Abstract
The continuous-time quantum walk on a one-dimensional graph of odd number of sites with an on-site potential at the center is studied. We show that such a quantum-walk system can construct an X-gate of a single qubit as well as a control gate for two qubits, when the potential is much larger than the hopping strength. We investigate the decoherence effect and find that the coherence time can be enhanced by either increasing the number of sites on the graph or the ratio of the potential to the hopping strength, which is expected to motivate the design of the quantum gate with long coherence time. We also suggest several experimental proposals to realize such a system.
Highlights
The quantum walk, proposed as the quantum mechanical counterpart of the classical random walk[1], has received increasing attentions in recent years due to its extensive potential application in many fields[2,3,4,5,6]
We further study the decoherence effect of the quantum gate constructed by the continuous-time quantum walk and show that such a decoherence effect can be suppressed by appropriately tuning the parameters of the quantum-walk system or increasing the number of sites on the graph, which enlightens one to optimize the capability of the quantum gate, such as the suppress of decoherence, the enhancement of fidelity in the quantum operation
We have investigated the dynamical properties of the continuous-time quantum walk of a particle in a one-dimensional graph of odd number of sites where the on-site potential at the central site differs from that at the other sites
Summary
The quantum walk, proposed as the quantum mechanical counterpart of the classical random walk[1], has received increasing attentions in recent years due to its extensive potential application in many fields[2,3,4,5,6]. We consider the continuous-time quantum walk of a single particle on the following one-dimensional graph. In order to construct quantum gates for a single qubit, it will be more illustrative to express (1) as follows
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