Low temperature ion trap fluorescence collection system and method of assembly thereof

Abstract

The application provides a low-temperature ion trap fluorescence collection system and an assembling method thereof, and relates to the technical field of quantum computing and quantum communication.The low-temperature ion trap fluorescence collection system comprises: a thermostat cooled to a target temperature by an external refrigerator; a cold finger arranged in the thermostat; and a low-temperature ion trap wrapped around the cold finger in the thermostat. The low-temperature ion trap wrap comprises: a main body for trapping ions under the excitation of an external voltage and manipulating the quantum state of the ions under the irradiation of a plurality of laser beams incident from the outside, and the ions emit fluorescence under the excitation of the plurality of laser beams; and a fluorescence collection mechanism for collecting the fluorescence. A continuous gas flow channel is formed between the fluorescence collection mechanism and the main body to discharge the gas in the main body in the process of forming a vacuum environment in the thermostat, and the low-temperature ion trap wrap has a vacuum environment therein and is at the target temperature, so that the residual gas is adsorbed, thereby inhibiting the backflow of the residual gas into the main body and colliding with the ions.

Description

Technical Field

[0001] This application relates to the technical fields of quantum computing and quantum communication, and more specifically, to a low-temperature ion trap fluorescence collection system and its assembly method. Background Technology

[0002] Cryogenic ion trap devices are widely used in quantum computing and quantum communication. To ensure the lifetime, coherence, and manipulation precision of the trapped ions, the ion trapping region typically needs to maintain an extremely high vacuum environment (requiring a vacuum level of 1 eV). - 12 To reduce the impact of residual gas collisions with ions (below Torr), the effects of ion loss, decoherence, and heating are minimized. Meanwhile, ion state detection typically relies on a fluorescence collection system to acquire ion radiation fluorescence; therefore, the long-term stability of the fluorescence collection system directly affects the accuracy of experimental results and its ability to operate continuously for extended periods.

[0003] Existing cryogenic ion trap devices suffer from at least the following problems during actual operation: First, existing cryogenic vacuum systems are limited by factors such as material outgassing, the stability of sealing structures, leakage rates at connections, and changes in the physical properties of components under cryogenic conditions. The ion trapping region still struggles to maintain the extremely high vacuum environment required for large-scale quantum experiments over long periods. Second, existing fluorescence collection systems are susceptible to thermal contraction, mechanical stress, structural shifts, and changes in the operating conditions of optical components under cryogenic conditions. This leads to changes in the optical path coupling state, resulting in fluctuations in fluorescence collection efficiency and decreased signal stability. Furthermore, frequent calibration is often required, making it difficult to meet the continuous data acquisition requirements of long-term quantum experiments. Summary of the Invention

[0004] To address at least one of the technical problems in the prior art, embodiments of this application provide a low-temperature ion trap fluorescence collection system and its assembly method, which can achieve effective room-temperature pre-extraction of gas inside the main body and suppress the backflow of residual gas into the main body under low-temperature conditions.

[0005] This application provides a cryogenic ion trap fluorescence collection system, comprising: a thermostat configured to cool to a target temperature by an external refrigerator; a cold finger disposed within the thermostat; and a cryogenic ion trap enclosure disposed within the thermostat and the cold finger, the cryogenic ion trap enclosure comprising: a body configured to trap ions under external voltage excitation and manipulate the quantum state of the ions under irradiation by multiple externally incident laser beams, the ions emitting fluorescence under the excitation of the multiple laser beams; and a fluorescence collection mechanism adapted to collect the fluorescence, wherein a continuous gas flow channel is formed between the fluorescence collection mechanism and the body to discharge gas from the body during the process of creating a vacuum environment within the thermostat, and, when the cryogenic ion trap enclosure has the vacuum environment and the target temperature is reached, adsorbing residual gas diffused from the thermostat into the body to suppress the residual gas from entering the body and colliding with the ions.

[0006] Optionally, the main body includes: a base disposed on the cold finger, with a receiving space formed within the base; a trap electrode assembly disposed within the receiving space, configured to trap the ions in the ion trapping region formed by the trap electrode assembly under the excitation of the external voltage; and a first cylinder extending from the side of the base and communicating with the receiving space, suitable for accommodating the fluorescence collection mechanism.

[0007] Optionally, the inner wall of the first cylinder is provided with an internal thread, and the fluorescence collection mechanism includes: a second cylinder, the outer wall of the second cylinder is provided with a first external thread along the circumferential direction to thread into the internal thread, and a spiral gas flow channel is formed between the first external thread and the internal thread; and a fluorescence collection lens, disposed on the side of the second cylinder facing the trap electrode assembly, to focus the fluorescence in the first cylinder.

[0008] Optionally, the cryogenic ion trap enclosure further includes: a retaining ring located on the side of the second cylinder facing the trap electrode assembly, the outer wall of the retaining ring being provided with a second external thread portion along the circumferential direction to engage with the internal thread portion; and an activated carbon ring disposed on the retaining ring to adsorb the residual gas when the cryogenic ion trap enclosure has the aforementioned vacuum environment and the cryogenic ion trap enclosure reaches the aforementioned target temperature, so that the vacuum degree inside the cryogenic ion trap enclosure is lower than the vacuum degree inside the thermostat.

[0009] Optionally, the base is configured as a polygonal prism coaxial with the first cylinder. The trap electrode assembly includes: two trap electrode seats, respectively mounted on two opposite faces of the polygonal prism; multiple trap electrodes connected between the two trap electrode seats and configured to be electrically connected to an external power supply device; the middle portion of the multiple trap electrodes forms the ion trapping region; and the multiple trap electrodes are configured to trap the ions in the ion trapping region under the excitation of the external voltage.

[0010] Optionally, the aforementioned polygonal prism is an octagonal prism, with the two aforementioned trap electrode holders respectively mounted on the first and second faces of the octagonal prism. The main body further includes: an ion source target disposed on the third face of the octagonal prism, and the line connecting the ion source target and the ion trapping region is orthogonal to the multiple trap electrodes. The ion source target is configured to generate ions under the excitation of multiple externally incident laser beams; and multiple light guides disposed on other faces of the octagonal prism to allow the multiple externally incident laser beams to irradiate the ion trapping region.

[0011] Optionally, the distance between adjacent threads on the first external thread portion and the distance between adjacent threads on the internal thread portion are both 0.17mm to 0.23mm.

[0012] Optionally, the cross-section of the gas guide channel has a radial dimension of 0.1 mm.

[0013] Optionally, a positioning mark is provided on the side of the second cylinder opposite to the fluorescence collecting lens, and an annular scale is provided on the side of the first cylinder away from the base, so that the screwing depth of the second cylinder can be adjusted by the positioning mark and the annular scale after the second cylinder is screwed into the first cylinder.

[0014] Another embodiment of this application provides an assembly method for a cryogenic ion trap fluorescence collection system, applied to the aforementioned cryogenic ion trap fluorescence collection system. The assembly method includes: mounting the main body of the cryogenic ion trap onto the cold finger of a thermostat; bonding a fluorescence collecting lens to the side of a second cylinder facing multiple trap electrodes; screwing a fixing ring with an activated carbon ring into a first cylinder; screwing a second cylinder with the aforementioned fluorescence collecting lens into the first cylinder; adjusting the screwing depth of the second cylinder into the first cylinder to adjust the collimation of the reference light incident from outside the thermostat exiting the fluorescence collecting lens, and determining the amount of thermal shrinkage between the first and second cylinders; further adjusting the screwing depth of the second cylinder using positioning marks and annular scales to compensate for the thermal shrinkage; performing a vacuuming operation inside the thermostat using an external vacuuming device, and cooling the temperature inside the thermostat to a target temperature using an external refrigerator.

[0015] According to an embodiment of this application, a cryogenic ion trap fluorescence collection system and its assembly method form a continuous gas flow channel between the fluorescence collection mechanism and the main body. This allows gas inside the main body to be discharged into the internal space of the cryostat via the gas flow channel during the process of creating a vacuum environment within the cryostat using external vacuum equipment. The gas is then extracted by the vacuum equipment, achieving effective room-temperature pre-evacuation. When a vacuum environment is created within the cryostat and the cryogenic ion trap reaches the target temperature, the inner wall of the gas flow channel acts as a cryogenic adsorption surface, adsorbing residual gas molecules. Due to the elongated structure of the gas flow channel, the probability of collision between residual gas molecules and the inner wall of the gas flow channel increases during diffusion from the cryostat into the main body. This facilitates adsorption and capture, thereby inhibiting the backflow of residual gas into the main body and its collision with ions, thus improving vacuum performance. Attached Figure Description

[0016] Figure 1 This is a perspective view of a cryogenic ion trap fluorescence collection system according to an embodiment of this application;

[0017] Figure 2 This is a partial cross-sectional view of a cryogenic ion trap fluorescence collection system according to an embodiment of the present application, wherein the fluorescence collection mechanism is installed inside a first cylinder;

[0018] Figure 3 This is a partial cross-sectional view of a cryogenic ion trap fluorescence collection system according to an embodiment of the present application, wherein the fluorescence collection mechanism is not installed in the first cylinder;

[0019] Figure 4 This is an exploded view of a component enclosed in a cryogenic ion trap according to an embodiment of this application;

[0020] Figure 5 This is a side view of a cryogenic ion trap enclosure according to an embodiment of this application;

[0021] Figure 6 This is a partial cross-sectional view from a first perspective of a cryogenic ion trap enclosure according to an embodiment of this application;

[0022] Figure 7 This is a cross-sectional view of the first external thread portion and the internal thread portion according to an embodiment of this application;

[0023] Figure 8 This is a partial cross-sectional view from a second perspective of a cryogenic ion trap enclosure according to an embodiment of this application;

[0024] Figure 9 This is a flowchart of an assembly method for a cryogenic ion trap fluorescence collection system according to an embodiment of this application;

[0025] Figure 10 This is a test diagram of the vacuum level inside a cryogenic ion trap according to one embodiment of this application.

[0026] In the accompanying drawings, the meanings of the reference numerals are as follows:

[0027] 1. Thermostat;

[0028] 2. Refrigeration unit;

[0029] 3. Vacuum equipment;

[0030] 4. Cold fingers;

[0031] 5. Encased in a cryogenic ion trap;

[0032] 51. Main body;

[0033] 510. First cylinder;

[0034] 511. Base;

[0035] 512. Trap electrode;

[0036] 513. Ion source target material;

[0037] 514. Light guide components;

[0038] 515. Circular scale;

[0039] 516. Ion confinement zone;

[0040] 517. Trap electrode holder;

[0041] 52. Fluorescence collection mechanism;

[0042] 520. Second cylinder;

[0043] 521. Fluorescence collecting lens;

[0044] 522. Location markers;

[0045] 53. Retaining ring;

[0046] 54. Activated carbon ring. Detailed Implementation

[0047] The embodiments of this application will now 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 this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0048] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0049] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0050] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). When using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0051] Low-temperature ion traps are core devices in quantum computing and quantum communication, and their performance directly determines the stability and precision of quantum experiments. For large-scale, long-term ion trap systems to operate normally, two conditions must be met simultaneously: first, the ion trapping region must maintain an extremely high vacuum environment (requiring a vacuum level of 1 eV). -12 To reduce collision interference from residual gas on ions and improve the precision and stability of ion trapping in quantum experiments, the fluorescence collection system must possess long-term stability, be able to stably output fluorescence signals from ion radiation, and require no frequent calibration to meet the long-term data collection requirements of large-scale quantum experiments.

[0052] Existing cryogenic ion trap systems still have shortcomings in maintaining vacuum during practical operation. Although cryogenic conditions can improve gas adsorption within the cavity to some extent, limitations such as material outgassing, the stability of the sealing structure, leakage rate at connections, and changes in the physical properties of components under cryogenic conditions make it difficult to maintain a consistently high vacuum environment in the ion trapping region to meet the requirements of large-scale quantum experiments over long periods. Current technology is insufficient to meet 1e... -13Vacuum requirements at the Torr level and below affect the trapping stability of ions and experimental accuracy.

[0053] Furthermore, existing cryogenic ion trap systems also have shortcomings in terms of fluorescence collection stability. In cryogenic environments, the mechanical structures and optical components of existing fluorescence collecting objectives are susceptible to thermal shrinkage, mechanical stress, structural shifts, and changes in the operating conditions of optical elements. This leads to changes in the optical path coupling state, resulting in fluctuations in fluorescence collection efficiency and a decrease in signal stability. Frequent calibration is often required, such as every 12 hours, which is insufficient to meet the continuous data acquisition requirements of long-term quantum experiments.

[0054] To address the aforementioned shortcomings, this application provides a low-temperature ion trap fluorescence collection system that can effectively pre-pump the gas inside the main body at room temperature and suppress the backflow of residual gas into the main body under low-temperature conditions, thereby improving vacuum performance.

[0055] Figure 1 This is a perspective view of a cryogenic ion trap fluorescence collection system according to an embodiment of this application. Figure 2 This is a partial cross-sectional view of a cryogenic ion trap fluorescence collection system according to an embodiment of this application, wherein the fluorescence collection mechanism is installed inside the first cylinder. Figure 3 This is a partial cross-sectional view of a cryogenic ion trap fluorescence collection system according to an embodiment of this application, wherein the fluorescence collection mechanism is not installed in the first cylinder.

[0056] A cryogenic ion trap fluorescence collection system is provided according to an embodiment of this application, such as... Figure 1 , Figure 2 and Figure 3 As shown, the cryogenic ion trap fluorescence collection system includes a thermostat 1, a cold finger 4, and a cryogenic ion trap enclosure 5. The thermostat 1 is configured to be cooled to a target temperature by an external refrigerator 2. The cold finger 4 is disposed inside the thermostat 1. The cryogenic ion trap enclosure 5 is disposed inside the thermostat 1 and is located within the cold finger 4. The cryogenic ion trap enclosure 5 includes a main body 51 and a fluorescence collection mechanism 52. The main body 51 is configured to trap ions under the excitation of an external voltage and manipulate the quantum state of the ions under the irradiation of multiple incident laser beams, causing the ions to emit fluorescence under the excitation of the multiple laser beams. The fluorescence collection mechanism 52 is adapted to collect fluorescence. A continuous gas flow channel is formed between the fluorescence collection mechanism 52 and the main body 51 to discharge the gas inside the main body 51 during the process of creating a vacuum environment inside the thermostat 1. Furthermore, when a vacuum environment is present inside the cryogenic ion trap enclosure 5 and the target temperature is reached inside the cryogenic ion trap enclosure 5, residual gas molecules diffusing from the thermostat 1 into the main body 51 are adsorbed, thereby preventing the residual gas inside the thermostat 1 from flowing back into the main body 51 and colliding with the ions.

[0057] In some embodiments, the thermostat 1 has an operating temperature range of 3.2K to 350K (Kelvin), a low-temperature operating temperature range of 3.2K to 12K, and a target temperature of, for example, 4.5K.

[0058] In some embodiments, during the room temperature pre-evacuation stage, a continuous gas flow channel is formed between the fluorescence collection mechanism 52 and the main body 51. When the thermostat 1 is pre-evacuated at room temperature (approximately 25°C), the gas inside the main body 51 is rapidly discharged through the gas flow channel. After a vacuum environment is created inside the thermostat 1 and the low-temperature ion trap enclosure 5 is lowered to the target temperature by the external refrigerator 2, the inner wall of the gas flow channel can serve as a low-temperature adsorption surface to adsorb residual gas molecules. Due to the elongated structure of the gas flow channel, the probability of collision between residual gas molecules and the inner wall of the gas flow channel increases during diffusion from the internal space of the thermostat 1 to the interior of the main body 51, thus facilitating adsorption and capture. This reduces the likelihood of residual gas flowing back into the main body 51 from the thermostat 1 and colliding with ions, improving the vacuum sealing and stability of the low-temperature ion trap enclosure 5 at low temperatures, and contributing to the achievement of extremely high vacuum (4e). -14 (Torrent magnitude) provides the foundation.

[0059] In this embodiment, a continuous gas flow channel is formed between the fluorescence collection mechanism 52 and the main body 51. This allows gas inside the main body 51 to be discharged into the internal space of the thermostat 1 via the gas flow channel during the process of creating a vacuum environment within the thermostat 1 using an external vacuum pumping device 3. The gas is then extracted by the vacuum pumping device 3, achieving room temperature pre-evacuation. When a vacuum environment is created within the thermostat 1 and the low-temperature ion trap 5 reaches the target temperature (e.g., 4.5K), the inner wall of the gas flow channel acts as a low-temperature adsorption surface, adsorbing residual gas molecules that have entered the main body 51. The elongated surface of the gas flow channel increases the probability of collisions between residual gas molecules and the inner wall of the channel as they diffuse from the internal space of the thermostat 1 into the main body 51, effectively capturing them and preventing backflow of residual gas from the thermostat 1 into the main body 51 to collide with ions, thus improving vacuum performance.

[0060] Figure 4 This is an exploded view of a component enclosed in a cryogenic ion trap according to one embodiment of this application. Figure 5 This is a side view of a cryogenic ion trap enclosure according to an embodiment of this application.

[0061] According to embodiments of this application, such as Figure 4 and Figure 5As shown, the main body 51 includes a base 511, a trap electrode assembly, and a first cylindrical body 510. The base 511 is disposed on the cold finger 4, and a receiving space is formed within the base 511. The trap electrode assembly is disposed within the receiving space and is configured to trap ions in an ion trapping region 516 formed by the trap electrode assembly under the excitation of an external voltage. The first cylindrical body 510 extends from the side of the base 511 and communicates with the receiving space. The first cylindrical body 510 is adapted to accommodate a fluorescence collection mechanism 52.

[0062] In some embodiments, the base 511 and the first cylinder 510 may be made of a material that balances low-temperature thermal conductivity and rigidity, such as oxygen-free copper.

[0063] In some embodiments, when the base 511 forms a vacuum environment within the thermostat 1 and cools to a target temperature (e.g., 4.5K), the inner surface of the base 511 can participate in the low-temperature adsorption of residual gas molecules.

[0064] In this embodiment, by placing the base 511 on the cold finger 4, the cold finger 4 transfers the low-temperature cooling energy from the thermostat 1 to the entire body 51, ensuring that both the trap electrode assembly and the first cylinder 510 are at the target temperature (e.g., 4.5K), thereby capturing residual gas molecules using the physical adsorption capacity of the low-temperature surface. Under the excitation of an external voltage, an electric field distribution is formed within the trap electrode assembly, trapping ions within the ion trapping region 516 formed by the trap electrode assembly, providing stable spatial constraint for the ions. The first cylinder 510 extends from the side of the base 511 and communicates with the receiving space, allowing the fluorescence collection mechanism 52 to be aligned with the ion trapping region 516, achieving lateral fluorescence collection.

[0065] According to an embodiment of this application, the inner wall of the first cylinder 510 is provided with an internal thread, and the fluorescence collection mechanism 52 includes a second cylinder 520 and a fluorescence collection lens 521. The outer wall of the second cylinder 520 is provided with a first external thread along the circumference to thread-fit with the internal thread. A spiral gas flow channel is formed between the first external thread and the internal thread. The fluorescence collection lens 521 is disposed on the side of the second cylinder 520 facing the trap electrode assembly to focus the fluorescence within the first cylinder 510.

[0066] In some embodiments, the first cylinder 510 is constructed as a hollow cylinder with a bottom diameter of 28 mm and a height of 20 mm. The inner wall of the first cylinder 510 is provided with an internal thread portion, the major diameter of which is 24 mm. The distance between adjacent threads on the internal thread portion is 0.2 mm and the thread pitch is uniform. The effective length of the internal thread along the axial direction of the first cylinder 510 is 20 mm.

[0067] In some embodiments, the second cylinder 520 is configured as a hollow cylinder. The second cylinder 520 can be made of a material that balances low-temperature thermal conductivity and rigidity, such as oxygen-free copper. The outer diameter of the second cylinder 520 is 24 mm. A first external thread is provided circumferentially on the outer wall of the second cylinder 520. The distance between adjacent threads on the first external thread is 0.2 mm, and the thread spacing is uniform. The first external thread serves both to achieve threaded engagement with the internal thread and to form a spiral gas flow channel between them.

[0068] In some embodiments, the fluorescence collecting lens 521 can be an aspherical fluorescence collecting lens. The aspherical fluorescence collecting lens is bonded to the side of the second cylinder 520 facing the trap electrode assembly by epoxy resin. After bonding, it is cured at room temperature for 24 hours to ensure that it is firmly fixed, without loosening and with low stress, which meets the stability requirements of optical components at low temperatures.

[0069] In this embodiment, the second cylinder 520 is fixed inside the first cylinder 510 by the threaded engagement of the first external thread and the internal thread, and the axial distance between the fluorescence collecting lens 521 and the trap electrode assembly is adjustable. A continuous gas flow channel is formed by the helical radial gap between the first external thread and the internal thread. During the room temperature pre-evacuation stage, gas molecules in the containment space diffuse into the thermostat 1 along the gas flow channel and are discharged by the external vacuum device 3, achieving room temperature pre-evacuation. After cooling to the target temperature (e.g., 4.5K), the narrow inner wall surface of the helical channel (including the opposing surfaces of the first external thread and the internal thread) is at a low temperature, resulting in physical adsorption of residual gas molecules. When residual gas molecules diffuse from the internal space of the thermostat 1 into the ion trapping region 516 and enter the spiral gas flow channel, the probability of collision between the residual gas molecules and the wall of the cryogenic channel increases due to the tortuous spiral shape and narrow radial dimension of the gas flow channel. This causes them to be trapped by the wall, suppressing the backflow of residual gas into the ion trapping region 516 and maintaining the high vacuum state of the ion trapping region 516. Simultaneously, the epoxy resin bonding of the fluorescence collecting lens 521 avoids the slight displacement that might occur with mechanical fixing. Combined with the direct connection method of threaded fixing, it avoids the mechanical gaps and cryogenic thermal deformation drift introduced by the displacement stage. This allows the fluorescence collecting lens 521 to maintain alignment at low temperatures for a long time after assembly at room temperature, achieving long-term stability in fluorescence collection.

[0070] Figure 6 This is a partial cross-sectional view from a first perspective of a cryogenic ion trap enclosure according to an embodiment of this application.

[0071] According to embodiments of this application, such as Figure 6As shown, the cryogenic ion trap enclosure 5 also includes a retaining ring 53 and an activated carbon ring 54. The retaining ring 53 is located on the side of the second cylinder 520 facing the trap electrode assembly, and the outer wall of the retaining ring 53 is provided with a second external thread along the circumferential direction to engage with the internal thread. The activated carbon ring 54 is disposed on the retaining ring 53 to adsorb residual gas when a vacuum environment is provided inside the cryogenic ion trap enclosure 5 and the target temperature is reached inside the cryogenic ion trap enclosure 5, so that the vacuum degree inside the cryogenic ion trap enclosure 5 is lower than the vacuum degree inside the thermostat 1.

[0072] In some embodiments, the outer diameter of the retaining ring 53 may be 24 mm, and the retaining ring 53 may be made of oxygen-free copper.

[0073] In some embodiments, the retaining ring 53 is assembled between the two trap electrode seats 517 (which will be described in detail below) of the trap electrode assembly and the second cylinder 520, and is located on the side of the second cylinder 520 facing the trap electrode assembly, and is positioned at the step provided on the internal thread portion.

[0074] In some embodiments, the inner wall of the fixing ring 53 is bonded with an oxygen-free copper mesh by epoxy resin, and the oxygen-free copper mesh is wrapped with an activated carbon block.

[0075] In some embodiments, the activated carbon ring 54 is made of high specific surface area activated carbon, which is suitable for capturing residual gas when a vacuum environment is formed in the thermostat 1 and the interior of the cryogenic ion trap 5 reaches the target temperature (e.g., 4.5K). It works in synergy with the flow conduction function of the gas guiding channel to improve the vacuum performance inside the cryogenic ion trap 5.

[0076] Specifically, the adsorption area of ​​the activated carbon ring 54 has been optimized to ensure that it can fully exert its adsorption effect at low temperatures without contaminating the ion trapping area, further reducing the vacuum level inside the low-temperature ion trap 5 so that the vacuum level inside the low-temperature ion trap 5 is lower than the vacuum level inside the thermostat 1, making it suitable for ultra-high vacuum (4e). -14 The demand is on the order of Torr.

[0077] In this embodiment, the activated carbon ring 54 is fixed to the side near the ion trapping region 516 by the threaded engagement of the second external thread of the fixing ring 53 with the internal thread of the first cylinder 510, and is located between the second cylinder 520 and the two trap electrode seats 517 of the trap electrode assembly. When the temperature inside the thermostat 1 is lowered to the target temperature (e.g., 4.5K) by an external refrigerator 2 and a vacuum environment is achieved within the cryogenic ion trap enclosure 5, the high specific surface area activated carbon material of the activated carbon ring 54 exhibits a strong physical adsorption capacity for residual gas molecules (e.g., hydrogen, helium, etc.) at low temperatures. Because the activated carbon ring 54 is located on the path between the ion trapping region 516 and the gas flow channel, residual gas molecules must pass near the activated carbon ring 54 to diffuse from the internal space of the thermostat 1 into the ion trapping region 516, thus being captured by the activated carbon. Utilizing the adsorption effect of the activated carbon ring 54, the gas molecule density near the ion trapping region 516 is further reduced. Therefore, the vacuum level inside the cryogenic ion trap 5 (especially the ion trapping region 516) is lower than the vacuum level inside the thermostat 1. At this point, the vacuum level inside the cryogenic ion trap 5 is superior to the vacuum level inside the thermostat 1, thus forming a differential vacuum gradient. This implementation method suppresses the backflow of residual gas molecules in the thermostat 1 into the ion trapping region 516 through the gas flow channel, thereby maintaining the ion trapping region 516 at 4°C. -14 The extremely high vacuum state on the order of Torr reduces collision interference between residual gas and ions, improving the long-term stability of ion confinement and the precision of quantum experiments.

[0078] According to embodiments of this application, such as Figure 4 , Figure 5 and Figure 6 As shown, the base 511 is constructed as a polygonal prism coaxial with the first cylindrical body 510. The trap electrode assembly includes two trap electrode holders 517 and multiple trap electrodes 512. The two trap electrode holders 517 are respectively mounted on two opposite faces of the polygonal prism. The multiple trap electrodes 512 are connected between the two trap electrode holders 517 and are configured to be electrically connected to an external power supply. The middle portion of the multiple trap electrodes 512 forms an ion trapping region 516. The multiple trap electrodes 512 are configured to trap ions in the ion trapping region 516 under the excitation of an external voltage.

[0079] In some embodiments, such as Figure 5 As shown, there can be four trap electrodes 512. The trap electrode holder 517 and the trap electrode 512 can be fixed and sealed with epoxy resin. Under the excitation of an external voltage, the multiple trap electrodes 512 generate a quadrupole electric field or a higher-order multipole electric field in the ion trapping region 516 to achieve ion confinement.

[0080] In this embodiment, by mounting two trap electrode holders 517 on opposite faces of a polygonal prism, multiple trap electrodes 512 connected between the two trap electrode holders 517 span the internal accommodating space of the base 511, forming an ion trapping region 516 in the central region of the accommodating space. By coaxially aligning the base 511 with the first cylindrical body 510, the optical axis of the fluorescence collecting lens 521 is aligned with the center of the ion trapping region 516, improving fluorescence collection efficiency. The low-temperature heat conduction path provided by the polygonal prism-shaped base 511, coaxially aligned with the first cylindrical body 510, effectively transfers the low-temperature cooling energy of the cold finger 4 to the trap electrode assembly and the ion trapping region 516, reducing the ion heating rate and improving the precision of quantum state manipulation.

[0081] According to an embodiment of this application, the polygonal prism is an octagonal prism, and two trap electrode holders 517 are respectively mounted on the first and second opposite faces of the octagonal prism. The main body 51 also includes an ion source target 513 and a plurality of light guides 514. The ion source target 513 is disposed on the third face of the octagonal prism, and the line connecting the ion source target 513 and the ion trapping region 516 is orthogonal to the plurality of trap electrodes 512. The ion source target 513 is configured to generate ions under the excitation of multiple externally incident laser beams. The plurality of light guides 514 are respectively disposed on the other faces of the octagonal prism to allow the multiple externally incident laser beams to irradiate the ion trapping region 516.

[0082] In some embodiments, the distance between opposite sides of the octagonal prism is 40 mm to ensure low-temperature adsorption specific surface area and thermal conductivity, while facilitating the arrangement of multi-directional optical paths.

[0083] In some embodiments, the ion source target 513 is configured to generate neutral atoms through laser ablation (e.g., pulsed laser ablation with a wavelength of 532 nm) under irradiation by an externally incident laser beam. The neutral atoms are ionized to form ions (the neutral atoms achieve photoionization and cooling through the combined action of ionizing light, Doppler cooling light, and pump light). The ion source target 513 is sealed with an indium seal between itself and the third facet of the octagonal prism.

[0084] In some embodiments, a plurality of light guides 514 are respectively disposed on the optical ports of other facets of the octagonal prism. Each light guide 514 allows one or more externally incident laser beams to pass through and guides the laser beams toward the ion trapping region 516. The light guides 514 may be made of fused silica, which is fixed to the optical ports by adhesive bonding. The fused silica and the optical ports of the facets of the octagonal prism are sealed with epoxy resin to maintain the vacuum seal of the base 511 while allowing the laser beam to enter the ion trapping region 516 with almost no loss.

[0085] In this embodiment, the ion source target 513 is disposed on the third face of an octagonal prism, and the line connecting the ion source target 513 and the ion trapping region 516 is orthogonal to the multi-well electrode 512. This allows ions generated by the ion source target 513 to enter the ion trapping region 516 in a direction perpendicular to the axial direction of the multi-well electrode 512, thereby improving ion loading efficiency. An externally incident laser beam irradiates the ion source target 513, causing neutral atoms to be released from its surface. These neutral atoms are then ionized by the laser near the ion trapping region 516, forming ions which are subsequently cooled by the nearby laser and trapped by the electric field generated by the multi-well electrode 512, thus achieving in-situ ion generation and loading. Light guides 514 are disposed on the other five faces, providing independent optical paths for the multiple laser beams. Each laser beam is incident from a different face, passes through the light guide 514, and is focused on the ion trapping region 516, irradiating ions from different directions to achieve coherent manipulation of the quantum state of the ions. Because the octagonal prism structure provides multiple flat mounting surfaces spaced 45° apart, the arrangement of multiple light guides 514 allows multiple laser beams to be incident in different directions and polarizations, satisfying the multiple requirements of ion quantum state manipulation for laser propagation direction. The vacuum seal between each light guide 514 and the facet of the octagonal prism maintains an extremely high vacuum environment inside the containment space, preventing external gas from leaking into the ion trapping region 516 through the mounting interface (optical port of the facet) of the light guide 514.

[0086] According to an embodiment of this application, the distance between adjacent threads on the first external thread portion and the distance between adjacent threads on the internal thread portion are both 0.17mm to 0.23mm.

[0087] In some embodiments, the distance between adjacent threads on the first external thread portion can be 0.17mm, 0.18mm, 0.19mm, 0.2mm, 0.21mm, 0.22mm, or 0.23mm. Preferably, the distance between adjacent threads on the first external thread portion can be 0.2mm.

[0088] In some embodiments, the distance between adjacent threads on the internal thread portion can be 0.17mm, 0.18mm, 0.19mm, 0.2mm, 0.21mm, 0.22mm, or 0.23mm. Preferably, the distance between adjacent threads on the internal thread portion can be 0.2mm.

[0089] Figure 7 This is a cross-sectional view of the first external thread portion and the internal thread portion according to an embodiment of this application.

[0090] According to embodiments of this application, such as Figure 7 As shown, the cross-section of the gas guide channel has a radial dimension of 0.1 mm.

[0091] Referring to the above structure, the distance between the large outer diameter of the internal thread portion and the large inner diameter of the first external thread portion is 0.1 mm. For example... Figure 7 As shown, the threaded engagement between a first external thread portion b and an internal thread portion a on one side is illustrated. The internal thread portion a is located on the upper side, and the first external thread portion b is located on the lower side. A gap is left between the crest of the first external thread portion b and the root of the internal thread portion a (e.g., Figure 7 The trapezoidal gap shown in the figure has a radial dimension of 0.1 mm, and two adjacent gaps form a continuous spiral gas flow channel.

[0092] In this implementation, the continuous spiral gas flow channel extends the total length of the gas flow channel, requiring gas molecules to travel a longer path during diffusion, thus increasing the chance of collisions between gas molecules and the inner wall of the gas flow channel. During the room temperature pre-evacuation stage, the external vacuum device 3 generates a low-pressure environment inside the thermostat 1, and gas molecules within the main body 51 diffuse outward along the gas flow channel under the drive of the pressure gradient. After cooling to the target temperature (10K and below, for example, 4.5K), the temperature of the inner wall of the gas flow channel decreases to a low temperature, and gas molecules are physically adsorbed when they collide with the inner wall. Almost every gas molecule entering the gas flow channel is captured by the inner wall, thereby effectively suppressing residual gas from flowing back from the thermostat 1 into the ion trapping region 516. At the same time, the radial dimension of the gas flow channel cross-section is 0.1mm, which can prevent the first external thread and internal thread from jamming due to thermal contraction at low temperatures, ensuring that the threaded fit remains adjustable after cycling from room temperature to low temperature.

[0093] In existing cryogenic ion trap architectures, the laser, ion source target, and trap electrode assembly are physically separate. Interference from intrinsic vibrations within the cryogenic system (such as vibrations caused by an external refrigerator connected to the thermostat 1) leads to relative motion between the modules. This relative vibration severely weakens the stability of the cryogenic ion trap architecture, particularly the relative displacement between the fluorescence collecting lens and the trap electrode assembly, limiting fluorescence collection stability and increasing the difficulty of maintaining the cryogenic ion trap architecture. To address this, this application implements an integrated design of the entire ion trapping module. Because the functional sub-modules, such as the laser, ion source target, and trap electrode assembly, are mechanically rigidly coupled, interference from external vibration sources is converted into common-mode vibration of the cryogenic ion trap fluorescence collecting system, effectively avoiding relative displacement between the functional sub-modules. In particular, the common-reference design of the fluorescence collecting lens 521 and the trap electrode assembly solves the signal disturbance caused by large relative vibrations between them in existing technologies. This improvement significantly enhances the stability of the low-temperature ion trap fluorescence collection system, greatly increasing its technological advantages in applications such as quantum computing and quantum communication where high fluorescence collection stability is required.

[0094] Figure 8 This is a partial cross-sectional view from a second perspective of a cryogenic ion trap enclosure according to an embodiment of this application.

[0095] According to embodiments of this application, such as Figure 8 As shown, a positioning mark 522 is provided on the side of the second cylinder 520 opposite to the fluorescence collecting lens 521. An annular scale 515 is provided on the side of the first cylinder 510 away from the base 511, so that the screwing depth of the second cylinder 520 can be adjusted by the positioning mark 522 and the annular scale 515 after the second cylinder 520 is screwed into the first cylinder 510.

[0096] In some embodiments, the side of the first cylinder 510 away from the base 511 is provided with an annular scale 515, which includes 180 equally divided angular graduations. The central angle corresponding to each graduation is 2°, and the axial adjustment distance corresponding to each graduation is 1.1μm. During the process of the second cylinder 520 being screwed into the first cylinder 510, for each graduation (2°) rotation, with the distance between adjacent threads on the first external thread and the distance between adjacent threads on the first internal thread both being 0.2mm, the axial displacement corresponding to each graduation is 1.1μm.

[0097] In this implementation, the rotation angle of the second cylinder 520 is converted into a readable axial displacement by the cooperation of the positioning mark 522 and the annular scale 515. As the operator rotates the second cylinder 520, the positional change of the positioning mark 522 relative to the annular scale 515 is observed. Each change in scale corresponds to a 1.1 μm axial displacement, providing a 1.1 μm axial adjustment resolution, thereby achieving micron-level adjustment of the distance between the fluorescence collecting lens 521 and the ion trapping region 516. During the room-temperature assembly stage, a Gaussian reference light system is incident on the fluorescence collecting lens 521, and the collimation of the emitted reference light is monitored using a CMOS camera. The required axial displacement is calculated based on the collimation deviation, and then the positioning mark 522 is moved by the corresponding scale number by rotating the second cylinder 520, thus completing the precise setting of the focal length. In low-temperature environments, due to material thermal contraction (e.g., from 25°C to 4.5K), the axial dimensions of the first cylinder 510 and the second cylinder 520 change, causing a shift in the focal position of the fluorescence collecting lens 521. The thermal shrinkage from room temperature to low temperature (e.g., 78 μm) is calculated using software simulation. During assembly at room temperature, the second cylinder 520 is rotated out by the corresponding number of graduations (e.g., 71 graduations, corresponding to 78.1 μm) to allow for thermal shrinkage. After cooling, thermal shrinkage causes the second cylinder 520 to automatically retract to the correct position, achieving thermal shrinkage compensation and preventing a decrease in fluorescence collection efficiency due to thermal deformation. The repeatable and quantifiable adjustment method provided by the positioning mark 522 and the annular scale 515 avoids repeated adjustments relying on the displacement stage, reducing assembly time and human error. Furthermore, the adjusted position remains stable over a long period at low temperatures, enabling fluorescence collection without calibration, avoiding interference from frequent calibrations, improving the stability of fluorescence collection, meeting the requirements for stable data collection over long periods, and reducing the difficulty of experimental maintenance.

[0098] By synergistically combining the gas flow channel formed between the first external thread and the internal thread with the activated carbon ring 54, efficient room-temperature pre-evacuation is achieved. Furthermore, it adapts to changes in material physical properties at low temperatures, effectively suppressing backflow of residual gas in the low-temperature operating range and at the target temperature, thus achieving 4e -14 The Torr vacuum level (two orders of magnitude higher than existing technologies) significantly reduces the collision interference of residual gas on ions, improves the stability of long-term ion confinement and the ability to expand the ion trap on a large scale, and greatly enhances the precision of quantum experiments. By integrating the gas flow channel formed between the first external thread and the internal thread and the dual function of fixing the fluorescence collecting lens 521, the vacuum sealing performance is improved, the assembly process is simplified, the assembly cost is reduced, and the rapid iteration requirements of cryogenic ion trap systems are met.

[0099] Figure 9 This is a flowchart of an assembly method for a cryogenic ion trap fluorescence collection system according to an embodiment of this application.

[0100] According to another embodiment of this application, such as Figure 9 As shown, an assembly method for a low-temperature ion trap fluorescence collection system is also provided, which is applied to the above-mentioned low-temperature ion trap fluorescence collection system. The assembly method includes the following steps S1 to S6.

[0101] Step S1: Install the body of the low-temperature ion trap onto the cold finger of the thermostat.

[0102] Before step S1, a pretreatment step is required. First, the main body, the second cylinder, and the fixing ring are ultrasonically cleaned to remove surface oil and impurities to ensure vacuum compatibility. Then, the fluorescence collecting lens is cleaned to prevent dust and other impurities from affecting optical performance.

[0103] Step S2: Attach the fluorescence collecting lens to the side of the second cylinder facing the multi-well electrodes.

[0104] In some embodiments, the fluorescence collecting lens is bonded to the side of the second cylinder facing the multi-well electrodes using epoxy resin. The bonding position of the fluorescence collecting lens is adjusted to ensure that the center of the fluorescence collecting lens coincides with the axis of the second cylinder. Then, it is placed in a room temperature environment for curing for 24 hours to ensure that it is firmly fixed, without gaps, and has stability suitable for low-temperature environments.

[0105] Step S3: Screw the fixing ring with the activated carbon ring into the first cylinder.

[0106] In some embodiments, the fixing ring with the activated carbon ring is slowly screwed into the first cylinder and embedded in the step of the internal thread to ensure that the fixing ring and the step fit tightly without loosening, so as to avoid affecting the cleanliness of the ion trapping area and to be suitable for low-temperature adsorption conditions.

[0107] Before step S4, a Gaussian reference beam system is set up, and the beam waist parameter of the reference beam is adjusted to ensure that the reference beam is incident from the top surface of the main body along the axis (e.g., Figure 2 As shown), parallel to the axis of the second cylinder, it serves as a reference for adjusting the focal length of the fluorescence collecting lens.

[0108] Step S4: Screw the second cylinder, which is equipped with a fluorescence collecting lens, into the first cylinder.

[0109] Step S5: Adjust the screwing depth of the second cylinder into the first cylinder to adjust the collimation of the reference light incident from the outside of the thermostat exiting the fluorescence collecting lens, and determine the amount of thermal shrinkage between the first and second cylinders. Then, adjust the screwing depth of the second cylinder through the positioning mark and the annular scale to compensate for the amount of thermal shrinkage.

[0110] In some embodiments, during the room temperature assembly stage, a Gaussian reference light system is incident on the fluorescence collecting lens. A CMOS camera monitors the collimation of the outgoing reference light, and the required axial displacement is calculated based on the collimation deviation. Then, the positioning mark is moved by a corresponding number of graduations by rotating the second cylinder until the optimal collimation is achieved, thus completing the precise setting of the focal length of the fluorescence collecting lens. In low-temperature environments, due to material thermal shrinkage (e.g., from 25°C to 4.5K), the axial dimensions of the first and second cylinders change, causing a shift in the focal position of the fluorescence collecting lens 521. The amount of thermal shrinkage from room temperature to low temperature (e.g., from 25°C to 4.5K) (e.g., 78 μm) is calculated using software (e.g., finite element software). During room temperature assembly, the second cylinder is rotated out by the corresponding number of graduations (e.g., 71 graduations, corresponding to 78.1 μm) to allow for thermal shrinkage. After cooling, the thermal shrinkage causes the second cylinder to automatically retract to the correct position, achieving thermal shrinkage compensation and preventing the positional shift of the fluorescence collecting lens due to thermal deformation, which would affect the fluorescence collection efficiency.

[0111] Step S6: Vacuum the thermostat using an external vacuum pump and cool it down to the target temperature using an external refrigeration unit.

[0112] In some embodiments, the vacuum equipment may be a molecular pump assembly.

[0113] In this implementation, while the thermostat is evacuated using external vacuum equipment, the cryogenic ion trap enclosure is heated to 80°C using a heater and vacuum-baked for 12 hours. Then, an external refrigerator is used to cool the thermostat to the target temperature (e.g., 4.5K) for vacuum testing, ensuring that the cryogenic ion trap enclosure can stably reach 4°C. -14 Torr-level vacuum. Simultaneously, fluorescence collection efficiency and stability are tested to ensure design requirements are met and adaptability to cryogenic conditions is maintained. The assembly method described above requires no complex equipment and is easily industrialized, making it widely applicable to various cryogenic ion trap systems, particularly suitable for large-scale quantum computing, quantum communication, and other scenarios with high requirements for vacuum performance and fluorescence collection stability.

[0114] Example 1

[0115] The main body is made of oxygen-free copper to withstand low temperatures and reduce thermal deformation. The base has a regular octagonal cross-section with a side-to-side distance of 40 mm and an axial length of 50 mm. A first cylindrical section with a bottom diameter of 28 mm and a height of 20 mm is located on the axial bottom surface of the base. The inner wall of the first cylindrical section has an internal thread with a major diameter of 24 mm. The distance between adjacent threads on the internal thread is 0.2 mm, and the thread spacing is uniform. The effective length of the internal thread along the axial direction of the first cylindrical section is 20 mm. An annular scale is located on the side of the first cylindrical section away from the base, comprising 180 equally divided angular graduations to provide an axial adjustment resolution of 1.1 μm. A laser path opening with a diameter of 16 mm and a numerical aperture of 0.6 is located on the axial top surface of the main body. The base is constructed as an octagonal prism, with five laser path openings (9 mm in diameter, 0.2 numerical aperture) pre-drilled on five of its faces. Two mounting openings for trap electrode holders are respectively formed on the first and second faces of the octagonal prism. An ion source target mounting opening (5 mm in diameter) is formed on the third face of the octagonal prism. All six laser path openings and the two trap electrode holder mounting openings are sealed with epoxy resin, while the ion source target mounting opening is sealed with indium gasket to ensure cryogenic vacuum sealing.

[0116] The retaining ring is made of oxygen-free copper, with an outer diameter of 24mm and a length of 2mm. A second external thread is provided circumferentially on the outer wall of the retaining ring. An oxygen-free copper mesh is bonded to the inner wall of the retaining ring using epoxy resin, and a 70 cubic millimeter volume high specific surface area activated carbon block is wrapped within the mesh. The end face of the retaining ring is polished to ensure a tight fit with the stepped area of ​​the internal thread, suitable for low-temperature adsorption conditions.

[0117] The second cylinder is made of oxygen-free copper to suit low-temperature operating conditions. The outer diameter of the second cylinder is 24mm, and its length is 20mm. The outer wall of the second cylinder has a first external thread along its circumference, which engages with the internal thread to form a spiral gas flow channel with a tolerance of 0.03mm. The distance between adjacent threads on the first external thread is 0.2mm, and the thread spacing is uniform. The inner diameter of the second cylinder is 22mm, allowing for the installation of a 15mm diameter aspherical fluorescence collecting lens with a focal length of 15mm and a numerical aperture of 0.39. The fluorescence collecting lens is bonded with epoxy resin and cured at room temperature (25±1℃) for 24 hours. A triangular positioning mark is laser-machined on the side of the second cylinder opposite the fluorescence collecting lens, aligned with the annular scale on the side of the first cylinder away from the base, for precise focal length adjustment and compensation for low-temperature thermal deformation.

[0118] The assembly method of this embodiment includes the following steps to adapt to changes in the physical properties of materials at low temperatures.

[0119] The first step is pretreatment. Clean the main body, second barrel, and retaining ring with anhydrous ethanol to remove surface oil and impurities, then dry them with nitrogen. Next, clean the aspherical fluorescence collecting lens with lens paper soaked in anhydrous ethanol to prevent dust residue.

[0120] The second step is to apply a layer of epoxy resin (0.1 mm thick) inside the second cylinder, embed the aspherical fluorescence collecting lens into the second cylinder, adjust the center of the aspherical fluorescence collecting lens to coincide with the axis of the second cylinder, and place it in a room temperature environment of 25°C for 24 hours to cure. After curing, check that the aspherical fluorescence collecting lens is not loose and has no gap with the bottom surface.

[0121] The third step is to slowly screw the fixing ring with the activated carbon ring into the first cylinder and embed it into the step of the internal thread. Press it with your hand until it fits tightly, ensuring there are no gaps or looseness.

[0122] The fourth step is to set up a Gaussian reference light system, adjust the reference light power to 0.2mW and the beam waist diameter to 5μm, so as to ensure that the reference light is parallel to the axis of the second cylinder and passes through the center of the multiple trap electrodes (i.e., the ion trapping region).

[0123] Fifth step: Screw the second cylinder, equipped with the aspherical fluorescence collecting lens, into the internal thread of the first cylinder. Slowly rotate the second cylinder until it reaches the approximate position. Every 10 scale increments (corresponding to an insertion depth of 11 μm) are rotated, and the collimation of the emitted reference light is monitored once with a CMOS camera. The scale adjustment can be reduced as it gets closer to the focal position of the aspherical fluorescence collecting lens until the divergence angle of the emitted reference light is less than 0.15 mrad. At this point, stop rotating to complete the focus adjustment.

[0124] The sixth step is to use software simulation (e.g., COMSOL) to calculate the thermal expansion and contraction of the first and second cylinders at the aligned center from room temperature (e.g., 25°C) to low temperature (e.g., 4.5K) as 78μm (to accommodate the deformation of low-temperature materials). Therefore, during assembly at room temperature, the second cylinder is rotated out by 71 more scales (corresponding to 78.1μm) to allow for shrinkage and achieve thermal shrinkage compensation.

[0125] Figure 10 This is a test diagram of the vacuum level inside a cryogenic ion trap according to one embodiment of this application.

[0126] Step 7: After assembly, vacuum seal the thermostat and perform a vacuum leak test (leakage rate ≤ 1e). -10(mbar·l / s). The external vacuum pump was activated to perform a room-temperature pre-evacuation and heat the cryogenic ion trap to 80°C for 12 consecutive hours. Then, an external refrigerator was used to lower the temperature inside the thermostat to 4.5K, ultimately achieving a vacuum level of 4e within the cryogenic ion trap. -14 Torr, such as Figure 10 As shown.

[0127] Finally, the stability of ion fluorescence collection was tested to determine the fluorescence collection efficiency.

[0128] After testing, this application has been found to be suitable for low-temperature operating conditions. It can maintain 4°C. -14 Torr's extremely high vacuum enables continuous collection of ion fluorescence without the need for calibration of a second chamber. This design achieves synergistic optimization of two key functions: extremely high vacuum and long-term stable ion fluorescence collection, meeting the requirements of long-term, large-scale quantum experiments.

[0129] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this application can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments and / or claims of this application can be combined and / or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application.

[0130] It should also be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of this application. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted where they may cause confusion in understanding this application, and the shapes and sizes of the components in the drawings do not reflect actual size and proportion, but only illustrate the content of the embodiments of this application.

[0131] Unless otherwise stated, the numerical parameters in this specification and the appended claims are approximate values ​​and can be varied according to desired characteristics derived from the content of this application. Specifically, all figures used in the specification and claims to indicate composition, reaction conditions, etc., should be understood to be modified by the term "about" in all cases. Generally, this means that a specific amount varies by ±10% in some embodiments, ±5% in some embodiments, ±1% in some embodiments, and ±0.5% in some embodiments.

[0132] The use of ordinal numbers such as "first," "second," "third," etc., in the specification and claims to modify the corresponding elements does not imply that the element has any ordinal number, nor does it represent the order of one element with another element, or the order of manufacturing methods. The use of these ordinal numbers is only to enable a named element to be clearly distinguished from another element with the same name.

[0133] Furthermore, unless specifically described or required to occur in a specific order, the order of the above steps is not limited to those listed above and can be varied or rearranged according to the desired design. Moreover, the above embodiments can be used in combination with each other or with other embodiments based on design and reliability considerations; that is, technical features from different embodiments can be freely combined to form more embodiments.

[0134] The embodiments of this application have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of this application. 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 this application 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 this application, and all such substitutions and modifications should fall within the scope of this application.

Claims

1. A low-temperature ion trap fluorescence collection system, characterized in that, include: Thermostat is configured to cool to the target temperature using an external refrigeration unit; The cold finger is located inside the thermostat; The cryogenic ion trap enclosure, located within a thermostat and positioned at the cold finger, comprises: The main body is configured to trap ions under the excitation of an external voltage and manipulate the quantum state of the ions under the irradiation of multiple laser beams incident from the outside. The ions emit fluorescence under the excitation of multiple laser beams. Fluorescence collection mechanism, suitable for collecting fluorescence; The main body includes: The base is set on the cold finger, and a receiving space is formed inside the base; The trap electrode assembly, disposed within the containment space, is configured to trap ions in the ion trapping region formed by the trap electrode assembly under the excitation of an external voltage. The first cylinder extends from the side of the base and communicates with the receiving space, and is suitable for accommodating the fluorescence collection mechanism; The inner wall of the first cylinder is provided with an internal thread, and the fluorescence collection mechanism includes: The second cylinder has a first external threaded part on its outer wall along the circumference, which is threaded to engage with the internal threaded part. The first external threaded part and the internal threaded part form a spiral continuous gas guiding channel to discharge the gas in the main body during the process of creating a vacuum environment in the thermostat. Furthermore, when a vacuum environment is provided in the low-temperature ion trap and the target temperature is reached in the low-temperature ion trap, the residual gas diffused from the thermostat into the main body is adsorbed to prevent the residual gas from entering the main body and colliding with the ions. A fluorescence collecting lens is disposed on the side of the second cylinder facing the trap electrode assembly to focus the fluorescence inside the first cylinder. The optical axis of the fluorescence collecting lens is aligned with the center of the ion trapping region. By determining the predetermined axial focal offset of the first and second cylinders as they cool from room temperature to the target temperature, the axial focal offset is converted into the number of rotations of the second cylinder according to the pitch and scale. A compensation distance is preset at the reference light collimation position during the room temperature assembly stage. After cooling to the target temperature, thermal shrinkage causes the focal point of the fluorescence collecting lens to automatically retract to the center of the ion trapping region, thus achieving thermal shrinkage compensation.

2. The low-temperature ion trap fluorescence collection system according to claim 1, characterized in that, The cryogenic ion trap package also includes: A retaining ring is located on the side of the second cylinder facing the trap electrode assembly. The outer wall of the retaining ring is provided with a second external thread portion along the circumferential direction to thread-mate with the internal thread portion. An activated carbon ring is disposed on the fixed ring to adsorb the residual gas when the low-temperature ion trap is in a vacuum environment and the target temperature is reached, so that the vacuum degree inside the low-temperature ion trap is lower than the vacuum degree inside the thermostat.

3. The low-temperature ion trap fluorescence collection system according to claim 1, characterized in that, The base is configured as a polygonal prism coaxial with the first cylindrical body, and the trap electrode assembly includes: Two trap electrode holders are respectively installed on two opposite facets of the polygonal prism; Multiple trap electrodes are connected between two trap electrode holders and configured to be electrically connected to an external power supply. The middle portion of the multiple trap electrodes forms the ion trapping region. The multiple trap electrodes are configured to trap the ions in the ion trapping region under the excitation of the external voltage.

4. The low-temperature ion trap fluorescence collection system according to claim 3, characterized in that, The polygonal prism is an octagonal prism, and the two well electrode holders are respectively mounted on the first and second faces of the octagonal prism. The main body also includes: An ion source target is disposed on the third face of the octagonal prism, and the line connecting the ion source target and the ion trapping region is orthogonal to the multiple trap electrodes. The ion source target is configured to generate ions under the excitation of multiple externally incident laser beams. Multiple light guides are respectively disposed on other facets of the octagonal prism to allow multiple externally incident laser beams to irradiate the ion trapping region.

5. The low-temperature ion trap fluorescence collection system according to claim 1, characterized in that, The distance between adjacent threads on the first external thread portion and the distance between adjacent threads on the internal thread portion are both 0.17mm~0.23mm.

6. The low-temperature ion trap fluorescence collection system according to claim 1, characterized in that, The cross-section of the gas guide channel has a radial dimension of 0.1 mm.

7. The low-temperature ion trap fluorescence collection system according to claim 1, characterized in that, The second cylinder has a positioning mark on its side opposite to the fluorescence collecting lens, and the first cylinder has an annular scale on its side away from the base, so that the screwing depth of the second cylinder can be adjusted by the positioning mark and the annular scale after the second cylinder is screwed into the first cylinder.

8. A method for assembling a cryogenic ion trap fluorescence collection system, applied to the cryogenic ion trap fluorescence collection system according to any one of claims 1-7, characterized in that, The assembly method includes: The main body encased in the low-temperature ion trap is mounted on the cold finger of the thermostat; The fluorescence collecting lens is bonded to the side of the second cylinder facing the multiple trap electrodes; Screw the retaining ring, which is fitted with activated carbon rings, into the first cylinder; Screw the second cylinder, on which the fluorescence collecting lens is installed, into the first cylinder; By adjusting the screwing depth of the second cylinder into the first cylinder, the collimation of the reference light incident from the outside of the thermostat exiting the fluorescence collecting lens is adjusted, and the amount of heat shrinkage between the first cylinder and the second cylinder is determined. Then, the screwing depth of the second cylinder is adjusted by the positioning mark and the annular scale to compensate for the amount of heat shrinkage. The thermostat is evacuated using an external vacuum pump, and the temperature inside the thermostat is cooled to the target temperature using an external refrigeration unit.

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