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

Fabricating the qubit on a silicon substrate was technically very challenging, but the Princeton team persisted and finally succeeded in overcoming the technical hurdles. —Ameya Paleja, Interesting Engineering, 17 Dec. 2025

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

The two possible spins of the quarks correspond to the 0 and 1 states of a qubit, a unit of quantum information. —Shalma Wegsman, Quanta Magazine, 25 Nov. 2025

Classical computers use bits, and quantum computers use quantum bits, called qubits. —Jyssica Schwartz, IEEE Spectrum, 19 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