# US 2021/0239779 A1 · High-resolution magnetic field fingerprinting of integrated circuit activity with a quantum diamond microscope

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- Number: US 2021/0239779 A1
- Document ID: US20210239779A1
- Status: Published application
- Kind: A1
- Application number: 17/163,476
- Filed: 2021-01-31
- Published: 2021-08-05
- Earliest claimed: 2020-01-30
- Assignees: The MITRE Corporation; President and Fellows of Harvard College
- Applicants: President and Fellows of Harvard College; The MITRE Corporation; Sandia National Laboratories
- Inventors: Matthew James TURNER; Edlyn Victoria LEVINE; Pauli KEHAYIAS; Daniel T. WALTERS; Ronald L. WALSWORTH; Marko LONCAR; Nicholas Ryan LANGELLIER
- Web page: https://patentgrep.com/patent/US20210239779A1

## CPC

- G01R 33/032: using magneto-optic devices, e.g. Faraday {or Cotton-Mouton effect}
- G01R 33/5608: {Data processing and visualization specially adapted for MR, e.g. for feature analysis and pattern recognition on the basis of measured MR data, segmentation of measured MR data, edge contour detection on the basis of measured MR data, for enhancing measured MR data in terms of signal-to-noise ratio by means of noise filtering or apodization, for enhancing measured MR data in terms of resolution by means for deblurring, windowing, zero filling, or generation of gray-scaled images, colour-coded images or images displaying vectors instead of pixels (image data processing or generation, in general G06T)}
- G01N 24/10: by using electron paramagnetic resonance (G01N24/12 takes precedence)
- G01R 33/0017: {Means for compensating offset magnetic fields or the magnetic flux to be measured; Means for generating calibration magnetic fields}
- G01R 33/10: Plotting field distribution {; Measuring field distribution}
- G01R 33/12: Measuring magnetic properties of articles or specimens of solids or fluids (involving magnetic resonance G01R33/20)
- G01R 33/26: using optical pumping
- G01R 33/323: {Detection of MR without the use of RF or microwaves, e.g. force-detected MR, thermally detected MR, MR detection via electrical conductivity, optically detected MR}
- G01R 33/389: Field stabilisation {, e.g. by field measurements and control means or indirectly by current stabilisation}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Devices for determining a state of a magnetic field-generating article are provided. In various embodiments, a device comprises: a single crystal diamond having a plurality of NV centers, the single crystal diamond configured to be disposed adjacent to a magnetic field-generating article, and configured to generate a fluorescent signal in response to being illuminated by a light source; a coherent light source configured to generate a light beam directed at the single crystal diamond; a microwave (MW) radiation source configured to irradiate the single crystal diamond with a MW signal; a magnetic field source configured to apply a bias magnetic field to the single crystal diamond; a photosensor configured to collect the fluorescent signal generated by the single crystal diamond; and a computing node operatively coupled to each of the coherent light source, the MW radiation source, the magnetic field source, and the photosensor.

## Claims

### Claim 1

A device, comprising:
a single crystal diamond having a plurality of NV centers, the single crystal diamond configured to be disposed adjacent to a magnetic field-generating article, and configured to generate a fluorescent signal in response to being illuminated by a light source;
a coherent light source configured to generate a light beam directed at the single crystal diamond;
a microwave (MW) radiation source configured to irradiate the single crystal diamond with a MW signal;
a magnetic field source configured to apply a bias magnetic field to the single crystal diamond;
a photosensor configured to collect the fluorescent signal generated by the single crystal diamond;
a computing node operatively coupled to each of the coherent light source, the MW radiation source, the magnetic field source, and the photosensor, the computing node configured to:
sweep at least one control parameter selected from: the MW signal power, MW signal frequency, MW signal duration, or the strength of the bias magnetic field, and
based on the control parameters and the fluorescent signal generated by the single crystal diamond, compute the magnetic vector field of the magnetic field-generating article.

### Claim 2 (depends on 1)

The device of claim 1, wherein the coherent light source is pulsed, and the computing node is configured to vary the coherent source pulse duration.

### Claim 3 (depends on 1)

The device of claim 1, wherein the magnetic field-generating article comprises an integrated circuit.

### Claim 4 (depends on 3)

The device of claim 3, wherein the integrated circuit is decapsulated.

### Claim 5 (depends on 1)

The device of claim 1 wherein the computing node is further configured to perform dimensionality reduction of the magnetic vector field.

### Claim 6 (depends on 5)

The device of claim 5 wherein performing dimensionality reduction comprises PCA.

### Claim 7 (depends on 3)

The device of claim 3, wherein the state comprises a number of active ring oscillators of the integrated circuit.

### Claim 8 (depends on 1)

The device of claim 1, wherein an incidence angle of the light beam on the single crystal diamond causes total internal reflection of the light beam within the single crystal diamond.

### Claim 9 (depends on 1)

The device of claim 1, wherein a power of the coherent light source is selected so as to saturate the photosensor.

### Claim 10 (depends on 1)

The device of claim 1, wherein:
a polarization of the coherent light source is aligned with a predefined NV crystal axis of the single crystal diamond; and
the computing node is configured to monitor a single resonance.

### Claim 11 (depends on 1)

The device of claim 1, wherein:
a polarization of the coherent light source is configured to be equalized across a plurality of crystal axes of the single crystal diamond; and
the computing node is configured to monitor the plurality of crystal axes for vector measurements.

### Claim 12 (depends on 1)

The device of claim 1, wherein the light beam is shaped by a flat-top beam shaper.

### Claim 13 (depends on 1)

The device of claim 1, wherein the microwave radiation source is configured to modulate the MW signal to provide robustness to external noise.

### Claim 14 (depends on 1)

The device of claim 1, wherein the microwave radiation source is configured to simultaneously drive multiple MW frequencies.

### Claim 15 (depends on 14)

The device of claim 14 wherein the multiple MW frequencies are selected based on spacing of NV resonances of the single crystal diamond.

### Claim 16 (depends on 1)

The device of claim 1, wherein the MW signal has a frequency of greater than or equal to 2 GHz and less than or equal to 4 GHz.

### Claim 17 (depends on 1)

The device of claim 1, wherein the magnetic field source comprises a permanent magnet.

### Claim 18 (depends on 1)

The device of claim 1, wherein the permanent magnet is configured to project the bias magnetic field onto each of a plurality of NV axes of the single crystal diamond in a different respective direction for each of the NV axes.

### Claim 19 (depends on 1)

The device of claim 1, wherein the bias magnetic field has a strength of greater than or equal to 1 mT and less than or equal to 100 mT.

### Claim 20 (depends on 1)

The device of claim 1, wherein the magnetic field source comprises a Helmholtz coil.

### Claim 21 (depends on 20)

The device of claim 20 wherein the computing node is configured to differentiate a ferromagnetic component of the magnetic vector field of the magnetic field-generating article from a paramagnetic component of the magnetic vector field of the magnetic field-generating article.

### Claim 22 (depends on 1)

The device of claim 1, wherein the photosensor is configured to detect wavelengths in a range of greater than or equal to 600 nm and less than or equal to 800 nm.

### Claim 23 (depends on 1)

The device of claim 1, wherein the photosensor has a sampling rate of greater than or equal to 10 MHz and less than or equal to 100 MHz.

### Claim 24 (depends on 1)

The device of claim 1, wherein the photosensor comprises one or more selected from the group of: a CMOS, a CCD, a photodiode array, and a single photodiode.

### Claim 25 (depends on 1)

The device of claim 1, wherein the single crystal diamond comprises an NV layer having a thickness of less than or equal to 100 nm.

### Claim 26 (depends on 1)

The device of claim 1, wherein the single crystal diamond has a footprint of greater than or equal to 4 mm by 4 mm.

### Claim 27 (depends on 1)

The device of claim 1, wherein the single crystal diamond has a footprint of less than or equal to 100 μm by 100 μm.

### Claim 28 (depends on 1)

The device of claim 1, wherein the single crystal diamond comprises an NV layer comprising Nitrogen-15.

### Claim 29 (depends on 1)

The device of claim 1, wherein the single crystal diamond comprises Carbon-12.

### Claim 30 (depends on 1)

The device of claim 1, wherein the single crystal diamond is configured to be disposed in contact with the magnetic field-generating article.

### Claim 31 (depends on 1)

The device of claim 1, wherein the single crystal diamond is configured to be disposed spaced apart from the magnetic field-generating article.

### Claim 32 (depends on 1)

The device of claim 1, wherein the single crystal diamond is disposed in a movable mount configured to move the single crystal diamond through a plurality of positions adjacent the magnetic field-generating article.

### Claim 33 (depends on 1)

The device of claim 1, wherein the single crystal diamond has a ppm of NV of greater than or equal to 0.1 and less than or equal to 10.

### Claim 34 (depends on 1)

The device of claim 1, wherein the single crystal diamond has a fractional lattice strain of less than or equal to 0.000001.

### Claim 35 (depends on 1)

The device of claim 1, wherein the computing node is configured to sweep at least one of the control parameters selected from the group: environmental temperature of the device and environmental humidity of the device.

### Claim 36 (depends on 1)

The device of claim 1, wherein the computing node is configured to sweep one or more control parameters selected from the group: a position of the single crystal diamond relative to the magnetic field-generating article and an orientation of the single crystal diamond relative to the magnetic field-generating article.

### Claim 37 (depends on 1)

The device of claim 1, wherein the computing node is configured to sweep one or more control parameters selected from the group: an intensity of the light beam, a wavelength of the light beam, a beam shape of the light beam, a spot size of the light beam, a duration of the light beam, and an angle of incidence of the light beam.

### Claim 38 (depends on 1)

The device of claim 1, wherein the computing node is configured to sweep one or more control parameters selected from the group: a direction of the bias magnetic field a temporal pattern of the bias magnetic field.

### Claim 39 (depends on 1)

The device of claim 1, wherein the computing node is configured to sweep one or more control parameters selected from the group: photosensor gain, photosensor position, photosensor orientation, photosensor exposure time, photosensor temporal exposure pattern, photosensor sensitivity, and photosensor spectral range.

### Claim 40 (depends on 1)

The device of claim 1, wherein:
the magnetic field-generating article comprises an integrated circuit; and
the computing node is configured to cause the integrated circuit to execute a computer program.

### Claim 41 (depends on 1)

The device of claim 1, wherein the computing node is configured to cause a predefined current to be passed through one or more wires of the magnetic field-generating article.

### Claim 42 (depends on 1)

The device of claim 1, wherein the sweeping of at least one of the control parameters by the computing node is performed in accordance with one or more measurement protocols selected from the group: CW ODMR, pulsed ODMR, Ramsey, Hahn echo, Dynamical decoupling, Rabi, and T1 relaxometry.

### Claim 43 (depends on 1)

The device of claim 1, wherein the computing node is further configured to provide to the magnetic vector field of the magnetic field-generating article to an algorithm and receive therefrom a state of the magnetic field-generating article.

### Claim 44 (depends on 43)

The device of claim 43 wherein the state of the magnetic field-generating article comprises an indication of one or more selected from the group: whether the magnetic field-generating article was in an operating state during the time the fluorescent signal was collected, an identity of the magnetic field-generating article, whether the magnetic field-generating article has been tampered with following fabrication, whether the magnetic field-generating article matches a predetermined profile within a predefined tolerance; information processed by the magnetic field-generating article during the time the time the fluorescent signal was collected, materials with which the magnetic field-generating article is fabricated, and whether one or more defects are present in the magnetic field-generating article.

### Claim 45 (depends on 43)

The device of claim 43 wherein the algorithm comprises one or more selected from the group: a trained classifier, a convolutional neural network, a principal component analysis algorithm, and a support vector machine model.

### Claim 46 (depends on 43)

The device of claim 43 wherein the computing node is further configured to provide temperature data pertaining to the magnetic field-generating article to the algorithm.

### Claim 47 (depends on 43)

The device of claim 43 wherein the computing node is further configured to provide data representing the fluorescent signal to the algorithm.

### Claim 48 (depends on 43)

The device of claim 43 wherein the computing node is further configured to provide data representing the structure of the magnetic field-generating article to the algorithm.

### Claim 49 (depends on 43)

The device of claim 43 wherein determining the state of the integrated circuit further comprises providing linewidth, contrast, and/or temperature of the integrated circuit to the algorithm.

### Claim 50

A method comprising:
directing a light beam from a coherent light source at a single crystal diamond, wherein the a single crystal diamond comprises a plurality of NV centers and is disposed adjacent to a magnetic field-generating article, wherein the single crystal diamond is configured generate a fluorescent signal in response to being illuminated;
irradiating the single crystal diamond with a MW signal generated by a microwave (MW) radiation source;
applying a bias magnetic field to the single crystal diamond by a magnetic field source;
collecting the fluorescent signal generated by the single crystal diamond by a photosensor;
sweeping, by a computing node operatively coupled to each of the coherent light source, the MW radiation source, the magnetic field source, and the photosensor, at least one control parameters selected from the group: the MW signal power, MW signal frequency, MW signal duration, and strength of the bias magnetic field, and
based on the control parameters and the fluorescent signal generated by the single crystal diamond, computing, by the computing node, a magnetic vector field of the magnetic field-generating article.

### Claim 51

A non-transitory computer-readable storage medium storing instructions that, when executed by a system comprising a computing node operatively coupled to each of a coherent light source, a microwave (MW) radiation source, and a magnetic field source, cause the system to:
directing a light beam from the coherent light source at a single crystal diamond, wherein the a single crystal diamond comprises a plurality of NV centers and is disposed adjacent to a magnetic field-generating article, wherein the single crystal diamond is configured generate a fluorescent signal in response to being illuminated;
irradiate the single crystal diamond with a MW signal generated by the MW radiation source;
apply a bias magnetic field to the single crystal diamond by the magnetic field source;
collect the fluorescent signal generated by the single crystal diamond by a photosensor;
sweep at least one control parameters selected from the group: the MW signal power, MW signal frequency, MW signal duration, and strength of the bias magnetic field, and
based on the control parameters and the fluorescent signal generated by the single crystal diamond, compute a magnetic vector field of the magnetic field-generating article.

### Claim 52

A method comprising:
receiving fluorescence data representing a fluorescent signal generated by a single crystal diamond comprising a plurality of NV centers and disposed adjacent a magnetic field-generating article;
receiving parameter data representing one or more of a plurality of parameters, wherein the plurality of parameters characterize one or more selected from: a microwave signal irradiating the single crystal diamond, a bias magnetic field applied to the single crystal diamond, a light beam incident on the single crystal diamond, and a photosensor used to collect the fluorescent signal; and
processing the received fluorescence data and the received parameter data to generate magnetic vector field data representing a magnetic vector field of the magnetic field-generating article.

### Claim 53 (depends on 52)

The method of claim 52, further comprising applying one or more algorithms to generate, based the magnetic vector field data, state data representing a state of the magnetic field-generating article.

### Claim 54 (depends on 53)

The method of claim 53, wherein generating the state data is further based on temperature data pertaining to the magnetic field-generating article.

### Claim 55 (depends on 53)

The method of claim 53, wherein generating the state data is further based on the fluorescence data.

### Claim 56 (depends on 53)

The method of claim 53, wherein generating the state data is further based on data representing a structure of the magnetic field-generating article

### Claim 57 (depends on 53)

The method of claim 53, wherein the one or more algorithms comprise one or more selected from the group: a trained classifier, a convolutional neural network, a principal component analysis algorithm, and a support vector machine model.

### Claim 58 (depends on 53)

The method of claim 53, wherein the generated state data indicates whether the magnetic field-generating article was in an operating state during a predetermined time period.

### Claim 59 (depends on 53)

The method of claim 53, wherein the generated state data indicates an identity of the magnetic field-generating article

### Claim 60 (depends on 53)

The method of claim 53, wherein the generated state data indicates whether the magnetic field-generating article has been tampered with following fabrication.

### Claim 61 (depends on 53)

The method of claim 53, wherein the generated state data indicates whether the magnetic field-generating article matches a predetermined profile within a predefined tolerance.

### Claim 62 (depends on 53)

The method of claim 53, wherein the generated state data indicates information processed by the magnetic field-generating article during a predetermined time period.

### Claim 63 (depends on 53)

The method of claim 53, wherein the generated state data indicates materials with which the magnetic field-generating article is fabricated.

### Claim 64 (depends on 53)

The method of claim 53, wherein the generated state data indicates whether one or more defects are present in the magnetic field-generating article.