Other attributes
The quantum Turing machine (QTM) is analogous to a classical Turing machine (TM) for quantum computing. Like the TM, the QTM is an abstract machine to model any quantum algorithm. However, several conceptual problems associated with the QTM remain unresolved.
The QTM was first described by David Deutsch in his 1985 article. The general concept describes the QTM as similar to the probabilistic Turing machine (PTM). However, instead of a real probability distribution defining the transition between states, the QTM uses complex transition amplitudes.
That is to say, rather than writing a 0 or 1 based on its machine state like in the TM, or writing a 0 or 1 based on real probabilities defined by the machine state like in the PTM, the QTM deals with qubits so it writes a complex superposition of states.
Unresolved conceptual problems remain regarding the universality, parallelism, and halting of the QTM.
