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

With enough qubits, a quantum computer could theoretically vastly outperform all classical computers on a number of applications. —IEEE Spectrum, 6 Feb. 2025

Real-time error correction is especially important for quantum computers built using qubits made from superconducting materials, as these circuits can only remain in a stable quantum state for brief fractions of a second. —Jeremy Kahn, Fortune, 26 Nov. 2024

Quantum computing has also been boosted by investor interest in artificial intelligence, the technology that’s led to surging demand for Nvidia’s graphics processing units, which use conventional transistors instead of qubits. —Kif Leswing, CNBC, 8 Jan. 2025

What is more straightforward are the modes of conveyance of qubits from one place to another. —Lucas Laursen, IEEE Spectrum, 6 Jan. 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