SIAM Journal on Computing
Quantum computation and quantum information
Quantum computation and quantum information
Computational complexity of uniform quantum circuit families and quantum Turing machines
Theoretical Computer Science
Succinct quantum proofs for properties of finite groups
FOCS '00 Proceedings of the 41st Annual Symposium on Foundations of Computer Science
Classical and Quantum Computation
Classical and Quantum Computation
Toward a quantum process algebra
Proceedings of the 1st conference on Computing frontiers
Towards a quantum programming language
Mathematical Structures in Computer Science
On Halting Process of Quantum Turing Machine
Open Systems & Information Dynamics
A lambda calculus for quantum computation with classical control
TLCA'05 Proceedings of the 7th international conference on Typed Lambda Calculi and Applications
Partial Observation of Quantum Turing Machines and a Weaker Well-Formedness Condition
Electronic Notes in Theoretical Computer Science (ENTCS)
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It is reasonable to assume that quantum computations take place under the control of the classical world. For modelling this standard situation, we introduce a Classically controlled Quantum Turing Machine (CQTM), which is a Turing machine with a quantum tape for acting on quantum data, and a classical transition function for formalised classical control. In a CQTM, unitary transformations and quantum measurements are allowed. We show that any classical Turing machine can be simulated by a CQTM without loss of efficiency. Furthermore, we show that any $k$-tape CQTM can be simulated by a 2-tape CQTM with a quadratic loss of efficiency. In order to compare CQTMs with existing models of quantum computation, we prove that any uniform family of quantum circuits (Yao 1993) is efficiently approximated by a CQTM. Moreover, we prove that any semi-uniform family of quantum circuits (Nishimura and Ozawa 2002), and any measurement calculus pattern (Danos et al. 2004) are efficiently simulated by a CQTM. Finally, we introduce a Measurement-based Quantum Turing Machine (MQTM), which is a restriction of CQTMs in which only projective measurements are allowed. We prove that any CQTM is efficiently simulated by a MQTM. In order to appreciate the similarity between programming classical Turing machines and programming CQTMs, some examples of CQTMs are given.