Abstract: A wavelength-multiplexed polarization entangled photon pair generator (1) includes: a pump light source (2); a polarization entangled photon pair generating body (4) on which pump light (3) outputted from the pump light source (2) falls; and a spectrometer (7) on which a wavelength-multiplexed parametric photon pair (5) outputted from the polarization entangled photon pair generating body 4 falls. The polarization entangled photon pair generating body (4) made of a nonlinear optical crystal (11) generates wavelength-multiplexed photon pairs by subjecting the pump light 3 to type II phase matching. As a nonlinear optical crystal 11, lithium tantalate of periodically poled structure (11A) can be used, and as a spectrometer (7), an arrayed-waveguide grating can be used. Wavelength-multiplexed polarization entangled photon pairs (5) can thus be generated with simple equipment.

Abstract: A wavelength-multiplexed polarization entangled photon pair generator (1) includes: a pump light source (2); a polarization entangled photon pair generating body (4) on which pump light (3) outputted from the pump light source (2) falls; and a spectrometer (7) on which a wavelength-multiplexed parametric photon pair (5) outputted from the polarization entangled photon pair generating body 4 falls. The polarization entangled photon pair generating body (4) made of a nonlinear optical crystal (11) generates wavelength-multiplexed photon pairs by subjecting the pump light 3 to type II phase matching. As a nonlinear optical crystal 11, lithium tantalate of periodically poled structure (11A) can be used, and as a spectrometer (7), an arrayed-waveguide grating can be used. Wavelength-multiplexed polarization entangled photon pairs (5) can thus be generated with simple equipment.

Abstract: A non-degenerate polarization-entangled photon pair generation device (1) that efficiently and easily generates non-degenerate polarization-entangled photon pairs includes: a quantum-entangled photon pair generator (2) including a single crystal in which periodically poled structures (3a, 3b) having different periods are formed; and a light radiating unit (4) for entering light into the quantum-entangled photon pair generator (2) such that the light passes through the periodically poled structure (3a) and then through the periodically poled structure (3b).

Abstract: A non-degenerate polarization-entangled photon pair generation device (1) that efficiently and easily generates non-degenerate polarization-entangled photon pairs includes: a quantum-entangled photon pair generator (2) including a single crystal in which periodically poled structures (3a, 3b) having different periods are formed; and a light radiating unit (4) for entering light into the quantum-entangled photon pair generator (2) such that the light passes through the periodically poled structure (3a) and then through the periodically poled structure (3b).

Abstract: A Littrow-type external-cavity diode laser optical axis displacement correction method and device to easily, inexpensively, and accurately correct displacement of optical axis in Littrow-type ECDLs is provided. In the Littrow-type ECDL optical axis displacement correction device and method, a means for introducing a laser beam, a jig 36 for integrally fixing a diffraction grating 33 and a prism 35 into which the laser beam is introduced in a predetermined arrangement, and a rotary shaft 34 capable of integrally rotating the diffraction grating 33 and the prism 35 are included. By the rotation of the diffraction grating 33 and the prism 35 around the rotary shaft 34, the wavelength of the incident light can be changed, and the optical axis of the output light 39 is not changed by the change of the wavelength.

Abstract: A method for generating a quantum-entangled photon pair is such that a biexciton in such a state that the angular momentum is 0 is generated through two-photon resonance induced by irradiating a semiconductor substance, e.g., CuCl, with two parent photons (angular frequency ?i). A photon pair is then generated by splitting the biexciton thus generated simultaneously into two photons (angular frequencies ?s and ?s?). Since the photon pair is generated by splitting such biexciton having an angular momentum of 0, it has a quantum entanglement with regard to polarization. Since the photon thus generated has a wavelength substantially equal to that of the parent photons, photons of shorter wavelength in a quantum entangled state can be generated.

Abstract: An optical nonlinear evaluation device (1) capable of accurately evaluating the optical nonlinearity of a Kerr medium in accordance with a phase difference caused by cross-phase modulation generated in the Kerr medium includes: a polarization Sagnac interference path (3) provided with a Kerr medium (4); an optical pulse light source (7) for supplying a signal beam (Dsig); a polarization beam splitter (PBS1) for splitting the signal beam (Dsig) into a signal beam (Hsig) and a signal beam (Vsig) polarized in a direction orthogonal to the signal beam (Hsig), for supplying the signal beam (Hsig) to a first side of the Kerr medium (4), and for supplying the signal beam (Vsig) to a second side of the Kerr medium (4); a glass plate (14) for entering, onto the signal beam (Hsig), a control beam (Vcont) for causing a change in phase difference between the signal beam (Hsig) and the signal beam (Vsig); separating means for separating the control beam (Vcont) from the signal beam (Hsig) having traveled through the Kerr

Abstract: An optical nonlinear evaluation device (1) capable of accurately evaluating the optical nonlinearity of a Kerr medium in accordance with a phase difference caused by cross-phase modulation generated in the Kerr medium includes: a polarization Sagnac interference path (3) provided with a Kerr medium (4); an optical pulse light source (7) for supplying a signal beam (Dsig); a polarization beam splitter (PBS1) for splitting the signal beam (Dsig) into a signal beam (Hsig) and a signal beam (Vsig) polarized in a direction orthogonal to the signal beam (Hsig), for supplying the signal beam (Hsig) to a first side of the Kerr medium (4), and for supplying the signal beam (Vsig) to a second side of the Kerr medium (4); a glass plate (14) for entering, onto the signal beam (Hsig), a control beam (Vcont) for causing a change in phase difference between the signal beam (Hsig) and the signal beam (Vsig); separating means for separating the control beam (Vcont) from the signal beam (Hsig) having traveled through the Kerr

Abstract: In one embodiment of the present invention, a quantum entangled photon-pair producing device is disclosed which includes a superposed state generating device for generating a superposed state of photon-pairs entering through N (N?2) different incident optical paths and being composed of photons having different polarization directions, and a light-guide device for separating the photon-pairs entering through the N (e.g. N is two) incident optical paths into photons having a first polarization direction (e.g. horizontally polarized light) and those having a second polarization direction (e.g. vertically polarized light) and guiding the photons having the first polarization direction and entering through the i-th (1?i?N) (e.g. the first) incident optical path and photons having the second polarization direction and entering through the (N?i+1) (e.g. the second) incident optical path to the i-th (e.g. the first) exit optical path through optical paths having the same optical path length.

Abstract: In one embodiment of the present invention, a quantum entangled photon-pair producing device is disclosed which includes a superposed state generating device for generating a superposed state of photon-pairs entering through N (N?2) different incident optical paths and being composed of photons having different polarization directions, and a light-guide device for separating the photon-pairs entering through the N (e.g. N is two) incident optical paths into photons having a first polarization direction (e.g. horizontally polarized light) and those having a second polarization direction (e.g. vertically polarized light) and guiding the photons having the first polarization direction and entering through the i-th (1?i?N) (e.g. the first) incident optical path and photons having the second polarization direction and entering through the (N?i+1) (e.g. the second) incident optical path to the i-th (e.g. the first) exit optical path through optical paths having the same optical path length.

Abstract: A Littrow-type external-cavity diode laser optical axis displacement correction method and device to easily, expensively, and accurately correct displacement of optical axis in Littrow-type ECDLs is provided. In the Littrow-type ECDL optical axis displacement correction device and method, a means for introducing a laser beam, a jig 36 for integrally fixing a diffraction grating 33 and a prism 35 into which the laser beam is introduced in a predetermined arrangement, and a rotary shaft 34 capable of integrally rotating the diffraction grating 33 and the prism 35 are included. By the rotation of the diffraction grating 33 and the prism 35 around the rotary shaft 34, the wavelength of the incident light can be changed, and the optical axis of the output light 39 is not changed by the change of the wavelength.

Abstract: A method for generating a quantum-entangled photon pair is such that a biexciton in such a state that the angular momentum is 0 is generated through two-photon resonance induced by irradiating a semiconductor substance, e.g., CuCl, with two parent photons (angular frequency ?i). A photon pair is then generated by splitting the biexciton thus generated simultaneously into two photons (angular frequencies ?s and ?s?). Since the photon pair is generated by splitting such biexciton having an angular momentum of 0, it has a quantum entanglement with regard to polarization. Since the photon thus generated has a wavelength substantially equal to that of the parent photons, photons of shorter wavelength in a quantum entangled state can be generated.