467 results about "Quantum interference" patented technology

Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned de superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

A superconducting flux digital-to-analog converter includes a superconducting inductor ladder circuit. The ladder circuit includes a plurality of closed superconducting current paths that each includes at least two superconducting inductors coupled in series to form a respective superconducting loop, successively adjacent or neighboring superconducting loops are connected in parallel with each other and share at least one of the superconducting inductors to form a flux divider network. A data signal input structure provides a respective bit of a multiple bit signal to each of the superconducting loops. The data signal input structure may include a set of superconducting quantum interference devices (SQUIDs). The data signal input structure may include a superconducting shift register, for example a single-flux quantum (SFQ) shift register or a flux-based superconducting shift register comprising a number of latching qubits.

Various embodiments provide a coupling mechanism, method of activation and a square lattice. The coupling mechanism comprises two qubits and a tunable coupling qubit that activates an interaction between the two qubits by modulation of a frequency of the tunable coupling qubit. The tunable coupling qubit capacitively couples the two qubits. The tunable coupling qubit is modulated at a difference frequency of the two qubits. The difference frequency may be significantly larger than an anharmonicity of the two qubits. The tunable coupling qubit may be coupled to the two qubits by two electrodes separated by a superconducting quantum interference device (SQUID) loop having two Josephson junctions or by a single electrode with a SQUID loop coupling to ground. The SQUID loop is controlled by an inductively-coupled flux bias line positioned at the center of the tunable coupling qubit.

The disclosed Quantum Optical Coherence Tomography apparatus and method includes a source of quantum entangled photons and a quantum interference device. The pair of entangled photons is divided into two beams, one of which illuminates a semi-reflective object and the second of which is reflected from a variable optical time-delay element (VTE). The VTE is scanned and the quantum interference in the QID is recorded to build up a reflectance profile of the object. A real scanning produces a full tomographic reflectance image. A method of processing the data to eliminate the effects of optical dispersion is disclosed.

A superconducting quantum interference devices (SQUID) comprises a superconducting inductive loop with at least two Josephson junction, whereby a magnetic flux coupled into the inductive loop produces a modulated response up through radio frequencies. Series and parallel arrays of SQUIDs can increase the dynamic range, output, and linearity, while maintaining bandwidth. Several approaches to achieving a linear triangle-wave transfer function are presented, including harmonic superposition of SQUID cells, differential serial arrays with magnetic frustration, and a novel bi-SQUID cell comprised of a nonlinear Josephson inductance shunting the linear coupling inductance. Total harmonic distortion of less than −120 dB can be achieved in optimum cases.

A gradiometer for measuring properties of a magnetic field and in particular, for measuring magnetic field gradient components, comprising at least two magnetic sensors wherein at least two of the magnetic sensors are arranged to sense the magnetic field component in substantially the same direction. The magnetic sensors may be super conducting quantum interference device (SQUID) magnetometers, Hall probes, flux gates or magneto-resistive magnetometers. The gradiometer also includes a computer processor loaded with an adaptive signal-processing algorithm, for performing adaptive signal balancing of the magnetometer outputs. In a preferred embodiment the gradiometer may comprise at least eight magnetometers in a three-dimensional arrangement, and a set of three orthogonal global feedback coils, one for each direction x, y, z, such that the five independent magnetic field gradient components may be measured. The gradiometer may also be used to measure second or higher order magnetic field gradient components.

A device for achieving multi-photon interference, said device comprising: at least two solid state photon emitters, each solid state photon emitter comprising nuclear and electron spin states coupled together, each solid state photon emitter being configured to produce photon emission comprising a photon emission peak, wherein the photon emission peaks from different solid state photon emitters have a first frequency difference between peak intensities, and wherein the electron spin states of each solid state photon emitter are resolvable; an excitation arrangement configured to individually address the at least two solid state photon emitters; a plurality of optical out coupling structures wherein each solid state photon emitter is provided with an associated optical out coupling structure; a tuning arrangement configured to reduce the first frequency difference between the peak intensities of the photon emission peaks from the at least two solid state photon emitters to a second frequency difference which is smaller than the first frequency difference; a photon interference arrangement configured to overlap photon emissions from the at least two solid state emitters after tuning; and a detector arrangement configured to detect photon emissions from the at least two solid state emitters after tuning and passing through the photon interference arrangement, wherein the detector arrangement is configured to resolve sufficiently small differences in photon detection times that tuned photon emissions from the at least two solid state emitters are quantum mechanically indistinguishable resulting in quantum interference between indistinguishable photon emissions from different solid state photon emitters.

The invention discloses a high-sensitivity magnetic measurement device in an environment field based on disturbance compensation and a realization method thereof. In the method, the low-frequency disturbance compensation in an environment magnetic field is realized by a second feedback branch and a second magnetic flux locking loop, wherein the second feedback branch is composed of a second integrator, a low-pass filter, a second feedback resistor and a feedback coil; and the second magnetic flux locking loop is formed based on the second feedback branch. A super-magnetic conduction sensor established based on the method can realize the high-pass response frequency characteristics for the environment field and the low-pass response frequency characteristics for the circuit noise at the same time, ensures the suppression of the influence of environment field disturbance on SQUID (superconducting quantum interference device) magnetic measurement without influencing the weak signal measurement, and avoids the overflow phenomenon. Based on the super-magnetic conduction sensor, the method is suitable for the application environment in which the frequency of the magnetic field signal tobe measured is higher than the disturbance frequency band (DC-30Hz) of the environment field.

Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. Additional signal to noise benefits are obtained by use of a low noise polarization coil, comprising litz wire or superconducting materials. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

The present invention comprises a high-transition-temperature superconducting device having low-magnitude low-frequency noise-characteristics in magnetic fields comprising superconducting films wherein the films have a width that is less than or equal to a critical width, wC, which depends on an ambient magnetic field. For operation in the Earth's magnetic field, the critical width is about 6 micrometers ( mu m). When made with film widths of about 4 mu m an inventive high transition-temperature, superconducting quantum interference device (SQUID) excluded magnetic flux vortices up to a threshold ambient magnetic field of about 100 microTesla ( mu T). SQUIDs were fabricated having several different film strip patterns. When the film strip width was kept at about 4 mu m, the SQUIDs exhibited essentially no increase in low-frequency noise, even when cooled in static magnetic fields of magnitude up to 100 mu T. Furthermore, the mutual inductance between the inventive devices and a seven-turn spiral coil was at least 85% of that for inductive coupling to a conventional SQUID.

A superconducting quantum interference devices (SQUID) comprises a superconducting inductive loop with at least two Josephson junction, whereby a magnetic flux coupled into the inductive loop produces a modulated response up through radio frequencies. Series and parallel arrays of SQUIDs can increase the dynamic range, output, and linearity, while maintaining bandwidth. Several approaches to achieving a linear triangle-wave transfer function are presented, including harmonic superposition of SQUID cells, differential serial arrays with magnetic frustration, and a novel bi-SQUID cell comprised of a nonlinear Josephson inductance shunting the linear coupling inductance. Total harmonic distortion of less than −120 dB can be achieved in optimum cases.

The invention relates to a magnetic-field dynamic compensation system and methods based on spatial correlation, wherein the system can realize the dynamic compensation of environment magnetic fields at the directions of three axles through a large set and a small set of Helmholtz coil racks and two fluxgate meters based on the spatial correlation of a PID (Proportion Integration Differentiation) negative feedback electronic circuit and the fluctuation of the environment magnetic fields. The invention further discloses three methods using the system, including (1) a proportioning type magnetic-field dynamic compensation method, (2) a series type integral magnetic-field dynamic compensation method, and (3) a parallel integral type magnetic-field dynamic compensation method. The system of the invention is easy to construct, has low cost and simple operation, and can achieve excellent dynamic compensation effect, and simultaneously, the methods can maximally eliminate the affects of the fluxgate meters to other magnetic detectors at the centers of coils, and have great application prospect in extremely-low field nuclear magnetic resonance, imaging thereof and other biological magnetic researches based on an SQUID (Superconducting Quantum Interference Device).

An amplifier and method for improving linear response includes a plurality of N bi-SQUIDs. Each bi-SQUID has a non-uniform bi-SQUID parameter βi, described by βi=2πLiIciΦ0 can be defined for each bi-SQUIDs from i=1 to N, where Li is the loop inductance, ic is the critical current, and Φ0 is a flux quantum for each bi-SQUID. The non-uniform bi-SQUIDs can be connected in series or in parallel to establish a Superconducting Quantum Interference Filter (SQIF) array of bi-SQUIDs. Once connected, a mutual inductance between the connected bi-SQUIDs can be established. If the mutual inductance between connected bi-SQUIDs is accounted for, careful manipulation of the critical current or the loop size, or both, of each bi-SQUID can result in extremely uniform behavior (linear response) of the SQIF when considered as a whole, even though the behavior of the element bi-SQUIDs is non-uniform (different βi, parameters).

A pressure detection apparatus (30) detects, among a plurality of superconductor thin films (11 to 14) having different critical pressures at which a transition from a superconductor to an insulator occurs, the superconductor thin films (12 to 14) that have undergone the transition to the insulator with ammeters (242, 252, 262); and to detect, as an internal pressure of a housing (10), the maximum critical pressure among the critical pressures of the detected superconductor thin films (12 to 14).

A quantum interference transistor may include a source; a drain; N channels (N≧2), between the source and the drain, and having N−1 path differences between the source and the drain; and at least one gate disposed at one or more of the N channels. One or more of the N channels may be formed in a graphene sheet. A method of manufacturing the quantum interference transistor may include forming one or more of the N channels using a graphene sheet. A method of operating the quantum interference transistor may include applying a voltage to the at least one gate. The voltage may shift a phase of a wave of electrons passing through a channel at which the at least one gate is disposed.

A flow cytometer. In one embodiment, the flow cytometer has a microfluidic structure defining a channel with a periodically modulated path for transporting a stream of fluid with magnetic particles along the modulated path, and a superconducting quantum interference device (SQUID) sensor positioned over the microfluidic structure to define a detecting zone in the microfluidic structure for detecting magnetic signatures of a magnetic particle passing along the periodically modulated path through the detecting zone, where in use the stream of fluid with magnetic particles is regulated such that each magnetic particle passes singly along the periodically modulated path through the detecting zone.

A superconducting switching amplifier embodying the invention includes superconductive devices responsive to input / control signals for clamping the output of the amplifier to a first voltage or to a second voltage. The amplifier includes a first set of superconducting devices serially connected between a first voltage line and an output terminal and a second set of superconducting devices serially connected between the output terminal and a second voltage line. The first set and the second set of devices are operated in a complementary fashion in response to control signals. When one of the first and second sets is driven to a superconducting (zero resistance) state the other set is driven to a resistive state. In accordance with the invention, the devices of each set are laid out in a pattern and driven in a manner to enable all the devices of each set to be driven to a selected state at substantially the same time. In one embodiment, the devices in each set are superconducting quantum interference devices (SQUIDs). Four sets of superconductive devices may be interconnected to function as a differential switching amplifier. The operating voltage applied to an amplifier may be varied to provide additional shaping of the output signal.

A quantum interference device for causing an electromagnetically induced transparency phenomenon to occur in an alkali metal atom by a resonant light pair including a first resonant light and a second resonant light, includes: a light source to generate a plurality of the first resonant lights different from each other in frequency by Δω and a plurality of the second resonant lights different from each other in frequency by Δω; a magnetic field generation unit that applies a magnetic field to the alkali metal atom; a light detection unit that detects intensities of lights including the first resonant lights and the second resonant lights passing through the alkali metal atom; and a control unit that controls to cause a frequency difference between the specified first resonant light and the specified second resonant light to become equal to a frequency difference corresponding to an energy difference between two ground levels of the alkali metal atom based on a detection result of the light detection unit, wherein the control unit controls at least one of the frequency Δω and intensity of the magnetic field generated by the magnetic field generation unit to satisfy at least one of 2×δ×n=Δω and Δω×n=2×δ (n is a positive integer) with respect to a frequency δ corresponding to an energy difference between two Zeeman split levels different from each other in magnetic quantum number by one among a plurality of Zeeman split levels generated in each of the two ground levels of the alkali metal atom by energy splitting due to the magnetic field.

A method and apparatus performs high resolution imaging. The disclosed apparatus includes a low temperature SQUID sensor mounted in close proximity to a dewar thin window. A radiation shield has an extension surrounding the detection coil.

An apparatus and method for remote NMR / MRI spectroscopy having an encoding coil with a sample chamber, a supply of signal carriers, preferably hyperpolarized xenon and a detector allowing the spatial and temporal separation of signal preparation and signal detection steps. This separation allows the physical conditions and methods of the encoding and detection steps to be optimized independently. The encoding of the carrier molecules may take place in a high or a low magnetic field and conventional NMR pulse sequences can be split between encoding and detection steps. In one embodiment, the detector is a high magnetic field NMR apparatus. In another embodiment, the detector is a superconducting quantum interference device. A further embodiment uses optical detection of Rb—Xe spin exchange. Another embodiment uses an optical magnetometer using non-linear Faraday rotation. Concentration of the signal carriers in the detector can greatly improve the signal to noise ratio.

The invention discloses a method for improving the luminescent efficiency of an AlGaN base deep ultraviolet light-emitting diode (LED) device. According to the method, a multi-cycle AlGaN quantum well structure is used as an electronic barrier layer to prevent electrons from escaping from an active region to a p-AlGaN potential barrier house. Compared with an ordinary single-layer AlGaN electronic barrier layer, the electronic barrier layer of the multiple AlGaN quantum well structure can more effectively reduce the electrons transmitted to a p type layer through a quantum interference effect so as to improve the injection efficiency of the electrons, and improve the luminescent efficiency of the LED device.

An optical system of an atomic oscillator includes: a coherent light source emitting two resonant light components each having a p-polarized light component and an s-polarized light component, the tow resonant light components being coherent light and having a different frequency each other; a polarization splitter arranged at an output side of the coherent light source, the polarization splitter transmitting one of the p-polarized light component and the s-polarized light component and changes an optical path of the other of the p-polarized light component and the s-polarized light component to be outputted; a quarter-wave plate arranged at an output side of the polarization splitter so as to convert one of circularly polarized light and linearly polarized light to the other of circularly polarized light and linearly polarized light; a gas cell in which metal atom vapor is enclosed; a light guide that guides light after passing through the gas cell back to the gas cell as a turned-back light; and a photodetector that detects the turned-back light, the turned-back light having been passed through the gas cell and changed the optical path by the polarization splitter. The atomic oscillator controls an oscillation frequency by using a light absorption characteristic caused by a quantum-interference effect when the two resonant light components are incident on the optical system.

In embodiments of the present invention, a non-blocking quantum interference switch includes a segmented electron wave coupler that splits an electron wave and couples its two parts to two arms of a Mach Zehnder interferometer. A voltage may be applied to an interferometer gate electrode to change the phase of the electron wave traveling in that arm. A second segmented electron wave coupler may receive the two electron waves from the interferometer arms and recombine them into one electron wave. If the two electron waves interfere constructively, then the recombined electron wave exits through one switch output port, which may be a “logical zero” switch port, and if the two electron waves interfere destructively, then the recombined electron wave exits through a second switch output port, which may be a “logical one” switch port.

A Superconducting Quantum Interference Device (SQUID) is disclosed comprising a pair of resistively shunted Josephson junctions connected in parallel within a superconducting loop and biased by an external direct current (dc) source. The SQUID comprises a semiconductor substrate and at least one superconducting layer. The metal layer(s) are separated by or covered with a semiconductor material layer having the properties of a conductor at room temperature and the properties of an insulator at operating temperatures (generally less than 100 Kelvins). The properties of the semiconductor material layer greatly reduces the risk of electrostatic discharge that can damage the device during normal handling of the device at room temperature, while still providing the insulating properties desired to allow normal functioning of the device at its operating temperature. A method of manufacturing the SQUID device is also disclosed.

The invention discloses a radio-frequency source frequency calibration method for jump frequency from direct tracing to a high excited state. According to the method, energy level splitting is produced by using the quantum interference effect of high excited atoms under the action of a radio-frequency field and an electric field, and the frequency of the measured radio-frequency field can be effectively traced to the energy level interval of atoms by measuring the characteristic ratio of two split transmitted spectrum peaks. The frequency measuring basis can be directly compared with the jump frequency of atoms, so that the accuracy of frequency measurement is effectively improved. The method can directly trace the frequency of the radio-frequency field to the jump frequency of atoms, a new method is provided for the frequency measurement of the high radio-frequency field, and the method has good measurement accuracy and self-calibration property.