KR101936205B1 - Temperature measurement device and method using diamond nv center - Google Patents

Abstract

The present invention is characterized in that a microwave for changing the quantum state of spin is applied to the diamond nitrogen vacancy and the temperature is measured by measuring the quantum phase of the spin of the nitrogen vacancy, And more particularly, to a temperature measurement apparatus and method using a diamond nitrogen vacancy defect, which can quickly and accurately measure the temperature of an object to be disposed, with high sensitivity.

Description

Technical Field [0001] The present invention relates to a TEMPERATURE MEASUREMENT DEVICE AND METHOD USING DIAMOND NV CENTER,

The present invention relates to an apparatus and a method for measuring temperature using diamond nitrogen vacancy defects, and more particularly, to a diamond nitrogen vacancy defect measuring method capable of measuring a minute temperature of a few mK by a quantum sensor using a nitrogen impurity spin in a diamond And more particularly, to a temperature measuring apparatus and method using the same.

Recently, quantum sensors using spins of nitrogen vacancy impurities in diamond have been developed.

These quantum sensors have excellent spatial resolution at the atomic level and are susceptible to strain and have a high temperature sensitivity of several tens of mK by measuring the minute volume expansion of the diamond by temperature change. The Ramsey interferometer (Ramsey interferometry, DC magnetic field) and dynamic decoupling (AC magnetic field).

In other words, such a quantum sensor measures the temperature using the property that the phase rotation frequency of the spin quantum state changes sensitively according to the external temperature.

Such a Ramsey interferometer and a sequence according to dynamic decoupling will prepare two states and use a pulse for measurement axis projection, that is, a? / 4 pulse and a? Pulse for decoupling.

However, this conventional technique has a fatal problem in that the sensitivity of the sensor is rapidly changed due to the experimental inaccuracy of the pulse generator.

Published Japanese Patent Application No. 10-2005-0085261

Disclosure of Invention Technical Problem [8] The present invention has been made in order to solve the problems described above, and it is an object of the present invention to provide a temperature measurement apparatus and method using diamond nitrogen vacancy defects, which can generate ideal pulses irrespective of changes in resonance frequency, .

In order to achieve the above object, the present invention is characterized in that a microwave for changing the quantum state of spin is applied to a diamond nitrogen vacancy and the temperature is measured by measuring the quantum phase of the spin of the nitrogen vacancy It is possible to provide a temperature measurement method using diamond nitrogen vacancy.

Here, the microwave is characterized in that the microwave has a plurality of amplitudes that are different from each other for the entire time set to be applied to the nitrogen vacancy.

Here, the microwave may include a divided wave having a different amplitude corresponding to a plurality of divided time periods in which the entire time is divided into different lengths or equal lengths of the whole time set so that the microwave is applied to the nitrogen vacancies .

The microwave is a sum of a plurality of sinusoidal waves having the same amplitude or different from each other and applied to the nitrogen vacancy for the entire time set so that the microwave is applied to the nitrogen vacancy.

The sinusoidal wave components of the arbitrary one period of the plurality of sinusoidal waves whose amplitudes at the start and the end of an arbitrary period are 0 during the entire time are extracted and the amplitudes of the extracted sinusoidal components are modulated, And the microwave to be applied to the cavity is generated.

The measurement of the magnetic field may include a confocal scanning unit including a light source for generating a beam capable of optically exciting the spin state of the nitrogen vacancy and the microwave capable of being applied to the nitrogen vacancy An NV sensor unit provided with a tip including the nitrogen vacancy, and an optical sensor for detecting the light emission after the beam passes through the NV sensor unit so that the absorption intensity of the optical radiation can be measured. And a detector for detecting the temperature of the sample.

The NV sensor unit may include a structure in which a plurality of the tips are arranged in parallel.

According to another aspect of the present invention, there is provided a method for measuring a temperature using a diamond nitrogen vacancy in which a microwave for changing a quantum state of spin is applied to a diamond nitrogen vacancy and the quantum phase of the spin of the nitrogen vacancy is measured, Device may be provided.

The present invention also provides a scanning electron microscope comprising a confocal scanning unit including a light source for generating a beam capable of optically exciting a spin state of a diamond nitrogen vacancy and a pulse for generating a microwave capable of being applied to the nitrogen vacancy An NV sensor unit having a tip including the nitrogen vacancy and a detector for detecting the light emission after the beam passes through the NV sensor unit so that the absorption intensity of the optical radiation can be measured And the microwave is applied to the nitrogen vacancy, and the temperature is measured by measuring the quantum phase of the spin of the NV sensor unit. It is a matter of course that the present invention also provides a temperature measurement apparatus using the diamond nitrogen vacancy .

Here, the microwave is characterized in that the microwave has a plurality of amplitudes that are different from each other for the entire time set to be applied to the nitrogen vacancy.

At this time, depending on the displacement of the measurement object disposed between the confocal scanning unit and the upper side of the NV sensor unit and connected to the confocal scanning unit and the NV sensor unit, And a feedback position corrector for performing position correction based on negative feedback.

And a spectral analyzer connected to the quantum sensor, the pulse generating unit and the confocal scanning unit, for measuring the light emission from the nitrogen vacancy irradiated with the beam.

According to the present invention having the above-described configuration, the following effects can be achieved.

First, the present invention can generate an ideal? / 4 or? Pulse irrespective of the change in the resonance frequency, thereby improving the sensitivity and accuracy of temperature measurement.

In particular, the present invention can be applied to a temperature measuring sensor for measuring temperature with a sensitivity of 8 mK / Hz or less at the unit of the size of the quantum sensor in nm.

FIG. 1 schematically shows a process of gradually changing the amplitude of a pulse in space-time and frequency space using a Fourier transform. FIG. 1 (a) is a graph showing a process of changing the amplitude of a pulse with respect to time , And FIG. 1 (b) is a graph showing a process of changing the amplitude shape of the pulse on the frequency space
2 is a block diagram schematically showing an apparatus for measuring temperature using diamond nitrogen vacancy defects according to an embodiment of the present invention.
FIG. 3 is a conceptual diagram illustrating the spin states of NV according to temperature measurement using diamond nitrogen vacancy defects according to an embodiment of the present invention.
FIG. 4 is a graph showing the comparison of temperature measurement in a wide band compared with the conventional method when the microwave generated by the bandwidth optimization control method is applied to the spin
FIG. 5 is a side cross-sectional view illustrating a process of fabricating a nanocantilever for temperature measurement using a diamond nitrogen vacancy defect according to an embodiment of the present invention. FIG.
6 is a perspective view illustrating a nanocantilever and an array of the nanocantilever fabricated for temperature measurement using a diamond nitrogen vacancy defect according to an embodiment of the present invention.
FIG. 7 is a side cross-sectional conceptual diagram illustrating a process of fabricating a nanocantilever for temperature measurement using diamond nitrogen vacancy defects according to another embodiment of the present invention.
FIG. 8 is a side cross-sectional view illustrating a process of fabricating a nanocantilever for temperature measurement using a diamond nitrogen vacancy defect according to another embodiment of the present invention

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and how to accomplish them, will become apparent by reference to the embodiments described in detail below with reference to the accompanying drawings.

However, the present invention is not limited to the embodiments described below, but may be embodied in various other forms.

The present embodiments are provided so that the disclosure of the present invention is thoroughly disclosed and that those skilled in the art will fully understand the scope of the present invention.

And the present invention is only defined by the scope of the claims.

Thus, in some embodiments, well known components, well known operations, and well-known techniques are not specifically described to avoid an undesirable interpretation of the present invention.

In addition, throughout the specification, like reference numerals refer to like elements, and the terms (mentioned) used herein are intended to illustrate the embodiments and not to limit the invention.

In this specification, the singular forms include plural forms unless the context clearly dictates otherwise, and the constituents and acts referred to as " comprising (or having) " do not exclude the presence or addition of one or more other constituents and actions .

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs.

Also, commonly used predefined terms are not ideally or excessively interpreted unless they are defined.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

First, FIG. 1 schematically shows a process of gradually changing the amplitude of a pulse in space-time and frequency space using a Fourier transform. FIG. 1 (a) shows a process of changing the amplitude of a pulse with respect to time And FIG. 1 (b) is a graph showing a process of changing the shape of the amplitude of the pulse on the frequency space.

2 is a block diagram schematically illustrating a temperature measuring apparatus using diamond nitrogen vacancy defects according to an embodiment of the present invention.

FIG. 3 is a conceptual diagram illustrating the spin states of NV according to the temperature measurement using the diamond nitrogen vacancy defect according to one embodiment of the present invention.

FIG. 4 is a graph comparing a magnetic field generated in a bandwidth optimization control method when a microwave is applied to a spin, in comparison with a conventional method, in which a magnetic field can be measured in a wide band.

Meanwhile, FIG. 5 is a side cross-sectional view illustrating a process of fabricating a nanocantilever for temperature measurement using a diamond nitrogen vacancy defect according to an embodiment of the present invention. FIG. 6 is a cross- A nanocantilever and an array of the nanocantilevers fabricated for temperature measurement using a nitrogen vacancy defect.

7 is a side cross-sectional view illustrating a process of fabricating a nanocantilever for temperature measurement using a diamond nitrogen vacancy defect according to another embodiment of the present invention.

FIG. 8 is a side cross-sectional view illustrating a process of fabricating a nanocantilever for temperature measurement using a diamond nitrogen vacancy according to another embodiment of the present invention. Referring to FIG.

According to the apparatus and method for measuring temperature using diamond nitrogen vacancy defects according to an embodiment of the present invention, a microwave for changing the quantum state of spin is applied to the diamond nitrogen vacancy and the quantum phase So that the temperature can be measured.

The object of the measurement described above is the quantum phase of the spin of the diamond nitrogen vacancy, and the temperature near the nitrogen vacancy is measured through the quantum phase of the spin.

In other words, temperature measurement means sensing the change of object temperature.

At this time, when the measurement object is placed near the diamond nitrogen vacancy, the temperature of the NV sensor unit 2 including the diamond nitrogen vacancy is measured by the amount of heat from the object, Or the amount of temperature change can be measured very sensitively.

In addition, the above-described microwave has a plurality of amplitudes that are different from one another over the entire time period in which the microwave is applied to the nitrogen vacancy.

In other words, the microwave may be described as the sum of divided waves having different amplitudes with periodicity for the whole time set for the microwave to be applied to the nitrogen vacancy.

Here, the amplitudes at the beginning and the end of one period of each of the divided waves are all 0, and as a result, the microwave is applied to the nitrogen vacancies during the entire time period in which the microwave is applied to the nitrogen vacancies, The sum of sine waves.

In other words, any one of a plurality of sine waves having an amplitude of 0 at the beginning and an end of an arbitrary one period during a whole time period may extract different sine wave components, modulate the amplitude of the extracted sine wave component, Thereby generating a microwave.

The temperature is measured by using the energy difference between | 0> and | 1+> of the spin of the nitrogen vacancy. When this energy difference is changed, the phase change rate with time is changed. When this phase change is measured, The temperature in the vicinity of the public can be measured.

Here, in order to measure the phase change, when an AC magnetic field corresponding to? / 4 is applied to the nitrogen vacancies and an AC magnetic field corresponding to -π / 4 is applied again after a certain period of time, So that the phase change can be measured from the brightness of the light.

At this time, the above-mentioned constant time can be said to be a very short time of several seconds to several microseconds.

Therefore, the above-mentioned microwave may include divided waves having different amplitudes obtained by dividing a very short time of about several minutes to several microseconds again into a plurality of divided waves, and it is assumed that one cycle of each divided wave having different amplitudes The amplitude of the beginning and end of each is 0.

For example, assuming a sine wave with a period of one second, the amplitude at the beginning and end of the period, 0s and 0s, is all zero, and so is the case for sine waves with a period of two seconds.

The amplitude of the start and end of the sine wave having a cycle of 0.5 second is also 0, and the amplitude of the start and the end of the sine wave having a cycle of 1/3 second is 0, If there is a time set to apply a wave, there will be infinite number of sine waves with zero amplitude at the beginning and end of the time.

Therefore, by extracting only a few frequency components from infinitely many sinusoidal waves and modulating the amplitude of each sinusoidal wave, the microwave can be produced.

In short, by determining the shape of the microwave, it is possible to calculate how the state of the spin changes when the microwave is applied to the spin.

It is assumed that there is artificial noise, and when one microwave is applied to each situation, it is confirmed that the state of spin is manipulated as desired, and the shape of the microwave is changed little by a mathematical calculation as shown in FIG. 1, The operation of the spin can be performed as desired in the noise condition.

The above-described temperature measurement can be performed using the temperature measuring apparatus shown in Fig.

The temperature measuring apparatus may include a confocal scanning unit 4 including a light source that generates a beam capable of optically exciting the spin state of the nitrogen vacancy as shown.

The temperature measuring apparatus includes a pulse generating unit 3 for generating a microwave capable of being applied to a nitrogen vacancy, an NV sensor unit 2 provided with a tip including a nitrogen vacancy, And a detector for detecting the light emission after the beam passes through the NV sensor unit 2 so that measurement can be made.

Here, the beam is a green beam having a wavelength of about 500 to 640 nm, more preferably about 532 nm, and the light emission has a wavelength of about 500 to 640 nm, more preferably about 640 nm It may be a red beam.

First, the NV sensor unit 2 is provided with a nanocantilever (see FIG. 6) in which a tip including a nitrogen vacancy is formed.

Here, instead of the nitrogen vacancy, a silicon vacancy center (hereinafter, referred to as SV) or quantum information in the diamond may be included. In the present invention, the NV will be mainly described.

The pulse generating unit 3 includes an Arbitrary waveform base-band generator (WBG) connected to the NV sensor unit 2 and giving an arbitrary pulse to the NV sensor unit 2 .

The confocal scanning unit 4 is disposed on the upper side of the NV sensor unit 2 and compares and analyzes the phase variation of any pulse given to the NV sensor unit 2 by the WBG and spin by NV When the temperature measurement of the object placed under the tip is completed, the NV sensor unit 2 is irradiated with a beam to initialize the phases of both spins.

The present invention further includes a piezostage controller 1 disposed on the lower side of the NV sensor unit 2 and the piezo stage controller 1 controls the above described object to be measured and the NV sensor The distance between the tips of the portions 2 can be controlled to 2 nm or less.

In addition, the piezo stage controller 1 may control the distance between the above described object to be measured and the tip of the NV sensor unit 2 to 0.5 nm or less by the open loop control.

And, the detector can largely include a single photon counter 5, a gated photon counting unit 6, and a main timing control unit 7.

The single photon counter 5 is connected to the confocal scanning unit 4 and is for detecting the amount of fluorescence after photoexcitation of both spins photographed by the confocal scanning unit 4 at a single photon level.

The gating photon counting unit 6 is connected to the single photon counter 5 and is for detecting gated photons among the detected single photons.

The main timing control unit 7 is also connected to the pulse generating unit 3, the confocal scanning unit 4, the single photon counter 5 and the gating photon counting unit 6, and the pulse generating unit 3 To synchronize the pulses given to the NV sensor and the pulses according to the TTL logic level output of the single photon counter 5.

The present invention is also characterized in that the present invention is disposed between the confocal scanning unit 4 and the upper side of the NV sensor unit 2 and connected to the confocal scanning unit 4 and the NV sensor unit 2, It is needless to say that the present invention may be further provided with a feedback position corrector 8 for performing position correction based on negative feedback in accordance with displacement of a measurement object disposed in a proximity.

Although not specifically shown in the confocal scanning unit 4, a focusing lens is provided so as to converge green light at one point of the NV included in the tip.

That is, the green light irradiated from the confocal scanning unit 4 is not irradiated over the entire area of the measurement object but is scanned through the above-described focusing lens in a state in which the NV is focused, whereby the whole of the tip and the lens or the measurement object Scan.

The problem is that when the distance between the focused lens and the tip is changed due to the displacement of the object to be measured, the focus is shifted from the focus point to the NV .

Such a shift in focus may lead to a problem of acquiring images to be photographed by irradiating green light to a wrong place, not a measurement target.

The feedback position corrector 8 of the present invention is provided for the purpose of solving this problem. The feedback position corrector 8 automatically performs the position feedback based on the negative feedback and outputs the position correction result to the confocal scanning unit 4 and the NV sensor unit 2, Thereby guiding the green light to be accurately irradiated in a state in which the focus is always adjusted to the NV.

On the other hand, the present invention relates to a spectrum analyzer (hereinafter referred to as " spectrometer ") which is connected to the quantum sensor 2, the pulse generating unit 3 and the confocal scanning unit 4 and measures the light emission from the NV illuminated with the green beam of the above- (Not shown) may be further applied.

Here, the reflected beam may be a red beam having a wavelength of 500 to 640 nm, more preferably a wavelength of about 638 nm.

The operation of the spectrum analyzer and the temperature measurement method using the spectrum analyzer will be described later in more detail.

On the other hand, the NV sensor unit 2 may include a structure in which a plurality of the tips described above are arranged in parallel.

As described above, the object of the measurement is the quantum phase of the spin of the diamond nitrogen vacancy.

What can be detected through the quantum phase of the spin of the nitrogen vacancy is the temperature near the nitrogen vacancy.

Measuring the spin of a specific material by arranging a plurality of tips in parallel as described above has a different meaning as far as the temperature of a small area of an atomic unit and a temperature change of an electron spin as a smallest magnet are measured.

The NV sensor unit 2 including the spin of the diamond nitrogen vacancy, that is, the nitrogen vacancy sensor, is very sensitive and has a very small size because it has the size of one atom.

Therefore, when such a nitrogen vacancy sensor is used, it is possible to measure not only the temperature in a small region of the atomic unit but also the temperature change of the electron spin, which is the smallest magnet, since the nitrogen vacancy sensor is a very sensitive ultra small sensor.

When there is an object to be measured for measuring the surface temperature, conventionally, there is a problem in that a single nitrogen public sensor is placed close to the object to be measured, and scanning is performed while measuring the object at one point.

On the other hand, according to the NV sensor unit 2 having a plurality of tips arranged in parallel as described above, the number of scanning times described above can be drastically reduced, so that the temperature of the surface of a measurement object having a large area can be measured at a high speed It will be possible.

Hereinafter, for convenience of explanation, "microwave" is replaced with "pulse "

When a pulse is applied to the nitrogen vacancy included in the tip of the NV sensor unit 2, the periphery of the NV sensor unit 2 generated as the phase changes after the spin of the nitrogen vacancy is rotated by the above- It is possible to measure the temperature of the liquid.

That is, an arbitrary waveform base-band generator (WBG) provided in the pulse generating unit 3 connected to the NV sensor unit 2 outputs an arbitrary pulse to the NV sensor unit 2 To the public spin (S1: first step).

Next, after the state preparation pulse applied to the NV sensor unit 2 is applied by the WBG, the phase change under the external magnetic field of the spin of the nitrogen vacancy is compared and analyzed to measure the temperature of the spin (S2: second step).

Particularly, in the first step S1, the focus of the rust blue light irradiated on the NV included in the tip from the above-mentioned confocal scanning unit 4 is shifted to the displacement of the measurement object placed in contact with or close to the end of the tip Accordingly, it is possible to additionally perform the position feedback based on the negative feedback by the feedback position corrector 8 described above.

This position correction operation is as mentioned in the description of the feedback position corrector 8 described above.

Here, when the temperature measurement of the spin is completed, the confocal scanning unit 4 irradiates the NV sensor unit 2 with a green beam having a wavelength of 532 nm as described above to initialize the phases of the spins Can be additionally performed.

At this time, when phase initialization of both spins is completed, the first step (S1) and the second step (S2) will be sequentially executed.

In addition, in the first step S1, when the phases of both of the spins are initialized as shown in Fig. 3, the WBG gives the start pulse 3i of the first waveform to both of the spins, and the magnetic field applied to the single electron spin is measured The final pulse 3f of the second waveform having the same phase as that of the first waveform is given.

For reference, in the 'input pulse signal' shown on the second line in FIG. 3, the (π / 4) x indicating the start pulse 3i and the (π / 4) x indicating the last pulse 3f A quadrangle indicates that π / 4 waves and -π / 4 waves having a constant amplitude along the x axis are repeatedly generated on the xy plane.

In the first step S1, an intermediate pulse 3m of a third waveform having a phase different from that of the first waveform and the second waveform is applied between the start pulse 3i and the final pulse 3f as shown in Fig. 3 A process of granting one time will be performed.

It can be seen that the first time interval between the start pulse 3i and the intermediate pulse 3m and the second time interval between the intermediate pulse 3m and the last pulse 3f are the same.

Further, the first waveform of the start pulse 3i is? / 4 wave, the second waveform of the last pulse 3f is? / 4 wave, and the third waveform of the intermediate pulse 3m is? Wave.

Also, the first time interval and the second time interval are from 100 占 to 99 占 퐏.

For example, the WBG sequentially applies? / 4 wave and? Wave to the NV sensor unit 2 as shown in FIG. 4, and the confocal scanning unit 4 photographs the behavior of both spins, The sensor unit 2 measures the temperature through the spin of the nitrogen vacancy.

At this time, in the second step S2, a? / 4 wave which is the start pulse 3i is applied to the nanocantilever of the NV sensor unit 2, and then a? / 4 wave for a first time interval, And then a step of applying a π wave, which is an intermediate pulse (3m), to the nitrogen vacancy after 100 to 99 μs has elapsed after the application of the pulse is stopped.

In addition, in the second step S2, a? -Wave, which is the intermediate pulse 3m, is applied to the nitrogen vacancy, and then the application of the? Wave is stopped during the second time interval, i.e., 100 to 99 占 퐏. And a process of applying -π / 4 wave, which is the final pulse 3f, to the nitrogen vacancies after the lapse of a predetermined period of time will be sequentially performed.

Therefore, by this sequential process, it is possible to measure the temperature change from the phase difference generated by measuring the red light emitted from the spin provided with the final pulse 3f.

Meanwhile, in the second step (S2) of the present invention, a process of measuring a red beam of 638 nm wavelength emitted from NV by irradiating a green beam having a wavelength of 532 nm to the above-mentioned NV with a spectrum analyzer .

The spectrum analyzer measures the debye wall factor, which is the ratio of the spectral width of the phonon of the 638 nm wavelength band to the spectral width of the zero-phonon line non-bonded red beam and the width of the red beam of 640 nm, .

Namely, NV that receives green beam of 532nm wavelength emits red beam of 638nm wavelength band.

At this time, the light of 638 nm is combined with phonon, which is the thermal vibration of the surrounding, to emit a red beam of a wide wavelength band near 640 nm.

The spectrum analyzer described above was used to calculate the ratio of the spectral width of the red phonon line red light beam not conjugated with the phonon of 638 nm to the red light beam width of 640 nm. The temperature can be measured by using the above principle.

Meanwhile, the present invention can perform magnetic field measurement by performing quantum sensing in a smooth optimal control scheme.

The above-mentioned bandwidth limitation optimal control will be described.

First, if an arbitrary function is a periodic function with a period of T, then this function can be described as the sum of trigonometric functions with 2π / T as the fundamental frequency.

For example, if 1 MHz is the fundamental frequency, it is possible to assume an integral multiple of 1 Mhz, 2 Mhz, 3 Mhz, and so on.

In this experimental situation, the pulses can be thought of as periodic functions that are 0 initially and then zero again after multiplying the pulses, which is the Hamiltonian sum of the trigonometric functions with a certain frequency as the fundamental frequency It can be described.

Therefore, when the Hamiltonian described in the time space is fourier transformed, it becomes visible in the frequency space.

Conversely, if we create a Hamiltonian in frequency space and transform it into a Fourier transform, we can see Hamiltonian in space and time.

The use of only integer multiples of the fundamental frequency does not violate the discrete nature of the computer at all. By arbitrarily defining the frequencies that we will use, we mean that high frequency components from grape or krotov can be automatically deleted This also means that it is easy to reproduce experimentally.

Gradient method is the method which occupies most of numerical analysis technique. When the slope at each point is obtained and moved in the direction of slope, the maximum or minimum value of the function is found. The maximum value of the fidelity function In this way.

Therefore, if a time evolution operator is obtained in Hamiltonian, it will have the form as shown in FIGS. 1 (a) and 1 (b).

On the other hand, the bandwidth limitation optimal control is based on the floquet theory, and the flow theory assumes that the shape of the pulse is the periodicity with respect to time (the pulse has a periodicity of zero at the beginning and end) , The Schrödinger equation describing such a system can be reduced to an eigenvalue problem.

That is, the pulse-like modulation process is performed in the frequency domain through the Fourier transform, not on the time axis.

By slightly changing the amplitude in the above-mentioned frequency space, the frequencies used for pulse modulation can be limited, so that it is possible to easily reproduce experimentally easily.

For example, 1 MHz, 2 MHz, 3 MHz, ... , 10 MHz Determines frequency components and number to be used for pulse modulation such as frequency components, and assigns an arbitrary value at first to see how much amplitude each frequency component has.

Then, we calculate the degree of fidelity when the pulse is applied to the spin.

Then, if the degree of agreement is not sufficiently large, the magnitude of each amplitude is slightly changed by mathematical calculation to increase the degree of agreement.

Therefore, if the calculated degree of agreement is not sufficiently large, the process of changing the magnitude of each amplitude is repeated to modulate the pulse so that the degree of agreement is greater than or equal to a desired value.

The Hamiltonian (H) mentioned above will be described in more detail,

Can be described as follows.

Where a is detuning from the resonant frequency when a square wave pulse is applied, an is the amplitude of the magnetic field in the x-axis direction with a frequency of n?, And bn is the amplitude of the magnetic field in the y- Amplitude.

At this time, the number of frequency components to be used is set in advance, Hamiltonian (H) is calculated through the above-described equation, and a time evolution operator is calculated from this to calculate gate fidelity .

When the calculated value (F) of the gate agreement is smaller than the threshold value, the process of gradually changing an and bn in the gradient direction is repeated using a gradient method.

Thus, even if there is detuning from the resonance frequency by applying the converged optimized pulse to the nitrogen vacancy, the fidelity of the pulse can be maintained at a high value as shown in FIG.

4 is a waveform (SOC) obtained by applying a pulse generated by a bandwidth limiting optimal control to a spin, and the phase is rotated by 45 degrees, that is, by? / 4, as shown in FIG. It is possible to know how much awareness it has.

In other words, it can be seen that the waveform (SOC) shows a similarity to 1 (Ideal) in a wider area as compared with a conventional rectangular wave (see a thin and thin line) The control is to prove that it can measure other properties including temperature over a wider range.

On the other hand, before the first step S1 is performed, the operator inserts an NV sensor unit 2 having a nanocantilever having a tip formed with a nitrogen vacancy between the piezo stage controller 1 and the confocal scanning unit 4, Can be disposed.

A process of fabricating the nanocantilever of the NV sensor unit 2 so that the temperature measurement as described above can be performed will now be described with reference to FIG.

First, an organic mask of PMMA is formed on diamond containing NV, and gold (Au) is deposited on the organic mask (S10: first process).

Thereafter, the organic mask is removed with acetone, and a lift off is performed in which a metal mask is formed only on a portion of the diamond where the organic mask is absent (Step S20: Step 2).

Subsequently, an oxygen plasma is applied to the diamond to form a tip having the NV while the portion of the diamond other than the metal mask is scraped off (S30: third process).

Next, after performing the first step (S1) and the second step (S2) again by turning the diamond upside down, the metal mask formed on the inverted diamond is removed and the array of cantilevers (see the upper part of FIG. 6) (Refer to the lower part of Fig. 6) (S40: fourth process).

Here, the cantilever is attached to the NV sensor unit 2, and an arbitrary one of the arbitrary values given through the WBG provided in the pulse generation unit 3 that is connected to the NV sensor unit 2 and gives a pulse to the NV sensor unit 2 The temperature can be measured through a single electron spin by the waveform, that is, the start pulse 3i, the intermediate pulse 3m, and the final pulse 3f.

Meanwhile, the first step S10 may be performed through the following process.

First, a boiling tri-acid mixture is mixed with sulfuric acid, perchloric acid, and nitric acid in a ratio of 1: 1: 1 and applied to the surface of the diamond to be cleaned .

Then, the diamonds to which the triacetic acid mixture is applied are sequentially washed in acetone, isopropyl alcohol, and deionized water.

Next, PMMA is coated on the diamond surface using a spincoater and heat-treated.

First, PMMA 495K a6 was coated on diamond with a spin coater at 500 rpm for 3 seconds and at 2000 rpm for 45 seconds. After heat treatment for 60 seconds on a 180 占 폚 hot plate, PMMA 950K was spin-coated at 500 rpm For 3 seconds, at 4000 rpm for 45 seconds, and heat-treated on a 180 占 폚 hot plate for 60 seconds.

Subsequently, an electron beam is irradiated to the diamond coated with PMMA to form an electron beam pattern. When the electron beam pattern is completed, chromium and gold are deposited on the diamond.

At this time, the diamond coated with PMMA is put into the SEM equipment with the electron beam function to form the electron beam pattern. The dose of the electron beam is adjusted to 50 to 500 μC / cm 2 according to the pattern size, .

Then, the diamond irradiated with the electron beam is taken out from the SEM equipment and immersed in a solution of methyl isobutyl ketone and isopropyl alcohol in a ratio of 1: 3 for 1 minute and 30 seconds.

At this time, the immersing time varies little by little depending on the pattern, and when soaked, PMMA remains only on the part where the electron beam is irradiated, thereby forming a soft organic mask.

When the above pattern is completed, chromium (Cr) is deposited to a thickness of 10 nm and gold or silver to a thickness of 200 nm using a sputter or an evaporator.

At this time, chromium is an adhesion layer so that gold and diamond are adhered to each other well.

Thereafter, in the second process (S20), a measurement object to which gold is deposited through chromium on diamond is immersed in acetone for one day, and PMMA which is a soft organic mask is erased so that only a portion lacking the organic mask is left with a metal mask (Lift Off process).

Subsequently, in the third process (S30), the diamond is shaved, that is, the etching process is performed in the state where the metal mask is formed.

When the plasma is applied to the diamond using inductively coupled plasma of oxygen (O2 45 SCCM at a pressure of 10 mtorr, bias power: 100 W, ICP power: 700 W) Only diamonds will be shaved.

Here, the etching is performed at about 220 nm per minute, and the etching time may be adjusted according to the length of the tip. In the present invention, the tip was etched for 5 minutes because the length was about 1.1 탆.

Then, in a fourth step S40, the diamond is turned upside down to form a cantilever shape.

First, the diamond cantilever is etched using O2 50 SCCM, Bias power: 200 W, ICP power: 2500 W at a pressure of 10 mtorr until the diamond cantilever has a thickness of about 50 μm, and the etching is performed at about 650 nm per minute .

Next, when the etching is completed, the PMMA coating and pattern are again performed to form a metal mask in a desired shape (for example, 20 탆 3 탆), and then etched with oxygen plasma to form the final shape Top).

In order to completely cut out the diamond with the above conditions (20 탆 3 탆), stop applying the plasma for 5 minutes at intervals of 5 minutes for 150 minutes and perform the etching.

6) and a cantilever array (see the lower part of FIG. 6) are formed through the etching process, and the diamond cantilever to be used is cut from the cantilever array by a focused ion beam device, So that it can be used after cutting.

For reference, all of the first to fourth steps (S10 to S40) described above proceed at room temperature.

The NV sensor unit 2 equipped with the nanocantilever including the nitrogen vacancy center (NV) fabricated as described above can be temperature-measured using the temperature measuring apparatus as shown in FIG. 2 described above.

In the meantime, the nanocantilever according to the present invention can be fabricated through the same process as shown in FIG. 5, and the nanocantilever can be fabricated through the processes shown in FIGS.

As described above, a process of fabricating a nanocantilever having a tip including NV before arranging the NV sensor unit 2 will be described as follows.

First, as shown in FIG. 7, a nanocantilever is manufactured by a first process of raising a solution 21 in which a nanodiamond 20 is diluted in a silicon mold 10 having a plurality of recessed grooves 11 formed in an inverted pyramid shape on its surface (S11). ≪ / RTI >

Thereafter, the second process S21 in which the nano-diamonds 20 are stacked and seated in the plurality of seating grooves 11 as the solution 21 evaporates will be performed.

Subsequently, the operator pours and polydimethylsiloxane (PDMS 30) on the surface of the silicon mold 10 including the plurality of seating grooves 11 described above and then coagulates with the nano diamond 20, The third step S31 of separating the PDMS 30 from the silicon mold 10 may be performed.

8, the nano-cantilever is made of a PDMS (nano-cantilever) mixed with a solution 21 in which a nanodiamond 20 is diluted in a silicon mold 10 having a plurality of seating grooves 11 having an inverted pyramid shape formed on its surface (S12) of pouring up the pellets (30).

Thereafter, a second process (S22) in which the nano-diamonds 20 mixed in the PDMS 30 are stacked and seated in the plurality of seating grooves 11 will be performed.

Subsequently, the worker can perform the work according to the third step (S32) of separating the solidified PDMS 30 from the silicon mold 10 together with the nano-diamonds 20.

7 and 8, the process of fabricating the nanocantilever is performed in such a manner that the bottom surface of the PDMS 30 separated from the silicon mold 10 and the bottom surface of the PDMS 30 separated from the bottom surface of the PDMS 30 A work according to a fourth step S40 of depositing gold (Au) on the outer surface of the tip 31 protruding in the corresponding inverted pyramid shape and solidified together with the PDMS 30 together with the nano- .

It goes without saying that the fifth step S50 of edge cutting the tip portion 31 of the gold 40 with the gold 40 may be further performed.

Therefore, when the green light 50 is irradiated to the nanodiamond 20 which is seated on the distal end of the tip 31, the nanodiamond 20 reflects the red light 60, thereby enabling center measurement of the NV.

7 and 8, a plurality of mounting grooves 11 recessed in an inverted pyramid shape are formed parallel to the surface of the silicon mold 10 (refer to FIG. 7 and FIG. 8) So as to form an etching mask.

It is needless to say that in the second process (S21, S22), the PDMS 30 may be heated at 80 DEG C for 10 hours for coagulation.

For reference, a conventional NV diamond cantilever, i.e., a nanocantilever and a tip, including the embodiment of FIG. 5, typically has a large area of diamond processed through an etching process, so that manufacturing cost and cost are high and a long time is required for the working process , Mass production was a difficult problem.

Particularly, the conventional nanocantilever and tip have a limitation in that it is impossible to measure the magnetic field by contacting the surface of the object to be measured because of the hardness of the diamond.

7 and 8, the tip 31 using the PDMS 30 and the tip 31 contain the nanodiamond 20, and thus the inexpensive and simple nanocantilever and nano- A cantilever array can be manufactured.

In particular, by increasing the area of the silicon mold 10 and increasing the number of the mounting grooves 11 formed on the surface of the silicon mold 10, it is possible to manufacture a large-area nano cantilever array as well as to produce a large number of nanocantilevers It is also possible to open the possibility.

This is due to the physical properties of the PDMS 30, which is flexible and smooth. Unlike conventional nano cantilevers and tips, it is possible to measure the temperature even when approaching or even contacting with the object to be measured. Obviously, acquisition will be possible.

As described above, the present invention provides an apparatus and a method for measuring temperature using a diamond nitrogen vacancy defect, which is capable of generating an ideal pulse irrespective of a change in resonance frequency to improve the sensitivity and accuracy of temperature measurement. .

It will be apparent to those skilled in the art that many other modifications and applications are possible within the scope of the basic technical idea of the present invention.

1 ... piezo stage controller
2 ... NV sensor unit
3 ... pulse generating unit
3i ... start pulse
3f ... final pulse
3m ... intermediate pulse
4 ... Confocal Scanning Unit
5 ... single photon counter
6 ... Gating photon counting unit
7 ... main timing control unit
8 ... feedback position compensator

Claims (12)

A microwave for changing the quantum state of spin is applied to the diamond nitrogen vacancy, the quantum phase of the spin of the nitrogen vacancy is measured to measure the temperature,
In the microwave,
Wherein the microwave has a plurality of different amplitudes over the entire time set to be applied to the nitrogen vacancies.
delete The method according to claim 1,
In the microwave,
And a divided wave having different amplitudes corresponding to a plurality of divided time periods in which the entire time is divided into different lengths or equal lengths of the whole time set so that the microwave is applied to the nitrogen vacancy. Method of measuring temperature using defects.
The method according to any one of claims 1 to 3,
In the microwave,
Wherein the microwave is a sum of a plurality of sine waves having the same amplitude or different amplitude and applied to the nitrogen vacancies for a total time set to be applied to the nitrogen vacancies.
The method of claim 4,
Wherein the sinusoidal wave component of the arbitrary one of the plurality of sinusoidal waves having an amplitude of 0 at the beginning and the end of an arbitrary one period during the entire time is extracted and the amplitude of the extracted sinusoidal component is modulated, And the microwave to be applied is generated.
The method according to claim 1,
The measurement of the spin quantum phase of the nitrogen vacancies is carried out,
A confocal scanning unit including a light source for generating a beam capable of optically exciting the spin state of the nitrogen vacancy,
A pulse generating unit generating the microwave that can be applied to the nitrogen vacancy,
An NV sensor unit having a tip including the nitrogen vacancy,
And a detector for detecting the emission of light after the beam passes through the NV sensor unit so that the absorption intensity of the light emission can be measured. How to measure.
The method of claim 6,
Wherein the NV sensor unit comprises:
And a plurality of the tips are arranged in parallel with each other.
A microwave for changing the quantum state of spin is applied to the diamond nitrogen vacancy, the quantum phase of the spin of the nitrogen vacancy is measured to measure the temperature,
In the microwave,
Wherein the microwave has a plurality of amplitudes that are different from each other for a total time set to be applied to the nitrogen vacancies.
A confocal scanning unit including a light source for generating a beam capable of optically exciting the spin state of the diamond nitrogen vacancy,
A pulse generating unit for generating a microwave which can be applied to the nitrogen vacancy,
An NV sensor unit having a tip including the nitrogen vacancy,
And a detector for detecting the light emission after the beam has passed through the NV sensor section so that the absorption intensity of the light emission can be measured,
Wherein the microwave is applied to the nitrogen vacancy and the temperature is measured by measuring the quantum phase of the spin of the NV sensor unit.
The method according to claim 8 or 9,
In the microwave,
Wherein the microwave has a plurality of amplitudes that are different from each other for a total time set to be applied to the nitrogen vacancies.
The method of claim 9,
Wherein the confocal scanning unit and the NV sensor unit are disposed between the confocal scanning unit and the upper side of the NV sensor unit and connected to the confocal scanning unit and the NV sensor unit, Based position correction of the temperature of the diamond nitrogen vacancy.
The method of claim 9,
Further comprising a spectral analyzer connected to the NV sensor unit, the pulse generating unit and the confocal scanning unit, the spectral analyzer measuring the light emission from the beam irradiated nitrogen vacancies Measuring device.

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