39 results about "Spin angular momentum of light" patented technology

We describe the structure and method of forming a STT-MTJ MRAM cell that utilizes transfer of spin angular momentum as a mechanism for changing the magnetic moment direction of a free layer. The device includes an IrMn pinning layer, a SyAP pinned layer, a naturally oxidized, crystalline MgO tunneling barrier layer that is formed on an Ar-ion plasma smoothed surface of the pinned layer and, in one embodiment, a free layer that comprises an amorphous layer of Co₆₀Fe₂₀B₂₀. of approximately 20 angstroms thickness formed between two crystalline layers of Fe of 3 and 6 angstroms thickness respectively. The free layer is characterized by a low Gilbert damping factor and by very strong polarizing action on conduction electrons. The resulting cell has a low critical current, a high dR/R and a plurality of such cells will exhibit a low variation of both resistance and pinned layer magnetization angular dispersion.

The invention provides a spin angular momentum-orbital angular momentum hybrid modulation quantum secret key distribution method and system. The spin angular momentum-orbital angular momentum hybrid modulation quantum secret key distribution system comprises a hybrid spin angular momentum-orbital angular momentum generation unit, a spin angular momentum modulation unit, an orbital angular momentum modulation unit, and a coincidence measurement decoding unit. The hybrid spin angular momentum-orbital angular momentum generation unit is used for generating spin angular momentum-orbital angular momentum hybrid entanglement quantum states. The spin angular momentum modulation unit is used for conducting phase position deflection modulation on the spin angular momentum of signal photons. The orbital angular momentum modulation unit is used for conducting phase position deflection modulation on the orbital angular momentum of idle photons and loading coded information. The coincidence measurement decoding unit is used for conducting coincidence measurement on the signal photons and the idle photons to decode quantum bit information. The safety of the spin angular momentum-orbital angular momentum hybrid modulation quantum secret key distribution system is improved, large-capacity quantum coding is achieved, and the quantum secret key distribution system is efficient in coding, simple in structure and high in safety.

The presently disclosed technology teaches a transducer head with a read sensor, a write pole, and one or more waveform sensors attached to the transducer head. Further, a waveform propagates in the direction of a BPM and the waveform sensor is configured to detect the waveform after it is reflected from the BPM. Additionally, a spin-polarized current is influenced by the BPM and a spin angular momentum sensor detects changes in spin angular momentum of the current. Further, a processor relates at least one property of the reflected waveform and/or current with positions of patterned bits on the BPM. The processor may then modify a timing signal and/or transducer head position to ensure that data bits are accurately written to the BPM. The end result is the ability to more quickly and accurately detect the patterned bits and synchronize a position of the transducer head with the patterned bits.

The present invention provides an atom magnetometer without a response blind area. The atom magnetometer comprises a laser, an expanded beam collimation device, a circularly polarized light conversiondevice, an acoustic optical modulator, an Helmholtz coil, an atom air chamber, a reflector set, a photoelectric detector, a lock-in amplifier, a signal processing system and a heating device. The atom magnetometer is simple in structure; and two exciting methods which apply an excitation magnetic field and perform light modulation are combined, and components of the total spin angular momentum ofa sensing atom in two directions are detected to achieve measurement of a blind area without response. The present invention further discloses a method for measuring an external magnetic field by employing an atom magnetometer without response blind area and method. The measurement method is simple, has no response blind area, can rapidly and accurately obtain related data of an external magneticfield, and is high in practicability.

The present invention relates to a method and system for using end resonances of highly spin-polarized alkali metal vapors for an atomic clock, magnetometer or other system. A left end resonance involves a transition from the quantum state of minimum spin angular momentum along the direction of the magnetic field. A right end resonance involves a transition from the quantum state of maximum spin angular momentum along the direction of the magnetic field. For each quantum state of extreme spin there are two end resonances, a microwave resonance and a Zeeman resonance. The microwave resonance is especially useful for atomic clocks, but it can also be used in magnetometers. The low frequency Zeeman resonance is useful for magnetometers.

The invention provides a continuous variable entanglement generation device and method. The continuous variable entanglement generation device comprises a high-order transverse mode astigmatism compensation device. A plurality of pairs of continuous variable high-order transverse mode entanglement states are simultaneously generated in a single OPO (Optical Parametric Oscillator) through compensating the astigmatism effect of a high-order transverse mode to achieve continuous variable multi-cluster entanglement, and the entanglement state is also a hyper-entanglement state with both track angular momentum and spin angular momentum entanglements. The continuous variable entanglement generation device has a simple structure, is easy to control, has strong practicability and can be used in space measurement, image processing and quantum communication.

The invention discloses a two-dimensional coding device and method for the spin angular momentum of a light field, and the method comprises the steps: achieving the different two-dimensional distribution of the photon spin angular momentum on a cross section of a radial change hybrid polarization vector light field through an uniaxial crystal; and achieving the coding from the photon spin angular momentum to digital logic '0'and '1'. The method provided by the invention is provided with the uniaxial crystal, a quarter-wave plate, a polaroid and a CCD sensor, wherein the uniaxial crystal, the quarter-wave plate, the polaroid and the CCD sensor are sequentially set from the left side to the right side in the propagation direction of a light beam. Compared with other common coding methods, the method is simple in optical path, is convenient and reliable, is easy for adjustment, and has the potential application perspective in the technical field of light field communication.

A plasmonic plate for generating optical vortices, formed by electrically conducting material and defining a plurality of slots that convert a first electromagnetic field having a non-null spin angular momentum into a second electromagnetic field having a non-null orbital angular momentum.

The invention discloses a measurement method for a photon spin-orbital angular momentum joint mode and a measurement system. The measurement method comprises the steps of vertically inputting a to-be-measured optical field with spin-orbital angular momentum into a plane (x, y), and enabling the center of the optical field to be aligned with the center of the plane; introducing phase modulation QL(x, y) into left-handed circular polarization state incident light with a spiral wavefront, and introducing phase modulation QR(x, y) into right-handed circular polarization state incident light with aspiral wavefront; enabling light fields with different spin angular momentum to be expanded along a spiral line and be separated to different positions on a plane (u, v); introducing a compensation phase PL(x, y) into the left-handed circular polarization incident light with the spiral wavefront, introducing a compensation phase PR(x, y) into the right-handed circular polarization incident lightwith the spiral wavefront, and converging the light fields passing through the plane (u, v) at different positions of the plane (m, n); and detecting light intensity distribution of the plane (m, n) to measure a spin-orbital angular momentum joint mode input into the light field or to demodulate the spin-orbital angular momentum joint mode input into the light field.

The invention discloses a graphene metasurface construction method used for spin angular momentum deflection in a three-dimensional direction. The method is applied to a computer device and comprisesthe following steps: constructing a graphene reflection unit which comprises a graphene sticker at the uppermost layer, a quartz dielectric plate at the middle layer and a metal floor at the bottom layer; inputting the quantity of graphene reflection units required by the graphene metasurface to be constructed; calculating the phase distribution of each position of the graphene metasurface to be constructed to determine the arrangement positions of all graphene units forming the graphene metasurface; and combining all the graphene units into the graphene metasurface according to the arrangement positions of all the graphene units of the graphene metasurface to be constructed. According to the embodiment of the invention, the graphene reflection units are used for constructing the graphenemetasurface; and the spin angular momentum and the deflection direction of electromagnetic waves in the three-dimensional direction can be controlled.

The invention discloses a graphene metasurface used for spin angular momentum deflection in a two-dimensional direction. The graphene metasurface is formed by arranging N * N graphene reflection units, and each graphene reflection unit comprises a graphene sticker at the uppermost layer, a quartz dielectric plate at the middle layer and a metal floor at the bottom layer, wherein the graphene sticker is arranged at the central point of the upper surface of the quartz dielectric plate. The rotation angle of each graphene sticker arranged on the upper surface of the quartz dielectric plate is theta, the metal floor is arranged on the lower surface of the quartz dielectric plate, and the central point of each graphene sticker coincides with the central point of the quartz dielectric plate, wherein the theta is an any angle ranging from -90 degrees to 90 degrees. The rotation angle theta of the graphene sticker of each graphene unit arranged on the upper surface of the quartz dielectric plate is determined by the reflection phase distribution at each position of the graphene metasurface. According to the invention, the spin angular momentum and the deflection direction of electromagnetic waves in the two-dimensional direction can be controlled.

The invention relates to the technical field of optical measurement, in particular to an optical field spin angle momentum measuring device and method. The optical field spin angle momentum measuringdevice is used for collecting and obtaining a transverse component of a light field through a signal collecting unit; a spin detection unit is used for obtaining a left-handed polarization component and a right-handed polarization component through extraction; a photoelectric conversion unit is used for obtaining a voltage signal corresponding to the left-handed polarization component and a voltage signal corresponding to the right-handed polarization component through conversion; a data acquisition unit obtains a digital signal corresponding to the left-handed polarization component and a digital signal corresponding to the right-handed polarization component through conversion; and a spin angle momentum calculation module carries out calculation based on the digital signal correspondingto the left-handed polarization component and the digital signal corresponding to the right-handed polarization component to obtain the spin angle momentum of the light field. The extraction method issimple, complex measurement and calculation processes are avoided, and the calculation efficiency of the spin angle momentum of the light field is improved.

The invention relates to the technical field of integrated photons, in particular to a photon spinning directional separator, and aims to solve the problem that a metal metasurface structure is low in stability of directional separation, and the photon spin directional separator comprises a substrate, a metal film layer is arranged on the substrate, and a wave guide structure is arranged on the metal film layer. The waveguide structure comprises a first dielectric waveguide and a second dielectric waveguide which are perpendicular to each other, an antenna structure is arranged on the metal film layer and comprises two sector ring structures, and the two sector ring structures are distributed on the two sides of the first dielectric waveguide and the two sides of the second dielectric waveguide at equal intervals respectively. When the spin angular momentum of the incident photon is matched with the orbital angular momentum of the antenna structure, the incident light is converted into an antenna resonant waveguide mode; meanwhile, by controlling the spinning state of incident photons, an antenna resonant waveguide mode is selectively coupled to a certain waveguide branch in the photon spin guided wave structure. The photon spinning directional separator is high in extinction ratio and integration level, and is suitable for the field of quantum communication.

The invention discloses a photon full-angular momentum state generation method and system based on cascaded light modulator. Two liquid crystal spatial light modulators are cascaded to modulate orbital angular momentum state distribution on two spin angular momentum components of a fundamental mode Gaussian beam to generate a full-angular momentum state structure beam. Due to the electric controlcharacteristics of the liquid crystal spatial light modulators, continuous and adjustable generation of the mode of any full-angular momentum state structure light beam can be realized on the premiseof not replacing any optical element in the system. The system is simple in structure and easy to control, and has great progress compared with the prior art.

The invention belongs to the technical field of optical fiber transmission, and adopts the specific technical scheme that the method for improving the optical fiber transmission capacity comprises the following steps: establishing a theoretical simulation system and an experimental verification system, and obtaining optical fiber transmission light field distribution and spin angular momentum distribution through the theoretical simulation system; optical fiber transmission light field distribution and spin angular momentum distribution are obtained through an experimental verification system, and transmission characteristics of column vector vortex beams with different topological charges or different orders and spin angular momentum thereof in a single-mode fiber, an annular fiber and a few-mode fiber are researched by adopting theoretical analysis and building an optical fiber coupling transmission system. According to the method, the optical field distribution and the spin angular momentum distribution of the cylindrical vector vortex light beams transmitted in three optical fibers are verified, an experiment system is improved, the optical field distribution and the spin angular momentum distribution are detected at the same time, the transmission capacity of the optical fibers is increased, and the method has great research significance in research of long-distance optical communication and big data optical interconnection.

The invention discloses a graphene metasurface construction method used for spin angular momentum deflection in a two-dimensional direction. The method is applied to a computer device and comprises the following steps of: constructing a graphene reflection unit which comprises a graphene patch at the uppermost layer, a quartz dielectric plate at the middle layer and a metal floor at the bottom layer; inputting the number of graphene reflection units required by the graphene metasurface to be constructed; calculating the phase distribution of each position of the graphene metasurface to be constructed to determine the arrangement positions of all graphene units forming the graphene metasurface; and combining all the graphene units into the graphene metasurface according to the arrangement positions of all the graphene units of the graphene metasurface to be constructed. According to the embodiment of the invention, the graphene reflection unit is used for constructing the graphene metasurface, and the spin angular momentum and the deflection direction of electromagnetic waves in the two-dimensional direction can be controlled.