A method and system for loading ion crystal configuration in an ion trap

Abstract

The present invention provides a method and system for loading an ion crystal configuration in an ion trap, specifically including: a method for loading an ion crystal configuration in an ion trap, the method comprising: S1: trapping a one-dimensional or multi-dimensional ion crystal in an ion trap and determining a preset ion crystal configuration; S2: applying a laser field of a corresponding arrangement configuration at a preset position, aligning the preset ion crystal configuration, and forming a local optical potential well for the preset ion crystal configuration; S3: forming a new total potential well based on the superposition of the local optical potential well and the electric potential well, increasing the probability of loading the preset ion crystal configuration, or realizing stable trapping of the preset ion crystal configuration, or guiding the ion crystal configuration outside the preset ion crystal configuration to be transformed into the preset ion crystal configuration. The present invention realizes the fixation of ions of a one-dimensional or multi-dimensional ion crystal, increasing the probability of the target configuration appearing, so that each time the ions are reloaded, a crystal configuration of a determined configuration can be obtained.

Description

Technical Field

[0001] The present invention belongs to the field of quantum computing technology, and in particular relates to a method and system for loading an ion crystal configuration in an ion trap. Background Art

[0002] Ion trap technology based on trapped ions is one of the mainstream technologies for realizing quantum computing, and it also plays an important role in the fields of quantum simulation and precision measurement.

[0003] Ion crystals are composed of multiple ions trapped in ion traps (Pual structures or Penning structures). The specific arrangement of ions is determined by the external potential field provided by the trap and the Coulomb force between ions. For common one-dimensional ion chain structures, the number of ions that can be trapped is generally less than 200 due to the limitation of the imaging field of view. Moreover, due to the large spatial scale, the interaction between the head and tail of the ion chain is weak, which brings challenges to the realization of large-scale quantum computing.

[0004] Compared with one-dimensional ion chains, two-dimensional or multi-dimensional ion crystals can accommodate more ions in the same imaging field of view, and the interaction between ions is also stronger, which is a promising quantum computing structure. However, two-dimensional or multi-dimensional ion crystals with the same number of ions have multiple stable crystal structures with different configurations.

[0005] During the ion crystal loading process, the two-dimensional or multi-dimensional crystal structure generated is different each time because of the different initial conditions for ion generation. Moreover, when the ion crystal is trapped, if it is disturbed by the external environment, such as background gas collisions, voltage fluctuations, etc., the ion crystal structure will also change. This defect of non-repeatability of the generated structure (that is, the probability of the target structure appearing is low) brings difficulties to ion addressing and manipulation. One method is to adjust the ions into a mist and then re-cool them into a lattice, or to use voltage to re-arrange the ion crystal, but the success rate of these methods is low.

[0006] Therefore, it is necessary to design a method and system for loading an ion crystal configuration in an ion trap to solve the above technical problems. Summary of the invention

[0007] In view of the above problems, the present invention provides a method for loading an ion crystal configuration in an ion trap, the method comprising:

[0008] S1: Trapping a one-dimensional or multi-dimensional ion crystal in an ion trap and determining a preset ion crystal configuration;

[0009] S2: by applying a laser field of a corresponding arrangement configuration at a preset position, aiming at a preset ion crystal configuration, forming a local optical potential well for the preset ion crystal configuration;

[0010] S3: Based on the superposition of the local optical potential well and the electric potential well, a new total potential well is formed to increase the loading probability of the preset ionic crystal configuration, or to achieve stable confinement of the preset ionic crystal configuration, or to guide the ionic crystal configuration outside the preset ionic crystal configuration to transform into the preset ionic crystal configuration.

[0011] Furthermore, the method further includes performing the following steps before step S1:

[0012] S0: The model is used to calculate the various possible ionic crystal configurations of N ions and to calculate the probability of occurrence of various configurations.

[0013] Furthermore, in step S1, determining the preset ionic crystal configuration further comprises:

[0014] After trapping a one-dimensional or multi-dimensional ionic crystal in an ion trap, the lattice coordinates of the corresponding different ionic crystal configurations are measured to determine the preset ionic crystal configuration, specifically including:

[0015] S11: Measuring the crystal configuration and lattice coordinates of loaded ions by imaging equipment And verify the accuracy of the probability, where x i ,y i and z i Respectively represent the x-, y- and z-axis coordinates of the i-th ion, N is the number of ions, and the imaging device includes CCD or CMOS;

[0016] S12: When the accuracy reaches the requirement, the preset ion crystal configuration can be determined.

[0017] Furthermore, when the accuracy does not meet the requirement, perform the following steps:

[0018] The DC electrode voltages and the radio frequency voltages of the ion trap are adjusted to increase the probability requirement of the occurrence of a preset ion crystal configuration.

[0019] Furthermore, in step S11, the configuration of the loaded ion crystal is measured by an imaging device, and the accuracy of the probability is verified, including:

[0020] S111: Control N ions to form a one-dimensional or multi-dimensional ionic crystal state, and confirm the corresponding ionic crystal configuration and its lattice coordinates by imaging method;

[0021] S112: repeat step S111 multiple times to obtain various ionic crystal configurations in which N ions appear, and calculate the actual probability of each configuration appearing;

[0022] S113: Compare the actual probability with the probability obtained in step S0.

[0023] Furthermore, the imaging method comprises:

[0024] Ion fluorescence is collected through an objective lens and an imaging device;

[0025] The objective lens magnifies the ions to a preset multiple and then displays an ion image on the imaging device;

[0026] The ion image is analyzed to obtain the corresponding ion crystal configuration and its grid coordinates, wherein, for a three-dimensional ion crystal, clear imaging of ions at different positions on an imaging device is achieved by changing the distance between the objective lens and the ions, or the distance between the objective lens and the imaging device.

[0027] Furthermore, the laser field of the corresponding arrangement configuration is obtained, including:

[0028] According to the lattice coordinates of different ionic crystal configurations, a local laser field is applied, and optical tweezers can be formed when the laser spot is less than 5um, wherein when the number of the optical tweezers is greater than one, an optical tweezer array is formed; the optical tweezers include red-detuned or blue-detuned laser optical tweezers in terms of frequency, and include different optical tweezers formed by Gaussian light field, non-Gaussian light field or Laguerre-Gaussian light field in terms of light spot structure;

[0029] By scanning the laser spot position, the grid coordinates of the actual ion crystal configuration are aligned to determine the laser field of the arrangement configuration corresponding to the current ion crystal configuration, so as to obtain the laser field of the corresponding arrangement configuration corresponding to the preset ion crystal configuration; wherein the laser field of the arrangement configuration is the array formed by the laser center of the optical tweezers when the optical tweezers are aligned with the desired ions, and its three-dimensional coordinates are Among them, x j ,y j and z j They represent the coordinates of the x, y and z axes of the laser center of the jth optical tweezers, respectively, M is the preset number of optical tweezers, and N is the number of ions;

[0030] Further, in step S2, aligning to a preset ionic crystal configuration comprises:

[0031] An ionic crystal configuration that conforms to the preset configuration is determined among the actually occurring ionic crystal configurations, and a laser field of the corresponding arrangement configuration is applied. The laser field of the arrangement configuration corresponding to the preset ionic crystal configuration is selected, and the ionic crystal containing N ions is aligned using M laser spots.

[0032] Further, the alignment method includes:

[0033] S21: Adjust the parameters of the external optical path of the ion trap so that the ion fluorescence and the optical tweezers are imaged on the CCD at the same time and their respective light spots are observed;

[0034] S22: Using the adjustment device to adjust the incident angle, the imaging of the ion fluorescence and the optical tweezers on the CCD can meet the preset requirements of overlap, and the grid alignment of the optical tweezers to the preset ion crystal configuration is completed.

[0035] Furthermore, in step S2, the alignment method further includes:

[0036] S23: Maintain the optical tweezers and perform Ramsey interferometry between the two bit energy levels of the ion to measure the AC Stark shift of the light of the optical tweezers on the lattice ions;

[0037] By adjusting the position of the optical tweezers, the AC Stark shift value of the lattice ions in the optical tweezers reaches a preset value, so as to achieve the final lattice alignment of the optical tweezers to the preset ion crystal configuration.

[0038] Furthermore, in step S2, the alignment method further includes:

[0039] S24: The position of the optical tweezers is adjusted so that the transition rate between the two energy levels of the ion reaches a preset value, so as to achieve the final lattice alignment of the optical tweezers to the preset ion crystal configuration.

[0040] Further, in step S3, increasing the loading probability of the preset ionic crystal configuration includes:

[0041] Reload N ions in the ion trap, turn on the preset K laser spots, aim at the preset K positions to form a localized optical potential well, and cool the N ions by laser to form a preset ion crystal configuration, thereby increasing the loading probability of the preset ion crystal configuration; or,

[0042] Using N laser spots, N isotope atoms are trapped in a local optical potential well according to the preset ion crystal configuration, and the N atoms are transformed into N ions using an ionizing laser. At this time, the ions are trapped in a new total potential well formed by the superposition of the electric potential well and the local optical potential well, increasing the loading probability of the preset ion crystal configuration.

[0043] Further, in step S3, the ionic crystal configuration other than the preset ionic crystal configuration is guided to be transformed into the preset ionic crystal configuration.

[0044] M optical tweezers are used to drag or disturb M ions in the corresponding ionic crystal so that the corresponding ionic crystal crosses the potential well and transforms into a preset ionic crystal configuration, wherein M≤N.

[0045] On the other hand, the present invention also provides a system for loading a two-dimensional ionic crystal configuration in an ion trap, characterized in that the system comprises:

[0046] The loading module includes a loading unit and a measuring unit, wherein:

[0047] The loading unit is used to ionize the outermost electrons of atoms in the ion trap through ionization laser to form ions, and the ions are trapped by the electric potential field to form a one-dimensional or multi-dimensional ion crystal;

[0048] The measuring unit is used to measure the lattice coordinates of different ionic crystal configurations and determine the preset ionic crystal configuration;

[0049] An application alignment module is used to align a preset ion crystal configuration by applying a laser field of a corresponding arrangement configuration at a preset position, and to form a local optical potential well for the preset ion crystal configuration;

[0050] The configuration adjustment module is used to form a new total potential well based on the superposition of the local optical potential well and the electric potential well, increase the loading probability of the preset ion crystal configuration, or achieve stable confinement of the preset ion crystal configuration, or guide the ion crystal configuration outside the preset ion crystal configuration to transform into the preset ion crystal configuration.

[0051] The present invention provides a method and system for loading ion crystal configurations in an ion trap, which achieves the fixation of ions in a one-dimensional or multi-dimensional ion crystal and increases the probability of the target configuration appearing, so that each time the ions are reloaded, a crystal configuration of a certain configuration can be obtained. The configuration that has not formed a preset ion crystal configuration can also be adjusted and converted into the preset ion crystal configuration, and at the same time, it also has the function of stabilizing the preset ion crystal configuration that has been formed.

[0052] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction is given below to the drawings to be used in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0054] Figure 1 A flow chart of a method for loading an ion crystal configuration in an ion trap according to an embodiment of the present invention is shown.

[0055] Figure 2 A shape diagram of Configuration 1 according to an embodiment of the present invention is shown.

[0056] Figure 3 A shape diagram of Configuration 2 according to an embodiment of the present invention is shown.

[0057] Figure 4 A schematic structural diagram of ions trapped in an ion trap according to an embodiment of the present invention is shown.

[0058] Figure 5 A schematic diagram showing the changes of the optical tweezers after deepening the configuration 1 according to an embodiment of the present invention is shown.

[0059] Figure 6 A schematic diagram is shown of dragging and disturbing M ions in an ionic crystal by optical tweezers according to an embodiment of the present invention so that the ionic crystal crosses a potential well to form a target two-dimensional ionic crystal configuration. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] like Figure 1 As shown, the present invention provides a method and system for loading ion crystal configurations in an ion trap, the purpose of which is to maximize the probability of occurrence of a certain one-dimensional or multi-dimensional ion crystal configuration (referred to as configuration). Among them, each module in the system can implement the steps of the method, wherein the method includes:

[0062] S1: Trapping a one-dimensional or multi-dimensional ion crystal in an ion trap and determining a preset ion crystal configuration;

[0063] S2: by applying a laser field of a corresponding arrangement configuration at a preset position, aiming at a preset ion crystal configuration, forming a local optical potential well for the preset ion crystal configuration;

[0064] S3: Based on the superposition of the local optical potential well and the electric potential well, a new total potential well is formed to increase the loading probability of the preset ionic crystal configuration, or to achieve stable confinement of the preset ionic crystal configuration, or to guide the ionic crystal configuration outside the preset ionic crystal configuration to transform into the preset ionic crystal configuration.

[0065] The method of the present invention is described in detail below.

[0066] Since the total energy U of an ionic crystal with a total number of N ions (i.e., a stable structure formed by ions after cooling and forming an ionic crystal configuration of a corresponding shape) tot The kinetic energy E of each ion i (i = 1, 2, 3, ... N) k,i, the electric potential energy between all ion pairs (i, j), and the ion trap potential U trap (i.e., potential well) and the potential energy U of the external light field opt (that is, the optical potential well) is jointly determined and can be expressed by the following formula:

[0067]

[0068] In the formula, Q represents the ionic charge, ε0 represents the dielectric constant, and r i,j represents the distance between ion i and ion j, that is, in, are the coordinates of ion i (i = 1, 2, 3...N), are the coordinates of ion j.

[0069] During the loading process, as the number of ions increases, the ionic crystal can have many different configurations, e.g. Figure 2 (Configuration 1, that is, the total energy U tot The two-dimensional ionic crystal configuration at its lowest point) and Figure 3 (Configuration 2, total energy U tot The slightly different configuration shown in the two-dimensional ionic crystal configuration when it is not the lowest) is due to the total energy U tot There are minimum values ​​of the total coordinate r of the lattice points corresponding to different configurations. Therefore, the ions can form a variety of stable crystal configurations by cooling, among which:

[0070] For different initial conditions, the ions will eventually evolve to a stable crystal configuration. Therefore, a simulation program can be used to randomly generate ions within a given range and simulate the cooling process until a stable ionic crystal configuration is formed. The corresponding grid coordinates can be recorded at this time. That is, before step S1, the following steps can be performed:

[0071] S0: The model is used to calculate various ionic crystal configurations that may appear (load) in N ions, and the probability of occurrence of various configurations is counted.

[0072] Wherein, in some embodiments of the present invention, in the above-mentioned step S0, the model can adopt LAMMPS (Large-scale Atomic / Molecular Massively Parallel Simulator, large-scale atomic molecular parallel simulator) model, according to this model, cooperate with (py)LIon package, can repeat simulation in large quantities, change the initial conditions such as the position and speed of randomly generated ions, find the coordinates and energy of each possible configuration grid point. Finally, it is possible to count which types of ionic crystal configurations that N ions correspond to and which types of ionic crystal configurations can be formed in the ion trap and the probability of the corresponding ionic crystal configurations appearing. For example, the various ionic crystal configuration types and corresponding occurrence probabilities are exemplarily represented by the following probability statistics table (only two types of configurations A and B are exemplarily described in the table, but in fact there can be multiple types).

[0073] Probability statistics table

[0074] Configuration Type Probability A configuration P1：83％ B configuration P2：17％

[0075] The above process is just the probability of various types of ionic crystal configurations corresponding to N ions statistically calculated by the model. However, there are still some discrepancies between this statistic and the actual process. Therefore, it is necessary to verify the accuracy of the above statistics, and finally achieve the best ground state loading effect by continuously optimizing the ion trap voltage parameters. The verification steps are described below.

[0076] In some embodiments of the present invention, before verifying the accuracy of the above statistics, it is also necessary to verify or calibrate the parameters of each part of the ion trap. After verification and calibration, the above accuracy can be verified, that is, the accuracy of the probability of occurrence of various configurations can be verified by conducting some experiments in actual processes, that is, after trapping a one-dimensional or multi-dimensional ion crystal in the ion trap, the grid coordinates of different ion crystal configurations are measured to determine the preset ion crystal configuration, specifically including:

[0077] S11: Measuring the crystal configuration and lattice coordinates of loaded ions by imaging equipment And verify the accuracy of the probability, where Among them, x i ,y i and z irepresent the x-, y- and z-axis coordinates of the i-th ion, respectively, N is the number of ions, and the imaging device includes a CCD (charge coupled device) camera or a CMOS (Complementary Metal Oxide Semiconductor) camera, wherein the steps of finally verifying the accuracy of the probability specifically include:

[0078] S111: Control N ions to form a one-dimensional or multi-dimensional ion crystal state, that is: through laser burning technology, use pulsed laser to bombard Yb or other element targets, release atoms and use atomic excitation light to excite atoms in the ion trap area, and then ionize them through ionization light, so that they can be trapped in an ion trap, such as a blade ion trap (referred to as blade trap, one type of ion trap). Among them, the atomic excitation light covers the central area of ​​the ion trap as much as possible, and the ionization light can adjust its spot size and intensity in the central area of ​​the ion trap by changing the lens position. This spot adjustment method can generate ions in a controllable specific area, so that they are trapped in the ion trap (at this time, N ions are in a hot ion group state), and can control the loading of one ion or multiple ions each time.

[0079] The axial direction of the ion trap is defined as the z direction, and the radial direction is defined as the x and y directions. The DC electrode voltages and RF voltages of the ion trap are set to adjust the trap frequency fy in the y direction to be much greater than the trap frequency fx in the x direction. For a specific number of target ions M, when fy / fx>1.23*M is satisfied, 0.25 When the relationship between the two is satisfied, the ionic crystal will only form in the xz plane. Therefore, by cooling the N trapped ions, a one-dimensional or multi-dimensional ionic crystal state can be formed, such as Figure 4 As shown, the one-dimensional or multi-dimensional ionic crystal configuration corresponding to the ionic crystal and its corresponding lattice coordinates (different ionic crystals have different lattice coordinates) can be confirmed by an imaging method, wherein the imaging method comprises: collecting ion fluorescence by an objective lens and an imaging device; wherein the objective lens magnifies the ions to a preset multiple and then presents an ion image on the imaging device; analyzing the ion image to obtain the corresponding ionic crystal configuration and its lattice coordinates, wherein for three-dimensional ionic crystals, clear imaging of ions at different positions on the imaging device is achieved by changing the distance between the objective lens and the ions, or the distance between the objective lens and the imaging device.

[0080] S112: repeat step S111 multiple times to obtain various ionic crystal configurations in which N ions appear, and calculate the actual probability of each configuration appearing;

[0081] S113: Compare the actual probability with the probability obtained in step S0.

[0082] Among them, after comparison, the following situations will occur:

[0083] 1) In some embodiments of the present invention, after comparing the actual probability with the probability of step S0, when the actual probability differs too much from the probability of step S0, that is, when the accuracy does not meet the requirements, the DC electrode voltage and the RF voltage of the ion trap are adjusted to increase the probability requirement value of the occurrence of a preset ion crystal configuration.

[0084] 2) S12: When the accuracy meets the requirement, the lattice coordinates of the preset ionic crystal configuration can be directly determined.

[0085] In addition, it should be understood that, since voltage is a global control method and is not precise enough, it is impossible to achieve a higher target configuration loading probability by adjusting voltage parameters alone, and it is difficult to change the non-target ion crystal configuration that has been loaded. On the basis of maximizing the probability of the target configuration by adjusting the DC electrode voltage and radio frequency voltage of the ion trap, the present invention also introduces a local laser field technology, namely, optical tweezers technology (it should be understood that in the present invention, the local laser field includes but is not limited to optical tweezers, and other local laser fields formed by optical coupler traps can also be used in the present invention. This embodiment is exemplified by optical tweezers), which can further increase the probability of the preset ion crystal configuration (if the above accuracy meets the requirements, the probability of the preset ion crystal configuration can also be further increased by optical tweezers technology). For example, the probability P1 of the preset A configuration in the above table can be further increased to greater than the original 83%. It is also possible to achieve stable confinement of the preset ion crystal configuration (for example, inhibiting configuration 1 from changing to configuration 2) by the introduced optical tweezers technology. It is also possible to introduce optical tweezers technology to guide the ion crystal configuration other than the preset ion crystal configuration to be transformed into the preset ion crystal configuration (for example, the already formed configuration 2 is transformed into configuration 1).

[0086] Among them, Figure 4 As shown in Figure 1, optical tweezers are formed by focusing the laser field through the objective lens into a smaller area where atoms or ions are located, thereby introducing the potential energy U of the external light field. opt When the size of the optical tweezers is smaller than the distance between the ions, the light intensity at the convergence point is higher, so it can bind a single ion and change the total potential energy U of the ion crystal. tot ,like Figure 5 As shown, the optical tweezers deepen the total potential energy of configuration 1. In this case, the greater the energy difference ΔE between the deepened configuration 1 (the shape of the deepened configuration 1 is the same as that of the undeepened configuration 1, but the total potential energy is different) and configuration 2, the easier it is for the ions to be loaded into the target configuration (configuration 1), which can increase the probability of the appearance of the preset crystal configuration.

[0087] In some embodiments of the present invention, the determination of the laser field of the corresponding arrangement configuration in the above step S2 needs to be determined by determining the laser fields of different arrangement configurations, that is, the laser field of the corresponding arrangement configuration can be selected by obtaining the laser fields of all arrangement configurations. Therefore, the acquisition of the laser fields of different arrangement configurations includes:

[0088] According to the lattice coordinates of different ionic crystal configurations, different localized laser fields are applied, and optical tweezers can be formed when the laser spot is smaller than 5um, wherein when the number of the optical tweezers is greater than one, an optical tweezer array is formed; the optical tweezers include red-detuned or blue-detuned laser optical tweezers in terms of frequency, and include different optical tweezers formed by Gaussian light field, non-Gaussian light field or Laguerre-Gaussian light field in terms of light spot structure;

[0089] By scanning the laser spot position, the grid coordinates of the actual ion crystal configuration are aligned to determine the laser field of the arrangement configuration actually corresponding to the current ion crystal configuration, so as to obtain the laser field of the corresponding arrangement configuration corresponding to the preset ion crystal configuration, wherein the laser field of the arrangement configuration is the array formed by the laser center of the optical tweezers when the optical tweezers are aligned with the desired ions (after alignment, the overlap between the laser center of the optical tweezers and the desired ion position is less than the preset value), and its three-dimensional coordinates are in, x j ,y j and z j They respectively represent the coordinates of the x, y and z axes of the laser center of the jth optical tweezers, M is the preset number of optical tweezers, and N is the number of ions.

[0090] Wherein, in step S2, aligning to a preset ionic crystal configuration comprises:

[0091] After an ionic crystal configuration that conforms to the preset configuration is determined among the actually occurring ionic crystal configurations, a laser field of the corresponding arrangement configuration may be applied, thereby using M laser spots to align the ionic crystal containing N ions.

[0092] Among them, the alignment methods include:

[0093] S21: adjusting the parameters of the external optical path of the ion trap so that the ion fluorescence and the optical tweezers are imaged on the CCD at the same time, and observing their respective light spots (before the ions and the optical tweezers are aligned, each has a light spot image);

[0094] S22: using adjustment devices such as AOD (Acousto Optical Deflectors), SLM (Spatial Light Modulator), AOM (Acoustic Optical Modulator) (the present invention is not limited to the above devices, and other devices that can be adjusted can be applied to the present invention) to adjust the incident angle so that the two light spots meet the preset requirements of overlap, and complete the preliminary alignment of the optical tweezers to the preset ion crystal configuration grid point alignment;

[0095] After step S21, the following method may be selected to perform a more accurate alignment:

[0096] Method 1, S23: Maintain the optical tweezers, and perform Ramsey interferometry between the two bit energy levels of the ions through a global microwave field (microwave field is emitted through an antenna, at which time all ions can receive the microwave field) or a light wave field, measure the AC Stark shift of the light of the optical tweezers on the grid point ions, and adjust the position of the optical tweezers so that the AC Stark shift value of the grid point ions in the optical tweezers reaches a preset value (proving that the optical tweezers are completely aligned with the ions), so as to achieve the final grid point alignment of the optical tweezers to the target ion crystal configuration.

[0097] Method 2, S24: The optical tweezers can stimulate the transition of two energy levels of the ion. Therefore, the transition rate of two energy levels of the ion can be adjusted to a preset value by adjusting the position of the optical tweezers, so as to achieve the final alignment of the optical tweezers with the ions in the lattice of the target ion crystal configuration.

[0098] After using the laser field that determines the arrangement configuration corresponding to different ionic crystal configurations, by applying the laser field of the corresponding arrangement configuration at the preset position (the grid coordinates of the preset ionic crystal configuration), the preset ionic crystal configuration is aligned to form a local optical potential well for the preset ionic crystal configuration. After the local optical potential well for the preset ionic crystal configuration is formed, step S3 can be performed.

[0099] In some embodiments of the present invention, in step S3, a new total potential well is formed based on the superposition of the local optical potential well and the electric potential well to increase the loading probability of the preset ion crystal configuration, including:

[0100] N ions are reloaded into the ion trap (at this time, the N ions collectively form a hot ion cluster state), the preset K laser spots are turned on, and the preset K positions are aligned to form a local optical potential well, and the N ions are cooled by laser (at this time, the N ions collectively form an ion crystal state, and the ion crystal in the ion crystal state has a structure of a certain shape, namely, a configuration). Since the preset K laser spots have been turned on, after the N ions are reloaded, the N ions can form a corresponding configuration under the action of the optical tweezers corresponding to the preset K laser spots, that is, the desired preset ion crystal configuration.

[0101] In addition, N laser spots can be used to trap N isotope atoms in a local optical potential well according to a preset ion crystal configuration, and an ionizing laser can be used to convert the N atoms into N ions. At this time, the ions are trapped in a new total potential well formed by the superposition of the electric potential well and the local optical potential well, thereby increasing the loading probability of the preset ion crystal configuration.

[0102] In some embodiments of the present invention, since the direction of parallel light is changed by an acousto-optic deflector or a spatial light modulator and other devices, it is possible to arbitrarily move the optical tweezers grid in the one-dimensional or multi-dimensional plane where the ions are located. Therefore, in the present invention, the desired ion crystal configuration can also be formed by another method in step S3, that is, on the basis of the above-mentioned reloading of N ions and the failure to load the desired target ion crystal configuration after applying optical tweezers, the ion crystal configuration outside the preset ion crystal configuration can be converted into the preset ion crystal configuration by adjusting the ion crystal, specifically including:

[0103] By using controllable local potential wells such as optical tweezers, the partial defects and dislocations of the ion crystal relative to the target configuration can be corrected. When the number of ions is large, the energies of multiple stable configurations are close and the potential barriers between them are shallow, such as Figure 6 As shown, M optical tweezers can be moved to drag or disturb M ions (M≤N) in the ion crystal so that the ion crystal crosses the potential well to form (fall into) the target ion crystal configuration, that is, Figure 6 In the example of (taking the above configuration 1 and configuration 2 as examples), the ion is dragged by the optical tweezers from the configuration 2 deepened by the optical tweezers to transfer (the transfer can change the current configuration of the ion), and finally the ion changes to Figure 6 The optical tweezers are shown in the deepened configuration 1.

[0104] In some embodiments of the present invention, in step S3, a new total potential well is formed based on the superposition of the local optical potential well and the electric potential well, which can also achieve stable trapping of the preset ionic crystal configuration. Specifically:

[0105] Under the influence of the above-mentioned total potential well, on the basis of increasing the loading probability of the preset ion crystal configuration to determine the preset ion crystal configuration and guiding the ion crystal configuration outside the preset ion crystal configuration to transform into the preset ion crystal configuration, maintaining this total potential well can stably trap the preset ion crystal configuration at this time and prevent the preset ion crystal configuration from changing.

[0106] In addition, in some embodiments of the present invention, a system for loading a two-dimensional ion crystal configuration in an ion trap is also provided, specifically comprising:

[0107] The loading module includes a loading unit and a measuring unit, wherein:

[0108] The loading unit is used to ionize the outermost electrons of atoms in the ion trap through ionization laser to form ions, and the ions are trapped by the electric potential field to form a one-dimensional or multi-dimensional ion crystal;

[0109] The measuring unit is used to measure the lattice coordinates of different ionic crystal configurations and determine the preset ionic crystal configuration;

[0110] An application alignment module is used to align a preset ion crystal configuration by applying a laser field of a corresponding arrangement configuration at a preset position, and to form a local optical potential well for the preset ion crystal configuration;

[0111] The configuration adjustment module is used to form a new total potential well based on the superposition of the local optical potential well and the electric potential well, increase the loading probability of the preset ion crystal configuration, or achieve stable confinement of the preset ion crystal configuration, or guide the ion crystal configuration outside the preset ion crystal configuration to transform into the preset ion crystal configuration.

[0112] In summary, the present invention fixes the ions of the ionic crystal through potential well parameter adjustment and optical tweezers technology to increase the probability of the target configuration appearing, so that each time the ions are reloaded, a definite ionic crystal configuration can be obtained. The configuration outside the preset ionic crystal configuration can also be adjusted and converted into the preset ionic crystal configuration. At the same time, it also has the function of stabilizing the preset ionic crystal configuration that has been formed.

[0113] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for loading an ion crystal configuration in an ion trap, characterized in that: The method comprises: S1: trapping a one-dimensional or multi-dimensional ionic crystal in an ion trap and determining a preset ionic crystal configuration, wherein after trapping the one-dimensional or multi-dimensional ionic crystal in the ion trap, measuring the lattice coordinates of corresponding different ionic crystal configurations to determine the preset ionic crystal configuration; S2: by applying a laser field of a corresponding arrangement configuration at a preset position, aiming at a preset ion crystal configuration, and forming a local optical potential well for the preset ion crystal configuration; S3: Based on the superposition of the local optical potential well and the electric potential well, a new total potential well is formed to increase the loading probability of the preset ionic crystal configuration, or to achieve stable confinement of the preset ionic crystal configuration, or to guide the ionic crystal configuration outside the preset ionic crystal configuration to transform into the preset ionic crystal configuration.

2. A method for loading an ion crystal configuration in an ion trap according to claim 1, characterized in that: The method further includes performing the following steps before step S1: S0: The model is used to calculate the various possible ionic crystal configurations of N ions and to calculate the probability of occurrence of various configurations.

3. A method for loading an ion crystal configuration in an ion trap according to claim 1, characterized in that: In step S1, after trapping a one-dimensional or multi-dimensional ionic crystal in an ion trap, the lattice coordinates of the corresponding different ionic crystal configurations are measured to determine a preset ionic crystal configuration, which specifically includes: S11: Measuring the crystal configuration and lattice coordinates of loaded ions by imaging equipment , and verify the accuracy of the probability, where , and represent the x-, y- and z-axis coordinates of the i-th ion, respectively, N is the number of ions, and the imaging device includes a CCD camera or a CMOS camera; S12: When the accuracy reaches the requirement, the preset ion crystal configuration can be determined.

4. A method for loading an ion crystal configuration in an ion trap according to claim 3, characterized in that: If the accuracy does not meet the requirement, perform the following steps: The DC electrode voltages and the radio frequency voltages of the ion trap are adjusted to increase the probability requirement of the occurrence of a preset ion crystal configuration.

5. A method for loading an ion crystal configuration in an ion trap according to claim 3, characterized in that: In step S11, the configuration of the loaded ion crystal is measured by an imaging device, and the accuracy of the probability is verified, including: S111: Control N ions to form a one-dimensional or multi-dimensional ionic crystal state, and confirm the corresponding ionic crystal configuration and its lattice coordinates by imaging method; S112: repeat step S111 multiple times to obtain various ionic crystal configurations in which N ions appear, and calculate the actual probability of each configuration appearing; S113: Compare the actual probability with the probability obtained in step S0.

6. A method for loading an ion crystal configuration in an ion trap according to claim 5, characterized in that: The imaging method comprises: Ion fluorescence is collected through an objective lens and an imaging device; The objective lens magnifies the ions to a preset multiple and then displays an ion image on the imaging device; The ion image is analyzed to obtain the corresponding ion crystal configuration and its grid coordinates, wherein, for a three-dimensional ion crystal, clear imaging of ions at different positions on an imaging device is achieved by changing the distance between the objective lens and the ions, or the distance between the objective lens and the imaging device.

7. A method for loading an ion crystal configuration in an ion trap according to any one of claims 1 to 5, characterized in that: The acquisition of the laser field of the corresponding arrangement configuration includes: According to the lattice coordinates of different ionic crystal configurations, a local laser field is applied, and optical tweezers can be formed when the laser spot is less than 5um, wherein when the number of the optical tweezers is greater than one, an optical tweezer array is formed; the optical tweezers include red-detuned or blue-detuned laser optical tweezers in terms of frequency, and include different optical tweezers formed by Gaussian light field, non-Gaussian light field or Laguerre-Gaussian light field in terms of light spot structure; By scanning the laser spot position, the grid coordinates of the actual ion crystal configuration are aligned to determine the laser field of the arrangement configuration actually corresponding to the current ion crystal configuration, so as to obtain the laser field of the corresponding arrangement configuration corresponding to the preset ion crystal configuration; wherein the laser field of the arrangement configuration is the array formed by the laser center of the optical tweezers when the optical tweezers are aligned with the desired ions, and its three-dimensional coordinates are ,in, , and Respectively represent j The x, y and z axis coordinates of the laser center of each optical tweezer, M is the preset number of optical tweezers, and N is the number of ions.

8. A method for loading an ion crystal configuration in an ion trap according to claim 7, characterized in that: In step S2, aligning a preset ionic crystal configuration includes: An ion crystal configuration that meets the preset configuration is determined among the actually occurring ion crystal configurations, and a laser field of the corresponding arrangement configuration is applied, and the ion crystal containing N ions is aligned using M laser spots.

9. A method for loading an ion crystal configuration in an ion trap according to claim 8, characterized in that: Alignment methods include: S21: adjusting the parameters of the external optical path of the ion trap so that the ion fluorescence and the optical tweezers are imaged simultaneously on the imaging device and their respective light spots are observed; S22: Using the adjustment device to adjust the incident angle, the ion fluorescence and the imaging of the optical tweezers on the imaging device are overlapped to meet the preset requirements, thereby completing the grid alignment of the optical tweezers to the preset ion crystal configuration.

10. A method for loading an ion crystal configuration in an ion trap according to claim 9, characterized in that: In step S2, the alignment method further includes: S23: Maintain the optical tweezers and perform Ramsey interferometry between the two bit energy levels of the ion to measure the AC Stark shift of the light of the optical tweezers on the lattice ions; By adjusting the position of the optical tweezers, the AC Stark shift value of the lattice ions in the optical tweezers reaches a preset value, so as to achieve the final lattice alignment of the optical tweezers to the preset ion crystal configuration.

11. A method for loading an ion crystal configuration in an ion trap according to claim 8, characterized in that: In step S2, the alignment method further includes: S24: The position of the optical tweezers is adjusted so that the transition rate between the two energy levels of the ion reaches a preset value, so as to achieve the final lattice alignment of the optical tweezers to the preset ion crystal configuration.

12. A method for loading an ion crystal configuration in an ion trap according to any one of claims 1 to 5, characterized in that: In step S3, increasing the loading probability of the preset ionic crystal configuration includes: Reload N ions in the ion trap, turn on the preset K laser spots, aim at the preset K positions to form a localized optical potential well, and cool the N ions by laser to form a preset ion crystal configuration, thereby increasing the loading probability of the preset ion crystal configuration; or, Using N laser spots, N isotope atoms are trapped in a local optical potential well according to a preset ion crystal configuration, and an ionizing laser is used to convert the N atoms into N ions. At this time, the ions are trapped in a new total potential well formed by the superposition of the electric potential well and the local optical potential well, increasing the loading probability of the preset ion crystal configuration.

13. A method for loading an ion crystal configuration in an ion trap according to claim 7, characterized in that: In step S3, guiding the ionic crystal configuration other than the preset ionic crystal configuration to be transformed into the preset ionic crystal configuration includes: M optical tweezers are used to drag or disturb M ions in the corresponding ionic crystal so that the corresponding ionic crystal crosses the potential well and transforms into a preset ionic crystal configuration, wherein M≤N.

14. A system for loading a two-dimensional ionic crystal configuration in an ion trap, characterized in that: The system comprises: The loading module includes a loading unit and a measuring unit, wherein: The loading unit is used to ionize the outermost electrons of atoms in the ion trap through ionization laser to form ions, and the ions are trapped by the electric potential field to form a one-dimensional or multi-dimensional ion crystal; The measuring unit is used to measure the lattice coordinates of different ionic crystal configurations and determine the preset ionic crystal configuration; An application alignment module is used to align a preset ion crystal configuration by applying a laser field of a corresponding arrangement configuration at a preset position, and form a local optical potential well for the preset ion crystal configuration; The configuration adjustment module is used to form a new total potential well based on the superposition of the local optical potential well and the electric potential well, increase the loading probability of the preset ion crystal configuration, or achieve stable confinement of the preset ion crystal configuration, or guide the ion crystal configuration outside the preset ion crystal configuration to transform into the preset ion crystal configuration.

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