A new type of superconducting circuit has been developed by scientists at the University of California, Santa Barbara.
The circuit behaves along the principles of quantum mechanics, but has up to five levels of energy instead of the usual two and can only gain or lose energy in packets, or quanta, by jumping between discrete energy levels.
Matthew Neeley, a graduate student at the university, explained: "This is the quantum analogue of a switch that has several allowed positions, rather than just two.
"Because it has more energy levels, the physics of a qudit is richer than for just a single qubit."
Qubits could one day serve as the building blocks of a quantum computer and Neeley believes that his qudits could also be used to speed up certain computations even further.
Researchers at the university last year announced a breakthrough in the quantum control of photons believed to have implications in banking, drug design and other applications.