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Both photons and semiconductor quantum-dot (QD) spins are promising candidates for quantum information science and technology. It is of critical significance to realize high-fidelity quantum controlled gates on photon-spin hybrid systems. In this paper, based on the novel balance condition for the interaction between a single input photon and a singly charged QD embedded in an optical single-sided microcavity, we present three schemes for implementing three universal quantum controlled gates, i.e., the two-qubit controlled-NOT (CNOT) gate, the three-qubit Toffoli gate, and the three-qubit Fredkin gate, on composite hybrid quantum systems consisting of flying photons and QD-confined electron spins. By exploiting the balance condition, the noise caused by the unbalanced reflectance of the coupled and uncoupled QD-cavity systems can be efficiently suppressed, so that the fidelity of each quantum gate operation can be raised to unity in principle. The balance condition can be met without the strict requirement of strong coupling, making the high-fidelity quantum gates easier to be demonstrated in experiments. These features can improve the fidelity and feasibility of these schemes, which can be applied to large-scaled quantum computing and quantum information networks. [ABSTRACT FROM AUTHOR]

E-payment has gradually become the mainstream globally in recent years. However, the security and anonymity of the traditional E-payment system are not perfectly guaranteed with the emergence of the quantum computer. In this paper, an E-payment security evaluation system based on quantum blind computing is proposed for evaluating the security of network transactions. Unitary operations and four-qubit cluster state are applied in this system to effectively defend against eavesdroppers. And a shared blind matrix used to encrypt the security scores prevents the curious third-party payment platform from obtaining the private data of users. Furthermore, our system guarantees that users cannot tamper with or disguise their security scores during transactions. We demonstrate the correctness and security of the system in detail and provide theoretical support for its extension to more types of evaluation systems. [ABSTRACT FROM AUTHOR]