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

Achieving this level of reliability will require fault tolerance through redundant encoding of quantum information in logical qubits, each consisting of hundreds of physical qubits, thus requiring a total of about a million physical qubits. —Chi Chen, IEEE Spectrum, 2 Mar. 2026

Quantum computers do this by using quantum bits (qubits) in superposition. —Georgina Jedikovska, Interesting Engineering, 2 Mar. 2026

Five years ago, researchers estimated tens of millions of physical qubits would be needed to break 2048-bit RSA encryption. —Javier Bastardo, Forbes.com, 23 Feb. 2026

This allows quantum bits, or qubits, to perform the same calculations at vastly greater speeds. —Tessa McCann,april Roach, CNBC, 19 Feb. 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