Josephson junctions, quantum devices, and computing devices for quantum devices

Abstract

This invention relates to the field of manufacturing qubits and superconducting devices for quantum computers, and more specifically, to systems based on thin-film Josephson junctions, which can be used after manufacturing to fine-tune the resonant frequency of superconducting qubits containing thin-film Josephson junctions, such as tunable or fixed-frequency qubits, and low-temperature Josephson parametric amplifiers. The essence of this invention is a method for manufacturing superconducting qubits using focused ion beam annealing, comprising manufacturing a thin-film aluminum / alumina / aluminum Josephson junction (2) connected to two plates of a capacitor (3) on a substrate (8); and treating the superconducting qubit (1) by annealing the thin-film aluminum / alumina / aluminum Josephson junction (2). The superconducting qubit (1) is annealed with a Gaussian focused ion beam (13) by localizing the properties of the thin-film aluminum / alumina / aluminum Josephson junction (3). The technical achievement of this invention is to improve the repeatability of resonant frequency tuning for any type of superconducting qubit and to reduce the labor intensity and cost of manufacturing superconducting qubits and superconducting devices for quantum computers.

Description

[0001] This application is a divisional application of Chinese National Application No. 2024800507677, filed on July 24, 2024, entitled "Method for Manufacturing Superconducting Quantum Bits by Focused Ion Beam Annealing".

[0002] The proposed invention relates to the fabrication of superconducting qubits and superconducting devices for quantum computers, particularly systems based on thin-film Josephson junctions, and can be used to precisely tune the resonant frequency of superconducting qubits composed of thin-film Josephson junctions after fabrication, such as frequency-tunable or fixed-frequency superconducting qubits, as well as low-temperature Josephson parametric amplifiers.

[0003] One existing method for annealing superconducting qubits involves placing an irradiation antenna directly over first and second thin-film Josephson junctions comprising the superconducting qubits, exposing the thin-film Josephson junctions to thermal shock from electromagnetic waves emitted from the irradiation antenna, and then moving the antenna to the next thin-film Josephson junction. This is known in US 11,050,009 B2, published June 29, 2021.

[0004] Its disadvantages include the need for additional equipment, including an illumination antenna, to anneal superconducting qubits. Due to the fixed size of the equipment, a new device needs to be fabricated for each new topology of superconducting qubits, limiting the flexibility of the superconducting qubit manufacturing process and leading to increased costs.

[0005] Another existing method for annealing superconducting qubits involves forming multiple superconducting qubits on a chip, determining an initial frequency for each superconducting qubit, and annealing the Josephson junction comprising the superconducting qubits. This is known in patent US 2019 / 0165244 A1, published May 30, 2019.

[0006] Its disadvantages include the fact that, due to the large contact points, it is impossible to place superconducting qubits close together on a chip, which limits the scalability of superconducting qubit circuits. Another disadvantage is the low discreteness of the energy values ​​used in superconducting qubit annealing, which makes it impossible to adjust the resonant frequency of superconducting qubits over a wide range.

[0007] Another method for laser thermal annealing of superconducting qubits involves treating a thin-film Josephson junction with a 532 nm laser. This method involves fabricating a thin-film Al / AlOx / Al Josephson junction on a substrate connected to two capacitor plates, and then annealing the Al / AlOx / Al Josephson junction with a laser that produces a Gaussian beam with a diameter of 20 μm. This is known in US Patent 10,424,713 B2, published September 24, 2019. This method can be considered the closest prior art to the proposed solution.

[0008] The drawbacks include the fact that during the laser annealing of superconducting qubits by processing thin-film Josephson junctions, the laser Gaussian beam has contact points comparable in size to the superconducting qubit, making it impossible to process the thin-film Josephson junction without affecting the substrate. This results in low repeatability of tuning the resonant frequency of the superconducting qubit. Another drawback is that laser annealing of thin-film Josephson junctions is only applicable to sparsely spaced thin-film Josephson junctions because the temperature gradient caused by the large contact points makes it impossible to process closely spaced thin-film Josephson junctions with the same energy. Therefore, the method does not allow tuning the resonant frequency of tunable superconducting qubits, and is only applicable to superconducting qubits with fixed frequencies. This leads to more stringent requirements for superconducting qubit fabrication, resulting in longer pipelines due to the need for additional cleaning stages, ultimately increasing the manufacturing cost.

[0009] The purpose of this invention is to improve the repeatability of tuning the resonant frequency of any type of superconducting quantum bit, and to reduce the labor intensity and cost of the production line for manufacturing superconducting quantum bits and superconducting devices for quantum computers.

[0010] The objective of this invention is achieved through a method for fabricating superconducting qubits using focused ion beam annealing. This method involves fabricating a thin-film Al / AlOx / Al Josephson junction connected to two capacitor plates on a substrate, and processing the superconducting qubit by annealing the thin-film Al / AlOx / Al Josephson junction, wherein the annealing is performed by locally altering the properties of the thin-film Al / AlOx / Al Josephson junction using a Gaussian focused ion beam.

[0011] According to an exemplary embodiment, the capacitor plate is made of aluminum, niobium, tantalum, or molybdenum.

[0012] According to an exemplary embodiment, the Gaussian focused ion beam is formed from helium ions, neon ions, gallium ions, gold ions, or silicon ions.

[0013] According to an exemplary embodiment, the superconducting qubit is processed by annealing a thin-film Al / AlOx / Al Josephson junction with a focused ion beam, which is performed by a Gaussian focused ion beam with a diameter of 0.3 to 30 nm.

[0014] According to an exemplary embodiment, superconducting qubits are processed by annealing a thin-film Al / AlOx / Al Josephson junction with a focused ion beam, thereby locally altering the properties of the thin-film Al / AlOx / Al Josephson junction by the focused ion beam.

[0015] According to an exemplary embodiment, when a superconducting quantum bit is processed by a focused ion beam annealed thin film Al / AlOx / Al Josephson junction, the penetration depth of charged particles in the volume of the thin film Al / AlOx / Al Josephson junction is determined by a 1×10⁻⁶ m / s² annealing process. 11 Up to 5×10 14 ions / cm 2 The radiation dose can be adjusted within a certain range.

[0016] According to an exemplary embodiment, when a superconducting quantum bit is processed by annealing a thin film Al / AlOx / Al Josephson junction with a focused ion beam, the beam is applied directly to the region of the thin film Al / AlOx / Al Josephson junction without heating the substrate.

[0017] According to an exemplary embodiment, when a superconducting quantum bit is processed by a focused ion beam annealing thin film Al / AlOx / Al Josephson junction, the beam is applied to the region of the thin film Al / AlOx / Al Josephson junction and the substrate.

[0018] According to an exemplary embodiment, when a superconducting quantum bit is processed by a focused ion beam annealing thin film Al / AlOx / Al Josephson junction, the area of ​​the processed region corresponds exactly to the area of ​​the thin film Al / AlOx / Al Josephson junction.

[0019] According to an exemplary embodiment, when a superconducting quantum bit is processed by a focused ion beam annealing thin film Al / AlOx / Al Josephson junction, the designated area of ​​the processed region is larger than the area of ​​the thin film Al / AlOx / Al Josephson junction.

[0020] According to an exemplary embodiment, when a superconducting quantum bit is processed by a focused ion beam annealed thin film Al / AlOx / Al Josephson junction, the shape of the processing region of the thin film Al / AlOx / Al Josephson junction is specified by a polygon, including simple and complex shapes.

[0021] According to an exemplary embodiment, when a superconducting quantum bit is processed by a focused ion beam annealed thin film Al / AlOx / Al Josephson junction, the energy of the charged particles applied to the thin film Al / AlOx / Al Josephson junction is specified for each processed region.

[0022] According to an exemplary embodiment, when processing fixed-frequency and frequency-tunable superconducting qubits, each thin-film Al / AlOx / Al Josephson junction in the superconducting qubit is processed independently and is not affected by the cross-interaction of adjacent thin-film Al / AlOx / Al Josephson junctions.

[0023] Figure 1 Circuits for (a) a fixed-frequency superconducting quantum bit, (b) a frequency-tunable superconducting quantum bit, and (c) a magnetic flux quantum bit are shown. According to a preferred embodiment, the superconducting quantum bit consists of one or more thin-film Josephson junctions and parallel capacitors. The Josephson junctions and capacitors can be capacitively coupled to a readout line and a ground plane.

[0024] Figure 2 The topology of a thin-film Al / AlOx / Al Josephson junction connected to two capacitor plates and a ground plane is shown. According to a preferred embodiment, the processing region is larger than the area of ​​the Josephson junction. However, alternatively, the area of ​​the processing region can be exactly the same as the area of ​​the Josephson junction.

[0025] Figure 3 The cross-section of the Josephson junction is shown when the thin-film Al / AlOx / Al Josephson junction is treated with a Gaussian focused ion beam. It should be noted that the size of the contact point is much smaller than the characteristic dimensions of the thin-film Josephson junction. According to a preferred embodiment, the penetration depth of charged particles is greater than the metal thickness of the upper electrode and the tunnel barrier. However, alternatively, the penetration depth of charged particles can be less than or exactly equal to the metal thickness of the upper electrode and the tunnel barrier.

[0026] Figure 4 A simplified diagram of a scanning helium ion microscope is shown for ion annealing of superconducting qubits, which can produce focused ion beams with a diameter of less than 30 nm.

[0027] Methods involving the fabrication of superconducting qubits using focused ion beam annealing (see...) Figure 1 Superconducting qubits can be fabricated using many known techniques. Two examples include 1) a subtraction process based on a three-layer thin-film Josephson junction and 2) a process based on a Dolan bridge. The following description uses a Dolan bridge-based process for fabricating superconducting qubits as an example.

[0028] On board 8 (see) Figure 2 , Figure 3The superconducting quantum bit 1 is formed from silicon, sapphire, or magnesium oxide, with a diameter between 25 mm and 300 mm and a thickness between 430 μm and 650 μm. It is fabricated using electron beam lithography and shadow evaporation on a thin-film Al / AlOx / Al or Nb-Al2O3-Nb Josephson junction 2. The lower thin-film electrode 9 has a thickness of 15-25 nm, the upper thin-film electrode 10 has a thickness of 35-60 nm, and the alumina tunnel barrier 12 has a thickness of 0.1-10 nm. In this process, the thin-film Josephson junction 2 is located between capacitor plates 3, and it can be capacitively coupled to line 7 via capacitor 6 or to ground plane 4 via capacitor 5. The layout and geometry of the superconducting quantum bit 1 are selected based on modeling and design data. According to an exemplary embodiment, the capacitance of capacitor 3 is in the range of 0.1 fF to 200 fF. According to an exemplary embodiment of the superconducting quantum bit 1, the critical current of the thin-film Josephson junction 2 is in the range of 10 nA to 100 nA. According to the Ambegaokar-Baratoff relation, the critical current is related to the room-temperature resistance of the thin-film Josephson junction 2. Specifically, this relation predicts that the resistance of the thin-film Josephson junction 2 before transitioning to a superconducting state is inversely proportional to the critical current after the transition. The fabrication process of the transport qubit is described below with an example.

[0029] According to an exemplary embodiment of the superconducting quantum bit 1, two resistive masks are formed on the surface of a substrate 8, the lower layer of which can be made of methyl methacrylate (MMA) copolymer and the upper, thinner layer of which can be made of polymethyl methacrylate (PMMA). Next, electron beam lithography is performed to form the geometry of a thin-film Josephson junction 2 within the two resistive masks. Then, the resistive mask regions exposed to the electron beam are removed in a 1:3 solution of methyl isobutyl ketone:isopropanol (MIBK:IPA). The MMA layer is more sensitive to the electron beam, which makes it possible to form a suspension bridge (also known as a Dolan bridge) made of PMMA. Next, the sample is placed in an electron beam evaporation unit, and aluminum is evaporated at two different angles through pre-formed holes in the resistive masks, with intermediate oxidation performed in an argon atmosphere between the aluminum evaporation stages. After evaporation, a thin-film Josephson junction 2 is formed in the region of the Dolan suspension bridge (see...). Figure 3 Then, by immersing the sample in N-methyl-2-pyrrolidone (NMP), the remaining resist material and unwanted metal are removed. This basic fabrication process can be used with other additional fabrication steps, such as plasma-enhanced chemical vapor deposition (PECVD), photolithography, and plasma and wet etching, to fabricate more complex devices. Next, the scanning helium ion microscope is locally modified (see [link to image]). Figure 4 The thin-film Josephson node 2 in chamber 15 of the cavity (see) Figure 3 The superconducting quantum bit 1 was annealed using a Gaussian focused ion beam 13 to utilize the properties of the superconducting quantum bit 1.

[0030] According to an exemplary embodiment, the capacitor plate 3 is made of aluminum, niobium, tantalum or molybdenum, the film thickness is 80 nm to 130 nm, and the feature size of the capacitor plate 3 is 1 μm to 500 μm.

[0031] According to an exemplary embodiment, the Gaussian focused ion beam 13 is formed from helium ions, neon ions, gallium ions, gold ions, or silicon ions, and the energy of the focused ion beam is from 10 keV to 30 keV.

[0032] According to an exemplary embodiment, the processing of superconducting qubit 1 using focused ion beam annealing of thin film Al / AlOx / Al Josephson junction 2 is performed by a Gaussian focused ion beam 13 with a diameter of 0.3 to 30 nm, wherein the diameter of the Gaussian focused ion beam 13 is adjusted by changing the diameter of the hole mounted in the electron optical column of a scanning helium ion microscope 16.

[0033] For example, thin-film Al / AlOx / Al Josephson junctions can be used with focused He. + and Ne + The focused ion beam 13 is used for processing, with beam energies between 10 keV and 30 keV and beam diameters between 3 nm and 15 nm. For a given aperture of the scanning helium ion microscope 16, variations in the diameter of the focused ion beam 13 can be indicated by variations in the focused ion beam current. For example, a 70 μm aperture corresponds to a focused ion beam current of 1.5 pA and a beam diameter of 15 nm, while a 5 μm aperture corresponds to a beam current of 0.2 pA and a beam diameter of 3 nm. The region processed by the focused ion beam 11 can be specified by a processing topology in a compiled electronic format. For example, for each thin-film Al / AlOx / Al Josephson junction 2, the area of ​​the processed region 11 can be equal to 5 × 5 μm, where the focused ion beam 13 will affect both the Josephson junction region 2 and the silicon substrate 8.

[0034] When the thin-film Josephson junction 2 is treated with a high-energy focused ion beam 13, the room-temperature resistance (Ro) of the Josephson junction 2 can be observed. N The increase in R is likely due to localized structural changes in the thin-film Josephson junction 2 caused by heating with the focused ion beam 3. Reducing the diameter (current) of the focused ion beam 13 can decrease R. N The range of the spread values. For example, for a focused ion beam 13 with a diameter of 8 nm (current: 0.6 pA), R NThe spread range can correspond to 8.3%; while for a beam with a diameter of 3 nm (current: 0.2 pA), it can correspond to 3.5%. Furthermore, the spread range can be reduced by decreasing the energy of the focused ion beam, which can be explained by reducing the degree of damage to the substrate due to the reduced number of back-reflected ions. For a beam with an energy of 30 keV, the spread range can be 15%; while for a beam with an energy of 10 keV, it can be 10%. According to embodiments, the energy, the diameter of the focused ion beam, and the room temperature resistance offset can be tested and determined with high processing accuracy under a given set of conditions.

[0035] According to an exemplary embodiment, the superconducting quantum bit 1 is processed by annealing the thin film Al / AlOx / Al Josephson junction 2 with a focused ion beam 13, thereby locally altering the properties of the thin film Al / AlOx / Al Josephson junction 2 using the focused beam 13. For example, the structure of the thin film Al / AlOx / Al Josephson junction 2 is then locally heated with phonons formed due to inelastic collisions between ions from the primary beam and atoms in the thin film Josephson junction structure, or holes are subsequently formed in the tunnel barrier structure of the Josephson junction using Al2O312.

[0036] According to an exemplary embodiment, when the superconducting quantum bit 1 is processed by annealing the thin film Al / AlOx / Al Josephson junction 2 with a focused ion beam 13, the 1×10 11 ions / cm 2 Up to 5×10 14 ions / cm 2 By varying the irradiation dose within a range of 0.5 μs to 50 μs, increasing the scan time at each point within a range of 0.5 μs to 50 μs, and changing the scan step size within a range of 20 nm to 0.5 nm, the penetration depth of charged particles 14 in the Al / AlOx / Al Josephson junction 2 volume of the thin film was adjusted within a range of 20 nm to 70 nm.

[0037] For example, thin-film Al / AlOx / Al Josephson junctions can be used with focused He. + and Ne + Beam 13 is used for treatment, and given a fixed area of ​​treatment region 11, the irradiation dose is 1×10⁻⁶. 11 ions / cm 2 Up to 5×10 14 ions / cm 2The area processed by the focused ion beam 11 can vary within a range. The processing topology can be specified by compiling an electronic format. The area of ​​the processing region 11 for each thin-film Al / AlOx / Al Josephson junction 2 can be exactly the same as its area. For example, the thin-film Josephson junction 2 can be processed in chamber 15 of the OrionNanoFab scanning helium ion microscope 16 with a beam energy of 10 keV and an ion beam current of 0.2 pA. However, other ion optics systems with different focused ion beam parameters can be used to achieve the optimal frequency shift parameters for the superconducting qubit.

[0038] When the irradiation dose of the focused ion beam changes (e.g., at 0.02 × 10⁻⁶), 13 ions / cm 2 Up to 7.90×10 13 ions / cm 2 When changing within the range), for the focused Ne + A focused beam can smoothly increase the room-temperature resistivity of thin-film Al / AlOx / Al Josephson junctions in the range of 1% to 40%; or for focused He... + The beam smoothly increases the room temperature resistivity of the thin film Al / AlOx / Al Josephson junction 2 within the range of 1% to 25%. For example, when the irradiation dose is less than 4 × 10⁻⁶, the resistance is increased. 13 ions / cm 2 When the focused ion beam 13 is used to process the thin film Al / AlOx / Al Josephson junction 2, the resonant frequency of the superconducting quantum bit 1 can be controllably changed in the range of 50 MHz to 100 MHz; while the irradiation dose is greater than 4 × 10⁻⁶ MHz, the resonant frequency of the superconducting quantum bit 1 can be controllably changed. 13 ions / cm 2 At this time, the resonant frequency of superconducting quantum bit 1 can vary in the range of 100 MHz to 400 MHz.

[0039] According to an exemplary embodiment, when the superconducting quantum bit 1 is treated by annealing the thin film Al / AlOx / Al Josephson junction 2 with a focused ion beam 13, the beam 13 is applied directly to the region of the thin film Al / AlOx / Al Josephson junction 2 without heating the substrate 8.

[0040] According to an exemplary embodiment, when the superconducting qubit 1 is treated by annealing the thin film Al / AlOx / Al Josephson junction 2 with a focused ion beam 13, the beam 13 is applied to the region of the thin film Al / AlOx / Al Josephson junction 2 and the substrate 8.

[0041] According to an exemplary embodiment, when the superconducting quantum bit 1 is treated by annealing the thin film Al / AlOx / Al Josephson junction 2 with a focused ion beam 13, the area of ​​the treated region 11 corresponds exactly to the area of ​​the thin film Al / AlOx / Al Josephson junction 2, and the range is 0.01 μm.2 up to 1μm 2 .

[0042] According to an exemplary embodiment, when the superconducting quantum bit 1 is treated by annealing the thin film Al / AlOx / Al Josephson junction 2 with a focused ion beam 13, the designated area of ​​the treatment region 11 is larger than the area of ​​the thin film Al / AlOx / Al Josephson junction 2, by a range of 1 μm. 2 Up to 100μm 2 .

[0043] According to an exemplary embodiment, when the superconducting quantum bit 1 is processed by annealing the thin film Al / AlOx / Al Josephson junction 2 with a focused ion beam 13, the shape of the processing region 11 of the thin film Al / AlOx / Al Josephson junction 2 is specified by a polygon, including simple and complex shapes, such as rectangles, circles, ellipses, or polygons whose shapes completely follow the shape of the thin film Al / AlOx / Al Josephson junction 2.

[0044] According to an exemplary embodiment, when the superconducting qubit 1 is processed by annealing the thin film Al / AlOx / Al Josephson junction 2 with a focused ion beam 13, polygons are formed in each region of the thin film Al / AlOx / Al Josephson junction 2, and the energy of the charged particles applied to the thin film Al / AlOx / Al Josephson junction 2 is specified to be 1×10⁻⁶ for each processing region 11. 11 ions / cm 2 Up to 5×10 14 ions / cm 2 Within the range.

[0045] According to an exemplary embodiment, when processing a fixed-frequency and frequency-tunable superconducting quantum bit 1, each thin-film Al / AlOx / Al Josephson junction 2 in the superconducting quantum bit 1 is processed independently by setting the processing region 11 and the energy of charged particles for each thin-film Al / AlOx / Al Josephson junction 2, without being affected by the cross-influence of adjacent thin-film Al / AlOx / Al Josephson junction 2.

[0046] For example, fixed-frequency and frequency-tunable transport qubits can be generated using a focused Ne wave with an energy of 10 keV and a beam current of 0.2 pA. +The transport qubit can be processed using a focused ion beam. For example, a transport qubit can be fixed at a frequency of 4.2 GHz with a relaxation time of 370 μs. This qubit can be processed and recharacterized using a focused ion beam, resulting in a resonant frequency of 4.1 GHz and a relaxation time of 340 μs. For example, a second fixed-frequency transport qubit with a resonant frequency of 4.52 GHz and a relaxation time of 159 μs can be processed with a more exposed focused ion beam, resulting in a frequency of 4.38 GHz and a relaxation time of 320 μs. The increase in relaxation time may be due to the widening gap between the qubit's resonant frequency and the TLS defect frequency. Furthermore, for example, frequency-tunable transport qubits can be processed using a focused neon ion beam. For example, their resonant frequencies before processing could be 4.85 and 4.66 GHz. The thin-film Josephson junction, comprising each frequency-tunable superconducting qubit, can be processed independently using a focused ion beam without cross-exposure. After processing, the final resonant frequencies of these superconducting qubits could be equal to 4.74 GHz and 4.57 GHz. The final frequency of a superconducting quantum bit can be determined to be suitable for current quantum applications, therefore the superconducting quantum bit can be fixed at this frequency.

[0047] In a method for fabricating superconducting qubits with focused ion beam annealing, the method involves fabricating a thin-film Al / AlOx / Al Josephson junction 2 connected to two capacitor plates 3 on a substrate 8, and treating the superconducting qubit 1 by annealing the thin-film Al / AlOx / Al Josephson junction 2. The fact that the properties of the thin-film Al / AlOx / Al Josephson junction 2 are locally altered by annealing with a Gaussian focused ion beam 13 improves the repeatability of tuning the resonant frequency of any type of superconducting qubit 1 and reduces the labor intensity and cost of the pipeline for fabricating the superconducting qubit 1. This is achieved by specifically confining the processing region 11 to a region of the thin-film Al / AlOx / Al Josephson junction 2, resulting in the individual processing of closely spaced thin-film Al / AlOx / Al Josephson junction 2 with the same and different energies, allowing for group processing of closely spaced thin-film Al / AlOx / Al Josephson junction 2, and reducing the fabrication quality requirements of the superconducting qubit 1.

[0048] The fact that capacitor plate 3 can be made of aluminum, niobium, tantalum or molybdenum means that the ion annealing of thin film Al / AlOx / Al Josephson junction 2 can be performed by any process pipeline used to manufacture superconducting qubit 1, which increases the flexibility of the manufacturing process of superconducting qubit 1 and thus improves the manufacturing quality of superconducting qubit.

[0049] The fact that the Gaussian focused ion beam 13 is formed by helium ions, neon ions, gallium ions, gold ions, or silicon ions allows the diameter of the focused beam 13 to be varied in the range of 30 nm to 0.3 nm during the ion annealing process of the thin film Al / AlOx / Al Josephson junction 2. This allows for adjustment of the diameter of the contact point of the focused beam 13, as well as the degree of amorphization of the structure of the thin film Al / AlOx / Al Josephson junction 2, thereby improving the repeatability of tuning the resonant frequency of any type of superconducting quantum bit 1.

[0050] The superconducting qubit 1 is processed by annealing the thin film Al / AlOx / Al Josephson junction 2 with a focused ion beam 13, which is performed by a Gaussian focused ion beam 13 with a diameter ranging from 0.3 to 30 nm. This fact means that the contact point of the focused beam 13 during the ion annealing of the thin film Al / AlOx / Al Josephson junction 2 can be reduced to 1 nm. This allows the target energy to be transferred from the beam 13 to the atoms of the thin film Al / AlOx / Al Josephson junction 2, thereby improving the repeatability of tuning the resonant frequency of any type of superconducting qubit 1.

[0051] The superconducting quantum bit 1 is treated by annealing the thin film Al / AlOx / Al Josephson junction 2 with a focused ion beam 13. This locally alters the properties of the thin film Al / AlOx / Al Josephson junction 2 with a focused ion beam 13. This fact increases or decreases the room temperature resistance of the thin film Al / AlOx / Al Josephson junction 2, thereby decreasing or increasing the resonant frequency of the superconducting quantum bit 1, and consequently reducing the manufacturing quality requirements of the superconducting quantum bit 1.

[0052] When superconducting qubit 1 is processed by annealing thin film Al / AlOx / Al Josephson junction 2 with focused ion beam 13, the penetration depth of charged particle 14 in thin film Al / AlOx / Al Josephson junction 2 is adjusted by 1×10 11 Up to 5×10 14 ions / cm 2 The room temperature resistance of the thin film Al / AlOx / Al Josephson junction 2 can be adjusted by changing the irradiation dose within a range of 1% to 40%, thereby allowing the resonant frequency of the superconducting quantum bit 1 to vary within a range of 50 MHz to 600 MHz. As a result, the manufacturing quality requirements for the superconducting quantum bit 1 are reduced.

[0053] When the superconducting quantum bit 1 is processed by annealing the thin film Al / AlOx / Al Josephson junction 2 with a focused ion beam 13, the beam 13 is applied directly to the region of the thin film Al / AlOx / Al Josephson junction 2 without heating the substrate 8. This fact ensures that the ion annealing does not cause any changes to the structure of the substrate 8, thereby minimizing defects in the substrate 8-capacitor 3 interface and improving the manufacturing quality of the superconducting quantum bit 1.

[0054] When superconducting qubit 1 is annealed with a focused ion beam 13 to the thin film Al / AlOx / Al Josephson junction 2, the beam 13 is applied to the region of the thin film Al / AlOx / Al Josephson junction 2 and the substrate 8. This fact causes the region of the thin film Al / AlOx / Al Josephson junction 2 to be heated directly due to the interaction with the focused ion beam 13 and indirectly due to the cross heating of the substrate 8, thus providing a greater thermal influence on the region with the thin film Al / AlOx / Al Josephson junction 2, resulting in an expanded resonant frequency tuning range of superconducting qubit 1.

[0055] When the superconducting quantum bit 1 is processed by annealing the thin film Al / AlOx / Al Josephson junction 2 with a focused ion beam 13, the area of ​​the processed region 11 corresponds exactly to the area of ​​the thin film Al / AlOx / Al Josephson junction 2. This fact means that the ion annealing of each thin film Al / AlOx / Al Josephson junction 2 can be performed individually with individually set parameters. This allows the irreproducibility of the electrical parameters of the thin film Al / AlOx / Al Josephson junction 2, including the frequency-tunable superconducting quantum bit 1, to be eliminated by ion annealing, thereby reducing the manufacturing quality requirements for the superconducting quantum bit.

[0056] When superconducting qubit 1 is processed by annealing thin film Al / AlOx / Al Josephson junction 2 with focused ion beam 13, the designated area of ​​the processing region 11 is larger than the area of ​​thin film Al / AlOx / Al Josephson junction 2. This fact allows multiple thin film Al / AlOx / Al Josephson junction 2 containing frequency-tunable superconducting qubit 1 to be processed together with the same focused beam 13 energy. This minimizes the positioning error when moving between adjacent thin film Al / AlOx / Al Josephson junction 2, thereby improving the accuracy of tuning the resonant frequency of any type of superconducting qubit 1.

[0057] When superconducting qubit 1 is processed by annealing thin film Al / AlOx / Al Josephson junction 2 with focused ion beam 13, the shape of the processed region 11 of thin film Al / AlOx / Al Josephson junction 2 is specified by polygons of simple and complex shapes. This fact provides a finite interaction region between the interface of focused beam 13 and superconducting qubit 1, thereby minimizing the number of defects in the volume of thin film Al / AlOx / Al Josephson junction 2 caused by thermal shock, resulting in improved fabrication quality of superconducting qubit 1.

[0058] When the superconducting quantum bit 1 is processed by annealing the thin film Al / AlOx / Al Josephson junction 2 with a focused ion beam 13, the energy of the charged particles applied to the thin film Al / AlOx / Al Josephson junction 2 is specified for each processing region 11. This fact means that for each thin film Al / AlOx / Al Josephson junction 2, the number of charged particles (including charged particles reaching the tunnel barrier of Josephson junction 12 and charged particles slowed down in the upper thin film aluminum electrode 10) is controlled, thereby allowing the number of hole-type defects appearing in the volume of the thin film Al / AlOx / Al Josephson junction 2 to be monitored during the ion annealing of the thin film Al / AlOx / Al Josephson junction 2, resulting in improved fabrication quality of the superconducting quantum bit 1.

[0059] When processing both fixed-frequency and frequency-tunable superconducting qubit 1, each thin-film Al / AlOx / Al Josephson junction 2 in superconducting qubit 1 is processed independently, unaffected by the cross-influence of adjacent thin-film Al / AlOx / Al Josephson junction 2. This fact allows multiple thin-film Al / AlOx / Al Josephson junction 2 containing frequency-tunable superconducting qubit 1 to be processed with the same and different energies, enabling the asymmetry of superconducting qubit 1 to be considered during ion annealing, thereby improving the repeatability of tuning the resonant frequency of any type of superconducting qubit 1.

Claims

1. A Josephson junction for quantum devices, characterized in that, The Josephson junction is a thin film Al / AlO on a substrate (8). x / Al Josephson junction (2), the Josephson junction being connected to at least two capacitor plates (3), wherein the Josephson junction (2) is generated by annealing using a Gaussian focused ion beam (13), thereby locally altering the properties of the Josephson junction (2).

2. The Josephson knot according to claim 1, characterized in that, The capacitor plate (3) is made of aluminum, niobium, tantalum or molybdenum.

3. The Josephson knot according to claim 1, characterized in that, The Gaussian focused ion beam (13) is formed from helium ions, neon ions, gallium ions, gold ions or silicon ions.

4. The Josephson knot according to claim 3, characterized in that, The diameter of the selected Gaussian focused ion beam (13) is 0.3 to 30 nm.

5. The Josephson knot according to any one of claims 3 or 4, characterized in that, The selected irradiation dose is 1×10 11 Up to 5×10 14 ions / cm 2 Within the range.

6. The Josephson knot according to any one of claims 1-4, characterized in that, During the fabrication of the Josephson junction (2), the substrate (8) is not exposed to the Gaussian focused ion beam (13).

7. The Josephson knot according to claim 6, characterized in that, During the manufacturing process of the Josephson junction (2), the area of ​​the processing region (11) is exactly the same as the area of ​​the Josephson junction (2).

8. The Josephson knot according to claim 5, characterized in that, During the fabrication of the Josephson junction (2), the substrate (8) is not exposed to the Gaussian focused ion beam (13).

9. The Josephson knot according to claim 8, characterized in that, During the manufacturing process of the Josephson junction (2), the area of ​​the processing region (11) is exactly the same as the area of ​​the Josephson junction (2).

10. The Josephson knot according to any one of claims 1-4, characterized in that, During the fabrication of the Josephson junction (2), both the region of the Josephson junction (2) and the substrate (8) are exposed to the Gaussian focused ion beam (13).

11. The Josephson knot according to claim 10, characterized in that, During the manufacturing process of the Josephson junction (2), the area of ​​the processing region (11) is larger than the area of ​​the Josephson junction (2).

12. The Josephson knot according to claim 5, characterized in that, During the fabrication of the Josephson junction (2), both the region of the Josephson junction (2) and the substrate (8) are exposed to the Gaussian focused ion beam (13).

13. The Josephson knot according to claim 12, characterized in that, During the manufacturing process of the Josephson junction (2), the area of ​​the processing region (11) is larger than the area of ​​the Josephson junction (2).

14. The Josephson knot according to any one of claims 1-4, characterized in that, During the manufacturing process of the Josephson junction (2), the shape of the processing area (11) is specified by a simple polygon and / or a complex polygon.

15. The Josephson knot according to claim 5, characterized in that, During the manufacturing process of the Josephson junction (2), the shape of the processing area (11) is specified by a simple polygon and / or a complex polygon.

16. A quantum device comprising a plurality of Josephson junctions according to any one of claims 1-15.

17. The quantum device according to claim 16, characterized in that, Each of its constituent Al / AlO films x / Al Josephson junctions (2) are all treated, without being affected by the Al / AlO film from the adjacent film. x Cross-influence of / Al Josephson knot (2).

18. A computing device comprising a plurality of quantum devices according to any one of claims 16 or 17.

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