kubit

Kubit is a term used in certain contexts to denote a unit of quantum information, analogous to the qubit. It is not a standard term in established quantum information science, where the accepted unit is the qubit. In those discussions, a kubit is typically defined as a two-level quantum system, with orthonormal basis states |0> and |1>, and a general state written as α|0> + β|1>, where α and β are complex amplitudes and |α|^2 + |β|^2 = 1. Like a qubit, a kubit can be prepared in superposition and subjected to quantum gates, and the state can be entangled with other kubits in multi-kubit systems. Measurement in the computational basis yields outcomes 0 or 1 with probabilities |α|^2 and |β|^2, respectively.

In practice, the kubit concept is informal and mostly used in educational or speculative contexts; some authors adopt the term to avoid implying the formal status of qubits, or as part of fictional narratives. When used, the mathematics aligns with that of standard qubits, and the Hilbert space for n kubits has dimension 2^n.

There is no official standardization of kubits; the term's usage varies by author or project. In scholarly literature and technical discussions, qubit remains the conventional unit of quantum information.

See also: Qubit, Quantum information, Quantum computation, Entanglement, Quantum state.