Trapped ion optical super-resolution imaging method, device, equipment and medium

Abstract

The present application discloses a method, apparatus, device and medium for optical super-resolution imaging of trapped ions, the method comprising: starting continuous laser cooling of ions and initializing the ions to a ground state; emitting a pulsed laser from a pulsed laser light source to excite the ions to an excited state, and emitting a synchronization signal at the same time as emitting the pulsed laser to trigger a photon counting camera to open a shutter; the excited state ions spontaneously radiate a single fluorescent photon, which is collected by a fluorescence collection system, and detected by a photon counting camera and the pixels at which the fluorescent photon arrives are recorded to obtain a captured image, and multiple images are cyclically captured to obtain a captured image sequence; and second-order or third-order intensity correlation processing is performed on the captured image sequence to obtain a super-resolution imaging image of the ions, thereby improving the technical problem that the resolution of existing imaging systems is limited by the optical diffraction limit, the highest resolution can only be around the wavelength of light, and is not suitable for detecting quantum phenomena related to the details of matter waves.

Description

Technical Field

[0001] The present application relates to the technical field of ion super-resolution imaging, and in particular to a trapped ion optical super-resolution imaging method, device, equipment and medium. Background Art

[0002] Trapped ion systems are one of the most promising platforms for achieving universal quantum computing. High-resolution optical detection and imaging are essential for such systems, as they allow direct observation of trapped ions. However, the resolution of conventional imaging systems is limited by the optical diffraction limit, reaching resolutions down to the wavelength of light (approximately hundreds of nanometers), making them unsuitable for probing quantum phenomena related to the details of matter waves. Summary of the Invention

[0003] The present application provides a trapped ion optical super-resolution imaging method, apparatus, device and medium for improving the technical problem that the resolution of existing imaging systems is limited by the optical diffraction limit, the highest resolution can only be around the wavelength of light, and is not suitable for detecting quantum phenomena related to matter wave details.

[0004] In view of this, the first aspect of the present application provides a trapped ion optical super-resolution imaging method, comprising:

[0005] S1, start continuous laser cooling and initialize the ions to the ground state;

[0006] S2, emitting a pulsed laser light source to excite the ion from the ground state to the excited state, and simultaneously emitting a synchronization signal to a photon counting camera, wherein the synchronization signal is used to trigger the photon counting camera to open a shutter;

[0007] S3, the excited state ions spontaneously radiate single fluorescent photons, the fluorescent photons are collected by a fluorescence collection system, and the single fluorescent photons are detected by a photon counting camera and the pixels at which the fluorescent photons arrive are recorded to obtain a captured image, and the process returns to step S1 until a preset acquisition time is reached to obtain a sequence of captured images;

[0008] S4. Performing second-order or third-order intensity correlation processing on the acquired image sequence to obtain an ion super-resolution imaging image.

[0009] Optionally, performing second-order or third-order intensity correlation processing on the acquired image sequence to obtain an ion super-resolution imaging image includes:

[0010] Performing sliding window processing on the acquired image sequence using a sliding window of a preset size;

[0011] Calculating a second-order intensity correlation value or a third-order intensity correlation value of a central pixel and non-central pixels in the same sliding window of the acquired image sequence;

[0012] The second-order antibunching signal is calculated based on the second-order intensity correlation value between the central pixel and the non-central pixel in each sliding window to obtain the ion super-resolution imaging image, or the third-order antibunching signal is calculated based on the third-order intensity correlation value between the central pixel and the non-central pixel in each sliding window to obtain the ion super-resolution imaging image.

[0013] Optionally, calculating the second-order intensity correlation value of the central pixel and the non-central pixel of the acquired image sequence within the same sliding window includes:

[0014] The second-order intensity correlation value of the central pixel and the non-central pixel in the same sliding window of the acquired image sequence is calculated based on the second-order intensity correlation function, and the second-order intensity correlation function is:

[0015]

[0016] Where g (2 )(x i ,τ) is the second-order intensity correlation function, n i (t) is the center pixel x in the sliding window i The number of photons detected at time t, n k (t+τ) is the non-center pixel x in the sliding window k The number of photons detected at time t+τ, <n i > represents all n in the same sliding window of the acquired image sequence i Find the average, <n k > represents all n in the same sliding window of the acquired image sequence k Find the average, obviously i≠k, τ is the delay between different frames, and K is the number of non-center pixels.

[0017] Optionally, the calculating of the second-order antibunching signal based on the second-order intensity correlation value between the central pixel and the non-central pixel in each sliding window to obtain the ion super-resolution imaging image includes:

[0018] The second-order intensity correlation value g between the central pixel and the non-central pixel in each sliding window when the delay τ = 0 is (2 )(x i ,0) calculate the average value to get the second-order intensity correlation average value of the center pixel and non-center pixel in each sliding window

[0019] According to the second-order intensity correlation average of the central pixel and non-central pixel in each sliding window The second-order antibunching signal is calculated to obtain the ion super-resolution imaging image. The second-order antibunching signal is:

[0020]

[0021] Optionally, calculating the third-order intensity correlation value of the central pixel and the non-central pixel in the same sliding window of the acquired image sequence includes:

[0022] The third-order intensity correlation value of the central pixel and the non-central pixel in the same sliding window of the acquired image sequence is calculated based on the third-order intensity correlation function, and the third-order intensity correlation function is:

[0023]

[0024] Where g (3 )(x i ,τ1,τ2) is the third-order intensity correlation function, n i (t) is the center pixel x in the sliding window i The number of photons detected at time t, n k (t+τ1) is the non-center pixel x in the sliding window k The number of photons detected at time t+τ1, n m (t+τ2=) is the non-center pixel x in the sliding window m The number of photons detected at time t+τ2, i≠k≠m, <n i > represents all n in the same sliding window of the acquired image sequence i Find the average, n k > represents all n in the same sliding window of the acquired image sequence k Find the average, <n m > represents all n in the same sliding window of the acquired image sequence m Find the average, τ1 and τ2 are the delays of different frames.

[0025] Optionally, the calculating of the third-order antibunching signal based on the third-order intensity correlation value between the central pixel and the non-central pixel in each sliding window to obtain the ion super-resolution imaging image includes:

[0026] The third-order intensity correlation value g of the central pixel and the non-central pixel in each sliding window when the delay τ1 = 0 and τ2 = 0 is (3 )(x i ,0,0) to obtain the average value of the third-order intensity correlation between the central pixel and the non-central pixel in each sliding window

[0027] According to the third-order intensity correlation average of the central pixel and non-central pixel in each sliding window The third-order antibunching signal is calculated to obtain the ion super-resolution imaging image. The third-order antibunching signal is:

[0028]

[0029] A second aspect of the present application provides a trapped ion optical super-resolution imaging device, comprising:

[0030] A continuous laser, used to start continuous laser cooling of ions and initialize the ions to the ground state;

[0031] A pulsed laser light source is used to emit pulsed laser light to excite ions from the ground state to the excited state, and to send a synchronization signal to the photon counting camera at the same time as emitting the pulsed laser light;

[0032] A fluorescence collection system for collecting single fluorescence photons spontaneously emitted by excited ions;

[0033] a photon counting camera, configured to open a shutter in response to the synchronization signal, detect a single fluorescent photon, and record the pixel at which the fluorescent photon arrives, thereby obtaining a captured image;

[0034] The image processor is used to perform second-order or third-order intensity correlation processing on the image sequence acquired within a preset acquisition time to obtain an ion super-resolution imaging image.

[0035] Optionally, the image processor is specifically configured to:

[0036] Performing sliding window processing on the acquired image sequence using a sliding window of a preset size;

[0037] Calculating a second-order intensity correlation value or a third-order intensity correlation value of a central pixel and non-central pixels in the same sliding window of the acquired image sequence;

[0038] The second-order antibunching signal is calculated based on the second-order intensity correlation value between the central pixel and the non-central pixel in each sliding window to obtain the ion super-resolution imaging image, or the third-order antibunching signal is calculated based on the third-order intensity correlation value between the central pixel and the non-central pixel in each sliding window to obtain the ion super-resolution imaging image.

[0039] A third aspect of the present application provides a trapped ion optical super-resolution imaging device, the device comprising a processor and a memory;

[0040] The memory is used to store program code and transmit the program code to the processor;

[0041] The processor is used to execute the trapped ion optical super-resolution imaging method described in any one of the first aspects according to the instructions in the program code.

[0042] In a fourth aspect, the present application provides a computer-readable storage medium for storing program code. When the program code is executed by a processor, the trapped ion optical super-resolution imaging method described in any one of the first aspects is implemented.

[0043] It can be seen from the above technical solutions that this application has the following advantages:

[0044] The present application provides a trapped ion optical super-resolution imaging method, comprising: S1, starting continuous laser cooling of ions and initializing the ions to a ground state; S2, emitting a pulsed laser from a pulsed laser light source to excite the ions from the ground state to an excited state, and simultaneously emitting a synchronization signal to a photon counting camera when the pulsed laser light source emits the pulsed laser, wherein the synchronization signal is used to trigger the photon counting camera to open a shutter; S3, the excited state ions spontaneously radiate a single fluorescent photon, the fluorescent photon is collected by a fluorescence collection system, and the single fluorescent photon is detected by a photon counting camera and the pixel at which the fluorescent photon arrives is recorded to obtain a captured image, and returning to step S1 until a preset capture time is reached to obtain a captured image sequence; S4, performing second-order or third-order intensity correlation processing on the captured image sequence to obtain an ion super-resolution imaging image.

[0045] In the present application, there is no need for a Fresnel lens placed in a vacuum cavity, nor is there a need for laser beam shaping and scanning of additional wavelengths. In any trapped ion imaging system, the duration of the modulated excitation light pulse is less than the fluorescence lifetime of the ion. By utilizing the photon counting function of the photon counting camera and statistically analyzing the secondary or tertiary intensity correlation of a series of acquired images of the photon counting camera, quantum imaging can break through the diffraction optical limit and achieve trapped ion optical super-resolution imaging, thereby improving the technical problem that the resolution of existing imaging systems is limited by the optical diffraction limit, and the highest resolution can only be around the wavelength of light, which is not suitable for detecting quantum phenomena related to the details of matter waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0047] Figure 1 A schematic flow chart of a trapped ion optical super-resolution imaging method provided in an embodiment of the present application;

[0048] Figure 2 A schematic structural diagram of an image acquisition device provided in an embodiment of the present application;

[0049] Figure 3 A schematic diagram of the arrangement of pixels within a 3*3 sliding window in the captured image provided in an embodiment of the present application;

[0050] Figure 4A schematic structural diagram of a trapped ion optical super-resolution imaging device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0051] In order to help those skilled in the art better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0052] Prior art suggests that the diffraction limit of a classical optical microscope is d = λ / (2*NA), where d is the resolution of the optical system (i.e., the distance between two points that can be resolved), λ is the wavelength of the detection light, and NA is the numerical aperture of the microscope objective lens, which is approximately 1. According to this formula, the resolution limit of an optical microscope system is approximately half the wavelength of the detection light, around 200 to 300 nanometers (visible light wavelength range is 400-700 nanometers). In other words, when two infinitesimal point sources are within 200 nanometers of each other, the images of the two point sources will overlap significantly, making them indistinguishable, thus reaching the optical diffraction limit.

[0053] In the imaging system of trapped ions, a single ion can be trapped using a pinhole trap. 174 Yb + , use laser to cool ions to the Doppler cooling limit temperature, and build a high-resolution optical imaging system to 174 Yb + The fluorescence imaging of the ions is magnified about 400 times and imaged on a camera. The method of statistical analysis of the imaging signal can locate the wave packet with a center accuracy of tens of nanometers. However, the optical imaging system in this method uses a phase Fresnel lens placed very close to the trapped ions in a vacuum chamber. It is very difficult to adjust, and the stray charges on the dielectric material of the lens are difficult to eliminate. There is a large Coulomb interaction with the trapped ions at close range, which will greatly affect the stability of the trapped ions in the trapped potential. It is also possible to apply the principle of microscopic imaging and use a single 40Ca + By using the SP dipole transition of ions (lifetime on the order of tens of nanoseconds) as probe fluorescence and the SD quadrupole transition (lifetime on the order of seconds) as annular depletion pump light, it is possible to measure moving ground-state ion wave packets of approximately 40 nanometers with a resolution of approximately 10 nanometers. However, this method uses probe light and annular depletion pump light, and the wavelengths of these two lights are inconsistent, which increases the cost of the laser light source. Moreover, the scanning of the annular depletion pump light must be precisely controlled to achieve a resolution on the order of tens of nanometers, which greatly increases the cost of super-resolution imaging.

[0054] To improve the above issues, please refer to Figure 1 , an embodiment of the present application provides a trapped ion optical super-resolution imaging method, comprising:

[0055] S1. Start continuous laser cooling of ions and initialize the ions to the ground state.

[0056] The continuous laser is started to cool the ions and initialize the ions to the ground state, and the continuous laser is turned off after a time of the order of ten microseconds.

[0057] S2. A pulsed laser light source is used to emit a pulsed laser to excite the ions from the ground state to the excited state, and a synchronization signal is sent to a photon counting camera at the same time as the pulsed laser light source emits the pulsed laser. The synchronization signal is used to trigger the photon counting camera to open the shutter.

[0058] The pulsed laser light source emits pulsed laser to excite the ions from the ground state to the excited state. At the same time as emitting the pulsed laser, the pulsed laser light source sends a synchronization signal to the photon counting camera (EMCCD camera) to trigger the photon counting camera to open the shutter.

[0059] S3. The excited ions spontaneously radiate single fluorescent photons, which are collected by a fluorescence collection system. The photon counting camera detects the single fluorescent photons and records the pixels where the fluorescent photons arrive to obtain a captured image. The process returns to step S1 until the preset acquisition time is reached to obtain a captured image sequence.

[0060] When ions are excited to an excited state, they spontaneously emit a single fluorescent photon, which is collected by the fluorescence collection system. A photon-counting camera, triggered by a synchronization signal delayed by nanoseconds, opens its shutter, detects the single fluorescent photon, and records the pixel where the fluorescent photon arrives. After an exposure time of approximately microseconds, the photon-counting camera closes its shutter and saves the image, resulting in a captured image.

[0061] After capturing an image, the next loop is entered, and step S1 is returned to capture the next image until the preset capture time is reached to obtain a captured image sequence. The preset capture time in the embodiment of the present application can be set to 1000 seconds or more, and the obtained captured image sequence can reach millions of images. In this cycle, the frequency of image capture is generally limited by the detection frame rate of the photon counting camera. When the detection area of the photon counting camera is reduced, the detection frame rate can reach the kHz level, that is, one image is generated in 1 millisecond. The duration of the laser pulse used for excitation needs to be much shorter than the lifetime of the ion excited state (on the order of ns).

[0062] The embodiment of the present application can be Figure 2 ( Figure 2The image acquisition device shown in the figure (not shown in the figure) collects images, and after obtaining the collected image sequence, it is input into the image processor for image processing to obtain ion super-resolution imaging. It should be noted that the image acquisition device in the embodiment of the present application is suitable for various ions that are laser-cooled and fluorescently detected by SP dipole transition, such as Be. + , Mg + , Ca + , Sr + , Ba + , Hg + , Cd + , Yb + and multiple isotope ions.

[0063] S4. Perform second-order or third-order intensity correlation processing on the acquired image sequence to obtain an ion super-resolution imaging image.

[0064] After acquiring the acquired image sequence, the following intensity-related processing can be performed on the acquired image sequence:

[0065] S41, performing sliding window processing on the acquired image sequence using a sliding window of a preset size;

[0066] A sliding window of a preset size can be used to perform sliding window processing on each acquired image in the acquired image sequence. The embodiment of the present application preferably uses a sliding window of 3*3 size. Considering that the boundary pixels of the acquired image are basically background and can be ignored, there is no need to fill the surrounding of the acquired image when performing sliding window processing.

[0067] S42, calculating the second-order intensity correlation value or the third-order intensity correlation value of the central pixel and the non-central pixel in the same sliding window of the acquired image sequence;

[0068] In one embodiment, the second-order intensity correlation value of the central pixel and the non-central pixel in the same sliding window of the acquired image sequence may be calculated based on a second-order intensity correlation function. The second-order intensity correlation function is:

[0069]

[0070] Where g (2 )(x i ,τ) is the second-order intensity correlation function, n i (t) is the center pixel x in the sliding window i The number of photons detected at time t (0 or 1), n k (t+τ) is the non-center pixel x in the sliding window k The number of photons detected at time t+τ (0 or 1), <n i > represents all n in the same sliding window of the acquired image sequencei Find the average, <n k > represents all n in the same sliding window of the acquired image sequence k Find the average, where i≠k, τ is the delay between different frames (in milliseconds), and K is the number of non-center pixels.

[0071] The <> in the second-order intensity correlation function represents time averaging. For ease of understanding, the specific calculation process of the second-order intensity correlation value is illustrated by an example. Assume that the preset acquisition time is 3 milliseconds, and the acquired image sequence includes three frames of images. A sliding window of 3*3 size is used to slide the three frames of images. When calculating the second-order intensity correlation value, first, the number of photons detected by the central pixel in the first sliding window of the first frame image is multiplied by the number of photons detected by each non-central pixel in the first sliding window of the first frame image (that is, the 8 pixels around the central pixel) to obtain the product of the number of photons of the central pixel i in the first sliding window of the first frame image and the pixel k in the 8 surrounding pixels (that is, n in the second-order intensity correlation function). i (t)n k (t+τ), τ=0, k=1,2,...,8), and multiply the number of photons detected by the center pixel i in the first sliding window of the second frame image and the number of photons detected by the non-center pixel k in the first sliding window of the second frame image respectively, to obtain the product of the 8 photon numbers of the center pixel and the surrounding 8 pixels in the first sliding window of the second frame image; the third frame is processed as above. The results of the three frames are added and then divided by the number of image frames in the acquired image sequence to obtain <n i (t)n k (t+τ)>, τ=0, k=1,2,...,8. It should be noted that the same order is used to calculate the product of the number of photons of the center pixel and the surrounding 8 pixels of these three frames of images, which can be referred to Figure 3 , assuming the current sliding window is Figure 3 In the gray area, when calculating the product of the number of photons of the center pixel i and the surrounding 8 pixels, if n is used when calculating the first frame image i n1、n i n2、n i n3、n i n4、n i n5、n i n6、n i n7、n i When calculating the product of the number of photons of the center pixel and each non-center pixel in the order of n8, the same n is used when calculating the second and third frames of images. i n1、n i n2、n i n3、n i n4、n i n5、ni n6、n i n7、n i The photon number product of the central pixel and each non-central pixel in the sliding window in the second and third frame images is calculated in the order of n8.

[0072] Secondly, multiply the number of photons of the central pixel i in the first sliding window of the first frame image by the number of photons of the kth photon in the first sliding window of the second frame image. Similarly, multiply the number of photons of the central pixel i in the first sliding window of the second frame image by the number of photons of the kth photon in the first sliding window of the third frame image. Then sum the products and divide them by the number of image frames in the acquired image sequence to calculate the second-order intensity correlation function. <n i (t)n k (t+τ)>, τ=1ms, k=1,2,...,8;

[0073] Then, the number of photons detected by the central pixel in the first sliding window of the first frame image is summed with the number of photons detected by the central pixel in the first sliding window of the second and third frames, and then divided by the number of image frames in the acquired image sequence, and the second-order intensity correlation function is calculated. <n i >, at the same time, the number of photons detected by each non-central pixel in the first sliding window of the first frame image is summed with the number of photons detected by the corresponding non-central pixels in the first sliding window of the second and third frames of image, and then divided by the number of image frames in the acquired image sequence, so as to calculate the second-order intensity correlation function <n k >, k = 1, 2, ..., 8;

[0074] Finally, calculate <n i (t)n k (t+τ)> and [ <n i > <n k The second-order intensity correlation value of the center pixel and the non-center pixel in the first window can be calculated by summing the ratio of

[0075] After calculating the second-order intensity correlation value between the center pixel and the non-center pixel in the first sliding window, the sliding window is moved by one pixel, and the second-order intensity correlation value between the center pixel and the non-center pixel in the second sliding window is calculated. This process is repeated until the second-order intensity correlation value between the center pixel and the non-center pixel in all sliding windows of the acquired image sequence is calculated. The calculation process for the second-order intensity correlation value between the center pixel and the non-center pixel in other sliding windows is similar to the calculation process for the second-order intensity correlation value between the center pixel and the non-center pixel in the first sliding window, and will not be repeated here.

[0076] In another embodiment, the third-order intensity correlation value of the central pixel and the non-central pixel in the same sliding window of the acquired image sequence can also be calculated based on the third-order intensity correlation function. The third-order intensity correlation function is:

[0077]

[0078] Where g (3 )(x i ,τ1,τ2) is the third-order intensity correlation function, n i (t) is the center pixel x in the sliding window i The number of photons detected at time t, n k (t+τ1) is the non-center pixel x in the sliding window k The number of photons detected at time t+τ1, n m (t+τ2) is the non-center pixel x in the sliding window m The number of photons detected at time t+τ2, i≠k≠m, <n i > represents all n in the same sliding window of the acquired image sequence i Find the average, n k > represents all n in the same sliding window of the acquired image sequence k Find the average, <n m > represents all n in the same sliding window of the acquired image sequence m Find the average, τ1 and τ2 are the delays of different frames.

[0079] Please refer to Figure 3 For a sliding window of size 3*3, eight combinations of 1i8, 2i7, 3i6, 4i5, 2i4, 2i5, 4i7, and 5i7 can be substituted into the third-order intensity correlation function to calculate the third-order intensity correlation value.

[0080] S43. Calculate the second-order antibunching signal based on the second-order intensity correlation value between the central pixel and the non-central pixel in each sliding window to obtain the ion super-resolution imaging image, or calculate the third-order antibunching signal based on the third-order intensity correlation value between the central pixel and the non-central pixel in each sliding window to obtain the ion super-resolution imaging image.

[0081] In one embodiment, a second-order antibunching signal may be calculated based on the second-order intensity correlation value between the central pixel and the non-central pixel in each sliding window to obtain an ion super-resolution imaging image. The specific process may be:

[0082] First, the second-order intensity correlation value g between the central pixel and the non-central pixel in each sliding window when the delay τ=0 is calculated. (2 )(x i,0) calculate the average value to get the second-order intensity correlation average value of the center pixel and non-center pixel in each sliding window Right now

[0083] Then, according to the second-order intensity correlation average of the central pixel and the non-central pixel in each sliding window Calculate the second-order antibunching signal to obtain the ion super-resolution imaging image. The second-order antibunching signal is:

[0084]

[0085] In another embodiment, a third-order antibunching signal may be calculated based on the third-order intensity correlation value between the central pixel and the non-central pixel in each sliding window to obtain an ion super-resolution imaging image. The specific process may be:

[0086] First, the third-order intensity correlation value g between the central pixel and the non-central pixel in each sliding window when the delay τ1 = 0 and τ2 = 0 is calculated. (3 )(x i ,0,0) to obtain the average value of the third-order intensity correlation between the central pixel and the non-central pixel in each sliding window When using a 3*3 sliding window,

[0087] Then, according to the third-order intensity correlation average of the central pixel and the non-central pixel in each sliding window Calculate the third-order antibunching signal to obtain the ion super-resolution imaging image. The third-order antibunching signal is:

[0088]

[0089] The embodiments of the present application take into account that after a single ion is excited from the ground state to the excited state by a sub-nanosecond pulse, it can only spontaneously radiate one photon and return to the ground state. If the repetition frequency of the sub-nanosecond pulse is less than the line width of the ion excited state, that is, the pulse interval time is greater than the lifetime of the ion excited state, then within the pulse interval time, only a single fluorescent photon can be generated, that is, the single photon emitted by a single quantum light source (single ion) has anti-bunching properties. While the classical ordinary thermal light source has bunching properties. Since the photons emitted by the single ion used in this application have the property of anti-bunching, the photon statistics at each point in the image plane are of sub-Poisson type, that is, the number of multi-photon simultaneous detection events is less than that of classical light in all levels of correlation functions. Quantifying the lost N-photon coincidence counting signal is equivalent to the N-photon coincidence counting signal (simultaneous detection), which can reduce the equivalent classical light source point spread function. The embodiment of the present application utilizes the antibunching effect of a trapped ion quantum light source to quantize the lost N photons and the coincidence counting signal, thereby breaking through the diffraction optical limit of quantum imaging and achieving trapped ion optical super-resolution imaging.

[0090] In the embodiment of the present application, there is no need for a Fresnel lens placed in a vacuum chamber, nor is there a need for laser beam shaping and scanning of additional wavelengths. In any trapped ion imaging system, the duration of the modulated excitation light pulse is less than the fluorescence lifetime of the ion. By utilizing the photon counting function of the photon counting camera and statistically analyzing the secondary or tertiary intensity correlation of a series of acquired images of the photon counting camera, quantum imaging can break through the diffraction optical limit and achieve trapped ion optical super-resolution imaging. This improves the technical problem that the resolution of existing imaging systems is limited by the optical diffraction limit, and the highest resolution can only be around the wavelength of light, which is not suitable for detecting quantum phenomena related to the details of matter waves.

[0091] Furthermore, the trapped ion optical super-resolution imaging method in the embodiment of the present application does not require the construction of a high-magnification optical imaging system, and there is no dielectric lens very close to the trapped ions, which will not affect the stability of the trapped ions; continuous laser Doppler cooling is introduced in the timing design to increase the stability of the trapped ions; the embodiment of the present application also does not require two beams of detection light of different wavelengths and annular depletion pump light, which reduces the cost of the laser light source; and there is no need for spatial scanning of the pump beam, which reduces the experimental requirements.

[0092] The above is an embodiment of a trapped ion optical super-resolution imaging method provided by the present application, and the following is an embodiment of a trapped ion optical super-resolution imaging device provided by the present application.

[0093] Please refer to Figure 4 , an embodiment of the present application provides a trapped ion optical super-resolution imaging device, comprising:

[0094] A continuous laser, used to start continuous laser cooling of ions and initialize the ions to the ground state;

[0095] A pulsed laser light source is used to emit pulsed laser light to excite ions from the ground state to the excited state, and to send a synchronization signal to the photon counting camera at the same time as emitting the pulsed laser light;

[0096] A fluorescence collection system for collecting single fluorescence photons spontaneously emitted by excited ions;

[0097] a photon counting camera, configured to open a shutter in response to a synchronization signal, detect a single fluorescent photon, and record the pixel at which the fluorescent photon arrives, thereby obtaining a captured image;

[0098] The image processor is used to perform second-order or third-order intensity correlation processing on the image sequence acquired within a preset acquisition time to obtain an ion super-resolution imaging image.

[0099] The trapped ion optical super-resolution imaging device in the embodiment of the present application is mainly composed of an image acquisition device and an image processor. The image acquisition device includes a continuous laser, a pulsed laser light source, a fluorescence collection system and a photon counting camera. The continuous laser starts the continuous laser cooling ions and initializes the ions to the ground state. The pulsed laser light source emits a sub-nanosecond laser pulse to excite the ions from the ground state to the excited state, and at the same time as the pulsed laser is emitted, a synchronization signal is emitted; the excited state ions will spontaneously radiate a single fluorescence photon, which is collected by the fluorescence collection system. The photon counting camera is triggered by a synchronization signal delayed by nanoseconds to open the shutter, detect the single fluorescence photon, and record the pixel where the fluorescence photon arrives. After an exposure time of about microseconds, the photon counting camera closes the shutter and saves the image. The image acquisition device can be used to cyclically acquire images. After acquiring images of a preset acquisition time, the acquired image sequence is transmitted to the image processor. The image processor performs second-order or third-order intensity correlation processing on the acquired image sequence acquired within the preset acquisition time to obtain an ion super-resolution imaging image.

[0100] As a further improvement, the image processor is specifically configured to:

[0101] Use a sliding window of preset size to perform sliding window processing on the acquired image sequence;

[0102] Calculating the second-order intensity correlation value or the third-order intensity correlation value of the central pixel and the non-central pixel in the same sliding window of the acquired image sequence;

[0103] The second-order antibunching signal is calculated based on the second-order intensity correlation value between the central pixel and the non-central pixel in each sliding window to obtain the ion super-resolution imaging image, or the third-order antibunching signal is calculated based on the third-order intensity correlation value between the central pixel and the non-central pixel in each sliding window to obtain the ion super-resolution imaging image.

[0104] In the embodiment of the present application, there is no need for a Fresnel lens placed in a vacuum chamber, nor is there a need for laser beam shaping and scanning of additional wavelengths. In any trapped ion imaging system, the duration of the modulated excitation light pulse is less than the fluorescence lifetime of the ion. By utilizing the photon counting function of the photon counting camera and statistically analyzing the secondary or tertiary intensity correlation of a series of acquired images of the photon counting camera, quantum imaging can break through the diffraction optical limit and achieve trapped ion optical super-resolution imaging. This improves the technical problem that the resolution of existing imaging systems is limited by the optical diffraction limit, and the highest resolution can only be around the wavelength of light, which is not suitable for detecting quantum phenomena related to the details of matter waves.

[0105] Furthermore, the embodiments of the present application do not require the construction of a high-magnification optical imaging system, and there is no dielectric lens very close to the trapped ions, which will not affect the stability of the trapped ions; continuous laser Doppler cooling is introduced in the timing design to increase the stability of the trapped ions; the embodiments of the present application also do not require two beams of detection light of different wavelengths and annular depletion pump light, which reduces the cost of the laser light source; and there is no need for spatial scanning of the pump beam, which reduces the experimental requirements.

[0106] The present application also provides a trapped ion optical super-resolution imaging device, which includes a processor and a memory;

[0107] The memory is used to store program codes and transmit the program codes to the processor;

[0108] The processor is used to execute the trapped ion optical super-resolution imaging method in the aforementioned method embodiment according to the instructions in the program code.

[0109] An embodiment of the present application further provides a computer-readable storage medium, which is used to store program code. When the program code is executed by a processor, the trapped ion optical super-resolution imaging method in the aforementioned method embodiment is implemented.

[0110] The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0111] It should be understood that in this application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0112] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0113] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0114] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0115] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for executing all or part of the steps of the method described in each embodiment of the present application through a computer device (which can be a personal computer, server, or network device, etc.). The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (English full name: Read-Only Memory, English abbreviation: ROM), random access memory (English full name: Random Access Memory, English abbreviation: RAM), magnetic disk or optical disk and other media that can store program code.

[0116] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A trapped ion optical super-resolution imaging method, characterized in that: include: S1, start continuous laser cooling and initialize the ions to the ground state; S2, emitting a pulsed laser light source to excite the ion from the ground state to the excited state, and simultaneously emitting a synchronization signal to a photon counting camera, wherein the synchronization signal is used to trigger the photon counting camera to open a shutter; S3, the excited state ions spontaneously radiate single fluorescent photons, the fluorescent photons are collected by a fluorescence collection system, and the single fluorescent photons are detected by a photon counting camera and the pixels at which the fluorescent photons arrive are recorded to obtain a captured image, and the process returns to step S1 until a preset acquisition time is reached to obtain a sequence of captured images; S4, performing second-order or third-order intensity correlation processing on the acquired image sequence to obtain an ion super-resolution imaging image, including: Performing sliding window processing on the acquired image sequence using a sliding window of a preset size; Calculating a second-order intensity correlation value or a third-order intensity correlation value of a central pixel and non-central pixels in the same sliding window of the acquired image sequence; Calculating a second-order antibunching signal based on a second-order intensity correlation value between a central pixel and a non-central pixel in each sliding window to obtain an ion super-resolution imaging image, or calculating a third-order antibunching signal based on a third-order intensity correlation value between a central pixel and a non-central pixel in each sliding window to obtain an ion super-resolution imaging image; Calculating the second-order intensity correlation value of the central pixel and the non-central pixel of the acquired image sequence within the same sliding window, including: The second-order intensity correlation value of the central pixel and the non-central pixel in the same sliding window of the acquired image sequence is calculated based on the second-order intensity correlation function, and the second-order intensity correlation function is: ； Where, is the second-order intensity correlation function, n i (t) is the center pixel x in the sliding window i The number of photons detected at time t, is the non-center pixel x in the sliding window k exist The number of photons detected at any moment, Indicates that all n in the same sliding window of the acquired image sequence i Find the average, Indicates that all n in the same sliding window of the acquired image sequence k Find the average, obviously i≠k, is the delay of different frames, K is the number of non-center pixels; The second-order antibunching signal is calculated based on the second-order intensity correlation value of the central pixel and the non-central pixel in each sliding window to obtain the ion super-resolution imaging image, including: Delay =0, the second-order intensity correlation value between the central pixel and the non-central pixel in each sliding window Average to get the second-order intensity correlation average of the center pixel and non-center pixel in each sliding window ; According to the second-order intensity correlation average of the central pixel and non-central pixel in each sliding window The second-order antibunching signal is calculated to obtain the ion super-resolution imaging image. The second-order antibunching signal is: ； Calculating the third-order intensity correlation value of the central pixel and the non-central pixel of the acquired image sequence within the same sliding window, including: The third-order intensity correlation value of the central pixel and the non-central pixel in the same sliding window of the acquired image sequence is calculated based on the third-order intensity correlation function, and the third-order intensity correlation function is: ； Where, is the third-order intensity correlation function, n i (t) is the center pixel x in the sliding window i The number of photons detected at time t, is the non-center pixel x in the sliding window k exist The number of photons detected at any moment, is the non-center pixel x in the sliding window m exist The number of photons detected at any moment, i≠k≠m, Indicates that all n in the same sliding window of the acquired image sequence i Find the average, Indicates that all n in the same sliding window of the acquired image sequence k Find the average, Indicates that all n in the same sliding window of the acquired image sequence m Find the average, is the delay of different frames; The method of calculating a third-order antibunching signal based on the third-order intensity correlation value of the central pixel and the non-central pixel in each sliding window to obtain an ion super-resolution imaging image includes: Delay The third-order intensity correlation value between the central pixel and the non-central pixel in each sliding window at Calculate the average value to obtain the third-order intensity correlation average value of the central pixel and non-central pixel in each sliding window ; According to the third-order intensity correlation average of the central pixel and non-central pixel in each sliding window The third-order antibunching signal is calculated to obtain the ion super-resolution imaging image. The third-order antibunching signal is: 。 2. A trapped ion optical super-resolution imaging device, characterized in that: include: A continuous laser, used to start continuous laser cooling of ions and initialize the ions to the ground state; A pulsed laser light source is used to emit pulsed laser light to excite ions from the ground state to the excited state, and to send a synchronization signal to the photon counting camera at the same time as emitting the pulsed laser light; A fluorescence collection system for collecting single fluorescence photons spontaneously emitted by excited ions; a photon counting camera, configured to open a shutter in response to the synchronization signal, detect a single fluorescent photon, and record the pixel at which the fluorescent photon arrives, thereby obtaining a captured image; An image processor is used to perform second-order or third-order intensity correlation processing on the image sequence acquired within a preset acquisition time to obtain an ion super-resolution imaging image; The image processor is specifically used for: Performing sliding window processing on the acquired image sequence using a sliding window of a preset size; Calculating a second-order intensity correlation value or a third-order intensity correlation value of a central pixel and non-central pixels in the same sliding window of the acquired image sequence; Calculating a second-order antibunching signal based on a second-order intensity correlation value between a central pixel and a non-central pixel in each sliding window to obtain an ion super-resolution imaging image, or calculating a third-order antibunching signal based on a third-order intensity correlation value between a central pixel and a non-central pixel in each sliding window to obtain an ion super-resolution imaging image; Calculating the second-order intensity correlation value of the central pixel and the non-central pixel of the acquired image sequence within the same sliding window, including: The second-order intensity correlation value of the central pixel and the non-central pixel in the same sliding window of the acquired image sequence is calculated based on the second-order intensity correlation function, and the second-order intensity correlation function is: ； Where, is the second-order intensity correlation function, n i (t) is the center pixel x in the sliding window i The number of photons detected at time t, is the non-center pixel x in the sliding window k exist The number of photons detected at any moment, Indicates that all n in the same sliding window of the acquired image sequence i Find the average, Indicates that all n in the same sliding window of the acquired image sequence k Find the average, obviously i≠k, is the delay of different frames, K is the number of non-center pixels; The second-order antibunching signal is calculated based on the second-order intensity correlation value of the central pixel and the non-central pixel in each sliding window to obtain the ion super-resolution imaging image, including: Delay =0, the second-order intensity correlation value between the central pixel and the non-central pixel in each sliding window Average to get the second-order intensity correlation average of the center pixel and non-center pixel in each sliding window ; According to the second-order intensity correlation average of the central pixel and non-central pixel in each sliding window The second-order antibunching signal is calculated to obtain the ion super-resolution imaging image. The second-order antibunching signal is: ； Calculating the third-order intensity correlation value of the central pixel and the non-central pixel of the acquired image sequence within the same sliding window, including: The third-order intensity correlation value of the central pixel and the non-central pixel in the same sliding window of the acquired image sequence is calculated based on the third-order intensity correlation function, and the third-order intensity correlation function is: ； Where, is the third-order intensity correlation function, n i (t) is the center pixel x in the sliding window i The number of photons detected at time t, is the non-center pixel x in the sliding window k exist The number of photons detected at any moment, is the non-center pixel x in the sliding window m exist The number of photons detected at any moment, i≠k≠m, Indicates that all n in the same sliding window of the acquired image sequence i Find the average, Indicates that all n in the same sliding window of the acquired image sequence k Find the average, Indicates that all n in the same sliding window of the acquired image sequence m Find the average, is the delay of different frames; The method of calculating a third-order antibunching signal based on the third-order intensity correlation value of the central pixel and the non-central pixel in each sliding window to obtain an ion super-resolution imaging image includes: Delay The third-order intensity correlation value between the central pixel and the non-central pixel in each sliding window at Calculate the average value to obtain the third-order intensity correlation average value of the central pixel and non-central pixel in each sliding window ; According to the third-order intensity correlation average of the central pixel and non-central pixel in each sliding window The third-order antibunching signal is calculated to obtain the ion super-resolution imaging image. The third-order antibunching signal is: 。 3. A trapped ion optical super-resolution imaging device, characterized in that: The device includes a processor and a memory; The memory is used to store program code and transmit the program code to the processor; The processor is used to execute the trapped ion optical super-resolution imaging method according to claim 1 according to the instructions in the program code.

4. A computer-readable storage medium, characterized in that The computer-readable storage medium is used to store program code, and when the program code is executed by a processor, the trapped ion optical super-resolution imaging method according to claim 1 is implemented.

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