arXiv subjects

Xianping Sun

Publications and source records attributed to Xianping Sun.

4 recordsLinked to original sources

arXiv2004

Realization of decoherence-free subspace using Multiple-Quantum coherences

This letter presents a two-dimensional nuclear magnetic resonance(NMR) approach for constructing a two-logical-qubit decoherence-free subspace (DFS) based on the fact that the three protons in a CH3 spin system can not be resolved in one-dimension NMR spectroscopy, but to a certain extent, can be distinguished by two-dimensional multiple-quantum NMR. We used four noisy physical nuclear spins, including three protons and one carbon in the CH3 spin system, to generate two decoherence-free logical quantum bits. It made full use of the unaddressed spins which could not be used in one-dimensional spectrum. Furthermore, we have experimentally demonstrated such an approach. Our experimental results have shown that our DFS can protect against far more types of decoherence than the one composed of four noisy physical qubits all with different chemical shifts. More importantly, this idea may provide new insights into extending qubit systems in the sense that it effectively utilizes the magnetically equivalent nuclei.

quant-ph↗

arXiv2003

NMR experimental realization of seventh-order coupling transformations and the seven-qubit modified Deutsch-Jozsa algorithm

We propose a scalable method on the basis of nth-order coupling operators to construct f-dependent phase transformations in the n-qubit modified Deutsch-Jozsa (D-J) quantum algorithm. The novel n-qubit entangling transformations are easily implemented via J-couplings between neighboring spins. The seven-qubit modified D-J quantum algorithm and seventh-order coupling transformations are then experimentally demonstrated with liquid state nuclear magnetic resonance (NMR) techniques. The method may offer the possibility of creating generally entangled states of n qubits and simulating n-body interactions on n-qubit NMR quantum computers.

quant-ph↗

arXiv2001

Quantum Computation Based on Magic-Angle-Spinning Solid State Nuclear Magnetic Resonance Spectroscopy

Magic-angle spinning (MAS) solid state nuclear magnetic resonance (NMR) spectroscopy is shown to be a promising technique for implementing quantum computing. The theory underlying the principles of quantum computing with nuclear spin systems undergoing MAS is formulated in the framework of formalized quantum Floquet theory. The procedures for realizing state labeling, state transformation and coherence selection in Floquet space are given. It suggests that by this method, the largest number of qubits can easily surpass that achievable with other techniques. Unlike other modalities proposed for quantum computing, this method enables one to adjust the dimension of the working state space, meaning the number of qubits can be readily varied. The universality of quantum computing in Floquet space with solid state NMR is discussed and a demonstrative experimental implementation of Grover's search is given.

quant-ph↗

arXiv2001

Experimental realization of 7-qubit universal perfect controlled-NOT and controlled square-root NOT gates

The controlled-NOT gate and controlled square-root NOT gate play an important role in quantum algorithm. This article reports the experimental results of these two universal quantum logic gates (controlled square-root NOT gate and controlled-NOT gate) on a 7-qubit NMR quantum computer. Further, we propose a simple experimental method to measure and correct the error in the controlled phase-shift gate, which is helpful to construct a more perfect phase-shift gate experimentally and can also be used in more qubits discrete Fourier transformation.

quant-ph↗