Coldquanta, Inc.

Judith Olson

Evan Salim

Andrew Kortyna

Flavio Cruz

Dina Genkina

Gabriel Ycas

A rubidium optical atomic clock uses a modulated 778 nanometer (nm) probe beam and its reflection to excite rubidium 87 atoms, some of which emit 758.8 nm fluorescence as they decay back to the ground state. A spectral filter rejects scatter of the 778 nm probe beams while transmitting the 775.8 nm fluorescence so that the latter can be detected with a high signal-to-noise ratio. Since the spectral filter is only acceptably effective at angles of incidence less than 8° from the perpendicular, the atoms are localized by a magneto-optical trap so that most of the atoms lie within a conical volume defined by the 8° angle so that the resulting fluorescence detection signal has a high signal-to-noise ratio. The fluorescence detection signal can be demodulated to provide an error signal from which desired adjustments to the oscillator frequency can be calculated.

Atomic clock with enhanced oscillator regulation

A method for controlling an atomic clock is described. The method includes receiving, at a processor, a request including an operational mode of multiple operational modes for the atomic clock. The atomic clock includes a local oscillator, a vapor cell, a detector, and a local oscillator controller. The vapor cell includes atoms and receives from the local oscillator a signal having a frequency. The signal causes transitions of the atoms between atomic energy states. The detector detects the transitions and provides to the local oscillator controller an error signal based on the transitions. The error signal indicates a difference between the frequency and a target frequency. The local oscillator controller controls the local oscillator based on the error signal. The processor determines, based on the operational mode, values for control parameters for the atomic clock. The atomic clock is controlled using the values of the parameters.

Flexible atomic clock

An atomic clock employs hybrid long/short quantum clock frequency regulation wherein each of a series of regulation cycles includes a relatively long (four Ramsey-cycle) combination error signal (CES) cycle and plural relatively short (two Ramsey-cycle) single error signal (SES) cycles. The CES cycles provide for better long-term stability than can be provided using only SES cycles. However, including the SES cycles between CES cycles improves short term stability with negligible diminishment of long-term stability.

Hybrid-cycle quantum-clock frequency regulation

A multi-quantum-reference (MQR) laser frequency stabilization system includes a laser system, an MQR system, and a controller. The laser system provides an output beam with an output frequency, and plural feedback beams with respective feedback frequencies. The feedback beams are directed to the MQR system which includes plural references, each including a respective population of quantum particles, e.g., rubidium 87 atoms, with respective resonant frequencies for respective quantum transitions. The degree to which the feedback frequencies match or deviate from the resonance frequencies can be tracked using fluorescence or other electro-magnetic radiation output from the references. The controller can stabilize the laser system output frequency based on plural reference outputs to achieve both short-term and long-term stability, e.g., in the context of an atomic clock.

Multi-quantum-reference laser frequency stabilization

A fluorescence detection process begins by localizing rubidium 87 atoms within an optical (all-optical or magneto-optical) trap so that at least most of the atoms in the trap are within a cone defined by an effective angle, e.g., 8°, of a spectral filter. Within the effective angle of incidence, the filter effectively rejects (reflects or absorbs) 778 nanometer (nm) fluorescence and effectively transmits 775.8 nm fluorescence. Any 775.8 nm fluorescence arrive outside the effective angle of incidence. Thus, using an optical trap to localize the atoms within the cone enhances the signal-to-noise ratio of the fluorescence transmitted through the spectral filter and arriving a photomultiplier or other photodetector, resulting fluorescence detection signal with an enhanced S/N.

Fluorescence detection with optical-trap-enhanced spectral filtering

A rubidium optical atomic clock uses a modulated 778 nanometer (nm) probe beam and its reflection to excite rubidium 87 atoms, some of which emit 758.8 nm fluorescence as they decay back to the ground state. A spectral filter rejects scatter of the 778 nm probe beams while transmitting the 775.8 nm fluorescence so that the latter can be detected with a high signal-to-noise ratio. Since the spectral filter is only acceptably effective at angles of incidence less than 8&#xb0; from the perpendicular, the atoms are localized by a magneto-optical trap so that most of the atoms lie within a conical volume defined by the 8&#xb0; angle so that the resulting fluorescence detection signal has a high signal-to-noise ratio. The fluorescence detection signal can be demodulated to provide an error signal from which desired adjustments to the oscillator frequency can be calculated.

Atomic clock with atom-trap enhanced oscillator regulation

A frequency-modulated spectrometry (FMS) output is used to stabilize an atomic clock by serving as an error signal to regulate the clock's oscillator frequency. Rubidium 87 atoms are localized within a hermetically sealed cell using an optical (e.g., magneto-optical) trap. The oscillator output is modulated by a sinusoidal radio frequency signal and the modulated signal is then frequency doubled to provide a modulated 788 nm probe signal. The probe signal excites the atoms, so they emit 775.8 nm fluorescence. A spectral filter is used to block 788 nm scatter from reaching a photodetector, but also blocks 775.8 nm fluorescence with an angle of incidence larger than 8&#xb0; relative to a perpendicular to the spectral filter. The localized atoms lie within a conical volume defined by the 8&#xb0; effective angle of incidence so an FMS output with a high signal-to-noise ratio is obtained.

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Northglenn, CO, United States of America

Judith Olson