Nanoscale nuclear quadrupole resonance spectroscopy

Patent metadata

Field	Value
Publication number	US-10895617-B2
Application number	US-201716304362-A
Country	US
Kind code	B2
Filing date	May 24, 2017
Priority date	May 24, 2016
Publication date	Jan 19, 2021
Grant date	Jan 19, 2021

Abstract

A method for probing the properties of nanoscale materials, such as 2D materials or proteins, via nanometer-scale nuclear quadrupole resonance (NQR) spectroscopy using individual atom-like impurities in diamond. Coherent manipulation of shallow nitrogen-vacancy (NV) color centers enables the probing of the NQR spectrum of nanoscale ensembles of nuclear spins. Measuring the NQR spectrum at different magnetic field orientations and magnitudes and fitting to a theoretical model allows for the extraction of atomic structural properties of the material with nanoscale resolution.

First claim

The invention claimed is:

1. A method of characterizing nanoscale materials, comprising:
(a) providing a sample having at least one nuclear spin I with a nonzero nuclear quadrupole moment in proximity to a sensor, wherein the sensor comprises at least one first solid state electronic spin qubit;
(b) applying a magnetic field at a first angle to the sample;
(c) applying light and a plurality of external spin perturbation sequences to the sensor to coherently manipulate the spin state of the spin qubit, wherein each of the external spin perturbation sequences filters for a selected magnetic field frequency produced by the nuclear spins; and
(d) detecting an output signal given by the strength of the magnetic field at each selected frequency at a first position to provide a first nuclear quadrupole resonance (NQR) spectrum of the sample.

2. The method of claim 1 , further comprising:
(e) applying a magnetic field at a second angle to the sample; and
(f) repeating said (c) applying light and a plurality of external spin perturbation sequences to the sensor to coherently manipulate the spin state of the spin qubit and said (d) detecting an output signal given by the strength of the magnetic field at each selected frequency at a second position to obtain a second nuclear quadrupole resonance spectrum of the sample, wherein fitting both the first and second nuclear quadrupole resonance spectra to a theoretical model provides orientation and/or structural information about the sample.

3. The method of claim 2 , wherein said (e) and said (f) are carried out at multiple angles to further improve the accuracy of the theoretical fit which provides information on the structural information.

4. The method of claim 1 , further comprising:
(g) identifying a second solid state electronic spin qubit in proximity to the sample;
(h) aligning the magnetic field to the second solid state electronic spin qubit; and
(i) repeating said (c) applying light and a plurality of external spin perturbation sequences to the sensor to coherently manipulate the spin state of the spin qubit and said (d) detecting an output signal given by the strength of the magnetic field at each selected frequency to provide a first nuclear quadrupole resonance spectrum of the sample at the second solid state electronic spin qubit to obtain a third nuclear quadrupole resonance spectrum of the sample, wherein comparison of the first and third nuclear quadrupole resonance spectra provides information about structure variation across different regions of the sample.

5. The method of claim 1 , wherein the solid state electronic spin qubit comprises a nitrogen vacancy center in a diamond crystal lattice.

6. The method of claim 1 , wherein the at least one nuclear spin has I≥1.

7. The method of claim 1 , wherein the plurality of external spin perturbation sequences uses a radio frequency (RF) electromagnetic field.

8. The method of claim 7 , wherein the plurality of external spin perturbation sequences comprises k microwave π-pulses with a modulation frequency in the range of 0.1 to 10 MHz, where k is in the range of 1 to thousands, depending on a coherence time of the solid state electronic spin qubit.

9. The method of claim 1 , wherein detecting the output signal is accomplished by measuring spin-dependent fluorescence.

10. The method of claim 1 , wherein the applied magnetic field strength is selected so that a Zeeman and quadrupole interactions are of the same order of magnitude.

11. The method of claim 1 , wherein the sample is at least one of a two dimensional material, a protein, a biological macromolecule.

12. The method of claim 1 , wherein the selected magnetic field frequencies are in the range of 0.1 to 10 MHz.

13. The method of claim 1 , wherein the first angle of the applied magnetic field is aligned with a symmetry axis of the solid state electronic spin qubit.

14. The method of claim 1 , further comprising fitting the NQR spectrum to a pre-determined model of the atomic structure of the sample.

15. The method of claim 1 , wherein at least one of a quadrupole coupling constant and a local electric field gradient is determined from fitting the NQR spectrum.

16. A system for measuring the nuclear spin interactions of a nanoscale material with nuclear quadrupole coupling, comprising:
a sensor for receiving a nanoscale sample, wherein the sensor comprises at least one solid state electronic spin qubit;
a magnetic field source capable of applying a magnetic field at more than one angle;
a light source;
an external spin perturbation source for providing a plurality of external spin perturbation sequences to the sensor, wherein the light source and external spin perturbation source are configured to coherently manipulate the spin state of the spin qubit, wherein each of the external spin perturbation sequences filters for a selected magnetic field frequency produced by the nuclear spins; and
a detector for detecting an output signal given by the strength of the magnetic field at each selected frequency to provide a first nuclear quadrupole resonance spectrum of the sample.

17. The system of claim 16 , wherein the sensor comprises a defect in a high purity diamond crystal lattice, and the defect comprises a nitrogen vacancy center in the diamond crystal lattice.

18. The system of claim 16 , wherein the selected magnetic field frequencies are in the range of 0.1 to 10 MHz.

19. The system of claim 16 , wherein the magnetic field source is selected to provide and applied magnetic field strength in the range of 1 to 2000 Gauss.

20. The system of claim 16 , wherein the external spin perturbation source comprises a radio frequency (RF) electromagnetic field source.

Assignees

• Harvard College

Inventors

• Lovchinsky Igor
• Sanchez Javier
• Urbach Elana K
• Choi Soonwon
• Andersen Trond
• Kim Philip
• Park Hongkun
• Lukin Mikhail D

Classifications

• G01N24/08

  by using nuclear magnetic resonance (G01N24/12 takes precedence) · CPC title

• G01R33/1284

  Spin resolved measurements; Influencing spins during measurements, e.g. in spintronics devices · CPC title

• G01R33/441 Primary

  Nuclear Quadrupole Resonance [NQR] Spectroscopy and Imaging · CPC title

• G01R33/032

  using magneto-optic devices, e.g. Faraday {or Cotton-Mouton effect} · CPC title