Magnetometry based on electron spin defects

Abstract

A magnetometer includes a sample signal device; a reference signal device; a microwave field generator operable to apply a microwave field to the sample signal device and the reference signal device; an optical source configured to emit light including light of a first wavelength that interacts optically with the sample signal device and with the reference signal device; at least one photodetector arranged to detect a sample photoluminescence signal including light of a second wavelength emitted from the sample signal device and a reference photoluminescence signal including light of the second wavelength emitted from the reference signal device, in which the first wavelength is different from the second wavelength; and a magnet arranged adjacent to the sample signal device and the reference signal device.

What is claimed is: 
     
         1 . A magnetometer comprising:
 a sample signal device;   a reference signal device;   a microwave field generator arranged to apply a microwave field to the sample signal device and the reference signal device;   an optical source configured to emit light comprising light of a first wavelength that interacts optically with the sample signal device and with the reference signal device;   at least one photodetector arranged to detect a sample photoluminescence signal comprising light of a second wavelength emitted from the sample signal device and a reference photoluminescence signal comprising light of the second wavelength emitted from the reference signal device, wherein the first wavelength is different from the second wavelength, and   wherein the light of the second wavelength emitted from the sample signal device and the light of the second wavelength emitted from the reference signal device share at least part of a common optical path to the at least one photodetector; and   a magnet arranged adjacent to the sample signal device and the reference signal device.   
     
     
         2 . The magnetometer of  claim 1 , comprising a computer system coupled to the at least one photodetector and configured to receive light measurement signals corresponding to the sample photoluminescence signal and to the reference photoluminescence signal from the at least one photodetector,
 wherein the computer system is configured to differentiate between the light measurement signals corresponding to the sample photoluminescence signal and the light measurement signals corresponding to the reference photoluminescence signal by applying time-gated detection, and   wherein the time-gated detection is based on different optical path lengths for (i) the light of the second wavelength emitted from the sample signal device and (ii) the light of the second wavelength emitted from the reference signal device.   
     
     
         3 . The magnetometer of  claim 1 , comprising a beamsplitter arranged to divide the light emitted by the optical source into two beams that are directed to the sample signal device and the reference signal device, respectively. 
     
     
         4 . The magnetometer of  claim 1 , comprising an optical switch configured to alternately direct the light emitted by the optical source towards either the sample signal device or the reference signal device. 
     
     
         5 . The magnetometer of  claim 4 , wherein the optical switch comprise an acousto-optic modulator. 
     
     
         6 . The magnetometer of  claim 4 , wherein the optical switch is configured to switch at a rate faster than a rate of change of a time-varying magnetic field to which the magnetometer is exposed. 
     
     
         7 . The magnetometer of  claim 1 , comprising an optical filter arranged on the common optical path to the at least one photodetector, the optical filter configured to filter light of at least one wavelength out of the light of the second wavelength emitted from the sample signal device and the light of the second wavelength emitted from the reference signal device. 
     
     
         8 . The magnetometer of  claim 1 , comprising an enclosure, wherein the sample signal device, the reference signal device, the microwave field generator, the optical source, the at least one photodetector, and the magnet are arranged within the enclosure,
 wherein the enclosure is configured to attach to an article of clothing, and wherein the enclosure is configured such that the sample signal device is closer to the article of clothing than is the reference signal device when the magnetometer is attached to the article of clothing.   
     
     
         9 . The magnetometer of  claim 1 , comprising an enclosure, wherein the sample signal device, the reference signal device, the microwave field generator, the optical source, the at least one photodetector, and the magnet are arranged within the enclosure,
 wherein the enclosure is configured to removably adhere to human skin, and wherein the enclosure is configured such that the sample signal device is closer to the human skin than is the reference signal device when the magnetometer is adhered to the human skin.   
     
     
         10 . The magnetometer of  claim 1 , wherein the at least one photodetector comprises a photodetector arranged to detect the sample photoluminescence signal and the reference photoluminescence signal. 
     
     
         11 . A magnetometer comprising:
 a sample signal device;   a reference signal device;   a microwave field generator arranged to apply a microwave field to the sample signal device and the reference signal device;   an optical source configured to emit light comprising light of a first wavelength that interacts optically with the sample signal device and with the reference signal device;   at least one photodetector arranged to detect a sample photoluminescence signal comprising light of a second wavelength emitted from the sample signal device and a reference photoluminescence signal comprising light of the second wavelength emitted from the reference signal device, wherein the first wavelength is different from the second wavelength;   a magnet arranged adjacent to the sample signal device and the reference signal device; and   a computer system coupled to the at least one photodetector and configured to receive light measurement signals corresponding to the sample photoluminescence signal and to the reference photoluminescence signal from the at least one photodetector,   wherein the computer system is configured to differentiate between the light measurement signals corresponding to the sample photoluminescence signal and the light measurement signals corresponding to the reference photoluminescence signal by applying time-gated detection, and   wherein the time-gated detection is based on different optical path lengths for (i) the light from the optical source directed to the sample signal device and (ii) the light from the optical source directed to the reference signal device.   
     
     
         12 . The magnetometer of  claim 11 , wherein the optical source is configured to emit the light of the first wavelength as encoded light, and
 wherein the computer system is configured to differentiate between the light measurement signals corresponding to the sample photoluminescence signal and the light measurement signals corresponding to the reference photoluminescence signal based on an encoding of the encoded light.   
     
     
         13 . The magnetometer of  claim 12 , wherein the encoded light comprises pulsed light. 
     
     
         14 . The magnetometer of  claim 11 , comprising an optical switch configured to alternately direct the light emitted by the optical source towards either the sample signal device or the reference signal device. 
     
     
         15 . The magnetometer of  claim 14 , wherein the optical switch comprise an acousto-optic modulator. 
     
     
         16 . The magnetometer of  claim 14 , wherein the optical switch is configured to switch at a rate faster than a rate of change of a time-varying magnetic field to which the magnetometer is exposed. 
     
     
         17 . The magnetometer of  claim 11 , wherein the computer system is configured to cause the at least one photodetector to detect the sample photoluminescence signal at a first time and the reference photoluminescence signal at a second time, wherein the first time is different from the second time. 
     
     
         18 . The magnetometer of  claim 17 , wherein the magnet is arranged such that the sample signal device and the reference signal device are exposed to approximately the same magnitude of a magnetic field originating at the magnet. 
     
     
         19 . The magnetometer of  claim 11 , comprising:
 a beamsplitter arranged to receive the light emitted by the optical source and split the light emitted by the optical source into a first portion and a second portion, wherein the first portion is directed to the reference signal device; and   a mirror arranged to receive the second portion and direct the second portion to the sample signal device.   
     
     
         20 . The magnetometer of  claim 11 , wherein a first optical path of the light from the optical source to the sample signal device has a common portion with a second optical path of the light from the optical source to the reference signal device.