Zero Genie

IBM scientists examine the inner workings of a quantum computer. The gold-colored cables resembling a chandelier are a common feature of quantum computers that use superconducting circuits. (IBM Research)

In a new story, we look at the intense competition between China and the United States to develop quantum technology, which is based on the field of quantum mechanics and holds the promise of transforming computers, surveillance and other aspects of modern society. Here are some basic questions and answers about the technology.

What is quantum technology?

Quantum technology, also known as quantum information technology, seeks to harness the peculiar laws of quantum mechanics to build more powerful tools for processing information. Scientists are using the technology to develop new kinds of computers and communications networks, and sensors for imaging and measuring things in novel ways.

What is quantum mechanics?

Quantum mechanics is a science that describes the unique behavior of matter and energy at the atomic and subatomic level. These particles don’t obey the laws of classical Newtonian physics. As legendary physicist Richard Feynman put it, “they do not behave like clouds, or billiard balls, or weights on springs, or like anything that you have ever seen.”

For example, they can be in “superposition,” meaning they can exist in multiple states at the same time. They can also exhibit “entanglement,” where two or more particles are inextricably linked and mirror each other exactly, even when separated by great physical distance. Einstein called this “spooky action at a distance.”

What is quantum computing?

A quantum computer uses quantum bits, or qubits, to process information in new ways. Qubits, which can be made of atoms or subatomic particles, behave according to the laws of quantum mechanics.

What makes a quantum computer different from a regular computer?

As Nobel laureate Bill Phillips said, quantum computers are as different from today’s digital computers as today’s computers are from an abacus. Existing computers store, process and transmit information by breaking it down into long streams of bits, which are typically electrical or optical pulses representing a zero or one.

Quantum bits, or qubits, can exist as zeros and ones at the same time, or in any position between, a flexibility that gives them the potential to perform many calculations simultaneously. Some physicists compare them to a spinning coin that is simultaneously in a heads and tails state.

Do quantum computers already exist?

Early prototypes do exist — IBM offers access to its online — but they are not yet more powerful than existing computers. Many companies, including Google, Microsoft, Intel, Rigetti and IonQ, are developing quantum computers. Universities and militaries in many countries are also investing in the research. (IonQ’s investors include AWS, a subsidiary of Amazon, whose founder, Jeff Bezos, owns The Washington Post.)

What hurdles do researchers face in developing a quantum computer?

To get a fully functioning computer — a goal still a decade or more away, most scientists agree — researchers must coax a large number of qubits into working together efficiently. That’s difficult because qubits are finicky and have the propensity to stop functioning at the slightest disturbance, such as a minor change in temperature.

What new feats might quantum computers be able to perform?

A fully functioning quantum computer has the potential to be transformative. The exponentially greater calculation power could help identify new chemical compounds to treat intractable diseases, and eliminate traffic snarls by predicting and managing the flow of vehicles.

However, the machines may also be able to crack all existing forms of encryption, which is a major worry for militaries, governments and businesses that handle sensitive data.