NMR experimental realization of seven-qubit DJ algorithm and controlled phase-shift gates with improved precision

Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Chinese Academy of Sciences, Peping, Beijing, China
Chinese Science Bulletin (Impact Factor: 1.37). 02/2003; 48(3):239-243. DOI: 10.1007/BF03183290

ABSTRACT In this study, we report the experimental realization of seven-qubit Deutsch-Jozsa (D-J) algorithm and controlled phase-shift
gates with improved precision using liquid state nuclear magnetic resonance (NMR). The experimental results have shown that

in the seven-qubit D-J algorithm have been implemented with different pulse sequences, and whetherf is constant or balanced is determined by using only a single function call (U

). Furthermore, we propose an experimental method to measure and correct the error in the controlled phase-shift gate that
is simple and feasible in experiments, and can have precise phase shifts. These may offer the possibility of surmounting the
difficulties of low signal-to-noise ratio (SNR) in multi-qubit NMR quantum computers, more complicated experimental techniques,
and the increase of gate errors due to using a large number of imperfect selective pulses. These are also applied to more
complicated quantum algorithms with more qubits, such as quantum Fourier transformation and Shor’s algorithm.

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