Superconducting quantum circuit and resonant frequency adjusting method

Abstract

The invention provides a superconducting quantum circuit and a resonant frequency adjusting method. The superconducting quantum circuit comprises quantum bits; and a read circuit coupled with the qubit, the read circuit comprising a resonator provided with a resonant frequency regulator, where the resonant frequency regulator is configured to be adjustable in position in the resonator to control the resonant frequency of the resonator. According to the invention, by adjusting the position of the resonant frequency regulator in the resonator, the resonant frequency of the resonator can be adjusted, the frequency control is stable, the frequency adjustment range is large, additional control lines do not need to be arranged at quantum bits, the number of signal lines is reduced, and the processing complexity and layout difficulty can be reduced.

Description

Technical Field

[0001] The present disclosure relates to the field of quantum computers, and in particular to a superconducting quantum circuit and a resonant frequency adjustment method. Background Art

[0002] Quantum chips are the core components of quantum computers, including superconducting quantum chips, semiconductor quantum chips, quantum dot chips, ion traps and NV (diamond) color centers, etc. Quantum chips have important applications in quantum computing, quantum communication, quantum simulation, quantum sensing and quantum security.

[0003] The resonator in a superconducting quantum chip is generally composed of a quarter-wavelength resonant structure. As the number of quantum bits increases, the quantum bits expand in two dimensions, resulting in a smaller space for laying out signal lines. The resonator occupies a larger area, which is not conducive to the layout of signal lines. In the prior art, there is a frequency-adjustable resonator structure that controls the resonator frequency through a magnetic flux excitation point. However, this structure adds additional magnetic flux excitation lines, increases the number of control lines, and the resonator frequency control depends on the signal stability of the magnetic flux excitation lines, so the frequency control has a certain instability. In addition, the increase in magnetic flux excitation lines is not conducive to the layout of signal lines, nor is it conducive to the expansion of quantum bits and more complicated processing. Summary of the invention

[0004] In order to solve the shortcomings of the prior art, the present disclosure adopts the following technical solution: a superconducting quantum circuit, comprising:

[0005] Quantum bits;

[0006] A read circuit is coupled to the quantum bit, wherein the read circuit includes a resonator, wherein the resonator is provided with a resonant frequency adjuster, wherein the resonant frequency adjuster is configured to be positionally adjustable in the resonator to control the resonant frequency of the resonator.

[0007] Optionally, the resonator includes a first resonator section and a second resonator section, and the resonant frequency adjuster is disposed between the first resonator section and the second resonator section, and is configured to adjust the length of the first resonator section and / or the length of the second resonator section.

[0008] Optionally, the resonant frequency adjuster includes a first Josephson junction, and two ends of the first Josephson junction are respectively connected to the first section of the resonator and the second section of the resonator.

[0009] Optionally, a length ratio range between the first section of the resonator and the second section of the resonator is 3-104, and a resonant frequency range of the resonator is 4.0 GHz-6.2 GHz.

[0010] Optionally, the reading circuit includes a first capacitor, which is connected in parallel with the resonator, and one end of the first capacitor is grounded.

[0011] Optionally, a second capacitor is provided between the quantum bit and the reading circuit, and the second capacitor is configured to control the coupling strength between the reading circuit and the quantum bit.

[0012] Optionally, the second capacitor is coupled to the quantum bit and the reading circuit respectively.

[0013] Optionally, the quantum bit includes a second Josephson junction, the second Josephson junction is connected in parallel with a third capacitor, and one end of the third capacitor is grounded.

[0014] Optionally, a fourth capacitor is connected to one side of the quantum bit, and the quantum bit is connected to another adjacent quantum bit through the fourth capacitor, thereby realizing the interconnection of quantum bits in the quantum chip.

[0015] The present disclosure also provides a resonant frequency adjustment method for adjusting the resonant frequency of a resonator in a superconducting quantum circuit, comprising:

[0016] The resonant frequency of the resonator is adjusted by adjusting the position of a resonant frequency adjuster disposed between the first section of the resonator and the second section of the resonator.

[0017] Optionally, the length ratio of the first section of the resonator to the second section of the resonator is controlled to form a resonator circuit to adjust the resonant frequency of the resonator.

[0018] Optionally, the first section of the resonator and the second section of the resonator are arranged on a substrate, and the distribution areas of the first section of the resonator and the second section of the resonator are adjusted;

[0019] The resonant frequency adjuster is configured to connect the first section of the resonator and the second section of the resonator to adjust the resonant frequency of the resonator.

[0020] The above technical solution has the following advantages or beneficial effects:

[0021] 1. By adjusting the position of the resonant frequency regulator in the resonator, the frequency of the resonator can be adjusted, the frequency control is stable, and the frequency adjustment range is large. There is no need to set additional control lines at the quantum bit, which reduces the number of signal lines and helps to reduce processing complexity and layout difficulty.

[0022] 2. The resonator frequency and length are variables of each other. The resonator frequency can be adjusted, which also makes the resonator length adjustable to a certain extent. The corresponding resonator length can be designed according to the resonator frequency, making the design more flexible and controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A circuit schematic diagram of the superconducting quantum circuit proposed in the present disclosure;

[0024] Figure 2 is a structural schematic diagram of a reading circuit in the present disclosure;

[0025] Figure 3 is a graph showing the relationship between the resonant frequency and the ratio of the length of the first section of the resonator to the length of the second section of the resonator in the present disclosure;

[0026] Figure 4 is a graph showing the relationship between the resonant frequency and the total length of the resonator in the present disclosure;

[0027] Figure 5 is a schematic diagram of the structure of the first Josephson junction in the present disclosure;

[0028] Figure 6 is a schematic diagram of the structure of the second Josephson junction in the present disclosure;

[0029] Figure 7 It is a schematic diagram of the structure of the resonator in the present disclosure.

[0030] Legend:

[0031] 1. Quantum bit; 11. Second Josephson junction; 12. Third capacitor; 2. Reading circuit; 21. Resonator; 211. First section of resonator; 212. Second section of resonator; 22. Resonant frequency adjuster; 221. Superconducting layer; 222. Semiconductor layer or insulator layer; 223. Gate electrode; 23. First capacitor; 3. Second capacitor; 4. Fourth capacitor; 5. Reading line; 6. Coupling part; 7. Substrate; 8. Superconducting film. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0033] In the prior art, in order to adjust the resonant frequency of the resonator in the superconducting quantum circuit, there is a problem of unstable frequency control, introducing additional control lines, which is not conducive to the layout of signal lines and the expansion of quantum bits, and makes the processing more complicated.

[0034] The present disclosure provides a superconducting quantum circuit, comprising: a quantum bit; a reading circuit coupled to the quantum bit, wherein the reading circuit comprises a resonator, and the resonator is provided with a resonant frequency regulator, wherein the resonant frequency regulator is configured to be positionally adjustable in the resonator to control the resonant frequency of the resonator.

[0035] The superconducting quantum circuit disclosed in the present invention adjusts the position of the resonant frequency regulator in the resonator so that the resonant frequency of the resonator is adjustable, the frequency control is stable, and the frequency adjustment range is large. There is no need to set additional control lines at the quantum bit, which reduces the number of signal lines and helps to reduce processing complexity and layout difficulty.

[0036] Reference Figure 1 and Figure 2 The present disclosure provides a superconducting quantum circuit, including: a quantum bit 1; a reading circuit 2, coupled to the quantum bit 1, the reading circuit 2 includes a resonator 21, the resonator 21 is provided with a resonant frequency regulator 22, wherein the resonant frequency regulator 22 is configured to be positionally adjustable in the resonator 21 to control the resonant frequency of the resonator 21.

[0037] In some embodiments of the present disclosure, a plurality of quantum bits 1 are provided, and the quantum bits 1 may include 8 quantum bits, 12 quantum bits, 16 quantum bits, 20 quantum bits, 100 quantum bits, etc. The present disclosure does not limit the number of quantum bits; and the plurality of quantum bits 1 are coplanarly arranged on the upper end surface of the substrate 7, and present a specific arrangement in the superconducting quantum circuit, and the specific arrangement may be periodic, and the quantum bits 1 present a regular repeated arrangement, specifically, the specific arrangement may be a square lattice arrangement, or a heavy hexagonal lattice arrangement; the present disclosure does not limit the arrangement of the quantum bits.

[0038] The reading circuit 2 is configured to read and transmit the output signal of the quantum bit 1, and is capable of detecting weak signals and converting them into the output signal of the quantum bit, removing noise through filtering, and improving the clarity and accuracy of the output signal.

[0039] In some embodiments of the present disclosure, the resonator 21 is configured to perform frequency selection and filter out noise of other frequencies. Specifically, by coupling the resonator 21 with the qubit 1 in the reading circuit 2, the resonant frequency of the resonator 21 is consistent with the frequency of the output signal of the qubit 1, and the resonator 21 is configured to read and transmit the output signal of the qubit 1, and use the output signal of the qubit 1 to obtain the information in the qubit.

[0040] In some embodiments of the present disclosure, the resonator 21 may be an electromagnetic resonator, including: a microwave cavity resonator, a dielectric resonator, a coplanar waveguide resonator, etc. Specifically, the resonator 21 is a coplanar waveguide resonator, which is suitable for microwave and radio frequency applications.

[0041] A resonant frequency regulator 22 is provided in the resonator 21. By adjusting the position of the resonant frequency regulator 22, the resonant frequency can be adjusted while the total length of the resonator 21 remains unchanged. This has the advantages of stable frequency control and a large frequency adjustment range. It is unnecessary to set an additional control line at the quantum bit 1, thereby reducing the number of signal lines, which is beneficial to reducing processing complexity and layout difficulty.

[0042] The resonator 21 includes a first resonator section 211 and a second resonator section 212 . The resonant frequency adjuster 22 is disposed between the first resonator section 211 and the second resonator section 212 and is configured to adjust the length of the first resonator section 211 and / or the length of the second resonator section 212 .

[0043] In some embodiments of the present disclosure, by adjusting the setting position of the resonant frequency adjuster 22, the lengths of the first section 211 and the second section 212 of the resonator are changed without changing the total length of the resonator 21. For example, by adjusting the position of the resonant frequency adjuster 22 toward the direction of the second section 212 of the resonator, the length of the second section 212 of the resonator is reduced, and the length of the first section 211 of the resonator is increased, wherein the length of the first section of the resonator is L1, and the length of the second section of the resonator is L2. By adjusting the position of the resonant frequency adjuster 22, the lengths of the first section 211 and the second section 212 of the resonator are adjusted, thereby keeping the total length of the resonator 21 unchanged. Specifically, the position of the resonant frequency adjuster 22 is different, so that the length ratio of L1 and L2 changes, for example, if L1 increases, L2 becomes shorter, and if L1 becomes shorter, L2 increases, so as to adjust the resonant frequency of the resonator 21.

[0044] The resonant frequency adjuster 22 includes a first Josephson junction, and two ends of the first Josephson junction are respectively connected to the first resonator section 211 and the second resonator section 212 .

[0045] In some embodiments of the present disclosure, the two ends of the first Josephson junction and the first section 211 and the second section 212 of the resonator can be integrally connected, and are prepared on the substrate 7 by deposition or magnetron sputtering to form an integrally connected resonant frequency regulator 22. The first Josephson junction includes: a DC Josephson junction, an AC Josephson junction, a single-junction Josephson junction, a quantum dot Josephson junction, a superconducting layer-semiconductor layer or insulator layer-superconducting layer (SIS) Josephson junction, a superconducting layer-metal layer-superconducting layer (SNS) Josephson junction, a superconducting layer-semiconductor layer or insulator layer-superconducting layer-semiconductor layer or insulator layer-superconducting layer (SISIS) Josephson junction, etc.

[0046] In some embodiments of the present disclosure, reference Figure 5The first Josephson junction is a superconducting layer-semiconductor layer or insulator layer-superconducting layer (SIS) Josephson junction. The first Josephson junction includes a superconducting layer 221 symmetrically arranged on both sides, and a semiconductor layer or insulator layer 222 arranged between the two superconducting layers 221, wherein the two superconducting layers 221 are respectively connected to the first section 211 of the resonator and the second section 212 of the resonator in an integrated manner. The two superconducting layers 221, the semiconductor layer or insulator layer 222, the first section 211 of the resonator and the second section 212 of the resonator are all arranged on the upper end surface of the substrate 7 to form a coplanar waveguide resonator, thereby adjusting the resonant frequency of the resonator 21. One end of the resonator 21 is coupled to the reading line 5 through a coupling portion 6 to form a reading circuit 2 to read the resonant frequency, wherein the coupling portion 6 can be a coupling capacitor or other coupling devices, which is not limited in the present disclosure.

[0047] A first Josephson junction is set in the resonator 21, and the resonant frequency of the resonator 21 is adjusted by adjusting the position of the first Josephson junction in the resonator 21. The resonant frequency of the resonator 21 is determined based on the position of the first Josephson junction in the resonator 21, so that the frequency control is stable and the frequency adjustment range is large. No additional control line is required at the quantum bit 1, which reduces the number of signal lines and helps to reduce processing complexity and layout difficulty.

[0048] The length ratio of the first section 211 of the resonator to the second section 212 of the resonator is in the range of 3-104, and the resonant frequency range of the resonator 21 is 4.0 GHz-6.2 GHz.

[0049] In some embodiments of the present disclosure, the first section 211 of the resonator and the second section 212 of the resonator are integrally connected on the substrate 7 through a first Josephson junction to form a resonator 21, the first Josephson junction, the first section 211 of the resonator and the second section 212 of the resonator are located on the same plane of the substrate 7, and the length of the first section 211 of the resonator is proportional to the length of the second section 212 of the resonator, wherein the length of the first section of the resonator is L1, the length of the second section of the resonator is L2, and the length ratio range of the first section 211 of the resonator and the second section 212 of the resonator is the ratio range of L1 / L2. While keeping the total length of L1 and L2 unchanged, the lengths of the adjusted first section 211 and the second section 212 of the resonator are determined by adjusting the position of the first Josephson junction, and the length ratio of L1 and L2 is changed by arranging the first Josephson junction at different positions in the resonator 21, so that the resonant frequency of the resonator is adjusted within the range of 4.0 GHz-6.2 GHz, and the relative frequency adjustment range of the resonator is about 40%, the frequency adjustment is efficient and simple, the frequency adjustment range is large, and no additional control signal line needs to be added.

[0050] In one embodiment of the present disclosure, the position of the first Josephson junction is adjusted, and the equivalent inductance is set to 5 nH. While keeping the total length of the first section L1 of the resonator and the second section L2 of the resonator unchanged, the position of the first Josephson junction is adjusted to change the length ratio of L1 and L2. Specifically, when L1 increases, L2 becomes shorter; when L1 becomes shorter, L2 increases; and then the superconducting quantum circuit is processed and prepared (refer to Figure 2 ), the resonant frequency range of the resonator is 4.0 GHz-6.2 GHz, and the relative frequency adjustment range is about 40%. Therefore, by setting the first Josephson junction at different positions in the resonator 21 to adjust the length ratio of the first resonator section L1 and the second resonator section L2 of the resonator, it is beneficial to adjust the resonant frequency of the resonator, and the frequency adjustment is efficient and simple without adding additional control signal lines.

[0051] In some embodiments of the present disclosure, Figure 3 is a graph showing the relationship between the resonant frequency of a resonator in a superconducting quantum circuit and the ratio of the length of the first section of the resonator to the length of the second section of the resonator. Figure 3 As can be seen from Table 1, the larger the ratio of the length of the first section of the resonator to the length of the second section of the resonator, the larger the resonant frequency, wherein the total length of the resonator 21 remains unchanged, that is, the total length of the first section L1 of the resonator and the second section L2 of the resonator remains unchanged, for example, the total length is 5249.268 μm, and the length ratio of L1 and L2 is changed by arranging the first Josephson junction at different positions in the resonator 21, so that the resonant frequency of the resonator can be adjusted within the range of 4.0 GHz-6.2 GHz. Specifically, the relationship between L1 / L2 and the resonant frequency is as follows

[0052] As shown in Table 1:

[0053]

[0054]

[0055] Table 1

[0056] When the length ratio L1 / L2 of the first section 211 of the resonator and the second section 212 of the resonator is 3.144892725, the resonant frequency is 4.097208147 GHz; when the length ratio L1 / L2 of the first section 211 of the resonator and the second section 212 of the resonator is 51.49268078, the resonant frequency is 6.100574818 GHz; when the length ratio L1 / L2 of the first section 211 of the resonator and the second section 212 of the resonator is 103.9853616, the resonant frequency is 6.101784990 GHz.

[0057] The reading circuit includes a first capacitor connected in parallel with the resonator, and one end of the first capacitor is grounded.

[0058] In some embodiments of the present disclosure, Figure 1 As shown, the resonator 21 is also connected in parallel with a first capacitor 23 with one end grounded, one plate of the first capacitor 23 is electrically connected to one end of the first section 211 of the resonator away from the first Josephson junction, and one plate of the first capacitor 23 electrically connected to the first section 211 of the resonator is also electrically connected to the quantum bit 1. The other plate of the first capacitor 23 is electrically connected to one end of the second section 212 of the resonator away from the first Josephson junction, and one end of the first capacitor 23 electrically connected to the second section 212 of the resonator is grounded to form a reading circuit 2. Among them, the positions of the first section 211 of the resonator and the second section 212 of the resonator can be interchanged. Specifically, one end of the second section 212 of the resonator is connected to the Josephson junction 22, and the other end is connected to the second capacitor 3, and one end of the first section 211 of the resonator is connected to the Josephson junction 22, and the other end is grounded, and the reading circuit 2 can also be formed.

[0059] A second capacitor 3 is provided between the quantum bit 1 and the reading circuit 2 , and the coupling strength between the reading circuit 2 and the quantum bit 1 is controlled by the second capacitor 3 .

[0060] In some embodiments of the present disclosure, one end of the first section 211 of the resonator connected to the first capacitor 23 is electrically connected to one plate of the second capacitor 3, and the other plate of the second capacitor 3 is electrically connected to the quantum bit 1. The reading circuit 2 and the quantum bit 1 are coupled by the second capacitor 3, and by adjusting the capacitance value of the second capacitor 3, the coupling strength between the quantum bit 1 and the resonator 21 can be adjusted, so as to operate and control the output signal of the quantum bit 1 read and transmitted from the quantum bit 1. The second capacitor 3 can isolate the DC component of the quantum bit 1 and the resonator 21 to prevent the DC current from affecting the operation of the quantum bit 1, and also prevent the signal of the resonator 21 from interfering with the quantum bit 1. The first capacitor 23 and the second capacitor 3 are used to assist in adjusting the resonant frequency of the resonator 21, and filter the noise in the reading circuit 2 to reduce the interference of the noise, which is conducive to improving the performance of the reading circuit 2 and improving the stability and accuracy of adjusting the resonant frequency.

[0061] The quantum bit 1 includes a second Josephson junction 11 and a third capacitor 12. The second Josephson junction 11 is connected in parallel with the third capacitor 12, and one end of the third capacitor 12 is grounded.

[0062] In some embodiments of the present disclosure, one plate of the third capacitor 12 is electrically connected to the second Josephson junction 11 and the second capacitor 3. The other plate of the third capacitor 12 is electrically connected to an end of the second Josephson junction 11 away from the second capacitor 3, and the other plate of the third capacitor 12 is grounded, so that the third capacitor 12 is connected in parallel with the second Josephson junction 11. The second Josephson junction 11 in the quantum bit 1 is filtered by the third capacitor 12 to reduce noise interference in the quantum bit 1, which is conducive to reducing the decoherence effect caused by circuit noise and environmental interference, and improving the decoherence time of the quantum bit. By adjusting the capacitance value of the third capacitor 12, the operating frequency and energy level difference of the quantum bit 1 can also be changed.

[0063] The structures of the second Josephson junction 11 and the first Josephson junction 22 may be the same or different. Figure 6 The second Josephson junction 11 has a different structure from the first Josephson junction 22. A gate electrode 223 is provided on one side of the second Josephson junction 11 to form a capacitor structure with the second Josephson junction 11. The gate electrode 223 is configured to provide a voltage control signal to the second Josephson junction 11 to control the frequency of the quantum bit 1. The gate electrode 223 is also configured to provide an xy control signal and a z control signal to the second Josephson junction 11 to implement an arbitrary gate operation on the quantum bit 1. A control line is connected to one side of the gate electrode 223 to provide an xy control signal and a z control signal to the second Josephson junction 11 through the same control line.

[0064] In some embodiments of the present disclosure, the second Josephson junction 11 has the same structure as the first Josephson junction 22, and the second Josephson junction 11 is not provided with a gate electrode 223 and a control line connected to the gate electrode 223, which is beneficial to reducing processing complexity and layout difficulty.

[0065] One end of the quantum bit 1 is coupled to the fourth capacitor 4, and the quantum bit 1 is coupled to another adjacent quantum bit through the fourth capacitor 4, thereby realizing the interconnection between multiple quantum bits 1 in the quantum chip.

[0066] In some embodiments of the present disclosure, the fourth capacitor 4 is electrically connected to the non-grounded end of the second Josephson junction 11 and the second capacitor 12, and is electrically connected to another quantum bit 1, and a plurality of mutually coupled quantum bits 1 are provided in the superconducting quantum circuit, wherein the plurality of quantum bits include 8 quantum bits, 12 quantum bits, 16 quantum bits, 20 quantum bits, 100 quantum bits, 200 quantum bits, etc.; the present disclosure does not limit the number of quantum bits. The specific structure of the fourth capacitor 4 and the coupling mode between the fourth capacitor 4 and the quantum bit can be set according to the actual situation, and are not specifically limited here.

[0067] The present disclosure also provides a resonant frequency adjustment method for adjusting the resonant frequency of a resonator in a superconducting quantum circuit, comprising adjusting the position of a resonant frequency adjuster 22 disposed between a first section 211 of the resonator and a second section 212 of the resonator to adjust the resonant frequency of the resonator.

[0068] In some embodiments of the present disclosure, the length of the first section 211 of the resonator and the length of the second section 212 of the resonator are changed while the total length of the resonator 21 remains unchanged. For example, the position of the resonant frequency adjuster 22 in the resonator 21 is adjusted to reduce the length of the second section 212 of the resonator and increase the length of the first section 211 of the resonator, wherein the length of the first section of the resonator is L1 and the length of the second section of the resonator is L2. The position of the resonant frequency adjuster 22 in the resonator 21 is adjusted to adjust the length of the first section 211 of the resonator and the length of the second section 212 of the resonator, thereby keeping the total length of L1 and L2 unchanged.

[0069] The resonant frequency regulator 22 includes a first Josephson junction, and the two ends of the first Josephson junction are respectively connected to the first section 211 of the resonator and the second section 212 of the resonator in an integrated manner, and are prepared on the substrate 7 by deposition or magnetron sputtering to form the resonator 21. The resonant frequency of the resonator 21 is adjusted by adjusting the position of the first Josephson junction in the resonator 21, and the frequency adjustment range is large. No additional control line may be set at the quantum bit 1, which reduces the number of signal lines and helps to reduce the processing complexity and layout difficulty.

[0070] The length ratio of the first resonator section 211 to the second resonator section 212 is controlled to adjust the resonant frequency of the resonator 21 .

[0071] In some embodiments of the present disclosure, a superconducting film 8 is deposited on a substrate 7, a photoresist is disposed on the superconducting film 8, and a first resonator section 211 and a second resonator section 212 are formed on the superconducting film 8 through operations such as photoresist exposure, development and etching, and a first Josephson junction is disposed between the first resonator section 211 and the second resonator section 212, and two ends of the first Josephson junction are integrated with the first resonator section 211 and the second resonator section 212 to form an integrated resonant frequency regulator 22, and the position of the first Josephson junction in the resonator 21 is adjusted to adjust the length ratio of the first resonator section 211 and the second resonator section 212, thereby adjusting the resonant frequency of the resonator 21.

[0072] When the length ratio of the first section 211 of the resonator to the second section 212 of the resonator is adjusted, the first Josephson junction is first removed, and the length ratio of the first section 211 of the resonator to the second section 212 of the resonator is determined based on the adjusted resonant frequency; based on the length ratio, while keeping the total length of the first section 211 of the resonator and the second section 212 unchanged, the length of the first section 211 of the resonator and the second section 212 of the resonator are reprocessed; then, the first Josephson junction is reprocessed on the substrate 7 to connect the first section 211 of the resonator and the second section 212 of the resonator.

[0073] The first section 211 and the second section 212 of the resonator are arranged on the substrate 7 to adjust the distribution area of ​​the first section 211 and the second section 212 of the resonator; a resonant frequency adjuster 22 is arranged to connect the first section 211 and the second section 212 of the resonator to adjust the resonant frequency of the resonator.

[0074] In some embodiments of the present disclosure, reference Figure 7 , a superconducting film 8 made of superconducting material is formed on the surface of the substrate 7 to form the resonator 21 and the reading circuit 2, wherein the superconducting material includes at least one of aluminum, tantalum, niobium, niobium nitride, titanium nitride or niobium titanium nitride, and the material of the substrate 7 is an insulating material, including but not limited to sapphire, high-resistance silicon, etc. Specifically, the superconducting film 8 is formed on the substrate 7 by deposition or magnetron sputtering; a layer of photoresist is coated on the superconducting film 8, and the photoresist is exposed and developed to form a photoresist layer to obtain a prefabricated structure of the superconducting quantum circuit; excess superconducting material in the superconducting film 8 is removed by an etching process to form a first resonator section 211 and a second resonator section 212, and the distribution area of ​​the first resonator section 211 and the second resonator section 212 is adjusted by performing etching processes at different positions; a first Josephson junction is processed between the first resonator section 211 and the second resonator section 212, and specifically, a layer of photoresist is processed by deposition or magnetron sputtering to form a superconducting quantum circuit. Another superconducting film 8 is formed, and an oxide layer is formed on the other superconducting film 8, for example, a thin oxide layer (such as aluminum oxide) is deposited between the two superconducting films 8, and exposed and developed on the photoresist to process the shape and structure of the first Josephson junction on the superconducting film 8, and the excess superconducting material in the superconducting film 8 is removed by an etching process (such as reactive ion etching) to form an electrode and an insulating layer of the first Josephson junction, and the shape of the first Josephson junction is processed. In addition, an additional metal layer can be deposited on the first Josephson junction for electrode connection or other functions; finally, annealing is performed to improve the quality and conductivity of the material, clean the surface, and remove photoresist residues.

[0075] In some embodiments of the present disclosure, the total length of the resonator 21 can also be adjusted in the superconducting quantum circuit of the present disclosure to control the resonant frequency of the resonator 21 so that the resonator 21 is not limited to a fixed length (such as a quarter wavelength). Specifically, Figure 4 is the relationship between the resonant frequency of the resonator 21 and the total length of the resonator 21, wherein the first Josephson junction is not added between the first section 211 of the resonator and the second section 212 of the resonator, and the length ratio of the first section 211 of the resonator and the second section 212 of the resonator is not adjusted. Figure 4 As shown, the total length of the resonator 21 ranges from 5200 μm to 7800 μm. By adjusting the total length of the resonator 21, the resonant frequency of the resonator can also be adjusted within the range of 4.0 GHz to 6.2 GHz, wherein the resonant frequency of the resonator 21 is inversely proportional to the total length of the resonator 21. As the total length of the resonator 21 increases, the resonant frequency decreases accordingly. The total length of the resonator 21 can be adjusted according to actual needs to obtain the desired resonant frequency. However, due to the processing design size of the quantum chip, when the required resonant frequency is very small, the total length of the resonator 21 cannot be very long, so it can also be adjusted together with the resonant frequency adjuster 22.

[0076] Finally, it should be noted that the above is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A superconducting quantum circuit, characterized in that: include: Quantum bits; A read circuit is coupled to the quantum bit, wherein the read circuit includes a resonator, wherein the resonator is provided with a resonant frequency adjuster, wherein the resonant frequency adjuster is configured to be positionally adjustable in the resonator to control the resonant frequency of the resonator.

2. The superconducting quantum circuit according to claim 1, characterized in that: The resonator includes a first resonator section and a second resonator section. The resonant frequency adjuster is disposed between the first resonator section and the second resonator section and is configured to adjust the length of the first resonator section and / or the length of the second resonator section.

3. The superconducting quantum circuit according to claim 2, characterized in that: The resonant frequency adjuster includes a first Josephson junction, and two ends of the first Josephson junction are respectively connected to the first section of the resonator and the second section of the resonator.

4. The superconducting quantum circuit according to claim 2, characterized in that: The length ratio of the first section of the resonator to the second section of the resonator is in the range of 3-104, and the resonant frequency range of the resonator is in the range of 4.0 GHz-6.2 GHz.

5. The superconducting quantum circuit according to claim 2, characterized in that: The reading circuit includes a first capacitor connected in parallel with the resonator, and one end of the first capacitor is grounded.

6. The superconducting quantum circuit according to claim 1, characterized in that: A second capacitor is provided between the quantum bit and the reading circuit, and the second capacitor is configured to control the coupling strength between the reading circuit and the quantum bit.

7. The superconducting quantum circuit according to claim 6, characterized in that: The quantum bit comprises a second Josephson junction, the second Josephson junction is connected in parallel with a third capacitor, and one end of the third capacitor is grounded.

8. A method for adjusting the resonant frequency, for adjusting the resonant frequency of a resonator in a superconducting quantum circuit, characterized in that: The adjustment method is applicable to the superconducting quantum circuit described in any one of claims 1 to 7, comprising: The resonant frequency of the resonator is adjusted by adjusting the position of a resonant frequency adjuster disposed between the first section of the resonator and the second section of the resonator.

9. The adjustment method according to claim 8, characterized in that: The length ratio of the first section of the resonator to the second section of the resonator is controlled to adjust the resonant frequency of the resonator.

10. The adjustment method according to claim 9, characterized in that: The first section of the resonator and the second section of the resonator are arranged on a substrate, and the distribution areas of the first section of the resonator and the second section of the resonator are adjusted; The resonant frequency adjuster is configured to connect the first section of the resonator and the second section of the resonator to adjust the resonant frequency of the resonator.

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