Quantum device and preparation method thereof

Abstract

The invention provides a quantum device and a preparation method thereof, and the quantum device comprises a superconducting ferromagnet structure which comprises a superconducting layer and a ferromagnet layer disposed on the superconducting layer; and the detector comprises a coplanar waveguide resonator, the coplanar waveguide resonator is in alternating current coupling with the superconducting ferromagnet structure, and the coplanar waveguide resonator is configured to detect the superconducting ferromagnet structure. According to the invention, the circuit quantum electrodynamics is introduced into the research of the superconducting ferromagnet structure, the coupling strength between the superconducting ferromagnet structure and the coplanar waveguide resonator is improved, and the accurate detection of the superconducting ferromagnet structure in the microwave range is realized; the efficiency and speed of quantum information processing are improved by realizing high-efficiency conversion and transmission between the magnetic vibrator and the photons.

Description

Technical Field

[0001] The present disclosure relates to the field of quantum devices, and in particular, to a quantum device and a preparation method thereof. Background Art

[0002] Circuit Quantum Electrodynamics (CQED) is a new means to study the fundamental interaction between light and matter (quantum optics). It combines the principles of quantum optics and circuit electrodynamics, adopts the framework of quantum field theory, and describes the interaction between quantum objects and photons through quantization methods.

[0003] Spin is an intrinsic property of particles. In magnetic materials, the generation of magnons comes from spin perturbations. In the magnon mode (Kittel mode), in ferromagnetic materials below the Curie temperature, even in the absence of an external magnetic field, spins will be ordered into a state with non-zero net magnetization, as Figure 1 shown in Figure a of [reference], which is the ordered ground state of a ferromagnet with the spin directions remaining consistent, and Figure b is the excited state of the magnon mode.

[0004] Since magnons can be coupled to photons through dipole interactions, however, due to the difficulty in miniaturizing the structure and the limited compatibility with two-dimensional circuits. Therefore, it is necessary to achieve strong coupling between a superconducting resonator and a ferromagnetic material etched on a chip.

[0005] Currently, in the traditional method of detecting a superconducting-ferromagnet system, the coupling strength between magnons and photons is insufficient, and the detection accuracy of the superconducting-ferromagnet system in the microwave frequency range is not enough. Summary of the Invention

[0006] To solve the problems existing in the prior art, the present disclosure provides a quantum device and a preparation method thereof, which can achieve strong coupling between a superconducting ferromagnet structure and a coplanar waveguide resonator, and improve the detection accuracy of the superconducting ferromagnet structure.

[0007] The present disclosure provides a quantum device, including:

[0008] A superconducting ferromagnet structure, which includes a superconducting layer and a ferromagnetic layer disposed on the superconducting layer;

[0009] A detector, which includes a coplanar waveguide resonator that is AC-coupled with the superconducting ferromagnet structure and is configured to detect the superconducting ferromagnet structure.

[0010] Optionally, the magnon mode frequency of the ferromagnetic layer of the superconducting ferromagnetic structure matches the photon mode frequency of the coplanar waveguide resonator, so that the coplanar waveguide resonator is AC-coupled to the superconducting ferromagnetic structure.

[0011] Optionally, the coplanar waveguide resonator includes a substrate and a coplanar waveguide resonator cavity disposed on the substrate, and the superconducting layer is disposed on the substrate, wherein the coplanar waveguide resonator cavity is formed by etching in the superconducting layer.

[0012] Optionally, a read line is etched on the superconducting layer, one end of the coplanar waveguide resonator cavity is coupled to the read line, and the other end of the coplanar waveguide resonator cavity is short-circuited to ground through the superconducting ferromagnetic structure.

[0013] Optionally, the coplanar waveguide resonator cavity includes a center conductor and side conductors located on both sides of the center conductor, a concave cavity is formed between the center conductor and the side conductors, and the impedance of the coplanar waveguide resonator cavity is determined by at least one of the width of the center conductor and the width of the concave cavity.

[0014] Optionally, by reducing the impedance of the coplanar waveguide resonator cavity, the coupling strength between the coplanar waveguide resonator and the superconducting ferromagnetic structure is increased.

[0015] Optionally, the ferromagnetic layer is disposed on the superconducting layer at one end of the center conductor of the coplanar waveguide resonator cavity.

[0016] Optionally, via holes are formed on the superconducting layer, and the via holes are arranged in an array and configured to fix vortices.

[0017] Optionally, the coplanar waveguide resonator cavity includes a bent section, a non-bent section, and a coupling section connected in sequence, a superconducting ferromagnetic structure is disposed at one end of the bent section, and the coupling section is coupled to the read line.

[0018] The present disclosure also provides a preparation method of the above-mentioned quantum device, and the preparation method includes:

[0019] S1. Substrate pretreatment;

[0020] S2. Superconducting layer deposition;

[0021] S3. Preset pattern exposure;

[0022] S4. Preset pattern etching;

[0023] S5. Photoresist layer stripping;

[0024] S6. Forming a superconducting ferromagnetic structure.

[0025] The present disclosure introduces circuit quantum electrodynamics into the research of superconducting ferromagnet structures, improves the coupling strength between superconducting ferromagnet structures and coplanar waveguide resonators, and enables precise detection of superconducting ferromagnet structures within the microwave range; by realizing efficient conversion and transmission between magnons and photons, the efficiency and speed of quantum information processing are improved. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the ferromagnetic ordered ground state and the magnon mode excited state of the present disclosure;

[0027] Figure 2 It is a schematic diagram of the structure of the quantum device of the present disclosure;

[0028] Figure 3 It is a schematic diagram of the coupling of the magnon mode in the superconducting ferromagnet structure and the photon mode in the coplanar waveguide resonator through magnetic dipoles of the present disclosure;

[0029] Figure 4 It is a schematic cross-sectional structure diagram of the coplanar waveguide resonator of the present disclosure;

[0030] Figure 5 It is a schematic diagram of the structure of the superconducting ferromagnet structure of the present disclosure;

[0031] Figure 6 is Figure 2 a schematic diagram of the structure of the through-hole in part A of

[0032] Figure 7 It is a schematic diagram of the segmented structure of the coplanar waveguide resonator cavity of the present disclosure;

[0033] Figure 8 It is a flowchart of the preparation method of the quantum device of the present disclosure.

[0034] In the figures: 10, substrate; 20, superconducting layer; 21, central conductor; 22, side conductor; 23, concave cavity; 30, read line; 40, coplanar waveguide resonator cavity; 41, bent section; 42, non-bent section; 43, coupling section; 50, superconducting ferromagnet structure; 51, ferromagnetic layer; 60, through-hole; 70, coplanar waveguide resonator. Detailed Embodiments

[0035] The technical solutions of the present disclosure will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present disclosure without creative efforts shall fall within the protection scope of the present disclosure.

[0036] The prior art uses a ferromagnetic material to couple with photons in a three-dimensional cavity to detect the superconducting ferromagnetic structure. However, the prior art relies on DC detection to achieve this, which has limitations in miniaturization and compatibility with two-dimensional circuits. Moreover, there are problems such as weak coupling strength between the detection device and the superconducting ferromagnetic structure and low detection accuracy, especially in the detection of the superconducting ferromagnetic structure in the microwave range.

[0037] A superconductor–ferromagnet system is a composite system that combines a superconductor and a ferromagnet; the superconducting ferromagnetic structure of the present disclosure is a superconductor–ferromagnet system.

[0038] As Figure 2 - Figure 7 shown, the present disclosure provides a quantum device, including:

[0039] A superconducting ferromagnetic structure 50, which includes a superconducting layer 20 and a ferromagnetic layer 51 disposed on the superconducting layer 20;

[0040] A detector, which includes a coplanar waveguide resonator 70. The coplanar waveguide resonator 70 is AC-coupled with the superconducting ferromagnetic structure 50 and is configured to detect the superconducting ferromagnetic structure 50.

[0041] In some embodiments of the present disclosure, the coplanar waveguide resonator 70 can detect the superconducting ferromagnetic structure 50 in the microwave range. Specifically, the coplanar waveguide resonator 70 can be a λ / 4 resonator with odd harmonics.

[0042] The present disclosure introduces circuit quantum electrodynamics into the research of the superconducting ferromagnetic structure 50, improves the coupling strength between the superconducting ferromagnetic structure 50 and the coplanar waveguide resonator 70, and realizes the precise detection of the superconducting ferromagnetic structure 50 in the microwave range; by realizing the efficient conversion and transmission between magnons and photons, the efficiency and speed of quantum information processing are improved.

[0043] In some embodiments of the present disclosure, the magnon mode frequency of the ferromagnetic layer 51 in the superconducting ferromagnetic structure 50 matches the photon mode frequency of the coplanar waveguide resonator 70, so that the coplanar waveguide resonator 70 is AC-coupled with the superconducting ferromagnetic structure 50.

[0044] As Figure 3 shown, by adjusting the external magnetic field, the frequency of the magnon mode in the ferromagnetic layer 51 matches the frequency ω of the photon mode in the coplanar waveguide resonator 70 r to achieve strong coupling between the magnon mode and the photon mode, thereby enabling strong coupling between the superconducting ferromagnetic structure 50 and the coplanar waveguide resonator 70.

[0045] When magnons are coupled with photons, due to the magnon decay effect, the hybrid mode exhibits broadening. The coupling strength g between magnons and photons is given by the following formula:

[0046]

[0047] where κ r is the internal loss rate of the coplanar waveguide resonator 70, κ r,ext is the external loss rate of the coplanar waveguide resonator 70, κ m is the magnon decay rate, ω r is the frequency of the coplanar waveguide resonator 70, H ∥ is the magnitude of the parallel magnetic field, ω is the scanning frequency of the network analyzer; S 21 (ω, H ∥ ) is the reading of the forward transmission coefficient (insertion loss) of the network analyzer at frequency ω under magnetic field H ∥ .

[0048] Based on the above formula, the coupling strength between magnons and photons can be determined as g. Based on the volume of the superconducting ferromagnetic structure 50, the coupling strength g per spin can be determined as g s = g / N spins , where N spins is the total number of spins. Therefore, the present disclosure can effectively enhance the coupling strength between the superconducting ferromagnetic structure 50 and the coplanar waveguide resonator 70, and such a quantum device with enhanced coupling can improve the information transmission speed between magnons and photons in the system, thus opening up new directions in quantum storage, quantum communication, and interface technologies with other quantum devices (such as superconducting qubits).

[0049] In some embodiments of the present disclosure, as Figure 4 shown, the coplanar waveguide resonator 70 includes a substrate 10 and a coplanar waveguide resonator cavity 40 disposed on the substrate 10. A superconducting layer 20 is disposed on the substrate 10, and the coplanar waveguide resonator cavity 40 is formed by etching in the superconducting layer 20.

[0050] The substrate 10 is a silicon substrate, the superconducting layer 20 is a superconducting niobium film layer, the thickness of the superconducting niobium film layer is 10 - 20 nm, and the coplanar waveguide resonator cavity 40 is patterned by reactive ion etching on the superconducting niobium film layer.

[0051] Using silicon material to fabricate the substrate 10, which has high resistivity, good microwave transmission performance, and stable chemical properties, is beneficial to reducing microwave loss and improving the performance of quantum devices.

[0052] The superconducting niobium film layer has an extremely thin characteristic, and the in-plane critical field can be significantly enhanced, so that the coplanar waveguide resonator cavity 40 can maintain a stable working state in an external strong magnetic field environment.

[0053] A read line 30 is etched on the superconducting layer 20. One end of the coplanar waveguide resonator 40 is coupled to the read line 30 and grounded. The read line 30 is configured to read the resonance frequency of the coplanar waveguide resonator 40. The other end of the coplanar waveguide resonator 40 is short-circuited to ground through a superconducting ferromagnetic structure 50. Among them, the read line 30 is a conductor located between two parallel grooves etched on the superconducting layer 20. The read line 30 is a key component connecting the signal source and the resonator, and is used to transmit signals from the signal source to the resonator.

[0054] In some embodiments of the present disclosure, as Figure 4 shown, the coplanar waveguide resonator 40 includes a center conductor 21 and side conductors 22 located on both sides of the center conductor 21. A concave cavity 23 is formed between the center conductor 21 and the side conductors 22. The impedance of the coplanar waveguide resonator 40 is determined by at least one of the width of the center conductor 21 and the width of the concave cavity 23.

[0055] The coplanar waveguide resonator 40 is formed by etching two parallel concave cavities 23 on the superconducting layer 20. The center conductor 21 is located between the two concave cavities 23, and the side conductors 22 are located on the side of the concave cavities 23 away from the center conductor 21. As Figure 4 shown, on the superconducting layer 20, from left to right, there are side conductors 22, concave cavities 23, center conductor 21, concave cavities 23, and side conductors 22 in sequence.

[0056] In some embodiments of the present disclosure, by reducing the impedance of the coplanar waveguide resonator 40, the coupling strength between the coplanar waveguide resonator 70 and the superconducting ferromagnetic structure 50 is increased.

[0057] The ferromagnetic layer 51 can be made of permalloy. Permalloy is easy to evaporate onto the coplanar waveguide resonator 40, can improve the compatibility with two-dimensional circuits, and is beneficial to the miniaturization of quantum devices.

[0058] In the present disclosure, by optimizing the coplanar waveguide resonator 40, the radio frequency magnetic field h of the coplanar waveguide resonator 40 experienced by the superconducting ferromagnetic structure 50 is rf maximized, and the radio frequency magnetic field h rf and are in direct proportion. Therefore, in order to enhance the radio frequency magnetic field h rf , and thus enhance the dipole coupling, it can be achieved by optimizing the impedance Z of the coplanar waveguide resonator 40 r . Therefore, there is the following formula

[0059]

[0060] where E is the complete elliptic integral of the first kind, ∈ r is the relative dielectric constant of the material, w is the width of the center conductor 21, and h is the width of the concave cavity. Generally, Z is designedr ≈50 Ω.

[0061] In the present disclosure, by utilizing the multi-mode characteristics of the coplanar waveguide resonator 40, not only the fundamental mode is detected but also the next harmonic ω n =(2n + 1)ω 0 can be detected. The current-voltage distribution of this design maximizes the current at the end of the coplanar waveguide resonator 40 (i.e., the position where the center conductor 21 is short-circuited to the ground through the superconducting ferromagnetic structure 50), thereby enhancing the dipole coupling.

[0062] Both the coplanar waveguide resonator 40 and the superconducting ferromagnetic structure 50 use the superconducting layer 20, so there are two forms. First, the coplanar waveguide resonator 40 and the superconducting ferromagnetic structure 50 use different superconducting layers 20, that is, they are separately arranged or made of different materials; second, the coplanar waveguide resonator 40 and the superconducting ferromagnetic structure 50 use the same superconducting layer 20, that is, they are integrally formed and made of the same material. As Figure 5 shown, in the present disclosure, the second form is adopted to arrange the ferromagnetic layer 51 on the superconducting layer 20 at the end of the center conductor 21 of the coplanar waveguide resonator 40 away from the read line 30, that is, the superconducting ferromagnetic structure 50 is directly formed on the substrate 10 of the coplanar waveguide resonator 40.

[0063] In some embodiments of the present disclosure, as Figure 6 shown, a plurality of vias 60 are provided on the superconducting layer 20. The plurality of vias 60 are arranged in an array and configured to fix vortices. The diameter of the via 60 is 100 nm, and the distance between adjacent vias 60 is between 1 - 10 μm. The plurality of vias 60 are arranged in a two-dimensional array to avoid the formation of eddy currents.

[0064] In the present disclosure, an in-plane magnetic field of at least about 100 mT is applied to the ferromagnetic layer 51 to precisely tune the frequency of the magnon mode to match the frequency of the photon mode. The use of these vias 60 enables the coplanar waveguide resonator 40 to still operate normally when the in-plane magnetic field reaches about 1 T.

[0065] In some embodiments of the present disclosure, as Figure 7 shown, the coplanar waveguide resonator 40 includes a bent section 41, a non-bent section 42, and a coupling section 43 connected in sequence. One end of the bent section 41 is provided with a superconducting ferromagnetic structure 50, and the coupling section 43 is coupled to the read line 30.

[0066] The bent section 41 includes a plurality of linearly arranged straight sections and arc sections connected between the ends of two adjacent straight sections. The non-bent section 42 is in a straight line form, and the coupling section 43 is also in a straight line form and parallel to the reading line 30. An arc transition exists between the bent section 41 and the non-bent section 42, and an arc transition exists between the non-bent section 42 and the coupling section 43.

[0067] In a specific embodiment of the present disclosure, as Figure 7 shown, the bent section 41 includes five straight sections and four arc sections. The five straight sections are respectively the first straight section, the second straight section, the third straight section, the fourth straight section, and the fifth straight section. The four arc sections are respectively the first arc section, the second arc section, the third arc section, and the fourth arc section. The connection method is that the first end of the first straight section is connected to the non-bent section 42, the second end of the first straight section is connected to the first arc section, and in sequence, the first arc section is connected to the second straight section, the second straight section is connected to the second arc section, the second arc section is connected to the third straight section, the third straight section is connected to the third arc section, the third arc section is connected to the fourth straight section, the fourth straight section is connected to the fourth arc section, the fourth arc section is connected to the fifth straight section, and the fifth straight section is connected to the superconducting ferromagnetic structure 50. The above is only an example, and the present disclosure does not limit the number and shape of the bent section 41, the non-bent section 42, and the coupling section 43.

[0068] The use of the bent section 41 can change the electromagnetic field distribution inside the coplanar waveguide resonator 40, adjust the resonant frequency of the coplanar waveguide resonator 40 by changing the effective length and shape of the coplanar waveguide resonator 40, and can also increase the mode diversity in the coplanar waveguide resonator 40, enabling the coplanar waveguide resonator 40 to excite more oscillation modes, thereby making the coplanar waveguide resonator 40 more flexible in setting, making the output impedance of the coplanar waveguide resonator 40 better match the input impedance of the external circuit, thereby reducing the reflection loss and transmission loss in the coplanar waveguide resonator 40 and improving the overall performance of the quantum device.

[0069] As Figure 8 shown, the present disclosure also provides a preparation method for a quantum device, and the preparation method includes:

[0070] S1. Substrate pretreatment, including: cleaning the substrate in a buffered oxide etchant for a specific time, and then putting it into a coating machine;

[0071] S2. Superconducting layer deposition, including: pre-sputtering metal Ti to improve the vacuum degree of the coating chamber, pre-sputtering metal Nb to remove impurities on the surface of the target, and then evaporating the superconducting layer;

[0072] S3. Exposure of the preset pattern, including: after applying a photoresist solution on the surface of the superconducting layer 20, baking and drying to form a photoresist layer, forming the preset pattern on the photoresist layer by electron beam exposure, then developing in a developer solution, and finally cleaning with oxygen plasma, where the preset pattern includes the patterns of the read line 30, the coplanar waveguide resonator 40, and the vias 60;

[0073] S4. Etching of the preset pattern, including: performing reactive ion etching to form the preset pattern on the superconducting layer 20;

[0074] S5. Stripping of the photoresist layer, including: soaking in acetone for a specific time, cleaning with ultrasonic waves to complete the stripping of the photoresist layer, and then cleaning with isopropyl alcohol;

[0075] S6. Forming the superconducting ferromagnetic structure, including: depositing a ferromagnetic layer 51 on the superconducting layer 20 at one end of the center conductor 21 of the coplanar waveguide resonator 40 away from the read line 30 to form the superconducting ferromagnetic structure 50.

[0076] Through the pretreatment of the substrate 10 and the fine deposition of the superconducting layer 20, the high-quality deposition of the superconducting material is ensured to guarantee the superconducting performance of the quantum device structure. The exposure and etching steps of the preset pattern achieve precise control of the structure shape, optimize the transmission path and coupling efficiency, and further improve the overall performance of the structure.

[0077] In the substrate pretreatment of step S1, a high-resistance silicon substrate with a resistivity greater than 10000 Ω / cm is used. The high-resistance silicon substrate is cleaned in a buffered oxide etchant for 25 s and then placed in a coating machine. Among them, the buffered oxide etchant is a 7:1 BOE etchant.

[0078] In the superconducting layer deposition of step S2, two metals are first pre-sputtered. In the first pre-sputtering, metal Ti is sputtered for 30 s, with an interval of 30 - 60 s, and then metal Ti is sputtered again for 30 s to improve the vacuum degree of the coating chamber in the coating machine; in the second pre-sputtering, metal Nb is sputtered for 30 s, with an interval of 30 - 60 s, and then metal Nb is sputtered again for 30 s to remove impurities on the surface of the target. Finally, a superconducting niobium film layer is evaporated on the surface of the high-resistance silicon substrate, and the evaporation thickness is 10 - 20 nm; the parameters for evaporating the superconducting niobium film layer are: evaporation time is 300 s, evaporation pressure is 3.5×10 －3 Torr, evaporation power is 150 W, and the gas flow rate of Ar is 18 sccm, N 2 is 1 sccm.

[0079] In the exposure of the preset pattern in step S3, the following steps are included:

[0080] a. Spin-coat a photoresist solution on the surface of the superconducting niobium film layer at a rotation speed of 4000 r / min for 60 s;

[0081] b. Bake it at a temperature of 100 °C for 5 minutes to dry and form a photoresist layer;

[0082] c. Form a preset pattern on the surface of the photoresist layer by electron beam exposure. The accelerator voltage for exposure is 25 kV, the aperture is 20 μm, the beam current is approximately 0.094 nA, and the exposure dose is 360 μC / cm 2 ;

[0083] d. Develop it in a developer for 1.5 min, where the developer is a developing solution of methyl isobutyl ketone (MIBK): isopropyl alcohol (IPA) at a ratio of 1:3;

[0084] e. Perform oxygen plasma cleaning for 30 s using a 30 W plasma cleaner.

[0085] Among them, the preset pattern includes the patterns of the read line 30, the coplanar waveguide resonator 40, and the via hole 60. The photoresist can be one of polymethyl methacrylate (PMMA), polymethylglutarimide (PMGI), phenol formaldehyde resin (DNQ)-based photoresist, and polyimide (PI)-based photoresist.

[0086] In the etching of the preset pattern in step S4, when performing reactive ion etching, the pressure is 10 mTorr, the ignition pressure is 25 mTorr, the He back pressure is 10 Torr, the RF power is 100 W, the Ar flow rate is 10 sccm, and the O 2 flow rate is 6 sccm, and the CF 4 flow rate is 30 sccm.

[0087] In the stripping of the photoresist layer in step S5, strip it in acetone for at least 10 hours, then clean it with ultrasonic waves for 5 s to complete the stripping of the photoresist layer, and finally clean it with isopropyl alcohol (IPA).

[0088] In the formation of the superconducting ferromagnetic structure in step S6, a layer of permalloy layer with a thickness of 30 nm and an area of 5 μm × 40 μm strip layer is selectively deposited on the superconducting niobium film layer at one end of the center conductor 21 of the coplanar waveguide resonator 40 away from the read line 30 by micro-nano processing technology (mask exposure). The high-resistance silicon substrate plays a supporting role, thus forming the superconducting ferromagnetic structure 50.

[0089] To ensure a clean interface between the two materials, before depositing the permalloy layer, pretreatment can be performed at the corresponding superconducting niobium film layer position for 25 s to remove any native oxides on the metal surface, where the pretreatment uses argon Plasma cleaning.

[0090] In summary, through the design of the above-mentioned quantum device and preparation method, the present disclosure has the following characteristics:

[0091] 1. Through circuit quantum electrodynamics (CQED), precise detection of the superconducting ferromagnetic structure in the microwave frequency range is achieved. This quantum device significantly enhances the coupling strength between magnons and photons, overcoming the problem of insufficient coupling strength in traditional methods; it opens up new directions for interface technologies in quantum storage, quantum communication, and other quantum devices (such as superconducting qubits). By realizing efficient conversion and transmission between magnons and photons, the efficiency and speed of quantum information processing are improved.

[0092] 2. Ferromagnetic materials are easily evaporated onto planar microwave resonators, making miniaturization and on-chip integration easier to achieve. The present disclosure can greatly improve the compatibility with two-dimensional (2D) circuits, which is beneficial to the miniaturization of quantum devices.

[0093] 3. Through refined control of the preparation method, precise control of the thickness and structural shape of each layer of the quantum device is achieved, optimizing the transmission path and coupling efficiency, and further improving the overall performance of the quantum device.

[0094] It should be emphasized that the above are only preferred embodiments of the present disclosure, and do not impose any form of limitation on the present disclosure. Any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present disclosure still fall within the scope of the technical solution of the present disclosure.

Claims

1. A quantum device, characterized in that: include: A superconducting ferromagnetic structure, the superconducting ferromagnetic structure comprising a superconducting layer and a ferromagnetic layer disposed on the superconducting layer; The detector comprises a coplanar waveguide resonator, the coplanar waveguide resonator is AC-coupled with the superconducting ferromagnetic structure and is configured to detect the superconducting ferromagnetic structure.

2. The quantum device according to claim 1, characterized in that: The magnon mode frequency of the ferromagnetic layer of the superconducting ferromagnetic structure matches the photon mode frequency of the coplanar waveguide resonator so that the coplanar waveguide resonator is AC-coupled with the superconducting ferromagnetic structure.

3. The quantum device according to claim 1, characterized in that: The coplanar waveguide resonator includes a substrate and a coplanar waveguide resonant cavity disposed on the substrate, the superconducting layer is disposed on the substrate, wherein the coplanar waveguide resonant cavity is formed by etching the superconducting layer.

4. The quantum device according to claim 3, characterized in that: A readout line is formed by etching on the superconducting layer, one end of the coplanar waveguide resonant cavity is coupled to the readout line, and the other end of the coplanar waveguide resonant cavity is short-circuited to ground through the superconducting ferromagnetic structure.

5. The quantum device according to claim 3, characterized in that: The coplanar waveguide resonant cavity comprises a central conductor and side conductors located on both sides of the central conductor, a concave cavity is formed between the central conductor and the side conductors, and the impedance of the coplanar waveguide resonant cavity is determined by at least one of the width of the central conductor and the width of the concave cavity.

6. The quantum device according to claim 5, characterized in that: The coupling strength between the coplanar waveguide resonator and the superconducting ferromagnetic structure is improved by reducing the impedance of the coplanar waveguide resonant cavity.

7. The quantum device according to claim 3, characterized in that: The ferromagnetic layer is disposed on the superconducting layer at one end of the central conductor of the coplanar waveguide resonant cavity.

8. The quantum device according to claim 3, characterized in that: Penetrating holes are provided on the superconducting layer, and the penetrating holes are arranged in an array and configured as a fixed vortex.

9. The quantum device according to claim 3, characterized in that: The coplanar waveguide resonant cavity comprises a bending section, a non-bending section and a coupling section connected in sequence, a superconducting ferromagnetic structure is arranged at one end of the bending section, and the coupling section is coupled with a read line.

10. A method for preparing a quantum device, for preparing the quantum device as claimed in any one of claims 1 to 9, characterized in that: The preparation method comprises: S1, substrate pretreatment; S2, superconducting layer deposition; S3, preset pattern exposure; S4, etching of a preset pattern; S5, stripping of the photoresist layer; S6. Forming superconducting ferromagnetic structure.

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