than just throwing a ton of qubits on a chip.

Qubits can be extremely sensitive to changes in their external environment that disturb their superpositioned state and introduce errors into a calculation. So companies need to not only scale up the number of qubits they have, but also make sure they’re doing it in a way where those qubits still behave.

The real scale of problems for quantum computers would involve hundreds of thousands of variables, not tens.

Quantum computers would have the capacity to be faster than traditional computers at optimization problems like analyzing supply chains, simulation problems like discovering new chemical combinations for drugs, machine learning and factorization.

Those last two categories could supercharge artificial intelligence, and could decode current encryption technology, requiring banks and other institutions to develop new methods of encryption.

Peter Champelli and Isabelle Bousquette are Wall Street Journal reporters in New York. Email them at peter.champelli@wsj.com and isabelle.bousquette@wsj.com.