It is also possible to carry out quantum computing without qubits using processes with a continuous spectrum of measurement.
As of 2020, these approaches seem less developed/promising, but who knows.
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Continuous-variable (CV) quantum information refers to a framework in quantum information theory that utilizes continuous variables for encoding, processing, and transmitting quantum information. Unlike discrete variable systems, such as qubits, which can take on specific values (0 or 1), continuous-variable systems use quantities that can vary smoothly over a continuum. The most common examples of continuous variables are the position and momentum of a particle, as well as the quadratures of an electromagnetic field, such as the electric field amplitude.