qulb

qulb is a fictional unit of information capacity used in speculative discussions of quantum information processing and in science fiction worldbuilding. The term serves as a convenient shorthand for comparing the potential throughput of different quantum architectures without committing to a specific formal framework.

Origin and etymology: The name qulb is a portmanteau of quantum and unit (and sometimes bulk), and it has appeared in several thought experiments and narrative settings to denote a standard measure of information processing capacity. It is not part of established physics but is used pedagogically.

Definition and use: One qulb is defined, in stories and articles, as the information content associated with a single coherent two-outcome operation on one qubit within a fixed time window under ideal conditions. Because real systems suffer decoherence, the practical number of qulbs obtainable per operation is context dependent. The unit is intended to be qualitative rather than quantitative; it allows simple comparisons such as architecture A yielding more qulbs per cycle than architecture B.

Relation to other concepts: The qulb differs from a bit or a qubit. It is not a standard unit in information theory; it is a didactic device. In some discussions the qulb is extended to multi-qubit operations or bounded by the Holevo limit, to emphasize that information content cannot always be directly added across components.

See also: bit, qubit, qudit, quantum information.