49 results about "Photon polarization" patented technology

Systems and methods for obtaining information on a key in the BB84 (Bennett-Brassard 1984) protocol of quantum key distribution are provided. A representative system comprises a quantum cryptographic entangling probe, comprising a single-photon source configured to produce a probe photon, a polarization filter configured to determine an initial probe photon polarization state for a set error rate induced by the quantum cryptographic entangling probe, a quantum controlled-NOT (CNOT) gate configured to provide entanglement of a signal with the probe photon polarization state and produce a gated probe photon so as to obtain information on a key, a Wollaston prism configured to separate the gated probe photon with polarization correlated to a signal measured by a receiver, and two single-photon photodetectors configured to measure the polarization state of the gated probe photon.

The invention relates to frequency lock of a laser device in the 1529 nm optical communication wave band, in particular to a method and device for stabilizing the 1529 nm optical fiber communication laser frequency to solve the technical problem that an existing laser frequency stabilization technology for the 1529 nm optical communication wave band is affected by noise brought by frequency modulation. The method for stabilizing the 1529 nm optical fiber communication laser frequency includes the following steps of firstly, converting a bundle of 780 nm laser locked by a polarization spectrum into a sigma+ circularly polarized light, and leading the circularly polarized light to a rubidium bubble filled with rubidium 87 steam; secondly, leading a bundle of linear polarization laser outputted by a 1529 nm semiconductor laser device to the rubidium bubble; thirdly, dividing a 1529 nm laser emitted from the rubidium bubble into two bundles of light with the perpendicular polarization directions, collecting magnitude signals of the two bundles of light, converting the magnitude signals into corresponding electrical signals respectively, and subtracting one of the electric signals from the other electrical signal to obtain a two-photon polarization spectrum signal; fourthly, feeding the two-photon polarization spectrum signal back to the 1529 nm semiconductor laser device. The method and the device can be applied to the superfine spectrum field, the frequency standard field, the precision measurement field and other fields.

One or more embodiments relate generally to the field of photoelectron spin and, more specifically, to a method and system for creating a controllable spin-polarized electron source. One preferred embodiment of the invention generally comprises: method for creating a controllable spin-polarized electron source comprising the following steps: providing one or more materials, the one or more materials having at least one surface and a material layer adjacent to said surface, wherein said surface comprises highly spin-polarized surface electrons, wherein the direction and spin of the surface electrons are locked together; providing at least one incident light capable of stimulating photoemission of said surface electrons; wherein the photon polarization of said incident light is tunable; and inducing photoemission of the surface electron states.

A cryptography method using a quantum phenomenon, which performs a multi-staged polarization process between a transmitter and a receiver to prevent a third party from knowing the polarization value of a photon. A transmitter rotates a photon flux by arbitrary angle θ and transmits it to a receiver. The receiver rotates the received photon flux by arbitrary angle φ and transmits it to the transmitter. The transmitter rotates the received photon flux by the reverse angle −θ of an angle, by which the transmitter 10 rotated it, then rotates it by polarization corresponding to an information bit, and transmits it to the receiver which rotates the received photon flux by the reverse angle −φ of an angle, and measures the polarization of the photon flux corresponding to the information bit, and recovers the information bit transmitted by the transmitter. Cryptography information may be transmitted using a plurality of photon fluxes.

The invention belongs to the technical field of electromagnetic wave polarization detection, in particular to a high-efficiency microwave polarization detection device based on the photon spin Hall effect. The detection device of the present invention decomposes the electromagnetic wave to be detected into left-handed and right-handed circularly polarized light through the efficient "photon spin Hall effect", then measures its modulus and phase respectively, and reversely obtains the polarization of the electromagnetic wave to be detected. The "photon spin Hall effect" is realized through the linear geometric Bell phase gradient of the total reflection "rotation structure" electromagnetic metamaterial metasurface. Compared with the traditional polarization detection method (directly measuring the sum component of the electromagnetic wave with a facing linear polarization horn), the present invention has the advantages of being more convenient and quicker, with less error and better stability. The working frequency band of the present invention can be extended to other working frequency bands by scaling or redesigning the structural constants of the specific medium unit.