794results about "Apparatus using atomic clocks" patented technology

A clock including: a portable, at least partially evacuated housing; a cell being positioned within the housing and including an internal cavity having interior dimensions each less than about 1 millimeter, an intra-cavity pressure of at least about 760 Torr, and containing a metal atomic vapor; an electrical to optical energy converter being positioned within the housing to emit light through the metal atomic vapor; an optical energy intensity detector being positioned within the housing to receive the light emitted by the converter through the metal atomic vapor; at least one conductive winding around the cavity to stabilize the magnetic field experienced in the cavity dependently upon the detector; and, an output to provide a signal from the housing dependently upon the detector detecting the light emitted by the converter through the metal atomic vapor.

A method of fabricating compact alkali vapor filled cells that have volumes of 1 cm³ or less that are useful in atomic frequency reference devices such as atomic clocks. According to one embodiment the alkali vapor filled cells are formed by sealing the ends of small hollow glass fibers. According to another embodiment the alkali vapor filled cells are formed by anodic bonding of glass plates to silicon wafers to seal the openings of holes formed in the silicon wafers. The anodic bonding method of fabricating the alkali vapor filled cells enables the production of semi-monolithic integrated physics packages of various designs.

A chip scale atomic clock is disclosed that provides a low power atomic time/frequency reference that employs direct RF-interrogation on an end-state transition. The atomic time/frequency reference includes an alkali vapor cell containing alkali atoms, preferably cesium atoms, flex circuits for physically supporting, heating, and thermally isolating the alkali vapor cell, a laser source for pumping alkali atoms within the alkali vapor cell into an end resonance state by applying an optical signal along a first axis, a photodetector for detecting a second optical signal emanating from the alkali vapor cell along the first axis, a pair of RF excitation coils for applying an RF-interrogation signal to the alkali atoms along a second axis perpendicular to the first axis, a pair of bias coils for applying a uniform DC magnetic field along the first axis, and a pair of Zeeman coils for applying a Zeeman interrogation signal to the alkali atoms and oriented and configured to apply a time-varying magnetic field along the second axis through the alkali vapor cell. Another flex circuit is used for physically supporting the laser source, for heating the laser source, and for providing thermal isolation of the laser source. The laser source can be a vertical cavity surface emitting laser (VSCEL). The bias coils can be Helmholtz coils.

An atomic clock having a physics package that includes a vacuum chamber cavity that holds atoms of Rb-87 under high vacuum conditions, an optical bench having a single laser light source, a local oscillator, a plurality of magnetic field coils, an antenna, at least one photo-detector and integrated control electronics. The single laser light source has a fold-retro-reflected design to create three retro-reflected optical beams that cross at 90° angles relative to one another in the vacuum chamber cavity. This design allows the single laser light source to make the required six trapping beams needed to trap and cool the atoms of Rb-87. The foregoing design makes possible atomic clocks having reduced size and power consumption and capable of maintaining an ultra-high vacuum without active pumping.

A CPT detector and a method for detecting CPT are disclosed. The CPT detector includes a quantum absorber, a polarization analyzer, and a detector. The quantum absorber includes a material having first and second low energy states coupled to a common high energy state. Transitions between the first low energy state and the common high energy state and between the second low energy state and the common high energy state are induced by electromagnetic radiation having a predetermined polarization state. The polarization analyzer blocks electromagnetic radiation of the predetermined polarization while passing electromagnetic radiation having a polarization state that is orthogonal to the predetermined polarization. The polarization analyzer is irradiated with a portion of the generated electromagnetic radiation that has passed through the quantum absorber. The detector generates a signal related to the intensity of electromagnetic radiation that leaves the polarization analyzer.

The present invention provides a method and system to simultaneously use the microwave and Zeeman end resonances associated with the same sublevel of maximum (or minimum) azimuthal quantum number m to lock both the atomic clock frequency and the magnetic field to definite values. This eliminates the concern about the field dependence of the end-resonance frequency. In an embodiment of the system of the present invention, alkali metal vapor is pumped with circularly-polarized D₁ laser light that is intensity-modulated at appropriate resonance frequencies, thereby providing coherent population trapping (CPT) resonances. In another embodiment, pumping with constant-intensity circularly-polarized D₁ laser light enhances magnetic resonances that are excited by alternating magnetic fields oscillating at appropriate resonance frequencies. In both embodiments, the resonances are greatly enhanced by concentrating most of the atoms in the initial state of the resonances, and by diminishing the spin-exchange broadening of the resonances. This leads to greater stability of optically pumped atomic clocks. This invention can also be used to operate an atomic magnetometer, where the feedback signal used to stabilize the magnetic field at the alkali-vapor cell can serve as a sensitive measure of the ambient magnetic field.

A microfabricated atomic clock (mfac) or magnetometer (mfam) vapor cell utilizing a method of forming a self-condensing silicon vapor cell cavity structure for the atomic clock or magnetometer.

The invention relates to a device and a method for continuously measuring the arrival time of a photon sequence. The device comprises a single photon detector, a preamplifier, a constant ratio discriminator, an atomic clock, a counter, a time-to-digital converter, a controller, a memory unit and a computer, wherein the output end of the constant ratio discriminator is connected with the controller; a square-wave pulse output by the atomic clock is used as a counting object of the counter and is transmitted into the time-to-digital converter; the rising edge of the square-wave pulse is used as a start signal of the time-to-digital converter, and the rising edge of a digital pulse signal is used as a stop signal of the time-to-digital converter; and the control end of the controller is respectively connected with the counter, a digit converter and the memory unit and used for controlling the synchronous storage of rough measuring time and fine measuring time into the memory unit. The invention solves the technical problems of continuous measurement incapability, narrow measurement range and limited application range of a traditional photon sequence arrival time measuring device, and the device has a wide measurement range and high accuracy in measuring the photon arrival time.

The invention discloses a foldable dual-beam magnetic light trap system which is mainly suitable for generating cold atoms in laser cooling. Three pairs of laser with opposite polarization and opposite travelling are formed in a vacuum chamber through reflecting incoming laser many times, and a magnetic light trap is formed under the mutual action of a magnetic field generated by an opposite Helmholtz coil. The foldable dual-beam magnetic light trap system is characterized in that multiple reflections are utilized, and laser energy is repeatedly utilized, thereby obtaining the cold atoms. Theinvention has the advantages of simple structure, easy power balance, stable atomicgroup, low input power of laser and easy adjustment, thereby providing a better cold atom resource for cold atom frequency scale, precise measurement and laser cooling physical test.

A microfabricated sensor includes a first reflector and a second reflector in a sensor cell, separated by a cavity path segment through a sensor cavity in the sensor cell. A signal window is part of the sensor cell. A signal emitter and a signal detector are disposed outside of the sensor cavity. The signal emitter is separated from the first reflector by an emitter path segment which extends through the signal window. The second reflector is separated from the second reflector by a detector path segment which extends through the signal window.

An atomic oscillator is disclosed, including an Alkaline metal cell, a light source illuminating a laser beam to the Alkaline metal cell, and a light detector detecting light passing through the Alkaline metal cell. The Alkaline metal cell includes a first member, a second member, a cell internal portion, and an Alkaline metal raw material. In the first member, a first glass substrate is bonded on a second surface of a first substrate where a first opening part is formed. In the second member, a second glass substrate is bonded to a fourth surface of a second substrate where a second opening part is formed. The cell internal portion is formed by the first opening part and the second opening part by bonding the first surface to the third surface. The Alkaline metal raw material is enclosed by the cell internal portion.

The invention discloses a device for achieving a minitype CPT atomic clock physical system. The device comprises a Bias-Tee, a VCSEL, a first quarter wave plate, an atomic gas chamber, a second quarter wave plate, a polarization beam splitter, a first photoelectric detector and a second photoelectric detector. The invention further discloses a method for achieving the minitype CPT atomic clock physical system. Elliptically-polarized light is adopted for resonance with atom CPT, and difference detection is conducted on the optical rotation effect generated by the resonance. According to the device and method for achieving the minitype CPT atomic clock physical system, background noise generated by optical frequency components which do not interact with atoms in multi-color light output by the VCSEL and conversion noise generated by light interacting with the atoms due to light frequency jitter which is converted into signal amplitude jitter through action with the atoms are eliminated, and the signal to noise ratio of CPT resonance signals is greatly increased; in addition, the device and the method further have the advantages that the influence on the obtained CPT resonance signals by environment magnetic field intensity fluctuation is small, and laser frequency stabilization can be easily achieved through an achieved atomic clock.

A device for an atomic clock, including: a laser source (102) that generates a laser beam; a splitter (101) that makes it possible to divert and allow a portion of the laser beam to pass therethrough in accordance with a predefined percentage; a quarter-wave plate (105) that modifies the linear polarization of the laser beam into circular polarization and vice versa; a gas cell arranged on the circular polarization laser beam; a mirror (107) sending the laser beam back toward the gas cell (106); a first photodetector (108a), and a polarizer (103) arranged between the laser beam outlet and the splitter in order to protect the laser source from the retroreflections emitted by different optical elements constituting the device.

A micro-fabricated atomic clock structure is thermally insulated so that the atomic clock structure can operate with very little power in an environment where the external temperature can drop to −40° C., while at the same time maintaining the temperature required for the proper operation of the VCSEL and the gas within the vapor cell.

The invention provides a high-precision time-frequency source capable of being tamed to a time-frequency standard in real time. The high-precision time-frequency source can obtain a first time-frequency clock difference sequence generated by a reference side and a global navigation satellite system (GNSS) remotely and in almost real time, and comprises a tamed side; the reference side generates N time-frequency signals of a to-be-calibrated clock; according to the N time-frequency signals and a satellite signal, a second time-frequency clock difference sequence is generated; according to the first time-frequency clock difference sequence and the second time-frequency clock difference sequence, a third time-frequency clock difference sequence between N time-frequency signals of a reference time-frequency source and the N time-frequency signals of the to-be-calibrated clock is obtained; according to the third time-frequency clock difference sequence, a relative frequency difference sequence is computed and acquired; and through the third time-frequency clock difference sequence and the corresponding relative frequency difference sequence, the to-be-calibrated clock is monitored and calibrated. The high-precision time-frequency source capable of being tamed to the time-frequency standard in real time can easily trace time performance and frequency performance of the reference time-frequency source (generally, the time-frequency standard, including a national time-frequency reference) in any laboratory, can trace the time and the frequency back to the International System of Units, and is relatively high in reliability, accuracy and stability.

The invention discloses a rubidium atomic clock with a high contrast ratio frequency discrimination signal. The rubidium atomic clock comprises a controlled crystal oscillator, a frequency multiplication synthesizer, a modulation oscillator, a direct current amplifier, a quantum system and a phase detector, wherein a first Glan-Taylor polarizer is placed on a light path between a beam expander and a physical device; a second Glan-Taylor polarizer is placed between the physical device and the photoelectric detector; and the first Glan-Taylor polarizer and the Glan-Taylor polarizer are orthogonally placed. The transmission backlight intensity is filtered, the first order light frequency shift is eliminated, and the contrast ratio of the frequency discrimination and the rubidium atomic clock property are improved. The high performance atomic clock is provided for satellite navigation, communication and precision measurement.