 Although cellular automata have been shown to describe many aspects of fundamental physics, it is difficult to see how to simulate the quantum mechanical features of the universe using a classical formalism such as cellular automata (Feynman 1982). This concern motivated the development of quantum computing formalisms (Deutsch 1985, Nielsen and Chuang 2000). Instead of relying on digits—most commonly, binary digits or bits—quantum computation relies on qudits—most commonly, binary qudits or qubits. The main difference between a digit and a qudit is that whereas a digit can take only one out of finitely many states, such as 0 and 1 (in the case of a bit), a qudit can also take an uncountable number of states that are a superposition of the basis states in varying degrees, such as superpositions of 0 and 1 (in the case of a qubit). Furthermore, unlike a collection of digits, a collection of qudits can exhibit quantum entanglement. According to the quantum version of ontic pancomputationalism, the universe is not a classical computer but a quantum computer—a computer that manipulates qubits (Lloyd 2006) or, more generally, qudits.