Method and device for suppressing non-ising term of nv color center ising machine, equipment and medium

Abstract

This invention relates to a method, apparatus, device, and medium for suppressing non-Ising terms in an NV-center Ising machine. The NV-center Ising machine includes an NV-center system with at least two NV-centers. The method includes: applying a pulse sequence to the NV-center system during the magnetic dipole coupling evolution period to suppress non-Ising terms in the Hamiltonian of the NV-center Ising machine. The pulse sequence is configured to utilize the difference in evolution symmetry between the Ising and non-Ising terms in the Hamiltonian under pulse action, causing the non-Ising terms to cancel each other out over time while the Ising terms are retained. This invention achieves selective suppression of non-Ising terms and retention of Ising terms without increasing hardware complexity, ensuring the rigor of the Hamiltonian form, avoiding ground-state configuration flips caused by non-Ising terms, and significantly improving the computational accuracy of the NV-center Ising machine.

Description

Technical Field

[0001] This invention relates to the field of quantum computing technology, and in particular to a method, apparatus, device, and medium for suppressing non-Ising terms in an NV color center Ising machine. Background Technology

[0002] The NV-center Ising machine is a dedicated quantum computing device that uses the electron spins of diamond nitrogen-vacancy (NV) centers as Ising spin carriers. It employs optically probed magnetic resonance (ODMR) readout and measurement feedback iteration to solve combinatorial optimization problems of the Ising model. In related technologies, the magnetic dipole-dipole interaction (magnetic dipole coupling) in the NV-center Ising machine is a crucial physical mechanism for achieving coupling between qubits. However, the electron spin orientations of the two NV centers inevitably have a certain deviation angle, leading to non-Ising terms in the Hamiltonian of the magnetic dipole-dipole interaction. Even small non-Ising terms can alter the commutation relation of the Hamiltonian, causing a flip in the ground state configuration of the Hamiltonian, severely affecting the computational accuracy of the Hamiltonian in the NV-center Ising machine. Therefore, how to actively suppress non-Ising terms while retaining the Ising terms is a critical technical problem that urgently needs to be solved in constructing high-fidelity quantum Ising machines.

[0003] There is currently no effective solution to the problem that the calculation accuracy of the Hamiltonian of the NV color center Ising machine is low because it is impossible to actively suppress non-Ising terms while retaining Ising terms in related technologies. Summary of the Invention

[0004] The non-Ising term suppression method, apparatus, device, and medium of the NV color center Ising machine provided by the embodiments of the present invention at least solve the problem in the related art that it is impossible to actively suppress non-Ising terms while retaining Ising terms, resulting in low calculation accuracy of Hamiltonian of NV color center Ising machine.

[0005] This invention provides a method for suppressing non-Ising terms in an NV center Ising machine, wherein the NV center Ising machine includes an NV center system having at least two NV centers, and the method includes: During the magnetic dipole coupling evolution period of the NV color center system, a pulse sequence is applied to the NV color center system to suppress the non-Ising terms in the Hamiltonian of the NV color center Ising machine; The pulse sequence is configured to utilize the difference in evolution symmetry between the Ising and non-Ising terms in the Hamiltonian of the NV color center Ising machine under pulse action, so that the non-Ising terms cancel each other out under time averaging while the Ising terms are retained.

[0006] In some embodiments, the pulse sequence comprises an even number of pulses, the phases of which are configured such that the cumulative phase signs of the non-Ising terms are opposite in adjacent time periods.

[0007] In some embodiments, the pulse is configured as a π pulse that rotates about the z-axis of a rotating coordinate system.

[0008] In some embodiments, the pulse spacing between any two adjacent pulses in the pulse sequence is:

[0009] in: This represents the total duration of the magnetic dipole coupling evolution cycle; Indicates the number of pulses.

[0010] In some embodiments, the method further includes: Decoupling operations are performed on the NV color centers in the NV color center system that do not participate in magnetic dipole coupling to eliminate the non-Ising interference terms they introduce.

[0011] In some embodiments, the decoupling operation includes: The NV color centers not involved in magnetic dipole coupling are flipped by continuous microwave driving, so that the time average of dipole coupling approaches zero; or The coupling contribution of the NV color centers that do not participate in magnetic dipole coupling is subtracted by numerical compensation.

[0012] In some embodiments, the method further includes: The residual amount of the non-Ising term is periodically measured; When the residual amount of the non-Ising term exceeds a preset threshold, the pulse parameters of the pulse sequence are adjusted.

[0013] In some embodiments, before applying a pulse sequence to the NV color center system, the method further includes: The actual orientation axis direction of each NV color center in the NV color center system is determined based on the optically detected magnetic resonance spectrum. Establish a calibration matrix based on the actual orientation axis direction; The coordinate system calibration is performed on the NV color center system based on the calibration matrix.

[0014] This invention provides a non-Ising term suppression device for an NV center Ising machine, wherein the NV center Ising machine includes an NV center system having at least two NV centers, and the device includes: The pulse control module is configured to apply a pulse sequence to the NV color center system during the magnetic dipole coupling evolution period of the NV color center system in order to suppress the non-Ising terms in the Hamiltonian of the NV color center Ising machine. The pulse sequence is configured to utilize the difference in evolution symmetry between the Ising and non-Ising terms in the Hamiltonian of the NV color center Ising machine under pulse action, so that the non-Ising terms cancel each other out under time averaging while the Ising terms are retained.

[0015] In some embodiments, the apparatus further includes: The coordinate system calibration module is configured to determine the actual orientation axis direction of each NV color center in the NV color center system based on the optically detected magnetic resonance spectrum, establish a calibration matrix based on the actual orientation axis direction, and perform coordinate system calibration on the NV color center system based on the calibration matrix; The decoupling module is configured to perform decoupling operations on the NV color centers that do not participate in magnetic dipole coupling in the NV color center system, so as to eliminate the non-Ising interference terms introduced by them; The diagnostic feedback module is configured to periodically measure the residual amount of the non-Ising term, and adjust the pulse parameters of the pulse sequence when the residual amount of the non-Ising term exceeds a preset threshold.

[0016] An electronic device provided by an embodiment of the present invention includes: a processor and a memory storing a program, the program including instructions that, when executed by the processor, cause the processor to perform the method described above.

[0017] The present invention provides a non-transitory machine-readable medium storing computer instructions for causing a computer to perform the above-described method.

[0018] This invention provides a method, apparatus, device, and medium for suppressing non-Ising terms in an NV center Ising machine. By applying a specifically configured pulse sequence during the magnetic dipole coupling evolution cycle of the NV center system, and utilizing the difference in evolution symmetry between Ising and non-Ising terms under pulse action, selective suppression of non-Ising terms and preservation of Ising terms are achieved. Compared to related technologies that simply pursue enhanced coherence through complete decoupling, this invention ensures the rigor of the Hamiltonian form of the NV center Ising machine and avoids ground state configuration flips caused by non-Ising terms, thereby significantly improving the computational accuracy of the NV center Ising machine. Attached Figure Description

[0019] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other embodiments based on these drawings without creative effort.

[0020] Figure 1This is a schematic flowchart of a method for suppressing non-Ising terms in an NV color center Ising machine according to an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the decomposition of the Ising and non-Ising components of the Hamiltonian in an embodiment of the present invention.

[0022] Figure 3 This is a timing diagram illustrating the π-pulse sequence for eliminating non-Ising terms, as described in an embodiment of the present invention.

[0023] Figure 4 This is a waterfall chart showing the suppression effect of the "four-dimensional synergy" scheme in an embodiment of the present invention.

[0024] Figure 5 This is an overall flowchart of the "four-dimensional collaboration" scheme of an embodiment of the present invention.

[0025] Figure 6 This is a schematic diagram of the NV color center array and multi-body coupling of an embodiment of the present invention.

[0026] Figure 7 This is a schematic diagram of the structure of a non-Ising term suppression device for an NV color center Ising machine according to an embodiment of the present invention.

[0027] Figure 8 This is a schematic diagram of the structure of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0028] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0029] In related technologies, in order to solve the problem that it is impossible to actively suppress non-Ising terms while retaining Ising terms, resulting in low calculation accuracy of Hamiltonian of NV color center Ising machine, the embodiments of the present invention provide a method, device, equipment and medium for suppressing non-Ising terms of NV color center Ising machine. By using pulse sequence to selectively eliminate the evolution symmetry differences of different components of Hamiltonian, non-Ising terms generated in magnetic dipole coupling evolution are suppressed.

[0030] This invention provides a method for suppressing non-Ising terms in an NV center Ising machine, wherein the NV center Ising machine includes an NV center system having at least two NV centers, such as... Figure 1As shown, the non-Ising term suppression method of the NV color center Ising machine includes: S102: During the magnetic dipole coupling evolution period of the NV color center system, a pulse sequence is applied to the NV color center system to suppress the non-Ising terms in the Hamiltonian of the NV color center Ising machine; The pulse sequence is configured to utilize the difference in evolution symmetry between the Ising and non-Ising terms in the Hamiltonian of the NV color center Ising machine under pulse action, so that the non-Ising terms cancel each other out under time averaging while the Ising terms are retained.

[0031] Understandably, in the Ising machine based on the NV color center system, magnetic dipole coupling (magnetic dipole-dipole interaction) represents the natural interaction between the electron spins of the two NV color centers through their respective generated local magnetic fields, such as... Figure 2 The diagram illustrates the decomposition of the Ising and non-Ising components of the Hamiltonian. Mathematically, the Hamiltonian of the magnetic dipole interaction between two spin particles can be decomposed into multiple components. Ideally, when the symmetry axes of the two NV centers involved in the magnetic dipole coupling are strictly along the line connecting the two centers and collinear with each other, the Hamiltonian of their interaction can be strictly reduced to a pure Ising form in the target subspace, retaining only the longitudinal coupling component. In this case, the Hamiltonian is completely consistent with the classical Ising model, and its computational basis vectors are the eigenstates of the system. The ground state search corresponds to solving a combinatorial optimization problem. However, in actual NV center arrays, the symmetry axes of the NV centers are difficult to achieve absolute collinearity, resulting in orientation deviation angles. These orientation deviation angles cause the magnetic dipole coupling tensor to generate a transverse component during projection. The relative strength of this component is related to the square of the sine of the orientation deviation angle. Even with a high level of uniform orientation, the residual transverse component is still not negligible, leading to a certain non-Ising component (non-Ising term) in the Hamiltonian of the NV center Ising machine.

[0032] In some embodiments, the mathematical expression for the Hamiltonian of the magnetic dipole-dipole interaction between the electron spins of the two NV color centers is:

[0033] in, The vacuum permeability; The Landé g-factor for electron spin; The Bohr magneton (the natural unit of the electron magnetic moment, the fundamental quantum unit of the electron magnetic moment); The distance between the two NV color centers; It is the unit vector along the line connecting the two NV color centers; and For the angular momentum operator of electron spins of two NV color centers.

[0034] Furthermore, after expanding the Hamiltonian into Cartesian components, it contains , , (in and Represents the transverse component operator of electron spin. (representing the electron spin z-component operator) and various cross terms; however, the Ising model requires the Hamiltonian to contain only the Ising term. When the axes of symmetry of both NV color centers are along Hamiltonian when the orientation is collinear Available Reduced to pure Ising form in the subspace At this point, only the Ising item is included. However, due to the deviation angle in orientation in practice... This leads to Hamiltonian Generates non-Ising components:

[0035] in, Indicates non-Ising coupling strength; This indicates the Ising coupling strength.

[0036] Understandably, due to the existence of this non-Ising component, even if the unification orientation rate is 99% ( The corresponding non-Ising component is This result still has a significant impact on the computational accuracy of the NV color center Ising machine. For constructing a quantum Ising machine, the Ising term is a "useful signal" that must be retained to build the computational model, while the non-Ising term is "interference noise" that causes computational errors. Therefore, it is necessary to suppress or eliminate the non-Ising term to ensure the computational accuracy of the NV color center Ising machine.

[0037] like Figure 3 The following is an example of this embodiment. The timing principle diagram for eliminating non-Ising terms using pulse sequences illustrates how applying a pulse sequence with a specific phase configuration to an NV color center system produces different transformations for the Ising and non-Ising terms in the Hamiltonian. For Ising terms (such as...) The mathematical sign of the Ising term remains unchanged before and after the pulse application. This means that the phase accumulation of the Ising term on the system wavefunction is monotonically increasing throughout the entire evolution cycle, such as... Figure 3 As shown by the solid blue line, its accumulated phase continuously increases positively over time (slope stabilizes), eventually reaching... Thus, it is fully preserved over time averaging. Conversely, for non-Ising terms (such as...), and A non-Ising term, under the influence of a pulse sequence, will have its mathematical sign reversed. By properly configuring the phase and application time of each pulse in the pulse sequence, it is possible to make the non-Ising term produce an evolution effect with opposite signs in adjacent time periods. For example... Figure 3 As shown by the red dashed line, the non-Ising term produces a positive phase accumulation in the first time interval and a negative phase accumulation in the second time interval after the pulse flip. After a complete evolution cycle, these positive and negative phase accumulations cancel each other out over time, and their net effect approaches zero, thus achieving the "zeroing" or suppression of the non-Ising term.

[0038] In this embodiment, by applying a pulse sequence to the NV color center system, the pulse sequence can take advantage of the difference in evolution symmetry between the Ising and non-Ising terms in the Hamiltonian of the NV color center Ising machine under pulse action. That is, during the magnetic dipole coupling evolution, the Ising and non-Ising terms respond to the pulse sequence in completely different ways. In this way, the non-Ising terms in the Hamiltonian can cancel each other out under time averaging (the pulse spacing between each pulse in the pulse sequence is the same), while the Ising terms are retained, thus avoiding the impact of the non-Ising terms on the calculation accuracy of the NV color center Ising machine.

[0039] In some embodiments, the pulse sequence comprises an even number of pulses, the phases of which are configured such that the cumulative phase signs of the non-Ising terms are opposite in adjacent time periods.

[0040] Specifically, combined Figure 3 The timing diagram shown illustrates that, to achieve mutual cancellation of non-Ising terms under time averaging, the pulse sequence must satisfy specific symmetry conditions. Therefore, in this embodiment, the number of pulses in the pulse sequence is configured to be even. According to the Average Hamiltonian Theory (AHT), within a complete evolution cycle, the transformation property of the Ising term under pulse action ensures that its sign remains unchanged, thus its accumulated phase monotonically increases with time. Non-Ising terms, on the other hand, undergo sign flipping under pulse action. By configuring an even number of pulses, it can be ensured that non-Ising terms accumulate positive and negative phases respectively in adjacent time periods. For example, in the first time period, the non-Ising term produces positive accumulation, with a slope of... During the second time period after the pulse action, due to sign reversal, it produces negative accumulation with a slope of This "alternating positive and negative" mechanism causes the total accumulation of non-Ising terms to approach zero over the entire period, thus achieving effective suppression of non-Ising terms. For example... Figure 3 The inset in the lower right corner shows the decay relationship between the non-Ising quantity residual and the number of pulses n, where the function is: When n=4, the proportion of non-Ising residual quantity is 6.25%; when n=8, the proportion of non-Ising residual quantity is 1.56%; and when n=12, the proportion of non-Ising residual quantity is 0.69%. Thus, it can be seen that the more pulses there are, the smaller the non-Ising residual quantity becomes.

[0041] In some embodiments, the pulse is configured as a π pulse that rotates about the z-axis of a rotating coordinate system. A π pulse is a microwave pulse capable of rotating a qubit (the electron spin of the NV color center) by 180 degrees, which acts as a quantum NOT gate.

[0042] Understandably, at the midpoint of the magnetic dipole coupling evolution cycle, if a π pulse around the z-axis is applied simultaneously to both electron spins, then the π pulse can achieve:

[0043] Thus, the π pulse can activate the transverse electron spin operator ( , The sign of the electron spin operator is flipped while the longitudinal electron spin operator is preserved. The sign of the electron spin operator remains unchanged. In this way, the anti-commutation of the transverse electron spin operator is achieved, so that the non-Ising terms have opposite signs in adjacent time periods and cancel each other out after time averaging; the commutation of the longitudinal electron spin operator is achieved, so that the Ising terms accumulate with the same sign throughout the entire process and are completely preserved.

[0044] In a complete magnetic dipole coupling evolution cycle middle, The term in the first half of the cycle ( )accumulation After applying a π pulse, two All signs change ( ).However, The pulse acts on the transverse component of the interaction representation. In the rotating coordinate system, The time evolution of the item was Pulse in The sign is flipped at time. Based on the zeroth-order average Hamiltonian ( Equal pulse spacing pulse):

[0045] For an even number of pulse, The item is not flipped (it is positive in all time periods), while and The terms alternate signs in adjacent time periods. Therefore, we get:

[0046]

[0047] In some embodiments, since the residual non-Ising component originates from the higher-order average Hamiltonian... , on the order of magnitude ( (As the pulse carrier frequency), therefore, the number of pulses can be increased. Further suppression:

[0048] when Time Residual ; Time Residual .

[0049] In some embodiments, the pulse spacing between any two adjacent pulses in a pulse sequence is:

[0050] in: This represents the total duration of the magnetic dipole coupling evolution cycle; Indicates the number of pulses.

[0051] Thus, in this embodiment, the total coupling evolution period is... Divided into an even number of equal-length sub-segments, this ensures that the cumulative phases of non-Ising terms in adjacent sub-segments are strictly equal in magnitude and opposite in sign, thus canceling each other out under the time average of the complete cycle, while the Ising terms are completely preserved because they have the same sign throughout.

[0052] In some embodiments, in addition to the electron spins of the two NV centers that are magnetically dipole coupled, the coupling of the dipole field of the electron spin of the third NV center (which can be understood as an NV center that does not participate in magnetic dipole coupling) to the first two electron spins is not negligible, even if it is beyond 30 nm. (Slow decay), which introduces multibody non-Ising terms. Therefore, in this embodiment, when suppressing non-Ising terms, it also includes: Decoupling operations are performed on NV color centers that do not participate in magnetic dipole coupling in the NV color center system to eliminate the non-Ising interference terms they introduce.

[0053] In some embodiments, the decoupling operation includes scheme 1 and scheme 2: Option 1: The NV color center that is not involved in magnetic dipole coupling is flipped by continuous microwave driving, so that the time average value of dipole coupling approaches zero.

[0054] Specifically, in Scheme 1, a continuous microwave driving field is applied to the NV color center (NV center) that is not involved in magnetic dipole coupling using a microwave radiation source. The strength of this driving field is configured to cause the NV color center to rapidly flip at the Rabi frequency. According to the average Hamiltonian theory, when the flipping speed of the NV color center is much faster than the dipole coupling strength between it and the target spin, the dipole field generated by the NV color center will approach zero on a time-averaged basis. This is analogous to a rapidly rotating magnet whose average magnetic effect at a distance is canceled out. Through this physical "averaging" process, the non-Ising interference term of the NV color center on the target spin pair is effectively eliminated without the need for complex post-processing algorithms.

[0055] Option 2: Subtract the coupling contribution of the NV color center that does not participate in the magnetic dipole coupling through numerical compensation.

[0056] Specifically, Scheme 2 is an active compensation strategy based on prior information. First, during system initialization, the many-body coupling coefficients between each NV color center not involved in magnetic dipole coupling and the target spin are pre-calibrated through spectral measurements or theoretical calculations, thus obtaining the "known many-body coupling contributions." Subsequently, during the operation of the quantum Ising machine, these known many-body coupling contributions are calculated in real time using a field-programmable gate array (FPGA) or a high-performance processor. The impact on system evolution is calculated, and this contribution is subtracted from the output signal. This numerical compensation method is equivalent to constructing a "virtual pure Ising system" at the data level, which can also achieve the goal of eliminating non-Ising interference terms. This scheme is particularly suitable for scenarios where microwave drive resources are limited or where there are a large number of NV color centers that do not participate in magnetic dipole coupling.

[0057] It should be understood that the two schemes for achieving decoupling described above can be used individually or in combination. For example, microwave continuous drive can be used for physical decoupling of NV color centers that are close to each other and not involved in magnetic dipole coupling, while numerical compensation can be used for algorithmic decoupling of NV color centers that are far apart, weakly coupled, but numerous. This flexible combination can maximize the elimination of non-Ising interference terms introduced by multi-body coupling, further improving the computational accuracy of the quantum Ising machine.

[0058] In some embodiments, the non-Ising term suppression method of the NV center Ising machine of this embodiment further includes step S103, which specifically includes: Periodically measure the residuals of non-Ising terms; When the residual amount of the non-Ising term exceeds the preset threshold, adjust the pulse parameters of the pulse sequence.

[0059] Specifically, during the operation of the quantum Ising machine, this embodiment does not blindly execute a preset pulse sequence, but instead inserts a diagnostic measurement phase at preset time intervals (e.g., every 10 evolution cycles). This diagnostic measurement phase probes the current state of the system by applying a specific diagnostic pulse sequence. For example, it can be achieved by applying... Pulse sequence measurement lateral correlation function < σ x σ x >or< σ y σ y The residual strength of the non-Ising term in the current Hamiltonian is inferred from the value of the value of the value. This measurement process is equivalent to performing a periodic check-up on the "health status" of the system, obtaining real-time feedback data on the suppression effect. After obtaining the residual value of the non-Ising term, the system compares it with a preset threshold. This preset threshold is a safety boundary pre-set according to the accuracy requirements of quantum computing, for example, it can be set to 0.01 (1%). If the measured residual value is lower than the preset threshold, it means that the current suppression effect meets the requirements, and the system continues to operate according to the current pulse parameters. If the measured residual value exceeds the preset threshold, the parameter fine-tuning mechanism is triggered. Figure 4 The waterfall chart showing the suppression effect and Figure 5 In the overall process diagram shown, the preset threshold is set to 0.01 (1%), that is, when Time-triggered pulse parameter fine-tuning, i.e., when the measured non-Ising residual reaches the target Ising coupling strength. When the deviation exceeds 1%, the system is considered to have deviated too far from the Ising model and requires correction. The system will automatically adjust the parameters of the pulse sequence, such as fine-tuning the phase angle of the pulses, adjusting the time interval between pulses, or correcting the pulse amplitude. This adjustment aims to compensate for errors caused by environmental drift, re-optimize the matching degree between the pulse sequence and the system Hamiltonian, thereby suppressing non-Ising terms back to a safe range.

[0060] Combination Figure 5 The flowchart shown in this embodiment illustrates the overall process of suppressing non-Ising terms in the NV color center Ising machine. This embodiment employs a real-time closed-loop correction mechanism of continuous "diagnosis-feedback-adjustment" to periodically monitor the residual amount of non-Ising terms and dynamically adjust parameters. This allows for real-time tracking and counteracting of the influence of environmental noise, ensuring that the suppression effect of non-Ising terms remains high and guaranteeing the stability of the suppression effect. Consequently, this ensures the computational accuracy and robustness of the quantum Ising machine under long-term operation.

[0061] In some embodiments, step S101 is further included before applying the pulse sequence to the NV color center system, specifically including: The actual orientation axis direction of each NV color center in the NV color center system is determined based on the optically detected magnetic resonance spectrum. Establish a calibration matrix based on the actual orientation axis direction; Coordinate system calibration is performed on the NV color center system based on the calibration matrix.

[0062] Specifically, during coordinate system calibration, optically detected magnetic resonance (ODMR) spectral measurements are first performed on each NV center in the NV center array to determine its actual axis of symmetry. Specifically, the magnitude of the applied static magnetic field is kept constant, and the magnetic field polar angle and azimuth angle are systematically changed in the experimental coordinate system using a magnetic field direction adjustment device, scanning the ODMR spectrum of each NV center angle by angle. For a single NV center, its electronic ground state is a spin triplet state, which undergoes Zeeman splitting under the influence of an external magnetic field (the phenomenon where the emitted spectral lines of an atom split into several polarized spectral lines under the influence of an external magnetic field). When the direction of the applied magnetic field is exactly aligned with the C of the NV center... 3v When the axes of symmetry (i.e., the longitudinal axis of its intrinsic coordinate system) coincide, and The transition frequencies between energy levels exhibit standard linear Zeeman splitting characteristics, with the highest contrast in the photodetector magnetic resonance spectrum and no additional peak mixing. When the magnetic field direction deviates from this symmetry axis, the combined effect of the lattice field and the magnetic field causes energy level mixing, leading to spectral broadening, splitting, or peak shift. By fitting the dependence curve of the photodetector magnetic resonance peak position of each NV center on the magnetic field direction, the polar angle and azimuth angle of the actual symmetry axis of the NV center in the experimental coordinate system can be deduced. Furthermore, based on the actual symmetry axis direction, a rotation matrix from the experimental coordinate system to its intrinsic coordinate system is established for each NV center. Rotation matrix This is a three-dimensional orthogonal matrix, where the third column corresponds to the unit direction vector of the eigenaxis of the NV color center in the experimental coordinate system, and the first two columns correspond to the complete orthogonal basis of the eigenaxis. Furthermore, the original control commands generated by the pulse control module (e.g., the phase, amplitude, and application direction of the microwave pulse) are processed through a rotation matrix. A linear transformation is performed to convert the coordinates to independent eigencoordinate systems for each NV color center before outputting to the microwave drive channel. In the calibrated coordinate system, the longitudinal Ising component of the magnetic dipole coupling ( The proportion of the magnetic dipole coupling tensor reaches the theoretical upper limit that the physical system can provide. This can eliminate the false transverse component caused by the misalignment between the experimental coordinate system and the intrinsic coordinate system of the NV color center, and make the longitudinal Ising component of the magnetic dipole coupling tensor in the intrinsic coordinate system reach the theoretical maximum proportion of the physical system under the current orientation deviation. This creates the optimal initial conditions for the selective elimination of the subsequent pulse sequence, ensuring that the applied pulse sequence can accurately act on the target spin component.

[0063] like Figure 6 As shown, in the application scenario of this embodiment, the hardware core of the quantum Ising machine includes an NV color center array disposed on a diamond substrate. This NV color center array contains four NV color centers (…). Figure 6 The four NV centers (a red sphere) are located at positions A, B, C, and D, arranged linearly, with a spacing of 20 nm between adjacent NV centers. Each NV center contains a spin axis (…). Figure 6 The blue arrow (in the middle) is used to carry qubit information, and its angle with the vertical direction is [value missing]. (include , , and The θ is used to represent the orientation deviation angle of the corresponding NV color center. Due to limitations in the manufacturing process, the spin axis directions of each NV color center are not absolutely parallel, and there is a slight orientation deviation. This causes the magnetic dipole interaction represented by the dipole coupling line to naturally contain non-Ising terms. Figure 6 middle, This represents the coupling strength between the NV color center at position A and the NV color center at position B. This represents the coupling strength between the NV color center at position B and the NV color center at position C. This represents the coupling strength between the NV color center at position C and the NV color center at position D. This represents the coupling strength between the NV color center at position A and the NV color center at position C. This represents the coupling strength between the NV color center at position B and the NV color center at position D. This represents the coupling strength between the NV color center at position A and the NV color center at position D. and All with ( The coupling strength is proportional to the distance between two NV color centers, and the coupling strength increases with distance. The cubic decay is weaker the farther away it is, but the decay is slower than the exponential decay, and there is still significant interference beyond 30nm. Figure 6 In the diagram, the MW at the top of the NV center at position C indicates that a microwave is applied to that NV center. This NV center does not participate in the coupling between the NV centers at positions A and B, B and D, or A and D. In these three magnetic dipole couplings, although the NV center at position C does not participate in the coupling, its electron spin generates a magnetic field, which is generated through long-range magnetic dipole coupling. The coupling evolution of ABD is interfered with. However, this embodiment applies continuous microwave drive to make its electron spin flip rapidly, so that its interference magnetic field averages zero on the target coupling time scale, thereby eliminating the multibody non-Ising term.

[0064] In some embodiments, the fabrication stage of the NV color center Ising machine also includes precise orientation control of the diamond substrate. Thus, by selecting a (111) crystal plane diamond substrate and combining it with stress-assisted annealing, the orientation deviation angle of the NV color center is controlled within a small range (e.g., less than 2°). This reduces the initial intensity of the non-Ising term from a physical source, laying the foundation for subsequent active suppression.

[0065] like Figure 5 The above-mentioned "precise orientation control", "coordinate system calibration", and " The overall flowchart of the "four-dimensional synergy" scheme of "pulse sequence correction" and "multi-body coupling cancellation" is combined with... Figure 4 The waterfall plot showing the inhibition effect quantitatively illustrates the inhibition effect. It can be seen that before any inhibition measures were applied, the proportion of non-Ising terms in the system was at a relatively high initial value (2%). After precise orientation adjustment in Dimension 1, the orientation deviation angle was controlled to less than 2°. At this point, the proportion of non-Ising terms decreased significantly to 0.12%, and the suppression factor reached 1 / 16. Then, after coordinate system calibration in Dimension 2, the proportion of non-Ising terms decreased slightly to 0.1%. Finally, after Dimension 3... After pulse sequence correction (pulse number n=8), the proportion of non-Ising terms dropped significantly again to 0.0016%, and the suppression factor reached 1 / 64. This shows that... Pulse sequence correction has a very good effect on suppressing non-Ising terms; finally, multibody coupling cancellation is performed in dimension 4 to eliminate multibody non-Ising terms generated by NV color centers that do not participate in magnetic dipole coupling. At this time, the proportion of non-Ising terms is reduced from 0.0016% to 0.001%.

[0066] In some embodiments, it is assumed that the initial deviation angle is If the pulse number is 8, then the proportion of the total residual of the non-Ising term to the Ising term after "four-dimensional synergy" is:

[0067] in: This represents the total residual amount of the non-Ising terms.

[0068] In this embodiment, after orientation control during the preparation stage, the proportion of non-Ising terms decreased to approximately 1%; after coordinate system calibration before operation, it decreased further; after applying pulse sequence correction, the proportion of non-Ising terms was significantly suppressed to below 0.01%; finally, combining many-body coupling cancellation and closed-loop correction, the proportion of non-Ising terms was successfully suppressed to an extremely low level of 0.002%, far below the preset target threshold. This data fully demonstrates the effectiveness and practicality of the active suppression method provided by this invention in the NV color center system, and can meet the stringent requirements of high-precision quantum Ising machines for the rigor of Hamiltonian forms.

[0069] The non-Ising term suppression method for the NV center Ising machine provided by the embodiments of the present invention has the following technical effects: (1) The non-Ising component was suppressed to 0.002% of the main coupling strength, which is far below the 1% target; (2) Shift from passive ideal conditions to active inhibition, breaking through the limitations of experimental conditions; (3) It does not increase hardware complexity, but is achieved only through pulse and algorithm optimization; (4) Real-time closed-loop correction adapts to temperature fluctuations and process deviations; (5) Ensure the rigor of the Hamiltonian of the directly coupled Ising machine and improve the accuracy of the ground state search.

[0070] Based on the non-Ising term suppression method for the NV center Ising machine provided by the embodiments of the present invention, the embodiments of the present invention also provide a non-Ising term suppression device for the NV center Ising machine, applied to the non-Ising term suppression method for the NV center Ising machine, such as... Figure 7 As shown, the device includes: The pulse control module 701 is configured to apply a pulse sequence to the NV color center system during the magnetic dipole coupling evolution period of the NV color center system in order to suppress the non-Ising terms in the Hamiltonian of the NV color center Ising machine. The pulse sequence is configured to utilize the difference in evolution symmetry between the Ising and non-Ising terms in the Hamiltonian of the NV color center Ising machine under pulse action, so that the non-Ising terms cancel each other out under time averaging while the Ising terms are retained.

[0071] Specifically, at the hardware implementation level, the pulse control module 701 may include components such as an arbitrary waveform generator (AWG), a microwave signal source, and a power amplifier. The arbitrary waveform generator is used to generate an electrical signal with a specific phase and timing according to a preset algorithm logic. This electrical signal is modulated by the microwave signal source and converted into a microwave pulse, which is then amplified by the power amplifier and applied to the spin particles in the magnetic dipole coupling system. It should be understood that the specific hardware form of the pulse control module is not limited to the above combination. Any hardware circuit or integrated circuit capable of generating a pulse sequence that satisfies the requirement of "evolutionary symmetry difference" is within the protection scope of this embodiment.

[0072] In some embodiments, the non-Ising term suppression device of the NV color center Ising machine further includes a coordinate system calibration module 702, which is configured to determine the actual orientation axis direction of each NV color center in the NV color center system based on the optically detected magnetic resonance spectrum, establish a calibration matrix based on the actual orientation axis direction, and perform coordinate system calibration on the NV color center system based on the calibration matrix.

[0073] Specifically, the coordinate system calibration module 702 includes a static magnetic field scanning unit, a microwave excitation unit, and a spectrum processing unit. The static magnetic field scanning unit changes the direction of the applied static magnetic field to scan the photodetector magnetic resonance spectrum of each NV color center; the spectrum processing unit inverts the actual symmetry axis direction of each NV color center based on the Zeeman splitting characteristics, constructs a rotation matrix, and stores it in the pulse control module 701. By setting the coordinate system calibration module 702, the pulse sequence output by the pulse control module 701 is mapped to the eigencoordinate system of each NV color center, eliminating the spurious transverse components introduced by coordinate system misalignment, and ensuring that the longitudinal Ising component reaches its theoretical maximum proportion.

[0074] In some embodiments, the non-Isching term suppression device of the NV color center Isching machine further includes a decoupling module 703, which is configured to perform decoupling operations on NV color centers in the NV color center system that do not participate in magnetic dipole coupling, so as to eliminate the non-Isching interference terms introduced therein.

[0075] The function of the decoupling module 703 corresponds to the multi-body coupling cancellation logic in the aforementioned embodiments. Specifically, the decoupling module 703 can be an independent microwave radiation channel configured to apply continuous microwave drive to the NV color center that is not involved in magnetic dipole coupling, causing it to flip rapidly; alternatively, the decoupling module 703 can also be integrated into the numerical processing unit of the pulse control module 701, configured to subtract the known multi-body coupling contribution through a numerical compensation algorithm. By setting the decoupling module 703, the device can eliminate the non-Ising interference term introduced by long-range multi-body coupling, further improving the suppression accuracy.

[0076] In some embodiments, the non-Ising term suppression device of the NV color center Ising machine further includes a diagnostic feedback module 704, which is configured to periodically measure the residual amount of the non-Ising term and adjust the pulse parameters of the pulse sequence when the residual amount of the non-Ising term exceeds a preset threshold.

[0077] The function of the diagnostic feedback module 704 corresponds to the closed-loop correction logic in the aforementioned embodiments. Specifically, in the hardware architecture, the diagnostic feedback module 704 typically includes a photodetector and a signal processing unit. The photodetector is used to acquire the fluorescence signal of the magnetic dipole coupling system under the action of the diagnostic pulse sequence. The signal processing unit inverts the quantum state of the system based on the fluorescence signal intensity, and then calculates the residual quantity of the non-Ising term. The diagnostic feedback module 704 feeds back the measurement results to the pulse control module 701 to achieve dynamic adjustment of parameters.

[0078] Embodiments of the present invention also provide a non-transitory machine-readable medium storing a computer program, wherein the computer program, when executed by a computer's processor, is used to cause the computer to perform a method according to an embodiment of the present invention.

[0079] Embodiments of the present invention also provide a computer program product, including a computer program, wherein the computer program, when executed by a computer's processor, is used to cause the computer to perform the method of an embodiment of the present invention.

[0080] An embodiment of the present invention also provides an electronic device, including: at least one processor; and a memory communicatively connected to the at least one processor. The memory stores a computer program executable by the at least one processor, which, when executed by the at least one processor, causes the electronic device to perform the method of the embodiment of the present invention.

[0081] refer to Figure 8 The present invention will now describe a structural block diagram of an electronic device that can serve as an embodiment of the present invention, serving as an example of a hardware device applicable to various aspects of the present invention. The electronic device is intended to represent various forms of digital electronic computer devices, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital assistants, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the present invention described and / or claimed herein.

[0082] like Figure 8As shown, the electronic device includes a computing unit 801, which can perform various appropriate actions and processes based on a computer program stored in a read-only memory (ROM) 802 or a computer program loaded from a storage unit 808 into a random access memory (RAM) 803. The RAM 803 may also store various programs and data required for the operation of the electronic device. The computing unit 801, ROM 802, and RAM 803 are interconnected via a bus 804. An input / output (I / O) interface 805 is also connected to the bus 804.

[0083] Multiple components in the electronic device are connected to I / O interface 805, including: input unit 806, output unit 807, storage unit 808, and communication unit 809. Input unit 806 can be any type of device capable of inputting information into the electronic device. Input unit 806 can receive input digital or character information and generate key signal inputs related to user settings and / or function control of the electronic device. Output unit 807 can be any type of device capable of presenting information and may include, but is not limited to, a display, speaker, video / audio output terminal, vibrator, and / or printer. Storage unit 808 may include, but is not limited to, disks and optical discs. Communication unit 809 allows the electronic device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks, and may include, but is not limited to, modems, network cards, infrared communication devices, and / or wireless communication transceivers, such as Bluetooth devices, WiFi devices, WiMax devices, cellular communication devices, and / or the like.

[0084] The computing unit 801 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of the computing unit 801 include, but are not limited to, CPUs, graphics processing units (GPUs), various special-purpose artificial intelligence (AI) computing units, various computing units running machine learning model algorithms, digital signal processors (DSPs), and any suitable processor, controller, microcontroller, etc. The computing unit 801 performs the various methods and processes described above. For example, in some embodiments, the method embodiments of the present invention can be implemented as computer programs tangibly contained in a machine-readable medium, such as storage unit 808. In some embodiments, part or all of the computer program can be loaded and / or installed on an electronic device via ROM 802 and / or communication unit 809. In some embodiments, the computing unit 801 can be configured to perform the methods described above by any other suitable means (e.g., by means of firmware).

[0085] Computer programs for implementing the methods of embodiments of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus, such that when executed by the processor or controller, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be performed. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0086] In the context of embodiments of this invention, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable signal medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, or infrared systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, compact optical disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0087] It should be noted that the term "comprising" and its variations used in the embodiments of this invention are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". The modifications of "one" and "a plurality" mentioned in the embodiments of this invention are illustrative and not restrictive, and those skilled in the art should understand that unless explicitly indicated otherwise in the context, they should be understood as "one or more".

[0088] The user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in the embodiments of this invention are all information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, use and processing of related data must comply with the relevant laws, regulations and standards of the relevant countries and regions, and corresponding operation entry points are provided for users to choose to authorize or refuse.

[0089] The steps described in the method embodiments provided by the present invention can be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of protection of the present invention is not limited in this respect.

[0090] The term "embodiment" in this specification refers to a specific feature, structure, or characteristic described in connection with an embodiment that may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily imply the same embodiment, nor does it imply independence or alternativeity from other embodiments. The various embodiments in this specification are described in a related manner, with reference to each other for similar or identical parts. In particular, for apparatus, device, and system embodiments, since they are substantially similar to method embodiments, the description is relatively simple, and relevant details are referred to in the description of the method embodiments.

[0091] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of protection. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for suppressing non-Ising terms in an NV center Ising machine, wherein the NV center Ising machine comprises an NV center system having at least two NV centers, characterized in that, The method includes: During the magnetic dipole coupling evolution period of the NV color center system, a pulse sequence is applied to the NV color center system to suppress the non-Ising terms in the Hamiltonian of the NV color center Ising machine; The pulse sequence is configured to utilize the difference in evolution symmetry between the Ising and non-Ising terms in the Hamiltonian of the NV color center Ising machine under pulse action, so that the non-Ising terms cancel each other out under time averaging while the Ising terms are retained.

2. The method for suppressing non-Ising terms in the NV color center Ising machine according to claim 1, characterized in that, The pulse sequence comprises an even number of pulses, the phases of which are configured such that the cumulative phase signs of the non-Ising terms are opposite in adjacent time periods.

3. The method for suppressing non-Ising terms in the NV color center Ising machine according to claim 2, characterized in that, The pulse is configured as a π pulse that rotates about the z-axis of a rotating coordinate system.

4. The method for suppressing non-Ising terms in the NV color center Ising machine according to claim 2, characterized in that, The pulse spacing between any two adjacent pulses in the pulse sequence is: in: This represents the total duration of the magnetic dipole coupling evolution cycle; Indicates the number of pulses.

5. The method for suppressing non-Ising terms in the NV color center Ising machine according to claim 1, characterized in that, The method further includes: Decoupling operations are performed on the NV color centers in the NV color center system that do not participate in magnetic dipole coupling to eliminate the non-Ising interference terms they introduce.

6. The method for suppressing non-Ising terms in the NV color center Ising machine according to claim 5, characterized in that, The decoupling operation includes: The NV color centers not involved in magnetic dipole coupling are flipped by continuous microwave driving, so that the time average of dipole coupling approaches zero; or The coupling contribution of the NV color centers that do not participate in magnetic dipole coupling is subtracted by numerical compensation.

7. The method for suppressing non-Ising terms in the NV color center Ising machine according to claim 1, characterized in that, The method further includes: The residual amount of the non-Ising term is periodically measured; When the residual amount of the non-Ising term exceeds a preset threshold, the pulse parameters of the pulse sequence are adjusted.

8. The method for suppressing non-Ising terms in the NV color center Ising machine according to claim 1, characterized in that, Before applying the pulse sequence to the NV color center system, the method further includes: The actual orientation axis direction of each NV color center in the NV color center system is determined based on the optically detected magnetic resonance spectrum. Establish a calibration matrix based on the actual orientation axis direction; The coordinate system calibration is performed on the NV color center system based on the calibration matrix.

9. A non-Ising term suppression device for an NV center Ising machine, the NV center Ising machine comprising an NV center system having at least two NV centers, characterized in that, The device includes: The pulse control module is configured to apply a pulse sequence to the NV color center system during the magnetic dipole coupling evolution period of the NV color center system in order to suppress the non-Ising terms in the Hamiltonian of the NV color center Ising machine. The pulse sequence is configured to utilize the difference in evolution symmetry between the Ising and non-Ising terms in the Hamiltonian of the NV color center Ising machine under pulse action, so that the non-Ising terms cancel each other out under time averaging while the Ising terms are retained.

10. The non-Ising term suppression device for the NV color center Ising machine according to claim 9, characterized in that, The device further includes: The coordinate system calibration module is configured to determine the actual orientation axis direction of each NV color center in the NV color center system based on the optically detected magnetic resonance spectrum, establish a calibration matrix based on the actual orientation axis direction, and perform coordinate system calibration on the NV color center system based on the calibration matrix; The decoupling module is configured to perform decoupling operations on the NV color centers that do not participate in magnetic dipole coupling in the NV color center system, so as to eliminate the non-Ising interference terms introduced by them; The diagnostic feedback module is configured to periodically measure the residual amount of the non-Ising term, and adjust the pulse parameters of the pulse sequence when the residual amount of the non-Ising term exceeds a preset threshold.

11. An electronic device, comprising: A processor and a memory storing a program, characterized in that the program includes instructions that, when executed by the processor, cause the processor to perform the method according to any one of claims 1 to 8.

12. A non-transitory machine-readable medium storing computer instructions, characterized in that, The computer instructions are used to cause the computer to perform the method according to any one of claims 1 to 8.

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