# US 2018/0321641 A1 · Architecture for compact cold atom clocks > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0321641 A1 - Document ID: US20180321641A1 - Status: Published application - Kind: A1 - Application number: 15/967,409 - Filed: 2018-04-30 - Published: 2018-11-08 - Earliest claimed: 2017-05-01 - Assignees: AOSense, Inc. - Applicants: AOSense, Inc. - Inventors: Martin M. Boyd; Adam T. Black; Thang Q. Tran; Matthew D. Swallows; Brian R. Patton; Miao Zhu; Thomas H. Loftus; Mark A. Kasevich - Web page: https://patentgrep.com/patent/US20180321641A1 ## CPC - H01S 5/0687: Stabilising the frequency of the laser - G04F 5/14: using atomic clocks - H01S 3/0085: {Modulating the output, i.e. the laser beam is modulated outside the laser cavity} - H01S 3/08086: {Multiple-wavelength emission} - H01S 3/10: Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating - H01S 3/10092: {Coherent seed, e.g. injection locking} - H01S 3/105: by controlling the mutual position or the reflecting properties of the reflectors of the cavity {, e.g. by controlling the cavity length}({H01S3/10076}, H01S3/13 take precedence) - H01S 3/13: Stabilisation of laser output parameters, e.g. frequency or amplitude - H01S 3/1305: {Feedback control systems} - H01S 5/12: the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers (comprising a photonic bandgap structure H01S5/11; surface-emitting lasers H01S5/18) - H01S 5/14: External cavity lasers (H01S5/18 takes precedence; mode locking H01S5/065) - H01S 5/142: {which comprises an additional resonator} - H03L 7/26: using energy levels of molecules, atoms, or subatomic particles as a frequency reference - H05H 3/02: Molecular or atomic-beam generation, e.g. resonant beam generation - H01S 5/0085: {for modulating the output, i.e. the laser beam is modulated outside the laser cavity} - H01S 5/02251: using optical fibres - H01S 5/125: Distributed Bragg reflector [DBR] lasers - H01S 5/146: {using a fiber as external cavity} - H01S 5/4012: {Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms} - H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL - G04F: TIME-INTERVAL MEASURING (measuring pulse characteristics G01R, e.g. G01R29/02; in radar or like systems G01S) - H03L: AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES (generation of oscillations H03B) - H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS ## Abstract An atomic oscillator device includes an atomic oscillator, a controlled oscillator, a resonance controller, and a cold-atom clock output. The atomic oscillator comprises a two-dimensional optical cooling region (2D OCR) for providing a source of atoms and a three-dimensional optical cooling region (3D OCR) for cooling and/or trapping the atoms emitted by the 2D OCR. The atomic oscillator comprises a microwave cavity surrounding the 3D OCR for exciting an atomic resonance. The controlled oscillator produces an output frequency. The resonance controller is for steering the output frequency of the controlled oscillator based on the output frequency and the atomic resonance as measured using an atomic resonance measurement. The cold-atom clock output is configured as being the output frequency of the controlled oscillator. ## Claims ### Claim 1 A device, comprising: an atomic oscillator, wherein the atomic oscillator comprises: a two-dimensional optical cooling region (2D OCR) for providing a source of atoms, a three-dimensional optical cooling region (3D OCR) for cooling and/or trapping the atoms emitted by the 2D OCR, and a microwave cavity surrounding the 3D OCR for exciting an atomic resonance; and a controlled oscillator, wherein the controlled oscillator produces an output frequency; a resonance controller for steering the output frequency of the controlled oscillator based on the output frequency and the atomic resonance as measured using an atomic resonance measurement; and a cold-atom clock output configured as being the output frequency of the controlled oscillator. ### Claim 2 (depends on 1) The device as in claim 1, further comprising a multi-layer magnetic shield surrounding the microwave cavity for separating the 3D OCR from strong magnetic fields of the 2D OCR. ### Claim 3 (depends on 1) The device of claim 1, wherein the controlled oscillator comprises a microwave generator. ### Claim 4 (depends on 1) The device of claim 1, wherein the resonance controller is used to control a laser for a temporal sequence including state preparation, atom cooling, and measurement. ### Claim 5 (depends on 1) The device of claim 1, wherein the 2D OCR comprises a two-dimensional optical molasses (2D OM). ### Claim 6 (depends on 1) The device of claim 1, wherein the 2D OCR comprises a two-dimensional magneto-optical trap (2D MOT). ### Claim 7 (depends on 1) The device of claim 1, wherein the 3D OCR comprises a three-dimensional optical molasses (3D OM). ### Claim 8 (depends on 7) The device of claim 7, wherein the 3D OCR comprises a three-dimensional magneto-optical trap (3D MOT). ### Claim 9 (depends on 1) The device of claim 1, wherein the 2D OCR, the 3D OCR, and the microwave cavity are in vacuum. ### Claim 10 (depends on 1) The device of claim 1, wherein the microwave cavity is surrounded by magnetic shielding, also in vacuum. ### Claim 11 (depends on 1) The device of claim 1, wherein the microwave cavity is a loop-gap resonator (LGR) cavity. ### Claim 12 (depends on 11) The device of claim 11, wherein the LGR cavity has multiple microwave feeds for improved homogeneity of a microwave field phase and/or a microwave field amplitude. ### Claim 13 (depends on 1) The device of claim 1, wherein a microwave cavity resonant frequency of the microwave cavity is tuned by adjusting a cavity end cap thickness. ### Claim 14 (depends on 1) The device of claim 1, wherein 2D OCR laser beams are generated by a single laser beam entering the 2D OCR and the single laser beam is routed in an optical racetrack configuration, wherein the optical racetrack configuration enables an incoming beam to retrace its path without lateral displacement. ### Claim 15 (depends on 1) The device of claim 1, wherein the 2D OCR and the 3D OCR share a common optical source with laser detuning and intensity control. ### Claim 16 (depends on 1) The device of claim 1, wherein a single laser generates all laser beams required for the device. ### Claim 17 (depends on 16) The device of claim 16, wherein the single laser generates a single laser beam transmitted to the atomic oscillator. ### Claim 18 (depends on 1) The device of claim 1, wherein 3D OCR laser beams are generated by a single laser beam routed in an optical racetrack configuration, wherein the optical racetrack configuration enables an incoming beam to retrace its path without lateral displacement. ### Claim 19 (depends on 18) The device of claim 18, wherein the 3D OCR laser beams are used for absorptive detection of a number of atoms in a particular atomic state. ### Claim 20 (depends on 18) The device of claim 18, wherein optics comprising the optical racetrack configuration are enclosed within the microwave cavity. ### Claim 21 (depends on 18) The device of claim 18, wherein the single laser beam is sent into the 3D OCR via a polarizing beamsplitter, and wherein polarization optics within the 3D OCR rotate a polarization of a returning beam by approximately 90 degrees. ### Claim 22 (depends on 1) The device of claim 1, wherein permanent magnets are used to generate magnetic fields in the 2D OCR and/or the 3D OCR. ### Claim 23 (depends on 1) The device of claim 1, wherein a series of adjacent beamsplitter cubes is used to divert laser light with an elongated beam shape toward the 2D OCR. ### Claim 24 A method for a cold atom clock, comprising: providing an atomic oscillator, wherein the atomic oscillator comprises: a two-dimensional optical cooling region (2D OCR) for providing a source of atoms, a three-dimensional optical cooling region (3D OCR) for cooling and/or trapping the atoms emitted by the 2D OCR, and a microwave cavity surrounding the 3D OCR for exciting an atomic resonance; and providing a controlled oscillator, wherein the controlled oscillator produces an output frequency; providing a resonance controller for steering the output frequency of the controlled oscillator based on the output frequency and the atomic resonance as measured using an atomic resonance measurement; and providing a cold-atom clock output configured as being the output frequency of the controlled oscillator.