Entanglement-assisted quantum logic gates for two remote qubits

Jing Mang Xu, Shou Zhang, 연규황 +1 more

Ming‐Xing Luo, Yun Deng, Xiaojun Wang

Distributed quantum computation requires that quantum operations may be acted on remote logical qubits. We investigate the possibility of the distributed quantum computation for nonlocal photons assisted by cavity quantum electrodynamics. We first give a compact circuit for the controlled-NOT gate on a remote two-photon system. For the Toffoli gate, we introduce two circuits for a bipartite system with one photonic Einstein-Podolski-Rosen (EPR) entanglement. Two EPR pairs are required for a tripartite system. These Toffoli gates cost a half of entanglements required in the previous teleportation-based quantum computation. These elementary gates may be combined flexibly up to special decompositions of joint system in large-scale quantum applications.

Schmidt-Kaler, Haffiier, Riebe +7 more

Liu‐Yong Cheng, Hong‐Fu Wang, Shou Zhang +1 more

We propose two effective schemes for local and remote unknown atomic state comparisons with a cavity-assisted single photon input—output process without any initial entanglement or auxiliary resource. The unambiguous state discrimination is considered using the state comparison process as the basic module. All the implementation schemes here just involve common quantum logic gates and the single qubit measurement. The analysis shows that our schemes are feasible under the current experimental conditions.

Yan‐Ling Li, Mao-Fa Fang, Zeng Ke

A scheme, based on the two two-level atoms resonantly driven by the classical field separately trapped in two cavities coupled by an optical fibre, for the implementation of remote two-qubit gates is investigated. It is found that the quantum controlled-phase and swap gates can be achieved with the assistance of the classical field when there are detunings of the coupling quantum fields. Moreover, the influence of the dissipation of the cavities and the optical fibre is analysed while the spontaneous emission of the atoms can be effectively suppressed by introducing λ-type atoms.

Svetoslav S. Ivanov, Nikolay V. Vitanov