A reading circuit, a reading method, and a quantum computer

Abstract

The present application discloses a reading circuit, a reading method, and a quantum computer, belonging to the technical field of quantum computing. The reading circuit provided by the present application establishes an indirect coupling connection between a component to be read coupled to a transmission element and a resonator through the coupling between the transmission element and the resonator. Furthermore, the reading of the component to be read can be realized based on a reading signal line coupled to the resonator, thereby breaking through the limitation in the related art that the reading can only be realized through a resonator directly coupled to the component to be read. The present application also provides a reading method for the above-mentioned reading circuit. By applying a measurement microwave signal to the reading signal line and acquiring the spectrum of the resonator response, then adjusting the first frequency of the component to be read and the second frequency of the transmission element, the spectrum with the maximum dispersion frequency shift value is determined as the target spectrum, that is, the reading of the component to be read is realized.

Description

Technical Field

[0001] This application belongs to the field of quantum information, especially the field of quantum computing technology. In particular, this application relates to a readout circuit, a readout method, and a quantum computer. Background Art

[0002] Currently, the readout of superconducting qubits adopts the dispersive readout method. The circuit structure for readout mainly includes a resonator coupled to the qubit to be read, and a readout bus coupled to the resonator. Based on this circuit structure, the state information of the qubit is transferred from the qubit to the transmission line. Therefore, each qubit on the superconducting quantum chip is connected to the readout bus through an independent resonator. However, this readout mechanism has certain limitations, and the object to be read is specific. Summary of the Invention

[0003] To overcome the limitations of the readout mechanism in related technologies, this application provides a readout circuit, a readout method, and a quantum computer.

[0004] An embodiment of this application provides a readout circuit, which includes: a transmission element coupled to the element to be read; a resonator coupled to the transmission element; and a readout signal line coupled to the resonator.

[0005] For the readout circuit as described above, in some embodiments, the readout circuit has a plurality of the transmission elements coupled in sequence.

[0006] For the readout circuit as described above, in some embodiments, the transmission element includes at least one of the following types: qubit, frequency tunable coupler.

[0007] For the readout circuit as described above, in some embodiments, the transmission element includes a qubit and a frequency tunable coupler coupled in sequence, and the qubit and the coupler are arranged alternately.

[0008] For the readout circuit as described above, in some embodiments, the element to be read includes one of the following types: qubit, frequency tunable coupler.

[0009] For the readout circuit as described above, in some embodiments, the coupler includes a superconducting quantum interference device formed by at least two Josephson junctions connected in parallel.

[0010] For the readout circuit as described above, in some embodiments, the qubit includes a superconducting quantum interference device formed by at least two Josephson junctions connected in parallel.

[0011] For the readout circuit as described above, in some embodiments, the resonator is formed by a coplanar waveguide transmission line.

[0012] The reading circuit as described above, in some embodiments, the resonant cavity is a half-wavelength resonant cavity or a quarter-wavelength resonant cavity.

[0013] Another embodiment of the present application provides a reading method for a reading circuit, including the following steps:

[0014] Apply a measurement microwave signal on the reading signal line and obtain the spectrum of the response of the resonant cavity;

[0015] Adjust the first frequency of the element to be read and the second frequency of the transmission element, and determine that the spectrum with the largest dispersion frequency shift value is the target spectrum.

[0016] The reading method as described above, in some embodiments, a magnetic flux signal is applied on the configured signal line to adjust the second frequency.

[0017] The reading method as described above, in some embodiments, when the transmission element is a qubit, the step of adjusting the second frequency of the transmission element includes: adjusting the second frequency to the degenerate point of the qubit.

[0018] The reading method as described above, in some embodiments, when the transmission element is a frequency-tunable coupler and a qubit coupled in sequence, the step of adjusting the second frequency of the transmission element includes: fixing the frequency of the qubit at the degenerate point and adjusting the frequency of the coupler.

[0019] The third embodiment of the present application provides a quantum computer, including the reading circuit as described above.

[0020] Compared with the prior art, in the reading circuit provided by the present application, through the coupling between the transmission element and the resonant cavity, the element to be read coupled to the transmission element is indirectly coupled to the resonant cavity, and then the reading of the element to be read can be realized based on the reading signal line coupled to the resonant cavity, thus breaking through the limitation in the related art that the reading can only be realized through the resonant cavity directly coupled to the element to be read. In an integrated extended quantum chip, based on the solution of the present application, the coupler between two qubits can be read by using the resonant cavity coupled to the qubit; it is also possible to use the resonant cavity of the adjacent qubit coupled to the qubit to realize the reading when the resonant cavity directly coupled to a qubit fails. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of qubits on a quantum chip in the related art;

[0022] Figure 2Structural schematic diagram of a reading circuit provided by an embodiment of the present application;

[0023] Figure 3 Flowchart of a reading method provided by an embodiment of the present application.

[0024] Description of reference numerals:

[0025] 1 - Reading signal line, 2 - Resonator, 3 - Quantum bit, 4 - Coupler

[0026] 21 - First resonator, 22 - Second resonator, 23 - Nth resonator,

[0027] 31 - First bit, 32 - Second bit, 33 - Nth bit,

[0028] 41 - First coupler, 42 - Second coupler. Detailed implementation manners

[0029] The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be construed as limiting the present application.

[0030] The following detailed description is only illustrative and is not intended to limit the embodiments and / or the application or use of the embodiments. In addition, there is no intention to be bound by any express or implied information presented in the foregoing "Background Art" or "Summary of the Invention" section or "Detailed Implementation Manner" section.

[0031] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, one or more embodiments are now described with reference to the accompanying drawings, in which like reference numerals are used throughout to refer to like components. In the following description, for the purpose of explanation, many specific details are set forth in order to provide a more thorough understanding of one or more embodiments. However, it is obvious that one or more embodiments can be practiced without these specific details, and the various embodiments can be combined and cross-referenced with each other on the premise of not being contradictory.

[0032] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products or devices.

[0033] According to the different physical systems used to construct qubits, the physical implementation of qubits includes superconducting quantum circuits, semiconductor quantum dots, ion traps, diamond vacancies, topological qubits, photons, etc.

[0034] Quantum computing with superconducting quantum circuits is currently the solid-state quantum computing implementation method with the fastest progress and best performance. Since the energy level structure of superconducting quantum circuits can be regulated by applying external electromagnetic signals, the controllability of circuit design and customization is strong. At the same time, thanks to the existing mature integrated circuit technology, superconducting quantum circuits have scalability that is difficult to match by many quantum physical systems.

[0035] In a superconducting quantum circuit, a qubit includes a Josephson junction, which is a structure formed by separating two thin-film superconducting layers with a non-superconducting material. When the temperature drops to a specific low temperature, the superconducting layers become superconducting, and Cooper pairs can tunnel from one superconducting layer through the non-superconducting layer to the other superconducting layer. In a qubit, the Josephson junction (which acts as a nonlinear inductive device) is connected in parallel with one or more capacitive devices to form a nonlinear microwave oscillator. The qubit has a resonance / transition frequency determined by the values of the inductance and capacitance therein.

[0036] The physical basis of qubit readout is dispersive readout. By using the nonlinear coupling between the qubit and the cavity, the information processed by the qubit is carried or transmitted in the form of microwave signals in the microwave frequency range. Capturing, processing, and analyzing the microwave signals can obtain the quantum information encoded therein. The readout circuit is the circuit coupled to the qubit and is used to capture, read, and measure the quantum information.

[0037] As an example of a superconducting quantum circuit, the structure of the qubit adopts a single capacitor grounded to the ground, and a superconducting quantum interference device with one end grounded and the other end connected to the capacitor. And this capacitor is often a cross-shaped parallel plate capacitor. See Figure 1 shown, the cross-shaped capacitor plate C q is surrounded by a ground plane (GND), and there is a gap between the cross-shaped capacitor plate C q and the ground plane (GND). One end of the superconducting quantum interference device squid is connected to the cross-shaped capacitor plate C q , and the other end is connected to the ground plane (GND). Since the first end of the cross-shaped capacitor plate C q is usually used to connect the superconducting quantum interference device squid, and the second end is used to couple with readout structures such as a resonator, a certain space needs to be reserved near the first end and the second end for wiring. For example, space for arranging xy signal lines and z signal lines needs to be reserved near the first end. The other two ends of the cross-shaped capacitor plate C q are used to couple with adjacent qubits.

[0038] The qubits using this structure are integrated and expanded in an array arranged in a one-dimensional chain. The qubits at adjacent positions are coupled and share a single readout signal line (ReadOut Line). The readout circuit structure mainly includes a resonator coupled to the qubit to be read and a readout signal line coupled to the resonator. Each qubit is connected to the readout signal line through an independent resonator, and based on its respective resonator and the readout signal line coupled to the resonator, the state information of the qubit is transferred from the qubit to the transmission line.

[0039] However, the applicant has found that this readout mechanism has great limitations, including but not limited to the following two aspects: First, the object of reading is specific, and only the qubits directly coupled through the resonator can be read, and structures such as couplers between qubits cannot be read; Second, in the way that each qubit is connected to the readout signal line through an independent resonator, when a fault occurs in the readout circuit of a certain qubit due to process fluctuations, the readout cannot be achieved.

[0040] Therefore, the present application provides a readout circuit, a readout method, and a quantum computer to solve the deficiencies in the prior art, which breaks through the limitation in the related art that the readout can only be achieved through a resonator directly coupled to the element to be read. The following will be combined with the attached Figure 2 to the attached Figure 3 to describe the embodiments of the present application in detail.

[0041] Figure 2 It is a schematic structural diagram of a readout circuit provided for the embodiment of the present application.

[0042] Figure 3 It is a flowchart of a readout method provided for an embodiment of the present application.

[0043] It should be noted that Figure 2 schematically shows the relationship between the readout signal line 1, the resonator 2, the qubit 3, and the frequency-tunable coupler 4. For example, each qubit 3 has an independently configured resonator 2, the resonator 2 is coupled to the readout signal line, and the qubits 3 at adjacent positions establish a coupling relationship through the coupler 4. The resonator 2 includes a first resonator 21, a second resonator 22... a first N resonators 23, the qubit 3 includes a first qubit 31, a second qubit 32... a first N qubits 33, the coupler 4 includes a first coupler 41, a second coupler 42... a first N couplers 43, and Figure 2 some of the components are omitted therein. For example, the resonators between the second resonator 22 and the first N resonators 23, etc.

[0044] Referring to Figure 2 shown, and can be combined with Figure 1 andFigure 3 As shown in Figure 3 , an embodiment of the present application provides a reading circuit, including: a transmission element coupled to an element to be read; a resonator 2 coupled to the transmission element; and a reading signal line 1 coupled to the resonator 2. The resonator 2 has a first end configured to be coupled to the transmission element and a second end configured to be coupled to the reading signal line 1, and the coupling form can be capacitive coupling or inductive coupling. In this reading circuit, the element to be read, the transmission element, and the resonator 2 are sequentially coupled, so that the element to be read and the resonator 2 are indirectly coupled, and then the reading of the element to be read can be realized based on the reading signal line 1 coupled to the resonator 2, thereby breaking through the limitation in the related art that the reading can only be realized by the resonator 2 directly coupled to the element to be read.

[0045] In the embodiment of the present application, the transmission element is an electrical element with a coupling connection function, and the element to be read and the resonator are indirectly coupled through the transmission element. It should be understood that the transmission element can have a first end configured to be coupled to the element to be read and a second end configured to be coupled to the resonator 2. The transmission element can be a qubit 3 coupled to the element to be read, and the coupling between the element to be read and the qubit 3 can be directly formed by their proximity or formed by other electrical structure elements.

[0046] In an integrated and extended quantum chip, based on the solution of the embodiment of the present application, the coupling between two qubits 3 can be read by using the resonator 2 coupled to the qubit 3; or based on the solution of the present application, the reading of one qubit 3 can be realized by using the resonator 2 of the adjacent qubit 3 coupled to the one qubit 3, so that the problem that the one qubit cannot be read when the resonator directly coupled to it fails can be solved.

[0047] In some embodiments, in combination with Figure 2, the first bit 31 and the second bit 32 are coupled through the first coupler 41 in the. Based on the solution of the present application, the reading circuit for the first bit 31 may include: a first coupler 41, a second bit 32, a second resonator 22, and a reading signal line 1 that are sequentially coupled. Among them, the first bit 31 is coupled to the first coupler 41, the first coupler 41 is coupled to the second bit 32, the second bit 32 is coupled to the second resonator 22, and the second resonator 22 is coupled to the reading signal line 1. Specifically, the dispersive readout technology principle is used with the reading signal line 1 to measure the state information of a specific element to be read (the first bit 31). The dispersive readout is based on the dispersive interaction between the first bit 31 and the second resonator 22, and this dispersion shift causes the frequency of the second resonator 22 to change according to the state of the first bit 31. When the first bit 31 can be indirectly coupled to the second resonator 22 through the first coupler 41 and the second bit 32, the frequency of the second resonator 22 changes according to the state of the first bit 31. The second resonator 22 is probed with a microwave pulse, and the phase and amplitude of the reflected signal are used to distinguish the state information of the first bit 31.

[0048] In some other embodiments, the reading circuit may have a plurality of the transmission elements that are sequentially coupled and connected. The plurality of transmission elements are sequentially coupled and connected to form a transmission link. One end of the transmission link is coupled to the element to be read, and the other end is coupled to the resonator, so as to ensure that the element to be read is indirectly coupled to the resonator through the transmission link. Based on this coupling connection, the spectral reading of the element to be read is realized. Exemplarily, the first bit 31 can be indirectly coupled to the Nth resonator 23 through a transmission link formed by sequentially coupling and connecting the first coupler 41, the second bit 32, the second coupler 42... the Nth bit 33. The frequency of the Nth resonator 23 changes according to the state of the first bit 31. The Nth resonator 23 is probed with a microwave pulse, and the phase and amplitude of the reflected signal are used to distinguish the state information of the first bit 31.

[0049] In an embodiment of the present application, the transmission element includes a qubit 3. Exemplarily, when reading the first coupler 41, the first resonator 21 and the first coupler 41 can be indirectly coupled by means of the first bit 31, or the second resonator 22 and the first coupler 41 can be indirectly coupled by means of the second bit 32, so that the first resonator 21 or the second resonator 22 can be probed with a microwave pulse to realize the reading of the first coupler 41. In another embodiment, the transmission element may also include a frequency-tunable coupler 4. For example, the first coupler 41 and the Nth resonator 23 are indirectly coupled through a transmission link formed by a qubit 3 and a coupler, so that the Nth resonator 23 can be probed with a microwave pulse to realize the reading of the first coupler 41.

[0050] In some other embodiments, the transmission element includes qubits 3 and a frequency-tunable coupler 4. Exemplarily, a plurality of qubits 3 and a plurality of couplers 4 may be coupled to form the transmission link, and the qubits 3 and the couplers 4 are arranged alternately in the transmission link. The frequency-tunable coupler 4 can control the coupling between adjacent qubits (the first qubit 31 and the second qubit 32) so as to reduce or eliminate microwave crosstalk and / or frequency conflicts between the qubits during readout or when applying control pulses to the qubits 3. Tuning the frequency of the first coupler 41 enables adjusting the coupling strength between the first qubit 31 and the second qubit 32 to allow the coupling between the first qubit 31 and the second qubit 32 to be adjusted from weak coupling to strong coupling.

[0051] The frequency of the coupler 4 can be tuned to be the same as or close to the transition frequency (qubit resonance frequency) of the qubit 3, or can be tuned to be at the far end of the frequency range of the qubit 3. When the frequency of the coupler 4 is tuned to be the same as or close to the frequency of the qubit 3, the coupler 4 resonates with the qubit 3. When the frequency of the coupler 4 is tuned to be significantly different from the frequency of the qubit 3, the coupler 4 does not resonate with the qubit 3.

[0052] In some embodiments, the element to be read includes one of the following types: qubit 3, frequency-tunable coupler 4. Exemplarily, the coupler 4 includes a superconducting quantum interference device squid formed by at least two Josephson junctions connected in parallel. It can be understood that the coupler 4 is configured with a signal line for realizing frequency tuning, and the frequency of the coupler 4 can be regulated based on the magnetic flux signal applied on the signal line. Exemplarily, the qubit 3 includes a superconducting quantum interference device squid formed by at least two Josephson junctions connected in parallel. It can be understood that the qubit 3 is configured with xy signal lines and z signal lines.

[0053] In some embodiments, the resonator 2 is formed by a coplanar waveguide transmission line. Exemplarily, the resonator 2 is a half-wavelength resonator or a quarter-wavelength resonator.

[0054] The present application also provides a spectrum reading method for the reading circuit as described above.

[0055] Referring to Figure 3 shown, and in combination with Figure 1 and Figure 2 shown, the reading method includes steps S601 to step S602, wherein:

[0056] Step S601: Apply a measurement microwave signal on the read signal line 1 and obtain the spectrum responded by the resonant cavity 2. Exemplarily, what can be obtained is a curve graph of the spectrum S21. Detect the resonant cavity 2 with a microwave pulse, which is usually at a frequency close to the midpoint of the resonant frequencies corresponding to the ground state and the excited state. The phase and amplitude of the reflected signal are used to distinguish the state information of the element to be read; Step S602: Adjust the first frequency of the element to be read and the second frequency of the transmission element, and determine the spectrum when the dispersion frequency shift value is the maximum as the target spectrum, and this target spectrum is used as the read result.

[0057] The reading method for the above-mentioned reading circuit provided by the embodiments of the present application realizes the reading of the element to be read by applying a measurement microwave signal on the read signal line 1, obtaining the spectrum responded by the resonant cavity 2, then adjusting the first frequency of the element to be read and the second frequency of the transmission element, and determining the spectrum when the dispersion frequency shift value is the maximum as the target spectrum. The reading method of the embodiments of the present application is particularly applicable to the case where the resonant cavity 2 directly coupled to the qubit 3 fails, and the reading is realized through the resonant cavity 2 corresponding to the adjacent qubit 3 coupled to the qubit 3. It should be noted that the coupling mechanism between the qubit 3 and the adjacent qubit 3 can be realized by a frequency-tunable coupler 4, or can be realized by a transmission link formed by sequentially coupling the frequency-tunable coupler 4 and the qubit 3. Among them, in this transmission link, the qubit 3 and the coupler 4 are arranged alternately.

[0058] In some embodiments, a magnetic flux signal is applied on the configured signal line to realize the adjustment of the second frequency. Exemplarily, the transmission element includes one of the following types: qubit 3, frequency-tunable coupler 4. Exemplarily, the coupler 4 includes a superconducting quantum interference device squid formed by at least two Josephson junctions connected in parallel. The coupler 4 is configured with a signal line for realizing frequency tuning, and the frequency of the coupler 4 can be regulated based on the magnetic flux signal applied on this signal line. Exemplarily, the qubit 3 includes a superconducting quantum interference device squid formed by at least two Josephson junctions connected in parallel. The qubit 3 is configured with a z signal line for realizing frequency regulation.

[0059] To improve the reading efficiency and quickly obtain the target spectrum, the coupling strength between the neighboring qubit 3 and resonator 2 in the reading circuit can be adjusted to the maximum. In some embodiments, when the transmission element is qubit 3, the step of adjusting the second frequency of the transmission element may include: adjusting the second frequency to the degenerate point of qubit 3. In other embodiments, when the transmission element is a tunable coupler 4 and qubit 3 coupled in sequence, the step of adjusting the second frequency of the transmission element includes: fixing the frequency of qubit 3 at the degenerate point and adjusting the frequency of coupler 4. When reading the first coupler 41, the reading circuit includes a first qubit 31, a first resonator 21, and a reading signal line 1 coupled in sequence. The frequency of the first qubit 31 can be fixed at the degenerate point, so as to maximize the coupling strength between the first qubit 31 and the first resonator 21, facilitating the acquisition of the modulation spectrum of the first coupler 41. When reading the first qubit 31, the reading circuit may include: a first coupler 41, a second qubit 32, a second resonator 22, and a reading signal line 1 coupled in sequence. The frequency of the second qubit 32 can be fixed at the degenerate point, and the frequency of the first coupler 41 can be adjusted.

[0060] An embodiment of the present application also provides a quantum computer, including the reading circuit as described above.

[0061] It should be noted here that: the quantum computer has the reading circuit with the above structure and has the same beneficial effects as the above reading circuit embodiments, so no further description will be given. For the technical details not disclosed in the quantum computer embodiments of the present application, those skilled in the art can refer to the description of the above reading circuit for understanding. To save space, no further description will be given here.

[0062] Embodiments of the present application use the same or similar processing technologies (such as lithography, material deposition such as sputtering or chemical vapor deposition, and material removal such as etching or lift-off) as those used in integrated circuit manufacturing to fabricate qubits, resonators, transmission elements, and reading signal lines. Each of the qubits, resonators, transmission elements, and reading signal lines can be formed / integrated on the same chip (such as the same silicon or sapphire substrate or wafer) and operate at a temperature below the critical temperature of the superconducting material forming them. Examples of superconducting materials include, but are not limited to, aluminum (e.g., superconducting critical temperature of 1.2 Kelvin), niobium (e.g., superconducting critical temperature of 9.3 Kelvin), and titanium nitride (e.g., superconducting critical temperature of 5.6 Kelvin).

[0063] During the operation of a quantum computing system using superconducting quantum circuit elements and / or superconducting classical circuit elements (such as the circuit elements described herein), the superconducting circuit elements are cooled to a temperature within a cryostat that allows the superconducting material to exhibit superconducting properties.

[0064] The structure, features, and effects of the present application have been described in detail based on the embodiments shown in the drawings. The above is only the preferred embodiment of the present application. However, the present application is not limited to the scope of implementation shown in the drawings. Any changes made in accordance with the concept of the present application, or equivalent embodiments modified to equivalent changes, that still do not exceed the spirit covered by the specification and the drawings should be within the protection scope of the present application.

Claims

1. A reading circuit, characterized in that, Comprising: A transmission element coupled to the element to be read; A resonator coupled to the transmission element, and the element to be read is indirectly coupled to the resonator through the transmission element; And A read signal line coupled to the resonator; When the element to be read is a tunable coupler, the transmission element is a qubit; When the element to be read is the qubit, the transmission element is the tunable coupler and the qubit coupled in sequence; The resonator includes a first resonator, a second resonator... an Nth resonator, the qubit includes a first qubit, a second qubit... an Nth qubit, and the coupler includes a first coupler, a second coupler... an Nth coupler; The read circuit of the first qubit includes: the first coupler, the second qubit, the second resonator and the read signal line coupled in sequence, wherein the first qubit is coupled to the first coupler, the first coupler is coupled to the second qubit, the second qubit is coupled to the second resonator, and the second resonator is coupled to the read signal line; The read circuit of the first coupler includes: indirectly coupling the first resonator and the first coupler by using the first qubit, or indirectly coupling the second resonator and the first coupler by using the second qubit.

2. The reading circuit according to claim 1, wherein The read circuit has a plurality of the transmission elements coupled in sequence.

3. The reading circuit according to claim 1, characterized in that The coupler includes a superconducting quantum interference device formed by at least two Josephson junctions connected in parallel.

4. The reading circuit according to claim 1, wherein The qubit includes a superconducting quantum interference device formed by at least two Josephson junctions connected in parallel.

5. The reading circuit according to any one of claims 1 to 4, characterized in that, The resonator is formed by a coplanar waveguide transmission line.

6. The reading circuit according to claim 1, wherein The resonator is a half-wavelength resonator or a quarter-wavelength resonator.

7. A reading method for a reading circuit according to any one of claims 1-6, characterized in that, Comprising: Applying a measurement microwave signal on the read signal line and acquiring the spectrum of the resonator response; Adjusting the first frequency of the element to be read and the second frequency of the transmission element, and determining the spectrum with the maximum dispersion frequency shift value as the target spectrum; When the element to be read is a tunable coupler, the transmission element is a qubit, and the step of adjusting the second frequency of the transmission element includes: Adjusting the second frequency to the degeneracy point of the qubit; When the element to be read is the qubit, the transmission element is a tunable coupler and a qubit coupled in sequence, and the step of adjusting the second frequency of the transmission element includes: Fixing the frequency of the qubit at the degeneracy point and adjusting the frequency of the coupler.

8. The reading method according to claim 7, wherein Adjusting the second frequency by applying a magnetic flux signal on the configured signal line.

9. A quantum computer, characterized in that, Including the read circuit according to any one of claims 1-6.

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