Fast preparation method of effective pure states for NMR-quantum computer with controlled-not gates

摘要

A fast method to prepare effective pure states for NMR-quantum computer in homo-nuclear spin system is proposed. The temporal averaging method has been introduced to prepare an effective pure state in NMR-quantum computer, but the method requires many experiments, whose number increases exponentially with the number of quantum bits (qubits), and it seems that a huge number of logical gates are required. The proposed method avoids this problem by eliminating a part of elements in the density matrices. This method requires only one ancillary qubit and two different experiments; the steps have been confirmed to be proportional to the number of qubits up to four-qubit. (C) 2004 Wiley Periodicals, Inc.