Zhiheng Lu

Simulation of Heisenberg XY interactions and realization of a perfect state transfer in spin chains using liquid nuclear magnetic resonance

The three-spin chain with a Heisenberg XY interaction is simulated in a three-qubit nuclear magnetic resonance quantum computer. The evolution caused by the XY interaction is decomposed into a series of single-spin rotations and the J-coupling evolutions between the neighboring spins. The perfect state transfer algorithm proposed by Christandl et al.[Phys. Rev. Lett. 92, 187902 (2004)] is realized in the XY chain.

Nuclear magnetic resonance implementation of a quantum clock synchronization algorithm

The quantum clock synchronization (QCS) algorithm proposed by Chuang [Phys. Rev. Lett. 85, 2006 (2000)] has been implemented in a three qubit nuclear magnetic resonance quantum system. The time difference between two separated clocks can be determined by measuring the output states. The experimental realization of the QCS algorithm also demonstrates an application of the quantum phase estimation.

Modularization of a multi-qubit controlled phase gate and its nuclear magnetic resonance implementation

A quantum circuit network is a set of circuits that implements a certain computation task. Being at the centre of the quantum circuit network, the multi-qubit controlled phase shift is one of the most important quantum gates. In this paper, we apply the method of modular structuring in classical computer architecture to the quantum computer and give a recursive realization of the multi-qubit phase gate. This realization of the controlled phase shift gate is convenient in realizing certain quantum algorithms. We have experimentally implemented this modularized multi-qubit controlled phase gate in a three-qubit nuclear magnetic resonance (NMR) quantum system. The network is demonstrated experimentally using line selective pulses in the NMR technique. The procedure has the advantage of being simple and easy to implement.

Synthesizing NMR analogs of Einstein-Podolsky-Rosen states using the generalized Grover’s algorithm

By designing a proper unitary operator U, we synthesize nuclear-magnetic-resonance (NMR) analogs of Einstein-Podolsky-Rosen (EPR) states (pseudo-EPR states) using the generalized Grovers algorithm on a NMR quantum computer. Experiments also demonstrate the generalized Grovers algorithm for the case in which there are multiple marked states.

Realization of generalized quantum searching using nuclear magnetic resonance

According to the theoretical results, the quantum searching algorithm can be generalized by replacing the Walsh-Hadamard transform by almost any quantum-mechanical operation. We have implemented the generalized algorithm using nuclear magnetic resonance techniques with a solution of chloroform molecules. Experimental results show a good agreement between the theory and experiment.