Electrometer with optical Rydberg frequency tuning

Patent metadata

Field	Value
Publication number	US-12429511-B2
Application number	US-202318465040-A
Country	US
Kind code	B2
Filing date	Sep 11, 2023
Priority date	Sep 14, 2022
Publication date	Sep 30, 2025
Grant date	Sep 30, 2025

Abstract

One embodiment includes an electrometer system. The system includes a sensor cell comprising alkali metal atoms within, and an optical beam system configured to provide at least one optical beam through the sensor cell to provide a first Rydberg energy state of the alkali metal atoms, the at least one optical beam exiting the sensor cell as a detection beam. The system also includes a tuning laser configured to generate a tuning beam having a predetermined tuning frequency between the first Rydberg energy state and an intermediate energy state of the alkali metal atoms. The system further includes a detection system configured to monitor the detection beam to detect an external signal having a frequency that is approximately equal to an energy difference between the first Rydberg energy state and a second Rydberg energy state based on monitoring the detection beam.

First claim

What is claimed is:

1. An electrometer system comprising:
a sensor cell comprising alkali metal atoms within;
an optical beam system configured to provide at least one optical beam through the sensor cell to provide a first Rydberg energy state of the alkali metal atoms, the at least one optical beam exiting the sensor cell as a detection beam;
a tuning laser configured to provide a tuning beam through the sensor cell, the tuning beam having a predetermined tuning frequency between the first Rydberg energy state and an intermediate energy state of the alkali metal atoms; and
a detection system configured to monitor the detection beam to detect an external signal having a frequency that is approximately equal to an energy difference between the first Rydberg energy state and a second Rydberg energy state based on monitoring the detection beam.

2. The system of claim 1 , wherein the tuning beam is configured to generate a pair of mixed energy states associated with the first Rydberg state and the intermediate energy state, wherein the detection system is configured to detect the external signal based on a frequency difference between the second Rydberg energy state and one of the mixed energy states.

3. The system of claim 2 , wherein the mixed energy states correspond to a respective pair of Autler-Townes frequency-spectrum transparency peaks, wherein the detection system is configured to detect the external signal in response to observing a change in the pair of Autler-Townes frequency-spectrum transparency peaks based on monitoring an intensity of the detection beam.

4. The system of claim 3 , wherein the detection system comprises:
a photodetector configured to monitor at least one of the intensity or phase of the detection beam and to generate a detection signal that corresponds to the intensity of the detection beam; and
a detection processor configured to detect the change in the pair of Autler-Townes frequency-spectrum transparency peaks based on the detection signal.

5. The system of claim 2 , wherein the tuning laser is adjusted by a tuning signal to adjust an energy difference between the respective one of the mixed energy states and the second Rydberg energy state to be approximately equal to the frequency of the external signal to detect the external signal.

6. The system of claim 5 , wherein the tuning signal is provided to the tuning laser to adjust at least one of a frequency and an intensity of the tuning beam to adjust the mixed energy states.

7. The system of claim 5 , wherein the detection system is configured to generate the tuning signal.

8. The system of claim 1 , wherein the optical system comprises:
a probe laser configured to generate a probe beam directed through the sensor cell in a first direction, the probe beam exiting the sensor cell as the detection beam; and
at least one coupling laser configured to generate a respective at least one coupling beam directed through the sensor cell collinearly with the probe beam to provide the first Rydberg energy state of the alkali metal atoms.

9. The system of claim 7 , further comprising optics configured to collimate the probe beam, the coupling beam, and the tuning beam to provide the probe beam, the coupling beam, and the tuning beam to be collinear on an optical axis with respect to each other, with the probe beam and the coupling beam being anti-parallel with each other, such that the detection system is configured to monitor the detection beam along the optical axis through the sensor cell to detect the external signal.

10. A method for detecting an external signal via an electrometer system, the method comprising:
providing a probe beam through a sensor cell comprising alkali metal atoms, the probe beam exiting the sensor cell as a detection beam;
providing a coupling beam through the sensor cell to excite the alkali metal atoms from a ground state to a first Rydberg energy state of the alkali metal atoms based on the probe beam and the coupling beam;
providing a tuning beam having a predetermined tuning frequency through the sensor cell, the predetermined tuning frequency being approximately equal to an energy difference between the first Rydberg energy state and an intermediate energy state of the alkali metal atoms; and
monitoring the detection beam to detect the external signal having a frequency that is approximately equal to an energy difference between the first Rydberg energy state and a second Rydberg energy state.

11. The method of claim 10 , wherein providing the tuning beam comprises providing the tuning beam having the predetermined tuning frequency equal to the energy difference between the first Rydberg state and the intermediate energy state.

12. The method of claim 10 , wherein providing the tuning beam comprises providing the tuning beam to generate a pair of mixed energy states associated with the first Rydberg state and the intermediate energy state, the method further comprising generating a tuning signal to adjust the mixed energy states to provide an energy difference between one of the mixed energy states and the second Rydberg energy state to be approximately equal to the frequency of the external signal to detect the external signal.

13. The method of claim 12 , wherein generating the tuning signal comprises adjusting at least one of a frequency and an intensity of the tuning beam to adjust the mixed energy states based on the tuning signal.

14. The method of claim 12 , wherein the mixed energy states correspond to a respective pair of Autler-Townes frequency-spectrum transparency peaks, wherein monitoring the detection beam comprises monitoring an intensity of the detection beam to observe a change in the pair of Autler-Townes frequency-spectrum transparency peaks.

15. The method of claim 10 , wherein providing the probe beam, the coupling beam, and the tuning beam comprises providing the probe beam, the coupling beam, and the tuning beam through a set of optics configured to collimate the probe beam, the coupling beam, and the tuning beam to provide the probe beam, the coupling beam, and the tuning beam to be collinear with respect to each other on an optical axis, such that the detection system is configured to monitor the detection beam along the optical axis through the sensor cell to detect the external signal.

16. An electrometer system comprising:
a sensor cell comprising alkali metal atoms within;
a probe laser configured to generate a probe beam directed through the sensor cell in a first direction, the probe beam exiting the sensor cell as the detection beam;
a coupling laser configured to generate a coupling beam directed through the sensor cell collinearly and anti-parallel with the probe beam to provide a first Rydberg energy state of the alkali metal atoms;
a tuning laser configured to provide a tuning beam through the sensor cell, the tuning beam having a predetermined tuning frequency between the first Rydberg energy state and an intermediate energy state of the alkali metal atoms; and
a detection system configured to monitor the detection beam to detect an external signal having a frequency that is approximately equal to an energy difference between the first Rydberg energy state and a second Rydberg energy state based on monitoring the detection beam.

17. The system of claim 16 , wherein the tuning beam is configured to generate a pair of mixed energy states associated with the first Rydberg state and the intermediate energy state, wherein the detection system is configured to generate a tuning signal to adjust the mixed energy states to provide an e

Assignees

• Northrop Grumman Systems Corp

Inventors

• Imhof Eric A

Classifications

• G01R29/12

  Measuring electrostatic fields {or voltage-potential} · CPC title

• G01R29/0885 Primary

  using optical probes, e.g. electro-optical, luminescent, glow discharge, or optical interferometers · CPC title