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In this paper, we consider a method for implementing a quantum logic gate with photons whose wave function propagates in a one-dimensional Kerr-nonlinear photonic crystal. The photonic crystal causes the incident photons to undergo Bragg reflection by its periodic structure of dielectric materials and forms the photonic band structure, namely, the light(More)
In this paper, we consider a quantum algorithm for solving the following problem: “Suppose f is a function given as a black box (that is also called an oracle) and f is invariant under some AND-mask. Examine a property of f by querying the oracle.” We compare the efficiency of our quantum algorithm with that of classical algorithms by evaluating the(More)
In this paper, we study how to generate entanglement by interaction-free measurement. Using Kwiat et al.’s interferometer, we construct a two-qubit quantum gate that changes a particle’s trajectory according to the other particle’s trajectory. We propose methods for generating the Bell state from an electron and a positron and from a pair of photons by this(More)
In this paper, we write down the separable Werner state in a two-qubit system as a convex combination of product states explicitly. The Werner state in a two-qubit system has a single real parameter and varies from inseparable state to separable state according to the value of its parameter. The convex combination of product states gives a hidden variable(More)