qubit

noun

qu·​bit ˈkyü-bət 

plural qubits

: a unit of computing information that is represented by a state of an atom or elementary particle (such as the spin) and can store multiple values at once due to the principles of quantum mechanics

And the most basic truth of quantum mechanics dictates that you cannot measure a qubit without destroying the superposition. The register that said 1 and 0 will randomly collapse into 1 or 0.

—George Johnson

compare bit entry 3 sense 1

Examples of qubit in a Sentence

Recent Examples on the Web

Google estimated that such systems would require 500,000 physical qubits, half of what the same team estimated last June was needed to break 2048-bit RSA. —Stephen Clark, ArsTechnica, 17 Apr. 2026

Quantum computers encode information in qubits, described by IBM as the equivalent in a way of the traditional bit used in old-fashioned computers to encode data in binary. —Adam Harrington, CBS News, 16 Apr. 2026

Using a technique called Bell-state measurement, the two qubits allowed simultaneous measurements of three parameters. —Ameya Paleja, Interesting Engineering, 15 Apr. 2026

The problem is, anyone who has wanted to simultaneously control millions of a certain kind of qubits has run into the problem of trying to control millions of laser beams. —IEEE Spectrum, 9 Apr. 2026

Word History

Etymology

qu- (in quantum entry 2) + bit entry 4, probably formed with punning allusion to cubit

Note: According to the American physicist Benjamin Schumacher, in the acknowledgments to a paper ("Quantum coding," Physical Review A, vol. 51, issue 4 [April, 1995], p. 2747), "The term 'qubit' was coined in jest during one of the author's many intriguing and valuable conversations with W. K. Wootters, and became the initial impetus for this work."

First Known Use

1994, in the meaning defined above

Rhymes for qubit

• cubit