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

Researchers have theoretically demonstrated that integrating tiny quantum batteries directly into a system can quadruple its qubit capacity. —Mrigakshi Dixit, Interesting Engineering, 29 Jan. 2026

This interaction also causes the state of the noise qubits to change, which is why the key can only be used once. —IEEE Spectrum, 25 Jan. 2026

Engineering challenges, including qubit coherence and error correction, could postpone D-Wave’s commercialization timelines and weaken its competitive edge. —Trefis Team, Forbes.com, 21 Jan. 2026

There's one big issue with quantum computers though: most qubits need to be kept at ultracold temperatures just above absolute zero in order to function correctly. —New Atlas, 28 Nov. 2025

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