An implementation method and an implementation device of an ion quantum bit gate operation

Abstract

This invention provides a method and apparatus for implementing ion qubit gate operations. The method is applied in an ion trap to confine multiple ion qubits, which form an ion array. The method includes: generating at least one gradient light field with an intensity gradient or a polarization gradient; controlling the at least one gradient light field to focus and project onto at least one target ion qubit in the ion array; and configuring the relative position of the target ion qubit and the focused light spot according to the type of qubit gate operation to be performed, thereby realizing a single-qubit gate or entanglement gate operation of the target ion qubit.

Description

Technical Field

[0001] At least one embodiment of the present invention relates to the field of quantum information technology, and more specifically, to a method and apparatus for implementing ion qubit gate operations. Background Technology

[0002] Quantum computers, as devices that utilize quantum mechanical principles (such as superposition and entanglement) for information processing, possess enormous potential to surpass traditional computers in solving specific computational problems. Among them, ion trap quantum computing platforms, with their advantages of long coherence time and high-fidelity gate operations, have become one of the most promising technological approaches for practical application. In ion trap architectures, quantum information is typically encoded in the hyperfine levels or Zeeman levels of ions (i.e., ion qubits), and universal quantum logic gates are implemented by manipulating the internal and dynamic states of ions using lasers or microwaves.

[0003] To achieve the two-qubit entanglement gate, which is the core of quantum algorithms, an interaction must be established between the ion qubits. Current mainstream schemes (such as the Mølmer-Sørensen gate) primarily rely on the stimulated Raman transition (SMR) mechanism. This mechanism typically requires irradiating the target ion simultaneously with two laser beams having a specific frequency difference, and the wave vector difference between these two laser beams must be large enough to excite the ion's motion modes (phonons). Therefore, in experimental setups, it is usually necessary to configure two laser beams incident from different directions (e.g., propagating in opposite directions or at a 90-degree angle), or a global beam combined with an independently addressed beam.

[0004] However, as ion trap systems expand to large-scale, multidimensional applications (e.g., from one-dimensional ion chains to two-dimensional and three-dimensional ion arrays), the aforementioned optical addressing schemes based on traditional Raman transitions face severe technical challenges: First, the optical path configuration and alignment are complex. Since two laser beams from different directions need to be precisely aligned simultaneously on the same micrometer-scale ion, extremely high demands are placed on the mechanical stability and alignment accuracy of the optical system. Especially in dual-sided addressing schemes, even a tiny jitter in the beam on either side can lead to Raman alignment failure or phase jitter, severely affecting the fidelity of gate operation. Second, interference (stray light problem) exists in addressing within multidimensional arrays. To achieve individual addressing of arbitrary ions in two-dimensional or three-dimensional arrays, cross-acoustic-optical deflectors (Cross-AOD) or dual-sided AOD schemes are often employed. However, when using Cross-AOD to address multiple ions simultaneously (e.g., two ions diagonally), the diffraction characteristics of the acousto-optic deflector not only generate a spot at the target location but also inevitably produce diffraction orders (i.e., stray spots or ghost spots) at non-target locations. If these stray spots illuminate other background ions, they will introduce severe addressing crosstalk, compromising the accuracy of quantum computing. Furthermore, hardware resources are limited. Existing alternatives, such as using micromirror arrays (DMDs), suffer from low light utilization, while the refresh rate of spatial light modulators (SLMs) is typically limited, making it difficult to meet the microsecond-level high-speed operation requirements of ion trap quantum computing.

[0005] Therefore, a new ion qubit gate operation method is needed to break away from the dependence of traditional schemes on the opposing configuration of two beams, achieve efficient manipulation of magnetically sensitive and magnetically insensitive qubits with a simpler single-sided optical path, and effectively solve the stray light crosstalk problem in multidimensional ion array addressing. Summary of the Invention

[0006] In view of this, the present invention provides a method and apparatus for implementing ion qubit gate operations. As a first aspect of the present invention, a method for implementing ion qubit gate operations is provided, the method being applied in an ion trap, the ion trap being used to trap multiple ions forming an ion array, the method comprising:

[0007] Generate at least one gradient optical field with an intensity gradient or a polarization gradient;

[0008] The at least one gradient light field is controlled to be focused and projected onto at least one target ion in the ion array;

[0009] Depending on the type of qubit gate operation to be performed, the relative position of the target ion and the focused spot is configured to realize single-qubit gate or entanglement gate operation of the target ion qubit.

[0010] According to an embodiment of the present invention, configuring the relative position of the target ion and the focused light spot to realize the single-qubit gate or entanglement gate operation of the target ion qubit includes:

[0011] When performing entanglement gate operation, if the gradient light field is a tightly focused fundamental Gaussian beam or a structured light field with a transverse gradient, the equilibrium position of the target ion qubit is configured at the position with the largest transverse light intensity gradient or transverse polarization gradient in the focused light spot; and if the gradient light field has a structured light field with a longitudinal gradient, the equilibrium position of the target ion is configured at the position with the largest longitudinal light intensity gradient or polarization gradient in the focused light spot.

[0012] When performing a single-bit gate operation, the equilibrium position of the target ion qubit is configured at the position of the intensity maximum or polarization maximum of the focused spot;

[0013] The horizontal direction is the radial direction of the focused light spot, and the vertical direction is the transmission direction of the gradient light field.

[0014] According to an embodiment of the present invention, the target ionic qubit is a qubit sensitive to a magnetic field, and when performing an entanglement gate operation, the method includes:

[0015] The intensity of the gradient light field projected onto the target ion qubit is kept constant, and the spatial position-dependent AC Stark level frequency shift gradient is generated using the gradient light field.

[0016] A microwave field is applied to the target ion, and the frequency of the microwave field is configured to match the sideband transition frequency of the target ion under the action of the gradient light field, so as to drive the spin-motion coupling of the target ion and realize the entanglement gate operation.

[0017] According to an embodiment of the present invention, the target ion qubit is a qubit insensitive to a magnetic field, and the gradient optical field includes two frequency components with a frequency difference, the frequency difference being approximately the sum of the energy level difference of the target ion qubit and the phonon frequency of the ion array, or the frequency difference being approximately the difference between the energy level difference of the target ion qubit and the phonon frequency of the ion array, so as to drive the stimulated Raman sideband transition of the target ion by utilizing the intensity gradient or polarization gradient of the gradient optical field at the target ion.

[0018] According to an embodiment of the present invention, after controlling the at least one gradient light field to focus and project onto at least one target ion in the ion array, the method further includes:

[0019] The intensity of the gradient light field is controlled to form a local optical potential well at the target ion qubit using the optical dipole force generated by the focused light spot;

[0020] The local vibrational frequency of the target ion qubit is altered by the local optical potential well, so that the vibrational mode of the target ion qubit is separated from the vibrational modes of other background ion qubits in the ion array in the spectrum.

[0021] According to embodiments of the present invention, the ion array is a one-dimensional ion chain, a two-dimensional ion array, or a three-dimensional ion array;

[0022] When the ion array is a two-dimensional or three-dimensional ion array, and the number of target ion qubits is multiple.

[0023] Multiple gradient light fields are projected from different positions of the ion array onto multiple target ion qubits located in different rows or columns; or,

[0024] Multiple gradient light fields are projected in parallel onto multiple target ions located in the same row or column.

[0025] According to an embodiment of the present invention, the diameter of the focused spot formed after the gradient light field is focused is smaller than the spacing between any two adjacent ion qubits in the ion array.

[0026] As a second aspect of the present invention, an apparatus for implementing ion qubit gate operations is also provided for the above-described method, the apparatus comprising:

[0027] At least one gradient light field generating unit is configured to generate at least one gradient light field having an intensity gradient or a polarization gradient;

[0028] At least one addressing unit, each addressing unit comprising:

[0029] An optical adjustment component is configured to receive the gradient light field and adjust the propagation direction of the gradient light field according to a control signal;

[0030] A focusing component is configured to focus the gradient light field emitted by the light adjustment component to form a focused spot at the target ion of the ion array;

[0031] The control unit is configured to adjust the relative position of the focused spot and the target ion to drive the target ion to perform single-bit gate or entanglement gate operations.

[0032] According to an embodiment of the present invention, the gradient light field generation unit includes:

[0033] Laser light source, suitable for generating lasers;

[0034] Modulation components, including acousto-optic modulators or electro-optic modulators, are configured to modulate the frequency, phase, or intensity of a laser emitted from a laser source to generate a modulated light field containing dual-frequency components or a specific pulse sequence, or include spatial light modulators or optical diffraction elements configured to modulate the spatial mode of the laser to generate a structured light field with an intensity gradient or polarization gradient.

[0035] According to an embodiment of the present invention, the optical adjustment component in the addressing unit includes:

[0036] The light adjustment component is configured to change the emission angle of the gradient light field under the drive of the control unit, or to split a single gradient light field into multiple beams and independently control the deflection direction of each beam, so as to achieve parallel addressing of single or multiple points in the ion array.

[0037] The embodiments of this invention employ a gradient optical field acting on a target ion to configure the relative position of the target ion and the focused spot, thus realizing a quantum gate. This breaks the dependence of the Raman scheme used in the traditional quantum gate implementation process on dual-beam counter-propagating lasers. Since the gradient optical field propagates in the same optical path, the relative phase jitter caused by optical path separation is naturally eliminated, significantly improving the coherence and stability of the gate operation. Attached Figure Description

[0038] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0039] Figure 1 A flowchart illustrating the implementation method of ion qubit gate operation according to an embodiment of the present invention is shown;

[0040] Figure 2 A schematic diagram illustrating the spin-motion coupling principle of Raman light driven ion qubits by two laser beams with a frequency difference, provided by an embodiment of the present invention, is shown.

[0041] Figure 3 A schematic diagram of the principle of driving spin-motion coupling of ionic qubits using a gradient magnetic field plus microwave driving scheme according to an embodiment of the present invention is shown.

[0042] Figure 4 A schematic diagram illustrating the principle of spin-motion coupling of driven ionic qubits using dynamic magnetic field gradients or near-field microwaves, according to an embodiment of the present invention, is shown.

[0043] Figure 5 A schematic diagram of a prior art Raman laser that achieves dual-sided addressing in a two-dimensional ion array is shown.

[0044] Figure 6An apparatus for implementing ion qubit gate operations for a one-dimensional ion array according to Embodiment 1 of the present invention is shown.

[0045] Figure 7 It shows 171 Yb + A schematic diagram of energy levels used for encoding ionic qubits in ions.

[0046] Figure 8 The differential AC Stark frequency shift of the target ion at different positions in a gradient light field according to Embodiment 1 of the present invention is shown.

[0047] Figure 9 The apparatus for implementing ion qubit gate operations for a two-dimensional ion array provided in Embodiment 2 is shown.

[0048] Figure 10 The Rabi frequency distribution of carrier transitions generated by the dual-frequency gradient light field in the focused spot according to Embodiment 2 of the present invention is shown.

[0049] Figure 11 The apparatus for implementing qubit gate operations in a three-dimensional ion array provided in Embodiment 3 is shown. Detailed Implementation

[0050] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0051] Figure 1 A flowchart of an implementation method for ion qubit gate operation according to an embodiment of the present invention is shown. The implementation method is applied to an ion trap for trapping multiple ions to form an ion array. The implementation method includes operations S1 to S3.

[0052] In operation S1, at least one gradient light field with an intensity gradient or a polarization gradient is generated.

[0053] In operation S2, the at least one gradient light field is focused and projected onto at least one target ion quantum bit (also referred to as the target ion) in the ion array to achieve optical addressing of the target ion quantum bit.

[0054] In operation S3, the relative position of the target ion and the focused spot is configured according to the type of qubit gate operation to be performed, so as to realize the single-bit gate or entanglement gate operation of the target ion qubit.

[0055] The embodiments of this invention employ a gradient optical field acting on a target ion to configure the relative position of the target ion and the focused spot, thus realizing a quantum gate. This breaks the dependence of the Raman scheme used in traditional quantum gate implementation on dual-beam counter-propagating lasers. Since the gradient optical field propagates in the same optical path, the relative phase jitter caused by optical path separation is eliminated, improving the coherence and stability of the gate operation.

[0056] According to an embodiment of the present invention, configuring the relative position of the target ion and the focused spot to realize the single-bit gate or entanglement gate operation of the target ion qubit includes operation S31 to operation S32.

[0057] In operation S31, when performing the entanglement gate operation, if the gradient light field is a tightly focused fundamental mode Gaussian beam or a structured light field with a transverse gradient, the equilibrium position of the target ion qubit is configured at the position with the largest transverse light intensity gradient or transverse polarization gradient in the focused light spot; and if the gradient light field has a structured light field with a longitudinal gradient, the equilibrium position of the target ion is configured at the position with the largest longitudinal light intensity gradient or polarization gradient in the focused light spot.

[0058] In operation S32, when performing a single-bit gate operation, the equilibrium position of the target ion qubit is configured at the position of the intensity maximum or polarization maximum of the focused spot.

[0059] The horizontal direction is the radial direction of the focused light spot, and the vertical direction is the transmission direction of the gradient light field.

[0060] According to embodiments of the present invention, by configuring the target ion in a differentiated manner for entanglement gates and single-qubit gates, the target ion is positioned in the optimal operating region for the corresponding gate operation. For entanglement gates, placing the target ion at the position of maximum gradient maximizes the coupling effect of the gradient light field, ensuring efficient establishment of spin-motion coupling and smooth driving of entanglement gate operation. For single-qubit gates, placing the equilibrium position of the target ion at the intensity or polarization maximum of the focused spot allows full utilization of the intensity or polarization characteristics of the light field to directly drive spin flipping, making single-qubit gate operation more direct and efficient.

[0061] According to an embodiment of the present invention, the relative position of the target ion qubit and the corresponding focused spot is achieved by changing the propagation direction of the structured light field incident on the target ion.

[0062] According to embodiments of the present invention, ion trap quantum computing typically uses the internal energy levels of ion qubits as qubits. Depending on the energy level selection, these are classified as Zeeman level qubits (~10 MHz), hyperfine level qubits (1~10 GHz), and optical qubits (~100 THz). Hyperfine level qubits, because they can select two first-order magnetically insensitive energy levels as qubits, can achieve very long coherence times and are therefore the most commonly used in various ion trap quantum computing schemes.

[0063] Single-qubit gate operations of hyperfine level qubits are generally achieved using microwaves or dual-color Raman lasers. Multi-qubit gate operations require the Coulomb interaction (phonons) between ions as a medium; for example, a typical MS gate requires simultaneous red-blue sideband operations on two ion qubits. This requires the ions to achieve spin-motion coupling (coupling of spin state and motion state) through an external field (optical field, electric field, or magnetic field).

[0064] There are three typical methods for achieving spin-motion coupling. First, using Raman lasers. Second, using a static magnetic field gradient and microwaves. Third, using near-field microwaves. These will be described in detail below.

[0065] Spin-motion coupling can be achieved using Raman lasers. This involves two opposing laser beams (with a significant angle between their propagation directions). When their frequency difference equals the + / - phonon frequency of the ion energy level, red-sideband and blue-sideband operations of the ion can be performed separately, thus achieving spin-motion coupling. This method requires two laser beams in different directions, with at least one capable of addressing the ion.

[0066] Figure 2 A schematic diagram illustrating the spin-motion coupling principle of Raman light driven ion qubits by two laser beams with a frequency difference, provided by an embodiment of the present invention, is shown.

[0067] like Figure 2 As shown, in ion trap quantum computing, ion qubits are typically encoded on a pair of stable ground-state energy levels of an ion (such as hyperfine levels). and The frequency corresponding to the energy difference between these two energy levels is the reference frequency that drives the flipping of the qubit. However, in order to achieve high-speed, precise manipulation of the qubit and realize entanglement gates, two beams with frequencies of... and The wave vectors are respectively and The laser beams induce stimulated Raman transitions, and the effect of the two laser beams can be considered as respectively activating the laser beams to induce Raman transitions. and Coupled to the same virtual intermediate state Above. Through this virtual intermediate process, the system will effectively... and A coupling is established between them. At this point, the frequency difference between the two laser beams is precisely adjusted. This scheme enables red-blue sideband manipulation of ions at the + / - phonon frequencies of the ion energy level. It requires two laser beams in different directions, with at least one beam capable of addressing the ions.

[0068] Figure 3 A schematic diagram of the principle of driving spin-motion coupling of ionic qubits using a gradient magnetic field plus microwave driving scheme according to an embodiment of the present invention is shown.

[0069] In schemes based on static magnetic field gradients, qubits are also encoded in a pair of ground-state energy levels (such as Zeeman sublevels). and Between ), its eigenfrequency is The core of this scheme is to utilize a spatially non-uniform static magnetic field, the gradient of which... This causes a linear Zeeman shift in the energy levels of the qubit, dependent on the ion position. When a large static magnetic field gradient exists, the ion magnetic quantum number increases due to the Zeeman effect. The energy levels shift with position, therefore when choosing two... When different energy levels are used as qubits, spin coupling of ions can be achieved through a static magnetic field gradient. In this case, sideband operations of ions can be realized through microwave manipulation. Furthermore, the energy differences between qubits at different positions are significant, allowing addressing via microwave frequency. The disadvantages of this scheme are that it can only use magnetically sensitive energy levels as qubits, reducing the fidelity of gate operations; achieving large magnetic field gradients and small magnetic field strengths is difficult, and the gate operation speed is slower than laser manipulation.

[0070] Figure 4 A schematic diagram illustrating the principle of spin-motion coupling of driven ionic qubits using dynamic magnetic field gradients or near-field microwaves, according to an embodiment of the present invention, is shown.

[0071] like Figure 4 As shown, in the dynamic gradient magnetic field scheme, the eigenfrequency of the ion qubit remains ω. F This scheme is typically implemented in a surface electrode ion trap, where the ion qubit can be driven by an alternating magnetic field (near-field microwave) generated by an alternating current. The amplitude of this near-field microwave is related to the distance between the ion qubit and the wire, and the magnetic field strength of the near-field microwave changes drastically with distance, which can be regarded as a dynamic magnetic field gradient close to the frequency of the ion qubit (denoted as ). This enables the coupling of ion spin and motion. However, this scheme is only applicable to surface traps. To achieve faster gate operations, the distance between the ion qubits and the wires needs to be as close as possible. The thermal rate of the ion trap has a significant impact on the gate operation fidelity. At the same time, the heating of the near-field microwave wires under high current may limit the improvement of gate operation speed. In this scheme, the ion qubits need to be off-center for addressing, which also leads to significant micro-motion and affects the operation fidelity.

[0072] Based on the above principles, the embodiments of the present invention propose corresponding implementation methods for the operation of single-bit gates and entanglement gates.

[0073] According to an embodiment of the present invention, the target ionic qubit is a qubit sensitive to a magnetic field. When performing an entanglement gate operation, the above method includes:

[0074] By keeping the intensity of the gradient light field projected onto the target ion qubit constant, a spatially position-dependent AC Stark level frequency shift gradient is generated using the gradient light field, thereby constructing an equivalent magnetic field gradient along the gradient direction at the target ion qubit.

[0075] A microwave field is applied to the target ion, and the frequency of the microwave field is configured to match the sideband transition frequency of the target ion under the action of a gradient light field, so as to drive the spin-motion coupling of the target ion and realize the entanglement gate operation.

[0076] According to an embodiment of the present invention, the frequency configuration of the microwave field is configured to match the sideband transition frequency of the target ion under the action of the gradient light field, indicating that the frequency configuration of the microwave field is approximately the same as the sideband transition frequency of the target ion under the action of the gradient light field.

[0077] According to an embodiment of the present invention, the frequency configuration of the microwave field, which is substantially the same as described above, has a preset gate operation detuning amount δ with respect to the sideband transition frequency of the target ion under the action of the gradient light field.

[0078] The following explanation uses a specific MS gate implementation as an example. The equivalent magnetic field gradient generated at the ion by the gradient light field allows the microwave field to couple the ion's motion state. Frequency-dependent inputs are applied to the target ion qubit at frequencies... and A two-color microwave field. It is the frequency of the target ion qubit. It is the frequency of a specific collective motion mode of the ion array, also known as the phonon frequency. Here, δ represents the gate operation detuning, which determines the gate operation time. In this configuration, the microwave field establishes a spin-spin interaction between two target ions by driving spin motion coupling. After a specific evolution time, the motion mode of the ions decouples from the spin state, retaining only the quantum entanglement between the two ions, thereby realizing a high-fidelity MS gate.

[0079] This invention eliminates the need for complex real static magnetic field gradient construction devices. It generates a spatially dependent AC Stark level frequency shift gradient using a gradient light field, thereby constructing an equivalent magnetic field gradient at the target ion qubit. This simplifies the hardware configuration and operational procedures related to magnetic field gradients, reducing experimental complexity and implementation difficulty. By maintaining a constant gradient light field intensity, the stability of the equivalent magnetic field gradient is effectively maintained, avoiding gradient fluctuations caused by sudden changes in light field intensity, thus ensuring high fidelity in entanglement gate operations. Furthermore, this method is specifically designed for magnetic field-sensitive qubits. By adjusting the gradient light field intensity and microwave field frequency, it can adapt to magnetic field-sensitive qubit systems with different parameters, meeting diverse entanglement gate operation requirements and further expanding the applicable scenarios of gradient light field-based ion qubit gate operation schemes.

[0080] According to an embodiment of the present invention, the target ion qubit is a qubit insensitive to a magnetic field, and the gradient optical field includes at least two frequency components with a frequency difference. During single-qubit operation, the frequency difference is approximately... During MS gate operations, two sets of Raman transitions can be formed with a frequency difference. .

[0081] According to an embodiment of the present invention, after controlling at least one gradient light field to focus and project onto at least one target ion in the ion array, the above method further includes the following operations.

[0082] The intensity of the gradient light field is controlled to form a local optical potential well at the target ion qubit using the optical dipole force generated by the focused light spot. The local vibration frequency of the target ion qubit is changed by the local optical potential well so that the vibration mode of the target ion qubit is separated from the vibration mode of other background ion qubits in the ion array in the spectrum.

[0083] According to an embodiment of the present invention, by changing the local vibration frequency of the target ion through a local optical potential well, the vibration modes of the target ion and the background ion are separated in the spectrum. This fundamentally avoids the excitation of the motion state of the background ion qubit during the ion quantum gate operation, reduces the interference of phonon crosstalk on the quantum state, and ensures the fidelity of the entanglement gate operation.

[0084] According to an embodiment of the present invention, the diameter of the focused light spot is smaller than the inter-ion spacing between any two adjacent ions in the ion array. According to an embodiment of the present invention, the gradient light field is focused to form a focused light spot smaller than the inter-ion spacing at the corresponding target ion. The spatial intensity gradient distribution of this light spot naturally constitutes a miniature optical potential well acting on the target ion qubit, thus realizing the generation and localization of optical tweezers. In quantum computers, since the inter-ion spacing is less than 10 micrometers, in order to manipulate specific ions and construct quantum circuits, it is necessary to focus the manipulation laser spot to a size smaller than the inter-ion spacing, thereby illuminating the gradient light field onto the target ion qubit to be manipulated without affecting other ion qubits. This method is called optical individual addressing. Because the effective range of the optical tweezers is strictly limited to the scale of a single ion, when manipulating a target ion, the optical tweezers will not overlap and interfere with neighboring ions, eliminating optical crosstalk.

[0085] According to embodiments of the present invention, the ion array is a one-dimensional ion chain, a two-dimensional ion array, or a three-dimensional ion array; when the ion array is a two-dimensional ion array or a three-dimensional ion array and the number of target ion qubits is multiple, multiple gradient light fields are projected from different positions of the ion array onto multiple target ion qubits located in different rows or different columns; or, multiple gradient light fields are projected in parallel onto multiple target ions located in the same row or the same column.

[0086] According to embodiments of the present invention, ions in the ion array having hyperfine energy levels, for example... 137 Ba + , 171 Yb + , 43 Ca + or 9 Be + etc.

[0087] Currently, there are two main structures for achieving optical individual addressing of ions and ion qubit gate operations using Raman lasers. The first is a scheme using single-sided addressing light plus global light. In this structure, multiple controllable laser beams are generated by a spatial light modulator (SLM), a micromirror array (DMD), an optical waveguide array, a multi-channel acousto-optic modulator (MCAOM), and a cross-acousto-optic deflector (Cross-AOD). These multiple laser beams are transformed by the optical system and finally converged onto different ions to achieve ion addressing. Simultaneously, global light is used to illuminate all ions from another direction. The second structure uses a two-sided addressing light scheme. This structure uses two sets of acousto-optic deflectors (AODs) to generate multiple laser beams from both sides. After transformation by the optical system, different beams are focused onto different ions, thus achieving addressing operations. Applying different radio frequency (RF) frequencies to the AODs can obtain deflected beams at different angles. Simultaneously applying multiple RF frequencies to the AODs can obtain multiple laser beams for addressing multiple ions. Because the dual-sided AOD beams are symmetrically focused onto multiple ions, the two beams on the same ion correspond to the same radio frequency at the AOD. Although the AOD causes a frequency shift in the laser, the frequency difference between the two lasers is a constant value. This means that the addressing laser does not affect the requirement of a constant frequency difference between the two lasers for the Raman laser. This scheme allows for flexible configuration and high-speed switching, enabling addressing of two-dimensional ions. However, both schemes have the following drawbacks: the spatial light modulator (SLM) has a slow switching time, not reaching the microsecond level; the micromirror array (DMD) has low light utilization; the optical waveguide array and multi-channel acousto-optic modulator (MCAOM) have fixed spacing and low scalability; and the cross-AOD (cross-acousto-optic deflector) has low light utilization and produces stray beams when addressing multiple ions, making it unsuitable for two-dimensional ion arrays.

[0088] Figure 5 A schematic diagram of a prior art Raman laser that achieves dual-sided addressing in a two-dimensional ion array is shown.

[0089] like Figure 5 As shown, a two-dimensional acousto-optic deflector is arranged on each side of the two-dimensional ion array. Figure 5 (Only one side is shown in the image) The two-dimensional acousto-optic deflector is essentially composed of two independent one-dimensional acousto-optic deflectors physically orthogonally spliced ​​together. Each one-dimensional acousto-optic deflector requires its own independent radio frequency signal to drive it. RF1 and RF2 are used to drive the first one-dimensional acousto-optic deflector, controlling the deflection of the beam of light illuminating the target ion in one direction. RF3 and RF4 are used to drive the second one-dimensional acousto-optic deflector, controlling the deflection of the beam of light illuminating the target ion in another direction.

[0090] However, dual-addressed Raman lasers illuminate ions from two different optical paths, requiring high alignment. When asymmetrical, the edge spots cannot overlap, limiting scalability. They can only achieve radial phonon mode operation of ions. Furthermore, when addressing in a two-dimensional ion array, stray light arrays are generated, which interfere with other ions.

[0091] In view of the above problems, as a second aspect of the present invention, an apparatus for implementing an ion qubit gate is also provided for implementing the above implementation method. The apparatus includes: at least one gradient light field generation unit, at least one addressing unit, and a control unit.

[0092] At least one gradient light field generating unit is configured to generate at least one gradient light field having an intensity gradient or a polarization gradient. According to an embodiment of the invention, if for a magnetically sensitive target ion qubit (microwave-assisted scheme), the unit mainly outputs continuous light or a modulated beam. If for a magnetically insensitive target ion qubit (Raman scheme), the unit includes an electro-optic modulator (EOM) or an acousto-optic modulator (AOM) for generating a dual-frequency laser component with a specific frequency difference.

[0093] Each addressing unit includes an optical adjustment component and a focusing component. The optical adjustment component is configured to receive a gradient light field and adjust its propagation direction according to a control signal. The optical adjustment component is preferably a two-dimensional acousto-optic deflector (2D-AOD) or a fast reflector, used to receive the gradient light field and precisely control its exit angle. The focusing component is configured to focus the gradient light field emitted by the optical adjustment component, forming a focused spot at the target ion in the ion array. The focusing component is preferably a high numerical aperture (NA) objective lens, used to focus the beam to a sub-micron scale (beam waist diameter smaller than the ion spacing, for example...). This creates an extremely strong focused light spot at the target ion.

[0094] The control unit is configured to adjust the relative position of the focused spot and the target ion to drive the target ion to perform single-bit gate or entanglement gate operations.

[0095] According to an embodiment of the present invention, the light adjustment component can precisely adjust the propagation direction of the gradient light field according to the control signal to ensure that the light field is accurately pointed to the target ion region; the focusing component focuses the gradient light field to form a small light spot (the diameter is smaller than the distance between adjacent ions), which enhances the gradient effect or intensity effect of the light field at the target ion; the control unit further finely adjusts the relative position of the focused light spot and the target ion, so that the target ion is at the intensity / polarization maximum position in the single-bit gate and in the gradient significant region in the entanglement gate. The precise control of the entire process from light field propagation and focusing to position alignment provides hardware guarantee for high-fidelity gate operation.

[0096] According to embodiments of the present invention, the gradient light field generation unit includes: an acousto-optic modulator (AOM) or an electro-optic modulator (EOM) configured to modulate the frequency, phase, or intensity of a laser emitted from a laser source to generate a modulated light field containing dual-frequency components or a specific pulse sequence; or, it further includes a spatial light modulator (SLM) or a diffractive optical element (DOE) configured to modulate the spatial mode of the laser to generate a structured light field with a significant intensity gradient or polarization gradient.

[0097] According to an embodiment of the present invention, the optical adjustment component in the addressing unit includes: a two-dimensional acousto-optic deflector (2D AOD), a cross-acousto-optic deflector (Cross-AOD), a micromirror array (DMD), or a spatial light modulator (SLM); the optical adjustment component is configured to change the emission angle of the gradient light field under the drive of the control module, or to split a single gradient light field into multiple beams and independently control the deflection direction of each beam, so as to realize parallel addressing of single or multiple points in the ion array.

[0098] According to an embodiment of the present invention, the above-described device is used to operate a three-dimensional ion array; the focusing component includes a tunable lens, an acousto-optic deflector assembly (AOD) driven by a chirped signal, or a deformable mirror; the control unit is configured to adjust the focal length of the tunable lens, the surface profile of the deformable mirror, or the chirp rate of the driving signal applied to the acousto-optic deflector assembly, thereby dynamically adjusting the focusing depth of the focused spot in the direction of gradient light field propagation to align with target ions in different planes of the three-dimensional ion array.

[0099] According to an embodiment of the present invention, the gradient light field generated by at least one addressing unit is incident via a single-sided optical path; the two frequency components in the gradient light field used to drive stimulated Raman transitions or the light field components used to generate equivalent magnetic field gradients are transmitted in the same optical path, so that the two frequency components or components have built-in relative phase stability, without the need for additional optical path interference stabilization devices.

[0100] According to an embodiment of the present invention, the general process for implementing ion qubit gate operation based on the above-described device is as follows:

[0101] Step A1: Gradient light field generation. Control the gradient light field generation unit to generate a gradient light field containing the desired frequency components. For entanglement gate operations, if structured light such as the TEM10 mode is used, mode shaping needs to be completed at this stage through a spatial light modulator; if a Gaussian beam is used, then a fundamental mode Gaussian beam is generated.

[0102] Step A2: One-sided addressing and coarse positioning.

[0103] A radio frequency signal of a specific frequency is sent to the light adjustment component (such as AOD) to change the propagation direction of the gradient light field, so that it is incident on the focusing component through a single-sided light path, and the focused light spot is projected onto the vicinity of the target ion quantum bit in the ion array.

[0104] Step A3: Precise positioning (core step).

[0105] The control module fine-tunes the deflection angle of the AOD (Aspect-Oriented Deflector) to precisely configure the relative position of the target ion and the focused spot, meeting the requirements of gate operation: For single-bit gate mode: the intensity extremum of the focused spot (i.e., the gradient zero-crossing point) is aligned with the target ion. At this point, the light intensity is maximum, the gradient is zero, and spin flipping is driven by the carrier wave. For entangled gate mode: the region of significant gradient of the focused spot is aligned with the target ion. At this position, the presence of the light field gradient establishes spin-motion coupling.

[0106] Step A4: Gate Operation Drive. After completing the position configuration, perform a gate operation. Taking driving a sideband transition as an example: the optical field can be kept constant (providing a static gradient) or modulated, while the global microwave is activated, with the microwave frequency matching the sideband transition frequency. Alternatively, the difference frequency of two frequency components in the optical field can be controlled to match the sideband transition condition, directly driving stimulated Raman transitions. Example 1

[0107] Figure 6 An apparatus for implementing ion qubit gate operations for a one-dimensional ion array according to Embodiment 1 of the present invention is shown.

[0108] This invention is used to implement addressing entanglement gate operations on a one-dimensional ion array, such as... Figure 6 As shown, the device comprises an optical adjustment assembly 1 and a focusing assembly 2 (e.g., a high numerical aperture objective lens NA>0.6) consisting of a horizontally placed two-dimensional acousto-optic deflector (two-dimensional AOD) and matching optical elements. The optical adjustment assembly 1 and the high numerical aperture objective lens 2 generate a gradient light field and align the target ion.

[0109] Figure 7 It shows 171 Yb + A schematic diagram of energy levels used for encoding ionic qubits in ions.

[0110] In this embodiment, the ions used are 171 Yb + Ions, selection and As a quantum bit state and The frequency difference between the states is denoted as . .

[0111] In this embodiment, the axis of the one-dimensional ion trap is horizontal, defined as the x-axis; the propagation direction of the gradient light field (also known as the addressing light) is the y-axis; and the quantization axis is the z-axis. The axial phonon frequency of the ion is denoted as... .

[0112] In Embodiment 1 of this invention, the gradient light field generation process is as follows: The gradient light field generation unit generates a laser beam with a specific linear polarization. Using a high numerical aperture objective lens (NA>0.6) in the addressing unit, this laser beam is tightly focused onto the target ion via a single-sided optical path. Near the focal point of the tightly focused spot, a significant polarization gradient exists, a phenomenon described by vector diffraction theory. Due to the selected... state and The states have different magnetic moments and polarizabilities. This gradient light field, through the AC Stark effect, generates an energy difference between the two energy levels of the target ion that varies drastically with position x. The spatial gradient of this energy level difference In terms of physical effects, this is equivalent to applying a huge local static magnetic field gradient along the x-axis at the target ion.

[0113] Figure 8 The differential AC Stark frequency shift of the target ion at different positions in a gradient light field according to Embodiment 1 of the present invention is shown.

[0114] like Figure 8 As shown, the horizontal axis represents the radial position of the ion in the light spot (unit: micrometer), and the vertical axis represents the frequency shift difference between the two energy levels of the ion qubit (unit: MHz). The solid line is the curve of the actual frequency shift difference as a function of position, and the green dashed line is the linear fit of the region at the center of the light spot (x≈0). Figure 8 It can be seen that the rate of change of frequency shift difference is the largest (gradient is the most significant) near the center of the light spot (x≈0). Therefore, placing the target ion qubit here can maximize the coupling effect between the light field and the ion, which is suitable for the requirements of entanglement gate operation.

[0115] Besides the simplest combination of Gaussian mode and X-ray polarization used in this embodiment, the spatial mode and polarization distribution of the incident light can also be in other forms, as long as the gradient light field can be obtained by adjusting the spatial distribution of the light field of the focused spot.

[0116] The steps for implementing the entanglement gate in Example 1 are as follows.

[0117] Step B1: Addressing and Gradient Application. Control the 2D-AOD to simultaneously project the focused beam onto two target ions (e.g., target ion A and target ion B) in the ion chain. Finely adjust the deflection angle of the AOD to position the two target ions in the significant gradient regions of their respective focused beams (e.g., the positions with the largest light intensity gradient or polarization gradient). At this point, the target ions experience a strong light field gradient and can generate significant spin-motion coupling under the influence of microwaves, while the unirradiated background ions, lacking a light field gradient, cannot satisfy the coupling condition.

[0118] Step B2: Microwave Drive. Activate a global microwave field covering the entire ion chain. Configure microwave frequency: Set the frequencies of the two-color microwave field as follows: and .

[0119] Step B3: Entanglement Generation. Under the combined action of the microwave field and the optical field gradient, the spin states of target ions A and B become entangled via phonons. Since there is no gradient at the background ions, the microwave field only exhibits a far-detuned carrier drive on the background ions, thus realizing a high-fidelity individually addressed entanglement gate.

[0120] In this embodiment 1, the virtual gradient generated by a single-sided focused laser replaces the real magnetic field gradient that is difficult to localize at the micrometer scale in the traditional scheme. This enables microwave gate operation for magnetically sensitive target ion qubits to have single-ion addressing capability, while maintaining the advantage of microwave control phase stability.

[0121] Example 2

[0122] Figure 9 The apparatus for implementing ion qubit gate operations for a two-dimensional ion array provided in Embodiment 2 is shown.

[0123] This embodiment 2 combines Figure 9 This paper demonstrates how to achieve stray-free parallel addressing and entanglement-gate operation for magnetically insensitive qubits in a two-dimensional ion array using the device of this invention. The experimental setup and the definition of the qubit are as follows: [The following text appears to be a separate, unrelated section:] Selected... Ions, selection and As a quantum bit state and The target ion qubit is insensitive to first-order magnetic field noise and has a long coherence time. Also, because the energy level difference of this qubit is insensitive to the light field intensity, the equivalent magnetic field gradient plus microwave scheme cannot be used. Therefore, the optical field gradient driven dual-frequency stimulated Raman transition scheme is adopted.

[0124] Figure 10The distribution of Rabi frequencies generated by the polarization gradient light field in the focused spot according to Embodiment 2 of the present invention is shown.

[0125] like Figure 10 As shown, the light field has two frequency components, and the frequency difference is configured as follows: The beam pattern drives the carrier wave transition of qubits. The horizontal axis represents the position of the light spot along the x-axis, and the vertical axis represents the Rabi frequency of the carrier wave. The gradient light field in the focused light spot is equivalent to a Rabi frequency distribution along the x-axis, generating a gradient at the Rabi frequency, thus producing a spin-dependent force used to construct entanglement gates. By adjusting the polarization and spatial distribution of the gradient light field within the focused light spot, entanglement can be achieved... This creates a significant spatial dependency, i.e., gradient coupling. Using the light field configuration in this embodiment, focusing a Gaussian light spot can achieve... Figure 2 Gradient coupling, The approximate spatial distribution form is , where x represents the relative position of the ion and the center of the light spot. When the ion or light spot is moved, the equilibrium position of the target ion is at the center of the light spot, i.e. hour, This allows for the realization of spin-dependent forces on the target ion, which can then be used to construct entanglement gates between different target ions. When the target ion's equilibrium position is... At the extreme value, that is, its derivative This is used to construct single-bit gates.

[0126] The target ion qubits are confined in a two-dimensional plane (such as the (xz) plane) to form a two-dimensional ion array; the dual-frequency gradient light field configuration (stimulated Raman mechanism) is specifically as follows: the gradient light field generating unit contains a broadband electro-optic modulator (EOM) or acousto-optic modulator (AOM) to generate light containing two frequency components. and The laser beam, adjusting the difference frequency between the two frequency components and set it (For single-bit gates) or (Used for entanglement gates), among which The phonon mode frequency is then used to tightly focus the dual-frequency beam onto the target ion using a high numerical aperture objective lens. This is achieved by utilizing the intensity or polarization gradient near the center of the focused spot as a coupling term, unlike traditional Raman methods that rely on... (Optical wave vector difference) transfers momentum. This scheme utilizes the spatial variation of the Rabi frequency to directly drive the sideband transitions of ions, and because... and Common-path propagation provides inherent phase stability. To address the stray spot problem inherent in traditional cross-acoustic-optical deflector (Cross-AOD) schemes in two-dimensional arrays, a multi-sided cooperative addressing strategy is employed. In terms of hardware layout, independent addressing units (denoted as addressing units A, B, C, etc.) are arranged at different orientations of the ion array (e.g., left and right sides, or four quadrants). Each addressing unit can independently cover the entire ion array region. This strategy includes two operating modes. Operating mode 1 is suitable for addressing ions located diagonally in the array. and In scenarios involving entanglement gates, traditional solutions would use a single Cross-AOD to simultaneously generate two light spots. and Due to the cross diffraction of sound waves, and The generation of useless stray light spots can easily damage background ions and reduce light utilization. However, the solution of this invention controls the addressing unit K1 to generate only one focused light spot to precisely align with the ions. The control addressing unit K2 generates only one focused spot to precisely align the ions. Since each AOD drives only one frequency combination and there are no cross-modulation terms, there are only two effective light spots in the entire array space, which completely eliminates stray light interference and realizes "clean" arbitrary point-to-point connection. Operation mode 2 is suitable for scenarios that require simultaneous operation on multiple ions in the same row (or column). The solution is to control a single addressing unit to generate a multi-frequency driving signal. Because the target ions are collinear, the AOD can generate a series of neatly arranged light spot arrays to cover these ions at the same time, and no off-axis stray light will be generated. This embodiment demonstrates the great advantage of the invention in terms of scalability. By using a multi-sided addressing strategy that trades space for complexity, combined with Raman transitions driven by a single-sided gradient light field, it not only solves the most intractable addressing crosstalk problem in large-scale ion arrays, but also allows parallel operation, providing a feasible engineering path for realizing large-scale ion trap quantum computing.

[0127] Example 3

[0128] This embodiment provides a device for realizing qubit gate operations in a three-dimensional ion array.

[0129] Figure 11 The apparatus for implementing qubit gate operations in a three-dimensional ion array provided in Embodiment 3 is shown.

[0130] This embodiment 3 combines Figure 11The invention demonstrates the application of its device in a three-dimensional ion array, focusing on how to achieve dynamic focusing and gate operation along the light propagation direction (depth direction, defined as the z-axis). The structure of the three-dimensional ion array is that ions are trapped in space to form a multi-layer structure (e.g., multiple layers of two-dimensional planes stacked). The corresponding technical challenge is that traditional two-dimensional AOD can only move the light spot in the (xy) plane perpendicular to the optical axis. To operate on ion layers of different depths, the focal length (z position) of the focused light spot must be dynamically changed. Moreover, the longitudinal gradient of a common Gaussian beam near the focal point is often weak, making it difficult to drive the vibration mode of ions along the z-axis.

[0131] To achieve 3D addressing, this embodiment integrates a fast zoom component in the addressing unit K3, specifically employing one of two schemes. Scheme one is a tunable lens / deformable mirror, where an electrically controlled tunable lens is placed after the AOD and before the objective lens. Its operating principle is that the control module adjusts the curvature of the lens by changing the driving voltage, thereby changing the divergence angle of the beam incident on the objective lens. This causes the focal point of the beam after focusing by the objective lens to move along the z-axis, thus enabling layer-by-layer alignment with target ions at different depths. Scheme two is a chirped signal-driven AOD (acousto-optic lensing effect). Its operating principle is to apply a radio frequency signal with a frequency that changes linearly with time (Chirp) to the AOD crystal. At this time, the refractive index grating inside the AOD crystal exhibits a Fresnel lens-like distribution, producing an equivalent cylindrical lens effect. The control module adjusts the chirp rate of the driving signal... This approach can directly change the focal length of the acousto-optic lens, and due to the extremely high speed of sound waves, it can achieve depth switching of the focal point in the microsecond range, making it very suitable for the high-speed requirements of ion trap quantum computing. To drive the ion motion along the z-axis (light propagation direction) to achieve entanglement gates, this embodiment has a special configuration for the spatial mode of the gradient light field. The incident laser is shaped into an optical bottle beam or optical chain using a spatial light modulator (SLM). The characteristic of this type of structured light field is that the light intensity near the focal point exhibits a drastic change along the z-axis (e.g., from bright to dark and then back to bright), thereby generating a huge longitudinal intensity gradient. The position configuration control module adjusts the zoom component to precisely position the target ion at the point of maximum longitudinal gradient in the light bottle beam (rather than the point of strongest light intensity). At this position, the gradient force of the light field along the z-axis can effectively couple the z-direction motion mode of the ion. Combined with microwave or dual-frequency Raman mechanisms, entanglement gate operation along the z-axis in a three-dimensional array can be realized. The advantage of this embodiment is that by introducing fast zoom technology and a special longitudinal gradient light field, the single-sided addressing scheme of this invention has been successfully extended from a two-dimensional plane to three-dimensional space. This not only solves the alignment problem in three-dimensional space, but also realizes flexible control of the longitudinal phonon mode through all-optical means, greatly expanding the scalability potential of ion trap quantum computers.

[0132] In the three embodiments described above, the average Stark shift of the ground state provides an optical dipole potential, i.e., optical tweezers. If this potential is approximately harmonic near the position of the irradiated cold ion, then the superposition of the optical dipole trap and the ion trap can modulate the motion of the target ion qubit, i.e., optical tweezers control of the target ion by the optical field. Simply put, assume the harmonic potential generated by the ion trap is of the form... The harmonic potential of optical tweezers is The total potential well sensed by the target ion is Therefore, after applying optical tweezers, the harmonic frequency of the target ion qubit changes from... Change to . and , respectively, are the characteristic coefficients of the harmonic potential. m is the mass of the target ion qubit. In this embodiment, or The gradient direction and the optical potential trap direction are consistent, thus enabling the manipulation of optical tweezers and entanglement gates.

[0133] According to the implementation method of this invention, ion coupling is achieved by utilizing the optical field gradient (polarization gradient or spatial gradient) in a focused spot (optical tweezers), thereby obtaining spin-dependent forces to construct ion gates. Optical tweezers acting on the target ion can effectively control ion motion and alter the phonon spectrum of the crystal, thus realizing ion qubit gates. The combined effect of these two aspects enables the expansion of ion trap quantum computers. Furthermore, this addressing method features a simpler optical path configuration, easily combining multiple similar objective lens addressing optical paths to address complex ion crystal configurations; it also possesses excellent optical stability, enabling high-fidelity quantum gates.

[0134] This invention allows operation to be completed by incident laser light from only one side (or the periphery) of the ion array, eliminating the instability of optical path interference. Based on the physical characteristics of the qubits (magnetically sensitive or insensitive), the equivalent magnetic field gradient (combined with microwaves) or dual-frequency stimulated Raman transitions are flexibly selected to drive spin-motion coupling through multi-sided coordination or single-sided parallelism, thus solving the stray light interference problem in two-dimensional and three-dimensional ion arrays.

[0135] The embodiments of the present invention, by flexibly configuring the intensity gradient or polarization gradient of the gradient light field, can be applied to both magnetically sensitive qubits (in conjunction with microwaves) and magnetically insensitive qubits (in conjunction with dual-frequency light), and have wide applicability.

[0136] According to the implementation method of the present invention, the ultrafine qubit can be directly manipulated, and the Raman phase of the manipulated qubit is stable and has a long coherence time.

[0137] The implementation apparatus according to embodiments of the present invention allows for multi-ion addressing and multi-ion entanglement operations on two-dimensional and three-dimensional ion arrays. By configuring multiple objective lenses to address individual units, stray light spot arrays are avoided, resulting in high light utilization and low crosstalk. By configuring identical Raman optical paths in different directions, parallel addressing of high-dimensional ion crystals is achieved, and addressing crosstalk is reduced. For example, if a single two-dimensional AOD is used to address two ions on its diagonal, the AOD will diffract four light spots, causing crosstalk to two ions on the diagonal in other directions; in this case, configuring two addressing beams, with each two-dimensional AOD generating only one light spot to illuminate the two ions, can effectively solve the above problem.

[0138] The embodiments of the present invention have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of the invention. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of the invention is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the invention, and all such substitutions and modifications should fall within the scope of the invention.

Claims

1. A method for implementing ion qubit gate operations, the method being applied in an ion trap, the ion trap being used to trap multiple ion qubits, the multiple ion qubits forming an ion array, the method comprising: Generate at least one gradient optical field with an intensity gradient or a polarization gradient; The at least one gradient light field is controlled to be focused and projected onto at least one target ion in the ion array; Depending on the type of ion qubit gate operation to be performed, the relative position of the target ion qubit and the focused spot is configured to realize the single-qubit gate or entanglement gate operation of the target ion qubit.

2. The implementation method according to claim 1, characterized in that, The configuration of the relative positions of the target ion and the focused light spot to achieve single-qubit gate or entanglement gate operations for the target ion qubit includes: When performing entanglement gate operation, if the gradient light field is a tightly focused fundamental Gaussian beam or a structured light field with a transverse gradient, the equilibrium position of the target ion qubit is configured at the position with the largest transverse light intensity gradient or transverse polarization gradient in the focused light spot; and if the gradient light field has a structured light field with a longitudinal gradient, the equilibrium position of the target ion is configured at the position with the largest longitudinal light intensity gradient or polarization gradient in the focused light spot. When performing a single-bit gate operation, the equilibrium position of the target ion qubit is configured at the position of the intensity maximum or polarization maximum of the focused spot; The horizontal direction is the radial direction of the focused light spot, and the vertical direction is the transmission direction of the gradient light field.

3. The implementation method according to claim 1, characterized in that, The target ionic qubit is a qubit sensitive to a magnetic field. When performing an entanglement gate operation, the method includes: The intensity of the gradient light field projected onto the target ion qubit is kept constant, and the spatial position-dependent AC Stark level frequency shift gradient is generated using the gradient light field. A microwave field is applied to the target ion, and the frequency of the microwave field is configured to match the sideband transition frequency of the target ion under the action of the gradient light field, so as to drive the spin-motion coupling of the target ion qubit and realize the entanglement gate operation.

4. The implementation method according to claim 3, characterized in that, The target ion qubit is a qubit insensitive to a magnetic field. The gradient optical field includes two frequency components with a frequency difference, which is approximately the sum of the energy level difference of the target ion qubit and the phonon frequency of the ion array, or approximately the difference between the energy level difference of the target ion qubit and the phonon frequency of the ion array, so as to drive the stimulated Raman sideband transition of the target ion by utilizing the intensity gradient or polarization gradient of the gradient optical field at the target ion.

5. The implementation method according to claim 1, characterized in that, After controlling the at least one gradient light field to focus and project onto at least one target ion in the ion array, the method further includes: The intensity of the gradient light field is controlled to form a local optical potential well at the target ion qubit using the optical dipole force generated by the focused light spot; the local vibration frequency of the target ion qubit is changed by the local optical potential well so that the vibration mode of the target ion qubit is separated from the vibration mode of other background ion qubits in the ion array in the spectrum.

6. The implementation method according to claim 1, characterized in that, The ion array is a one-dimensional ion chain, a two-dimensional ion array, or a three-dimensional ion array. When the ion array is a two-dimensional or three-dimensional ion array, and the number of target ion qubits is multiple. Multiple gradient light fields are projected from different positions of the ion array onto multiple target ion qubits located in different rows or columns; or, Multiple gradient light fields are projected in parallel onto multiple target ions located in the same row or column.

7. The implementation method according to claim 1, characterized in that, The diameter of the focused spot formed by the gradient light field after focusing is smaller than the distance between any two adjacent ion qubits in the ion array.

8. A device for implementing ion qubit gate operations, used to implement the method according to any one of claims 1 to 7, characterized in that, The implementing device includes: At least one gradient light field generating unit is configured to generate at least one gradient light field having an intensity gradient or a polarization gradient; At least one addressing unit, each addressing unit comprising: An optical adjustment component is configured to receive the gradient light field and adjust the propagation direction of the gradient light field according to a control signal; A focusing component is configured to focus the gradient light field emitted by the light adjustment component to form a focused spot at the target ion of the ion array; The control unit is configured to adjust the relative position of the focused spot and the target ion to drive the target ion to perform single-bit gate or entanglement gate operations.

9. The implementing apparatus according to claim 8, characterized in that, The gradient light field generation unit includes: Laser light source, suitable for generating lasers; Modulation components, including acousto-optic modulators or electro-optic modulators, are configured to modulate the frequency, phase, or intensity of a laser emitted from a laser source to generate a modulated light field containing dual-frequency components or a specific pulse sequence, or include spatial light modulators or optical diffraction elements configured to modulate the spatial mode of the laser to generate a structured light field with an intensity gradient or polarization gradient.

10. The implementing apparatus according to claim 9, characterized in that, The optical adjustment component in the addressing unit includes: The light adjustment component is configured to change the emission angle of the gradient light field under the drive of the control unit, or to split a single gradient light field into multiple beams and independently control the deflection direction of each beam, so as to achieve parallel addressing of single or multiple points in the ion array.

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