HIGH-PRECISION GHZ CLOCK GENERATION USING SPIN STATES IN DIAMOND

• US 20140247094A1
• Filed: 03/13/2014
• Published: 09/04/2014
• Est. Priority Date: 09/16/2011
• Status: Active Grant

• Current Assignee: Trustees Of Columbia University In The City Of New York (Columbia University), President and Fellows of Harvard College (Harvard Corporation)
• Original Assignee: Trustees Of Columbia University In The City Of New York (Columbia University)
• Inventors: Englund, Dirk R., Lukin, Mikhail D., Hodges, Jonathan, Yao, Norman Y.
• Granted Patent: US 9,385,654 B2
• Time in Patent Office: Days
• US Class Current: 331/94.1
• CPC Class Codes: G01R 33/1284 Spin resolved measurements; Influencing spins during measurements, e.g. in spintronics devices G01R33/093 takes precedence; semiconductor devices using spin polarized carriers H01L29/66984
• CPC Class Codes: G04F 5/14 using atomic clocks
• CPC Class Codes: H03B 17/00 Generation of oscillations using radiation source and detector, e.g. with interposed variable obturator
• CPC Class Codes: H03L 7/00 Automatic control of frequency or phase; Synchronisation
• CPC Class Codes: H03L 7/26 using energy levels of molecules, atoms, or subatomic particles as a frequency reference

Abstract

Techniques for obtaining a frequency standard using the crystal field splitting frequency of nitrogen vacancy center in diamond are disclosed. In certain exemplary embodiments, a microwave field is applied to the diamond and optically exciting the diamond under green light. The photoluminescent response of the diamond is measured by a photodetector. The intensity of the photoluminescent response can be used to determine the phase shift between the microwave and the crystal field splitting frequency. The microwave field frequency can be adjusted until the phase shift is below a predetermined threshold, and the microwave frequency can then be output for use as a standard.

Claims

1. A method for obtaining a frequency standard using the crystal field splitting frequency of at least one nitrogen vacancy center in at least one diamond structure, comprising:

applying a microwave field to the at least one diamond structure, the microwave field having an adjustable and an initial frequency;

optically exciting the at least one diamond structure to create photoluminescence having a photoluminescent characteristic based at least on the frequency of the microwave field;

detecting at least a first measurement of the photoluminescent characteristic at the initial microwave frequency;

determining, based on the first measurement, a phase shift for the known microwave frequency from the constant crystal field splitting frequency of the at least one diamond structure;

varying the frequency of the microwave field until the phase shift is below a predetermined threshold; and

using the frequency of the microwave field as a frequency standard.

2. The method of claim 1, wherein the frequency of the microwave field is continuously monitored to prevent drift of the frequency standard.

3. The method of claim 1, further comprising surrounding the at least one diamond structure with a dielectric cavity prior to applying the microwave field to allow optical excitation at a lower output power.

4. The method of claim 1, wherein the optically exciting further comprises optically pumping the at least one diamond structure.

5. The method of claim 4, wherein detecting at least a first measurement further comprises continuously detecting measurements.

6. The method of claim 1, wherein the optically exciting further comprises continuously optically pumping the at least one diamond structure.

7. The method of claim 1, wherein the optically exciting further comprises applying pulsed emissions to excite the at least one nitrogen vacancy center.

8. The method of claim 7, wherein the at least one nitrogen vacancy center is optically excited prior to the microwave pulse emissions.

9. The method of claim 7, further comprising:

optically exciting the at least one nitrogen vacancy center with a pulse of light having a wavelength of 532 un;

applying a n/4 microwave pulse;

waiting a time of period T;

applying a pi microwave pulse;

waiting a second time of period T;

applying a π

/4 microwave pulse in the same phase as the first π

/4 microwave pulse;

optically exciting the at least one nitrogen vacancy center with a pulse of light having a wavelength of 532 nm;

measuring the transient fluorescence response of the at least one nitrogen vacancy center; and

determining, from the transient fluorescence response, the phase shift of the applied microwave pulse from the crystal field splitting frequency of the at least one nitrogen vacancy center in the at least one diamond structure.

10. The method of claim 1, wherein the at least one diamond structure comprises a first and a second diamond structures, each having at least one nitrogen vacancy center, and

wherein the first measurement detecting further comprises simultaneously detecting a first measurement for the first diamond structure and a first measurement for the second diamond structure, to thereby stabilize the detected measurements with respect to temperature.

11. The method of claim 1, the at least one nitrogen vacancy having a temperature dependence, and further comprising controlling the temperate dependence of the at least one nitrogen vacancy center by engineered strain.

12. A system for obtaining a frequency standard using the crystal field splitting frequency of at least one nitrogen vacancy center in at least one diamond structure, comprising:

a dielectric cavity adapted to at least partially encompass the at least one diamond structure;

a light source, operatively configured to excite the at least one nitrogen vacancy, thereby allowing the at least one nitrogen vacancy center to produce a photoluminescent response;

a photodetector disposed proximal to the dielectric cavity and opposite the light source for detecting photoluminescence;

a stripline, disposed in the plane of and at least partially encompassing the at least one diamond structure, for applying microwave emissions to the at least one diamond structure;

a processor, coupled to the photodetector and the stripline, to calculate the phase shift of the frequency of the microwave emissions from the crystal field splitting frequency of the at least one nitrogen vacancy center in the at least one diamond structure; and

a controller, coupled to the processor and the stripline, to adjust the frequency of the microwave emissions from the stripline based on the determined frequency from the processor.

13. The system of claim 12, wherein the photodetector comprises a silicon photodiode.

14. The system of claim 12, wherein the dielectric cavity comprises a pair of Bragg reflectors to create a 532 nm resonant cavity.

15. The system of claim 14, wherein the pair of Bragg reflectors comprises one reflector placed on one face of the at least one diamond structure outside the plane of the stripline for applying microwave emissions, and further comprises the second Bragg reflector placed on the opposite face of the at least one diamond structure.

16. The system of claim 12, wherein the light source comprises a surface emitting laser adapted for generation of a doubled 1064 nrn beam.

17. The system of claim 12, wherein the light source comprises a laser adapted to continuously irradiate the at least one diamond structure.

18. The system of claim 17, wherein the stripline comprises a microwave source adapted to apply microwave emissions continuously upon the at least one diamond structure.

19. The system of claim 12, wherein the light source comprises a laser adapted for generation of pulses for application to the at least one diamond structure.

20. The system of claim 19, wherein the stripline comprises a microwave source adapted for generation of pulsed emissions upon the at least one diamond structure.

21. The system of claim 12, wherein the at least one diamond structure comprises a first and a second diamond structures, each having at least one nitrogen vacancy center,

wherein the processor is further adapted for simultaneously detecting a first measurement for the first diamond structure and a first measurement for the second diamond structure, to thereby stabilize the detected measurements with respect to temperature.

22. The system of claim 21, further comprising a first substrate having a first thermal expansion coefficient and a second substrate having a second thermal expansion coefficient, wherein the first diamond structure is coupled to the first substrate and the second diamond structure is coupled to the second substrate, and wherein the first and second thermal expansion coefficients are different.

23. The system of claim 12, wherein the at least one diamond structure is coupled to a single clamp to thereby induce strain thereon.