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 more than 4,400 qubits, the system is aimed at applications such as resource scheduling, supply chain optimization, transportation planning, and materials science. —Neetika Walter, Interesting Engineering, 28 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

Willow was able to reduce errors exponentially by using more qubits and perform a standard benchmark computation in under 5 minutes that would take one of today’s fastest supercomputers 10 septillion years, the report said. —Pia Singh, CNBC, 19 Jan. 2026

These groups of physical qubits encoding one qubit’s worth of information are known as logical qubits. —IEEE Spectrum, 23 Dec. 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