A truncated non-linear interferometer-based sensor system includes an input that receives an optical beam and a non-linear amplifier that generates a probe beam and a conjugate beam from the optical beam. The system's local oscillators are related to the probe beam and the conjugate beam. The system includes a sensor that transduces an input with the probe beam and the conjugate beam. The transduction detects changes in the phase of each of the probe beam and the conjugate beam. The system's phase sensitive detectors detect phase modulations between the respective local oscillators, the probe beam, and the conjugate beam and outputs phase signals based on detected phase modulations. The system measures phase signals indicative of the sensor's input resulting from a sum or difference of the phase signals. The measurement exhibits a quantum noise reduction in an intensity difference, a phase sum, or an amplitude difference quadrature.

A quantum device includes a non-reciprocal transmission structure, wherein the transmission structure is designed such that for first waves traversing the transmission structure in a forward direction the phases of the first waves are at least partially conserved, and for second waves traversing the transmission structure in a backward direction, the phases of the second waves are at least partially replaced by random ones, such that the phase conservation is more pronounced in the forward direction than in the backward direction.

An atomic beam is irradiated with a first laser beam, a second laser beam, and a third laser beam. The first laser beam and the third laser beam each have a wavelength corresponding to a transition between a ground state and a first excited state. The second laser beam has a wavelength corresponding to a transition between the ground state and a second excited state. First, atoms each having a smaller velocity component than a predetermined velocity in a direction orthogonal to the traveling direction of the atomic beam are changed from the ground state to the first excited state by the first laser beam. Subsequently, a momentum is provided for individual atoms in the ground state by the second laser beam, which removes the atoms from the atomic beam. Finally, atoms in the first excited state are returned from the first excited state to the ground state by the third laser beam.

An atomic beam is irradiated with a first, a second, and a third laser beam. The first laser beam and the third laser beam each have a wavelength corresponding to a transition between a ground state and a first excited state. The second laser beam has a wavelength corresponding to a transition between the ground state and a second excited state. First, atoms each having a smaller velocity component than a predetermined velocity in a direction orthogonal to the traveling direction of the atomic beam are changed from the ground state to the first excited state by the first laser beam. Subsequently, a momentum is provided for individual atoms in the ground state by the second laser beam, which removes the atoms from the atomic beam. Finally, atoms in the first excited state are returned from the first excited state to the ground state by the third laser beam.

A truncated non-linear interferometer-based sensor system includes an input port that receives an optical beam and a non-linear amplifier that amplifies the optical beam with a pump beam and renders a probe beam and a conjugate beam. The system’s local oscillators have a relationship with the respective beams. The system includes a sensor that transduces an input with the probe beam and the conjugate beam or their respective local oscillators. It includes one or more phase-sensitive detectors that detect a phase modulation between the respective local oscillators and the probe beam and the conjugate beam. Output from the phase-sensitive-detectors is based on the detected phase modulation. The phase-sensor-detectors include measurement circuitry that measure the phase signals. The measurement is the sum or difference of the phase signals in which the measured combination exhibit a quantum noise reduction in an intensity difference or a phase sum or an amplitude difference quadrature.

An atomic interferometer and methods for measuring phase shifts in interference fringes using the same. The atomic interferometer has a laser beam traversing an ensemble of atoms along a first path and an optical components train with at least one alignment-insensitive beam routing element configured to reflect the laser beam along a second path that is anti-parallel with respect to the first laser beam path. Any excursion from parallelism of the second beam path with respect to the first is rigorously independent of variation of the first laser beam path in yaw parallel to an underlying plane.

Coherent spectroscopic methods are described, to measure the total phase difference during an extended interrogation interval between the signal delivered by a local oscillator (10) and that given by a quantum system (QS). According to one or more embodiments, the method may comprise reading out at the end of successive interrogation sub-intervals (Ti) intermediate error signals corresponding to the approximate phase difference (φ) between the phase of the LO signal and that of the quantum system, using coherence preserving measurements; shifting at the end of each interrogation sub-intervals (Ti) the phase of the local oscillator signal, by a known correction value (.sub.φ(i).sub.FB) so as to avoid that the phase difference approaches the limit of the inversion region; reading out a final phase difference (φf) between the phase of the prestabilized oscillator signal and that of the quantum system using a precise measurement with no restriction on the destruction; reconstructing a total phase difference over the extended interrogation interval, as the sum of the final phase difference (φf) and the opposite of all the applied phase corrections figure (I).

Nonlinear interferometers include a nonlinear optical medium that is situated to produce a conjugate optical beam in response to a pump beam and a probe beam. The pump, probe, and conjugate beams propagate displaced from each other along a common optical path. One of the beams is selectively phase shifted, and the beams are then returned to the nonlinear medium, with the selectively phase shift beam phase shifted again. The nonlinear medium provides phase sensitive gain to at least one of the probe or conjugate beams, and the amplified beam is detected to provide an estimate of the phase shift.

A non-contact angle measuring apparatus includes a matter-wave and energy (MWE) particle source and a detector. The MWE particle source is used for generating boson or fermion particles. The detector is used for detecting a plurality peaks or valleys of an interference pattern generated by 1) the boson or fermion particles corresponding to a slit, a bump, or a hole of a first plane and 2) matter waves' wavefront-split associated with the boson or fermion particles reflected by a second plane, wherein angular locations of the plurality peaks or valleys of the interference pattern, a first distance between a joint region of the first plane and the second plane, and a second distance between the detector and the slit are used for deciding an angle between the first plane and the second plane.

A truncated non-linear interferometer-based sensor system includes an input that receives an optical beam and a non-linear amplifier that generates a probe beam and a conjugate beam from the optical beam. The system's local oscillators are related to the probe beam and the conjugate beam. The system includes a sensor that transduces an input with the probe beam and the conjugate beam. The transduction detects changes in the phase of each of the probe beam and the conjugate beam. The system's phase sensitive detectors detect phase modulations between the respective local oscillators, the probe beam, and the conjugate beam and outputs phase signals based on detected phase modulations. The system measures phase signals indicative of the sensor's input resulting from a sum or difference of the phase signals. The measurement exhibits a quantum noise reduction in an intensity difference, a phase sum, or an amplitude difference quadrature.