0304061v5

related topics
{qubit, qubits, gate}
{measurement, state, measurements}
{states, state, optimal}
{state, phys, rev}
{algorithm, log, probability}
{let, theorem, proof}

Nonunitary quantum circuit

Hiroaki Terashima, Masahito Ueda

abstract: A quantum circuit is generalized to a nonunitary one whose constituents are nonunitary gates operated by quantum measurement. It is shown that a specific type of one-qubit nonunitary gates, the controlled-NOT gate, as well as all one-qubit unitary gates constitute a universal set of gates for the nonunitary quantum circuit, without the necessity of introducing ancilla qubits. A reversing measurement scheme is used to improve the probability of successful nonunitary gate operation. A quantum NAND gate and Abrams-Lloyd's nonlinear gate are analyzed as examples. Our nonunitary circuit can be used to reduce the qubit overhead needed to ensure fault-tolerant quantum computation.

oai_identifier:
oai:arXiv.org:quant-ph/0304061
categories:
quant-ph
comments:
19 pages, 6 figures; added a reference
doi:
10.1142/S0219749905001456
arxiv_id:
quant-ph/0304061
journal_ref:
Int.J.Quantum Inform. 3 (2005) 633-647
created:
2003-04-09
updated:
2005-04-06

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