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 and Microsoft say a truly useful quantum computer will need 1 million qubits. —Kif Leswing, CNBC, 27 June 2025

In DeMarco’s lab, researchers make qubits from the spin of single atoms. —F.d. Flam, Twin Cities, 27 June 2025

Unlike classical computing, which processes data in binary bits, quantum computers use qubits that can exist in multiple states simultaneously. —David Henkin, Forbes.com, 25 June 2025

But if the masses are closer together, the energy capacity of each qubit drops, so the total energy has to be spread over more qubits. —George Musser, Quanta Magazine, 13 June 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 acknowledgements 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