11 results about "Coherence time" patented technology

The present invention provides a design method and device for a space-based ultra-long baseline interferometric SAR system, belonging to the field of radar measurement, including: for bistatic interferometry, analyzing the relationship between elevation accuracy, phase error, and coherence, thereby deriving the relationship between elevation accuracy and the vertical baseline; for bistatic interferometry, combining the critical baseline, analyzing the relationship between coherence, the vertical baseline, and the critical baseline; obtaining the relationship between the ratio of the vertical baseline to the critical baseline and elevation accuracy; performing an analysis of the deformation rate error in the interferometric SAR time series, thereby deriving the relationship between the deformation rate accuracy and each error source; deriving the influence of decorrelation noise on the deformation rate accuracy; obtaining the relationship between the ratio of the coherence time baseline to the revisit period and the deformation rate accuracy. The present invention meets the requirements of high-precision terrain and deformation measurement tasks for space-based SAR technology.

A terminal is disclosed including a processor that measures for beam management: a Doppler spread or a coherence time associated with a beam and one or more reporting quantities. The terminal also includes a transceiver that reports the Doppler spread or the coherence time. In other aspects, a method for a terminal and a base station are also disclosed.

Fermions are the building blocks of matter. Here, we disclose a robust quantum register composed of hundreds of fermionic atom pairs trapped in an optical lattice. With each fermion pair forming a spin-singlet, the qubit is realized as a set of near-degenerate, symmetry-protected two-particle wavefunctions describing common and relative motion. Degeneracy is lifted by the atomic recoil energy, which depends on mass and lattice wavelength, thereby rendering two-fermion motional qubits insensitive to noise of the confining potential. The quantum coherence can last longer than ten seconds. Universal control is provided by modulating interactions between the atoms. Via state-dependent, coherent conversion of free atom pairs into tightly bound molecules, we tune the speed of motional entanglement over three orders of magnitude, yielding 104 Ramsey oscillations within the coherence time. For site-resolved motional state readout, pairs are coherently split into their constituent fermions via a double-well, creating entangled Bell pairs.

In some embodiments, an optical communication system may include a light source, a modulator, and a light receiver. The light source may be configured to generate a beam comprising a series of light pulses. The light receiver may have a detection window duration of 1 nanosecond or less. As a first pulse travels through a variable refractive medium, photons in the first pulse may be refracted to travel along different ray paths to reach the light receiver according to a time profile. A full width at half maximum (FWHM) value of the time profile may be greater than a coherence time value of the first pulse, and a detection window of the light receiver may be greater than the FWHM value of the time profile.

Disclosed herein is a method of quantum communication comprising transmitting photons from at least two different transmitters 202, 204, and receiving the transmitted photons at a receiver 208. Receiving the photons involves interfering the received photons 210 in interference events, registering detections of photons from the interference events, using at least two different detectors 212, 214, and analysing the interference events. Analysing the interference includes distinguishing between a single-photon interference event and a two-photon interference event, the latter describing two single-photon interference events occurring either simultaneously or within a coherence time of the photons. The transmitting step preferably involves encoding a first portion of the transmitted photons with quantum states chosen from a first basis and encoding a second portion of transmitted photons with quantum states chosen from a second basis. The analysing interference step allows the basis to be identified, because single-photon interference events may be associated with the first basis, and two-photon interference events with the second basis.

The invention provides an incoherent light long-distance three-dimensional imaging device using multi-beam synthesis, and relates to the technical field of incoherent light correlated imaging. The three-dimensional imaging device adopts multi-beam emission and optical synthetic aperture receiving, the number of emission beams can be increased according to application scenes, the emission power is improved, and the three-dimensional imaging device is suitable for long-distance imaging; the increase of the receiving aperture baseline can further improve the imaging resolution; in addition, long-distance amplitude random and phase random incoherent light synthesis can be realized by utilizing multi-channel modulation and atmosphere random modulation; according to the mode of combining active and passive amplitude and phase random modulation, a high-collimation, high-intensity and narrow-band thermal light source is synthesized, the disadvantage of short coherence time caused by inherent periodicity of active modulation and too low atmospheric modulation speed is made up, and anti-turbulence high-resolution three-dimensional imaging of a long-distance target can be achieved through second-order coherence of the light source.

In some embodiments, an optical communication system may include a light source, a modulator, and an optical receiver. The light source may be configured to generate a beam comprising a series of light pulses. The optical receiver may have a detection window duration of 1 nanosecond or less. As the first pulse travels through a variable refractive medium, photons in the first pulse may be refracted, thus traveling along different ray paths to reach the optical receiver according to a time distribution curve. The full width at half maximum (FWHM) value of the time distribution curve may be greater than the coherence time value of the first pulse, and the detection window of the optical receiver may be greater than the FWHM value of the time distribution curve.

In some embodiments, an optical communication system may include an optical source, a modulator, and a photoreceiver. The optical source may be configured to generate a beam comprising a series of light pulses each having a duration of less than 100 picoseconds. The photoreceiver may have a detection window duration of less than 1 nanosecond. When a first pulse travels through a variably refractive medium, photons in the first pulse may be refracted to travel along different ray paths to arrive at the photoreceiver according to a temporal distribution curve. A full width at half maximum (FWHM) value of the temporal distribution curve may be at least three times as large as a coherence time value of the first pulse, and the detection window of the photoreceiver may be at least six times as large as the FWHM value of the temporal distribution curve.

A LIDAR system is adapted for performing anemometrical measurements relating to a focusing zone of a laser beam which is emitted by the system. The system includes a temporal control device for the laser beam, which is adapted for putting this laser beam in successive laser pulse form, so that each laser pulse has an individual length which is greater than or equal to twice the Rayleigh length divided by the propagation speed of the laser pulses in the atmosphere, and less than 20 μs. Advantageously, the individual length of each laser pulse is between 0.2 and 5 times the coherence time of the atmosphere which is effective in the focusing zone. Such a LIDAR system provides values for a spectral CNR ratio which are better than those of systems from the state-of-the-art, at equivalent spatial resolution.

The invention provides a coherent enhanced microwave receiving system and method, in the microwave receiving system, probe light enters an atomic gas chamber and is used for exciting atoms in the atomic gas chamber from a ground state energy level to a metastable state energy level, coupling light enters the atomic gas chamber and coincides with the probe light, and the probe light is used for exciting the atoms in the atomic gas chamber from the ground state energy level to the metastable state energy level. The coupled light is used for exciting atoms from a metastable state energy level to a first Rydberg energy level; the microwave system is arranged to apply a pulsed microwave field to the atomic gas chamber in a first working mode for exciting atoms from a first Rydberg energy level to a second Rydberg energy level so as to enhance coherence between excitation of the first Rydberg energy level and excitation of the second Rydberg energy level; and the microwave system is set to apply a continuous local oscillation microwave field to the atomic gas chamber in a second working mode, and the continuous local oscillation microwave field and the to-be-detected microwave field jointly cause the energy level periodic change of atoms, so that the intensity of the detection light is periodically modulated. By adopting the microwave receiving system provided by the invention, the coherence time of the atomic Rydberg state can be prolonged, and the microwave receiving performance is improved.

The invention relates to a superconducting quantum bit control reflected wave calibration method, which comprises the following steps of: integrating a reflected wave engineering mechanism in a pulse control system, pre-generating a reflected wave offset waveform which has the same frequency and the same shape as a reflected pulse and is opposite to the phase of the reflected pulse, and inhibiting a system error caused by reflection to 105 magnitude under the premise of not introducing additional hardware by combining DRAG parameter optimization; the defects that in a traditional scheme, the gate operation duration is increased, and the error rate is accumulated are overcome, finally, the overall single-bit gate fidelity is improved, the gate operation fidelity anisotropy is remarkably weakened, the single-bit gate fidelity remarkably approaches the coherence time limit of a current quantum bit, meanwhile, the modular expansion capacity is achieved, and the implementation cost is reduced. And the method can be adapted to various chip structures and large-scale parallel quantum bit systems.