Optical addressing system and method and quantum computer

Abstract

The invention relates to the technical field of quantum computing, and provides an optical addressing system and method and a quantum computer.The system and method conduct deflection regulation and control on Gaussian laser beams with Doppler frequency shifts.Corresponding diffraction spots with the same Doppler frequency shiftsbetween any positions are obtained, then wavefront aberration of the diffraction spots is measured, and the optical addressing effect is achieved. Aberration compensation is carried out on the diffraction light spot or the Gaussian laser beam according to the detected wavefront aberration, and an addressing light spot is obtained; and focusing the addressing light spot on each target quantum of a one-dimensional ion chain in an ion trap to realize ion addressing. According to the system and the method disclosed by the invention, the wavefront aberration of the diffracted light wave is detected through the light modulation module, aberration compensation is carried out according to the detected wavefront aberration, and then optical independent addressing with excellent image quality, flexibility, controllability and strong expansibility is realized for a plurality of target quantum sites on a one-dimensional ion chain in an ion trap.

Description

Technical Field

[0001] This invention relates to the field of quantum computing technology, and more particularly to an optical addressing system, method, and quantum computer. Background Technology

[0002] The ion-addressing scheme drives each beam in the laser array to be tightly focused onto each ion in the ion chain. Each optical qubit is manipulated individually by controlling each driving beam independently.

[0003] To achieve complete quantum control of ion chains, optical addressing systems need to provide fast and independent control over the intensity, frequency, and phase of each beam, thereby enabling manipulation of arbitrary single qubits. However, due to intensity crosstalk between ion sites caused by overlapping adjacent laser beams, or due to different Doppler frequency shifts in the addressing optical arrays generated in existing technologies, existing optical addressing systems cannot flexibly manipulate multiple ions on the same ion chain.

[0004] Therefore, the existing technology needs further improvement. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide an optical addressing system, method and quantum computer to solve the defect that the addressing optical array generated in the prior art cannot flexibly control multiple ions on the same ion chain.

[0006] The solution provided by this invention is as follows: In a first aspect, the present invention provides an optical addressing system, comprising: A light source assembly for emitting a Gaussian laser beam with a Doppler frequency shift applied; An orthogonal AOD addressing module is located in the optical path of the Gaussian laser beam. It is used to receive the Gaussian laser beam and deflect and control the Gaussian laser beam to obtain diffraction spots with the same Doppler frequency shift between any two positions. An optical modulation module is disposed in the optical path of the diffraction spot. It is used to measure the wavefront aberration of the diffraction spot and perform aberration compensation on the diffraction spot or the Gaussian laser beam according to the detected wavefront aberration, and output the addressing spot. A focusing imaging module is disposed in the optical path of the addressing spot, for receiving the addressing spot and focusing the addressing spot onto each target quantum site of the one-dimensional ion chain in the ion trap.

[0007] Optionally, the light source assembly includes: a laser module and an acousto-optic modulator; Laser module, used to output Gaussian laser beam; An acousto-optic modulator is disposed in the optical path of the Gaussian laser beam to apply a Doppler frequency shift to the Gaussian laser beam through acousto-optic interaction, thereby controlling the frequency of the Gaussian laser beam and obtaining a Gaussian laser beam with a Doppler frequency shift applied.

[0008] Optionally, the optical modulation module includes: an SLM aberration compensation module and a wavefront characterization module; the SLM aberration compensation module, the orthogonal AOD addressing module, and the wavefront characterization module are arranged in sequence. The SLM aberration compensation module is used to receive a Gaussian laser beam with applied Doppler frequency shift, and after performing wavefront phase compensation on the Gaussian laser beam, transmit it to the orthogonal AOD addressing module. The wavefront characterization module is located on the optical path of the diffraction spot output by the orthogonal AOD addressing module. It is used to receive the diffraction spot and measure the wavefront aberration of the received diffraction spot so that the SLM aberration compensation module can perform wavefront phase compensation on the diffraction spot based on the measured wavefront aberration.

[0009] Optionally, the orthogonal AOD addressing module includes a first acousto-optic deflector, a first plano-convex lens, a second plano-convex lens, and a second acousto-optic deflector arranged in sequence. The first acousto-optic deflector is used to receive the Gaussian laser beam with a Doppler frequency shift applied, and to transmit the diffracted light generated by the Gaussian laser beam after deflection modulation to the first plano-convex lens at a preset first deflection angle. The first plano-convex lens is used to control the input diffracted light to be output in a parallel direction; The second plano-convex lens is used to receive parallel input diffracted light and transmit the diffracted light to the second acousto-optic deflector at a preset second deflection angle. The second acousto-optic deflector is used to receive diffracted light transmitted at a preset second deflection angle, and to deflect and modulate the diffracted light to obtain a diffracted light spot; The diffracted light output from the first acousto-optic deflector is conjugate to the same point source at the incident surface of the second acousto-optic deflector.

[0010] Optionally, the SLM aberration compensation module includes: a wavefront modulation unit; the wavefront modulation unit is a spatial light modulator or a digital micromirror array.

[0011] Optionally, the wavefront characterization module includes: a wavefront analysis unit; the wavefront analysis unit is a Shack-Hartmann wavefront analyzer, a shear interferometer wavefront sensor, or a curvature sensor.

[0012] Optionally, the focusing imaging module includes a magnifying lens group, a static compensation lens, a focusing objective lens, and a viewing plate glass of the ion trap; The magnifying lens group includes a cemented doublet lens for magnifying the received addressing spot; The static compensation lens is used to compensate for static aberrations caused by the refraction of received light by the flat glass of the ion trap window. The focusing objective is used to focus the received addressing spot onto each target quantum site of the ion chain.

[0013] Optionally, the system further includes a data processing module; the data processing module is used to acquire the layout information of the focusing imaging module, and to perform simulation analysis on the optical path of the focusing imaging module according to the layout information to obtain the static aberration, so that the static compensation lens can perform aberration compensation according to the static aberration.

[0014] Secondly, the present invention also provides a method for implementing optical addressing using the aforementioned optical addressing system, comprising: The light source assembly is controlled to emit a Gaussian laser beam with a Doppler frequency shift applied. The Gaussian laser beam is received using an orthogonal AOD addressing module, and the Gaussian laser beam is deflected and controlled to obtain diffraction spots with the same Doppler frequency shift at any position. The wavefront aberration of the diffraction spot is measured using an optical modulation module, and aberration compensation is performed on the diffraction spot or the Gaussian laser beam based on the detected wavefront aberration, and the addressing spot is output. The addressing light spot output by the optical modulation module is received by the focusing imaging module, and the addressing light spot is focused onto each target quantum site of the one-dimensional ion chain in the ion trap.

[0015] Thirdly, the present invention provides a quantum computer, wherein the optical addressing system described above is included.

[0016] Beneficial effects: This invention provides an optical addressing system, method, and quantum computer. The system includes a light source assembly, an orthogonal AOD addressing module, an optical modulation module, and a focusing imaging module. By deflecting and controlling a Gaussian laser beam with a Doppler frequency shift emitted from the light source assembly, diffraction spots with the same Doppler frequency shift at arbitrary positions are obtained. The wavefront aberration of the diffraction spot is then measured, and aberration compensation is performed on the diffraction spot based on the detected wavefront aberration, resulting in an aberration-free addressing spot. The addressing spot is then focused onto each target quantum site in a one-dimensional ion chain within an ion trap, thereby achieving addressing of each target quantum site in the one-dimensional ion chain within the ion trap. The method disclosed in this invention detects the wavefront aberration of the diffracted light wave through the optical modulation module and performs aberration compensation on the wavefront beam based on the detected wavefront aberration, achieving high-quality, flexible, controllable, and highly scalable optical independent addressing of multiple target quantum sites on a one-dimensional ion chain within an ion trap. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the optical addressing system provided by the present invention; Figure 2 This is a schematic diagram of the orthogonal AOD addressing module structure in an embodiment of the present invention; Figure 3 This is a schematic diagram of the orthogonal AOD addressing module in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the SLM aberration compensation module and the wavefront characterization module in an embodiment of the present invention; Figure 5 This is a schematic diagram of the focusing imaging module structure in an embodiment of the present invention; Figure 6 This is a flowchart of the steps of the optical addressing method provided by the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0019] Trapped ion systems are a technology that uses electromagnetic fields to stably confine charged ions in a specific potential well. They dynamically trap ions using a Paul trap, then encode qubits on the energy levels of the ions, and use the common external motion modes of the same ion chain to transmit information, thereby forming a relatively independent multi-qubit error correction structure. Finally, they are manipulated by means of microwaves, lasers, etc., to achieve quantum computing.

[0020] To achieve universal quantum computing using trapped ions, single-qubit rotation gates and two-qubit gates need to be implemented on arbitrary single-qubit and two-qubit qubits, respectively. Therefore, it is necessary to distinguish each ion and apply the driving field to different individual target qubits, i.e., to perform addressing control on each qubit.

[0021] The technical solution of optical addressing systems is to drive each beam in a laser array so that each beam is closely focused on each ion in the ion chain. By independently controlling each driving beam, we can manipulate each optical qubit individually. For complete quantum control of the ion chain, the optical addressing system should provide fast and independent control over the intensity, frequency, and phase of each beam. This is a key requirement for realizing arbitrary single-qubit operations, high-fidelity multi-qubit entanglement gates, and quantum simulation protocols. However, the intensity crosstalk between ion sites caused by the overlap of adjacent laser beams places high demands on the optical system, especially when the diffraction limit of the addressing beam (1-2 μm) is close to the ion spacing in a typical chain (5-6 μm). This results in existing technologies being unable to flexibly manipulate multiple ions on the same ion chain and cannot guarantee that the laser frequency addressed to each ion qubit site is the same. Therefore, there is a need to propose an ion addressing scheme suitable for independent ion addressing of arbitrary one-dimensional ion chains, and to improve the beam spot quality by controlling the beam wavefront in a closed loop.

[0022] To overcome the aforementioned shortcomings, this embodiment provides an optical addressing system, method, and quantum computer. By controlling the transmission direction of the optical addressing array, diffraction spots with the same Doppler frequency shift are obtained. The wavefront aberration of the diffraction spot output by the orthogonal AOD addressing module is then measured. An optical modulation module is used to compensate for the aberration of the diffraction spot, resulting in an aberration-free addressing spot. This allows for the addressing of a single target quantum site in a one-dimensional ion chain within an ion trap. The system and method disclosed in this invention compensate for the aberration of the wavefront beam based on the detected wavefront aberration, achieving the addressing of a single target quantum site in a one-dimensional ion chain within an ion trap. This improves addressing accuracy and offers flexibility, controllability, and strong scalability.

[0023] The optical addressing system, method, and quantum computer provided in this embodiment will be described in further detail below with reference to the accompanying drawings.

[0024] In a first aspect, the present invention provides an optical addressing system, such as Figure 1 As shown, the optical addressing system includes: A light source assembly is provided for emitting a Gaussian laser beam with a Doppler frequency shift. The light source assembly includes a laser module 10 for generating the Gaussian laser beam and an acousto-optic modulator 20 for modulating the Gaussian laser beam output from the laser module 10. The Gaussian laser beam emitted from the laser module 10 is transmitted to the acousto-optic modulator 20, which modulates the Gaussian laser beam to obtain a Gaussian laser beam with a Doppler frequency shift.

[0025] In detail, combined Figure 1As shown, the laser assembly includes a laser module 10 and an acousto-optic modulator 20. The laser module 10 outputs a raw Gaussian laser beam. The acousto-optic modulator 20 is disposed in the optical path of the raw Gaussian laser beam and is used to apply a Doppler frequency shift to the raw Gaussian laser beam through acousto-optic interaction, thereby modulating the frequency of the raw Gaussian laser beam to obtain a Gaussian laser beam with a Doppler frequency shift.

[0026] An orthogonal AOD addressing module 60 is provided in the optical path of the Gaussian laser beam. The orthogonal AOD addressing module is used to receive the Gaussian laser beam and deflect and control the Gaussian laser beam to obtain diffraction spots with the same Doppler frequency shift between any positions.

[0027] An optical modulation module is disposed in the optical path of the diffraction spot. It is used to measure the wavefront aberration of the diffraction spot and perform aberration compensation on the diffraction spot or the Gaussian laser beam according to the detected wavefront aberration, and output the addressing spot.

[0028] Furthermore, the optical modulation module includes an SLM aberration compensation module 50 and a wavefront characterization module; the SLM aberration compensation module 50, the orthogonal AOD addressing module 60, and the wavefront characterization module are arranged in sequence.

[0029] The SLM aberration compensation module 50 is used to receive a Gaussian laser beam with applied Doppler frequency shift, and after wavefront image position compensation, transmit the Gaussian laser beam to the orthogonal AOD addressing module 60.

[0030] The wavefront characterization module is located on the optical path of the diffraction spot output by the orthogonal AOD addressing module 60. It is used to receive the diffraction spot and measure the wavefront aberration of the received diffraction spot so that the SLM aberration compensation module 40 can perform wavefront position compensation on the diffraction spot based on the measured wavefront aberration.

[0031] Combination Figure 1 As shown, the wavefront characterization module includes a wavefront analysis unit. The diffraction spot output from the orthogonal AOD addressing module 60 is transmitted to the wavefront analysis unit to measure the wavefront aberration of the diffraction spot. Additionally, the wavefront characterization module also includes a flip mirror 70, which reflects the diffraction spot output from the orthogonal AOD addressing module 60 to the wavefront analysis unit.

[0032] In practice, the SLM aberration compensation module performs phase compensation of the diffraction spot or Gaussian laser beam based on the wavefront aberration detected by the wavefront characterization module.

[0033] Furthermore, a focusing imaging module is provided in the optical path of the addressing spot. This focusing imaging module is used to receive the addressing spot and focus the addressing spot onto each target quantum of the one-dimensional ion chain in the ion trap to achieve ion addressing.

[0034] In detail, such as Figure 2 As shown, the orthogonal AOD addressing module includes a first acousto-optic deflector 601, a first plano-convex lens 602, a second plano-convex lens 603, and a second acousto-optic deflector 604 arranged in sequence.

[0035] The first acousto-optic deflector 601 is used to receive the Gaussian laser beam with a Doppler frequency shift applied, and to transmit the diffracted light generated by the Gaussian laser beam after deflection modulation to the first plano-convex lens 602 at a preset first deflection angle.

[0036] The first plano-convex lens 602 is used to control the input diffracted light to be output in a parallel direction.

[0037] The second plano-convex lens 603 is used to receive parallel input diffracted light and transmit the diffracted light to the second acousto-optic deflector 604 at a preset second deflection angle.

[0038] The second acousto-optic deflector 604 is used to receive diffracted light transmitted at a preset second deflection angle, and to deflect and modulate the diffracted light to obtain a diffracted light spot.

[0039] The diffracted light output by the first acousto-optic deflector 601 is conjugate to the same point source at the incident surface of the second acousto-optic deflector 604.

[0040] Since the orthogonal AOD addressing module in this embodiment contains two acousto-optic deflectors, and the two acousto-optic deflectors are orthogonal to each other, that is, perpendicular to each other, they control the deflection angle of the input Gaussian laser beam in the horizontal and vertical directions respectively, thereby realizing the independent adjustment of their respective radio frequency frequencies, so as to achieve arbitrary angle deflection of the Gaussian laser beam in the two-dimensional plane.

[0041] like Figure 3 The principle of the orthogonal AOD addressing module 60 is integrated. When multiple radio frequency signals of the same frequency are applied simultaneously to the first acousto-optic deflector 601 and the second acousto-optic deflector 604, the resulting diffraction spots are the diffraction spots with the same Doppler frequency shift between any two positions. These diffraction spots are also the spots used to address ion quantum dot sites.

[0042] In one implementation, the orthogonal AOD addressing module and the SLM aberration compensation module can be replaced by a digital micromirror array. Since a digital micromirror array consists of multiple micromirror units, each corresponding to a pixel, precise control of each pixel can be achieved by adjusting the micromirror units. Therefore, a digital micromirror array can also be used to control a Gaussian laser beam to obtain a diffraction spot. However, its limitation lies in the slow switching rate of the micromirrors, resulting in an excessively long response time and making it impossible to quickly implement complex qubit gate operations.

[0043] Furthermore, in specific implementations, the wavefront analysis unit can be a Shack-Hartmann wavefront analyzer, a shearing interferometer wavefront sensor, or a curvature sensor. Utilizing any one of these methods can achieve the effect of detecting wavefront aberrations.

[0044] Furthermore, such as Figure 4 The diagram shows the specific structure of the SLM aberration compensation module 50 and the wavefront characterization module. Figure 4 It is known that the SLM aberration compensation module includes a first reflecting mirror 502, a second reflecting mirror 503, and a reflective liquid crystal spatial light modulator (LCOS-SLM) 501. The wavefront characterization module includes a flip-up reflecting mirror 70 and a wavefront analysis unit 80. After the beam passes through the beam splitter prism 40, the reflected portion passes through the first reflecting mirror 502 and the second reflecting mirror 503 and is incident on the liquid crystal spatial light modulator 501.

[0045] Combination Figure 1 and Figure 4 As shown, the Gaussian laser beam wavefront is modulated by the spatial light modulator 501 and reflected back to the beam splitter prism 40. The transmitted portion then enters the orthogonal AOD addressing module 60. The diffracted spot generated by the orthogonal AOD addressing module 60, without Doppler frequency shift differences, can be incident on the wavefront analysis unit 9 through the flip mirror 70, thereby measuring the wavefront aberration of the diffracted light. Based on the wavefront aberration measurement results, the corresponding modulation phase on the liquid crystal spatial light modulator can be changed in real time to compensate for the aberration introduced in the orthogonal AOD addressing module 60.

[0046] Furthermore, such as Figure 5 As shown, the focusing imaging module includes a magnifying lens group, a static compensation lens 903, a focusing objective lens 904, and a viewing window plate glass 905 for the ion trap.

[0047] The magnifying lens group includes cemented doublet lenses, namely a first cemented lens 901 and a second cemented lens 902, which are used to magnify the received addressing spot.

[0048] The static compensation lens 903 is used to compensate for static aberrations caused by the refraction of received light by the flat glass of the ion trap window.

[0049] The focusing objective 904 is used to focus the received addressing spot onto each target quantum site of the ion chain.

[0050] The first and second plano-convex lenses are two plano-convex lenses with a focal length of 50mm each in the orthogonal AOD addressing module. The cemented doublet lens is used to enlarge the diameter of the output beam from the orthogonal AOD addressing module to match the entrance pupil of the objective lens. The static compensation lens is used to compensate for the fixed aberrations introduced by the ion trap window glass plate. The focusing objective lens is used to focus the laser onto the ion quantum sites on the ion chain.

[0051] In one embodiment, the beam corresponding to the addressing spot is magnified to approximately 9.4 mm after passing through a magnification system consisting of a cemented doublet lens (the first cemented lens has a focal length of 40 mm and the second cemented lens has a focal length of 250 mm). After being focused by the focusing objective lens, the spot diameter at the ion quantum site is approximately 1.4 μm.

[0052] Before implementation, the entire optical path can be simulated and analyzed using Zemax software, such as... Figure 5 The diagram shown is a two-dimensional layout diagram in the Zemax software (which can also be seen as a layout schematic of the focusing imaging module). The theoretical focused spot diameter obtained by the focusing imaging module described above using Zemax software is approximately 0.8 μm, which is smaller than the Airy disk diameter of 1 μm. This indicates that the design of the entire system is close to the diffraction limit and meets the requirements of an optically independent addressing system for trapped ion quantum computing systems.

[0053] Furthermore, such as Figure 1 As shown, the ion trapped in the ion trap 100 located after the focusing imaging module 90 can be ytterbium ions. The laser wavelength for controlling the ions is selected as 435 nm. When changing the selected ion, the laser wavelength needs to be changed to the corresponding wavelength according to the energy level structure of the ions to be controlled.

[0054] The system provided by the present invention will be further described in more detail below with reference to specific application embodiments.

[0055] The laser module includes a laser and a single-mode fiber coupler. The single-mode fiber coupler is used to output a Gaussian beam. In this embodiment of the invention, a fiber coupler with a focal length of 4mm is selected, and the single-mode fiber connected to the coupler has a mode field diameter of 3.3μm. To save space and reduce the optical path length, in this embodiment of the invention, the Gaussian laser beam diverges directly after exiting the fiber coupler. At the location of the acousto-optic modulator, i.e., 150mm away from the coupler, the diameter of the Gaussian spot is 120μm, which is smaller than the entrance aperture of the acousto-optic modulator, which is 150μm.

[0056] An acousto-optic modulator is a device that uses the acousto-optic effect to load information onto an optical frequency carrier. Taking the positive first-order diffraction order as an example, the beam of the positive first-order diffraction order exhibits a radio frequency shift relative to the original beam. In practical implementation, such as... Figure 1 As shown, a third plano-convex lens 30 with a focal length of 250 mm is also provided after the acousto-optic modulator 20. The distance between the third plano-convex lens 30 and the acousto-optic modulator 20 is 216 mm. After passing through the third plano-convex lens 30, the Gaussian laser beam is collimated into a Gaussian spot with a diameter of 1.5 mm.

[0057] In practical implementation, since the incident light to the acousto-optic deflector requires horizontal polarization, and in the embodiments of this invention, the acousto-optic deflector is placed at a 45-degree angle to the optical platform to match the ion arrangement direction in the ion trap, two half-wave plates and a polarizing beam splitter are installed before the acousto-optic deflector 1. The two half-wave plates are located before and after the polarizing beam splitter, respectively, and another half-wave plate is installed between the two acousto-optic deflectors. After receiving the radio frequency signal corresponding to the center frequency, the total diffraction efficiency of the acousto-optic deflector (the ratio of the intensity of the diffracted light emitted from the orthogonal acousto-optic deflector system to the intensity of the incident light) is maximized by adjusting the incident angles of the first and second acousto-optic deflectors and the two half-wave plates behind the prism.

[0058] like Figure 2 As shown, the Gaussian laser beam, after passing through the first acousto-optic deflector 601, generates -1st order diffracted light which exits at a certain deflection angle. This light then passes through a first plano-convex lens 602 with a focal length of 50mm and propagates in a direction parallel to the optical axis. It then passes through a second plano-convex lens 603 with the same focal length of 50mm and enters the second acousto-optic deflector 604 at a certain deflection angle. The subsequent optical path uses the +1st order diffracted light generated by the second acousto-optic deflector 604. The second plano-convex lens is 50mm away from the first acousto-optic deflector, the first plano-convex lens 602 and the second plano-convex lens 603 are 100mm apart, and the second plano-convex lens 603 is 50mm away from the second acousto-optic deflector. Therefore, the light exiting the first acousto-optic deflector is conjugate to the same point source at the incident surface of the second acousto-optic deflector. The acousto-optic modulator can be an acousto-optic deflector of model SGP90-435-5PA.

[0059] In a specific embodiment, with a diffraction efficiency reduction to 50% as the standard, the bandwidth of the orthogonal acousto-optic deflector system is 45MHz. The center frequency of the acousto-optic deflector is 90MHz, and the bandwidth range is 60-105MHz.

[0060] The diffraction spot output by the orthogonal AOD addressing module is reflected by the flip mirror to the wavefront characterization module. The wavefront characterization module performs wavefront aberration detection on the received diffraction spot to obtain the wavefront aberration, so that the SLM aberration compensation module can compensate for the aberration introduced by the orthogonal AOD addressing module according to the wavefront aberration.

[0061] Furthermore, in this embodiment, the first plano-convex lens and the second platform lens can be plano-convex lenses of model LA1113-A, made of N-BK7 material, with a diameter of 1 inch, a focal length of 50mm, and covered with an anti-reflective coating in the 350-700nm wavelength band.

[0062] The cemented doublet in the focusing imaging module can be an achromatic cemented doublet of model AC254-040-A, made of N-BK7 and SF5 materials, with a diameter of Ø1 inch, a focal length of 40mm, and covered with an anti-reflective coating in the 400-700nm band.

[0063] The static compensation lens is cemented together with a plano-concave lens and a plano-convex lens. The plano-concave lens can be a model LC1120-A, made of N-BK7 material, with a diameter of 1 inch, a focal length of -100mm, and coated with an anti-reflective coating covering the 350-700nm wavelength range. The plano-convex lens can be, for example, but not limited to, a model LC1229-A, made of N-BK7 material, with a diameter of 1 inch, a focal length of 175mm, and coated with an anti-reflective coating covering the 350-700nm wavelength range.

[0064] The focusing objective can be a PLNAPO10X plan apochromatic objective with a numerical aperture of 0.28, magnification of 10, focal length of 20mm, working wavelength of 400-700nm, and working distance of 33.9mm. The imaging plane of the plan apochromatic objective is a flat plane, aligned with the ion chain alignment, effectively reducing coma caused by diffraction angles at different radio frequency frequencies.

[0065] Furthermore, the system also includes a data processing module; the data processing module is used to acquire the layout information of the focusing imaging module, and to perform simulation analysis on the optical path of the focusing imaging module according to the layout information to obtain the static aberration, so that the static compensation lens can perform aberration compensation according to the static aberration.

[0066] The main components of a liquid crystal spatial light modulator are the liquid crystal layer and transparent electrodes. In the absence of an external field, the direction of the liquid crystal director is determined by the anchoring energy of the alignment layer molecules. When an external electric field is applied to the liquid crystal, it reorients due to the dielectric interaction between the liquid crystal and the applied electric field. The electric field of the liquid crystal layer is controlled by a silicon backplane containing a pixel array. Each pixel can be individually addressed to control the alignment of the liquid crystal molecules above it. When the alignment direction changes, the refractive index of the liquid crystal layer at each pixel also changes. Therefore, when a Gaussian laser beam passes through the liquid crystal layer, the beam phase can also be modulated by changing the voltage at each pixel.

[0067] Before using a liquid crystal spatial light modulator (SLM), calibration is required. The first step of calibration is to ensure that the highest and lowest voltages of the transparent electrode correspond to the 2π beam phase and the pi beam phase, respectively. The calibration method is as follows: Apply a vertically separated phase map to the SLM, where the gray values ​​of the upper and lower regions can be set separately. Then, by adjusting the upper and lower voltage limits, when the gray value difference between the upper and lower regions is 128, the spot shape at the focal point is a TEM01 Hermit-Gaussian mode; when the gray value difference between the upper and lower regions is 0 and 255, the spot at the focal point is a single-mode Gaussian spot.

[0068] The second step in calibration is to calibrate the Gamma curve of the SLM. Since the electro-optic response of liquid crystal materials is typically non-linear (similar to an S-curve), a Gamma curve is needed to ensure a linear relationship between the input grayscale value of the SLM and the actual output optical response (i.e., the modulation phase). Calibration methods can include, but are not limited to: constructing a Twyman-Green interferometer; applying vertically separated phase maps to the SLM in two regions with separately set grayscale values; measuring and recording interference image information at different grayscale values ​​in the two regions; calculating the actual modulation phase applied by the SLM at different grayscale values ​​using the width and displacement of the interference fringes; and finally obtaining the correct Gamma curve and loading it onto the SLM.

[0069] When using the Shack-Hartmann wavefront analyzer, the positions of the reflector and the wavefront analyzer need to be adjusted so that the Zernike coefficients Z2 and Z3 measured on the wavefront analyzer are close to 0, that is, the beam is close to perpendicular incidence, and the spot area must cover the center of the sensor in the wavefront analyzer.

[0070] Wavefront aberration refers to the optical path difference between the optical wavefront and the ideal reference wavefront, which can be represented in polar coordinates using Zernike polynomials: ; in Zernike coefficient, These are Zernike polynomials. Zernike polynomials are a set of functions that are orthogonal in a continuous manner on the unit circle, meaning they are mathematically independent of each other. Therefore, they are very useful for describing the shape of wavefront aberrations in complex optical systems. Zernike polynomials are typically expressed in polar coordinates. The definition in the middle, where It is a radial coordinate ranging from 0 to 1. It is a range from 0 to 2 The azimuth angle. Each Zernike polynomial consists of three components: a normalization factor, a radial component, and an azimuth component.

[0071] ; in, It is a normalization factor. It is the azimuth component. The radial component is a polynomial function. The orthogonality of the Zernike basis functions makes it easy to calculate the RMS wavefront error (the RMS wavefront error is the square root of the total variance of the wavefront). Since the total variance of the wavefront is the sum of the variances of each Zernike mode, only the coefficient values ​​need to be scanned to identify the mode with the greatest influence in the total RMS wavefront error. Therefore, an important method for characterizing aberrations is to use a wavefront sensor to collect wavefront data and then use Zernike polynomials to fit and obtain Zernike coefficients, thereby analyzing the aberration structure.

[0072] In an embodiment of the present invention, the implementation of a closed-loop feedback system combining a Shack-Hartmann wavefront analyzer and an SLM is based on Zernike polynomials. After the Shack-Hartmann wavefront analyzer measures the Zernike coefficients corresponding to the wavefront aberrations, the phase image corresponding to the opposite Zernike coefficients can be applied to the SLM to compensate for the wavefront aberrations. At this time, by adjusting the parameters corresponding to the phase image on the SLM, the wavefront aberrations can be reduced through closed-loop feedback.

[0073] When implementing the above process, it should be noted that the normalized pupil radius defined by the Zernike polynomial on the wavefront analyzer and the SLM needs to be matched. If they cannot be matched, the Zernike coefficients need to be changed according to the ratio between the two. In addition, the normalized coefficients in the Zernike polynomial definitions of the two may also be different. If they are different, the specific Zernike coefficients corresponding to the phase image also need to be changed accordingly.

[0074] This embodiment of the invention employs two orthogonally placed first acousto-optic deflectors to achieve multi-point optical addressing of 20 ions without Doppler shift. Actual trap testing showed that the intensity crosstalk between two ions 5.7 μm apart was approximately 3.15%. However, to meet the requirements of fault-tolerant quantum computing, the intensity crosstalk needs to be further reduced to below the error threshold of 1%. Analysis revealed that the main source of crosstalk is the dynamic wavefront aberration generated by AOD (Alternating Optical Discharge). To address this issue, this embodiment introduces a closed-loop feedback system consisting of an LCOS-SLM (Liquid Crystal on Silicon Spatial Light Modulator) and a Shack-Hartmann wavefront analyzer, effectively achieving real-time compensation for the aforementioned dynamic aberration. Furthermore, this closed-loop feedback control system corrects wavefront phase drift caused by RF frequency switching or environmental disturbances in real time, ensuring the long-term stability of single-bit gate operations in large-scale ion chains.

[0075] Furthermore, the method of the present invention adopts a dynamic and static aberration collaborative compensation strategy: cemented lens group solves static aberrations and SLM solves dynamic aberrations, realizing full-link wavefront optimization and significantly improving the quality of focused spot.

[0076] The optically independent addressing system with aberration compensation provided by this invention can be widely used in trapped ion quantum computing systems. This system enables high-quality, flexible, and highly scalable optically independent addressing, thereby supporting high-performance arbitrary single-qubit logic gate operations and high-fidelity multi-qubit entanglement gate implementation, providing a reliable optical control foundation for large-scale quantum information processing.

[0077] This invention discloses not only an optical addressing system, but also an optical addressing method, such as... Figure 6 As shown, it includes: Step S1: Control the light source assembly to emit a Gaussian laser beam with a Doppler frequency shift.

[0078] Step S2: Receive the Gaussian laser beam using the orthogonal AOD addressing module and deflect the Gaussian laser beam to obtain diffraction spots with the same Doppler frequency shift at any position.

[0079] Step S3: Measure the wavefront aberration of the diffraction spot using the optical modulation module, and perform aberration compensation on the diffraction spot or the Gaussian laser beam based on the detected wavefront aberration, and output the addressing spot.

[0080] Step S4: Receive the addressing light spot output by the optical modulation module using the focusing imaging module, and focus the addressing light spot onto each target quantum site of the one-dimensional ion chain in the ion trap.

[0081] Based on the optical addressing system disclosed above, this invention also provides a quantum computer that includes the optical addressing system described above.

[0082] This invention provides an optical addressing system, method, and quantum computer, comprising: a light source assembly, an orthogonal AOD addressing module, an optical modulation module, and a focusing imaging module. By deflecting and controlling a Gaussian laser beam with applied Doppler frequency shift, diffraction spots with the same Doppler frequency shift are obtained at arbitrary positions. The wavefront aberration of the diffraction spot is then measured, and aberration compensation is performed on the diffraction spot based on the detected wavefront aberration, outputting an aberration-free addressing spot. The addressing spot is then focused onto each target quantum point in a one-dimensional ion chain within an ion trap, thereby achieving addressing of individual target quantum points within the one-dimensional ion chain in the ion trap. The method disclosed in this invention detects the wavefront aberration of the diffracted light wave through the optical modulation module and performs aberration compensation on the wavefront beam based on the detected wavefront aberration, achieving high-quality, flexible, controllable, and highly scalable optical independent addressing of multiple target quantum points on a one-dimensional ion chain in an ion trap.

[0083] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0084] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0085] It is understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present application.

Claims

1. An optical addressing system, characterized in that, include: A light source assembly for emitting a Gaussian laser beam with a Doppler frequency shift applied; An orthogonal AOD addressing module is located in the optical path of the Gaussian laser beam. It is used to receive the Gaussian laser beam and deflect and control the Gaussian laser beam to obtain diffraction spots with the same Doppler frequency shift between any two positions. An optical modulation module is disposed in the optical path of the diffraction spot. It is used to measure the wavefront aberration of the diffraction spot and perform aberration compensation on the diffraction spot or the Gaussian laser beam according to the detected wavefront aberration, and output the addressing spot. A focusing imaging module is disposed in the optical path of the addressing spot, for receiving the addressing spot and focusing the addressing spot onto each target quantum site of the one-dimensional ion chain in the ion trap.

2. The optical addressing system according to claim 1, characterized in that, The light source assembly includes: a laser module and an acousto-optic modulator; Laser module, used to output Gaussian laser beam; An acousto-optic modulator is disposed in the optical path of the Gaussian laser beam to apply a Doppler frequency shift to the Gaussian laser beam through acousto-optic interaction, thereby controlling the frequency of the Gaussian laser beam and obtaining a Gaussian laser beam with a Doppler frequency shift applied.

3. The optical addressing system according to claim 1, characterized in that, The optical modulation module includes an SLM aberration compensation module and a wavefront characterization module; the SLM aberration compensation module, the orthogonal AOD addressing module, and the wavefront characterization module are arranged in sequence. The SLM aberration compensation module is used to receive a Gaussian laser beam with applied Doppler frequency shift, and after wavefront image position compensation, transmit the Gaussian laser beam to the orthogonal AOD addressing module. The wavefront characterization module is located on the optical path of the diffraction spot output by the orthogonal AOD addressing module. It is used to receive the diffraction spot and measure the wavefront aberration of the received diffraction spot so that the SLM aberration compensation module can perform wavefront position compensation on the diffraction spot based on the measured wavefront aberration.

4. The optical addressing system according to claim 1, characterized in that, The orthogonal AOD addressing module includes a first acousto-optic deflector, a first plano-convex lens, a second plano-convex lens, and a second acousto-optic deflector arranged in sequence. The first acousto-optic deflector is used to receive the Gaussian laser beam with a Doppler frequency shift applied, and to transmit the diffracted light generated by the Gaussian laser beam after deflection modulation to the first plano-convex lens at a preset first deflection angle. The first plano-convex lens is used to control the input diffracted light to be output in a parallel direction; The second plano-convex lens is used to receive parallel input diffracted light and transmit the diffracted light to the second acousto-optic deflector at a preset second deflection angle. The second acousto-optic deflector is used to receive diffracted light transmitted at a preset second deflection angle, and to deflect and modulate the diffracted light to obtain a diffracted light spot; The diffracted light output from the first acousto-optic deflector is conjugate to the same point source at the incident surface of the second acousto-optic deflector.

5. The optical addressing system according to claim 3, characterized in that, The SLM aberration compensation module includes a wavefront modulation unit; the wavefront modulation unit is a spatial light modulator or a digital micromirror array.

6. The optical addressing system according to claim 3, characterized in that, The wavefront characterization module includes a wavefront analysis unit; the wavefront analysis unit is a Shack-Hartmann wavefront analyzer, a shear interferometer wavefront sensor, or a curvature sensor.

7. The optical addressing system according to claim 1, characterized in that, The focusing imaging module includes a magnifying lens group, a static compensation lens, a focusing objective lens, and a viewing plate glass of the ion trap; The magnifying lens group includes a cemented doublet lens for magnifying the received addressing spot; The static compensation lens is used to compensate for static aberrations caused by the refraction of received light by the flat glass of the ion trap window. The focusing objective is used to focus the received addressing spot onto each target quantum site of the ion chain.

8. The optical addressing system according to claim 7, characterized in that, The system further includes a data processing module; the data processing module is used to acquire the layout information of the focusing imaging module, and to perform simulation analysis on the optical path of the focusing imaging module based on the layout information to obtain the static aberration, so that the static compensation lens can perform aberration compensation based on the static aberration.

9. A method for implementing optical addressing using the optical addressing system as described in any one of claims 1-8, characterized in that, include: The light source assembly is controlled to emit a Gaussian laser beam with a Doppler frequency shift applied. The Gaussian laser beam is received using an orthogonal AOD addressing module, and the Gaussian laser beam is deflected and controlled to obtain diffraction spots with the same Doppler frequency shift at any position. The wavefront aberration of the diffraction spot is measured using an optical modulation module, and aberration compensation is performed on the diffraction spot or the Gaussian laser beam based on the detected wavefront aberration, and the addressing spot is output. The addressing light spot output by the optical modulation module is received by the focusing imaging module, and the addressing light spot is focused onto each target quantum site of the one-dimensional ion chain in the ion trap.

10. A quantum computer, characterized in that, It includes the optical addressing system as described in any one of claims 1-8.

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