A superconducting quantum chip and its processing method, and a method for detecting surface hydrogen bonds

Abstract

The present application provides a method for detecting hydrogen bonds on the surface of a superconducting quantum chip, comprising: photographing a target superconducting device using the TEM mode of a spherical aberration scanning transmission electron microscope to obtain an electron microscope image; performing an EELS scan on the electron microscope image within a preset energy range using the STEM mode of a spherical aberration scanning transmission electron microscope to obtain energy loss data; comparing the energy loss data with a set consisting of energy values ​​of hydrogen bond breakage; if the energy loss data has the same energy value within the set, determining that hydrogen bonds exist on the surface of the target superconducting device; wherein each energy value contained in the set is within the preset energy range. A method for processing a superconducting quantum chip is further provided, which solves the TLS loss caused by hydrogen impurities by covering the surface of a superconducting device with hydrogen bonds with a graphene layer. A superconducting quantum chip obtained by the method for processing a superconducting quantum chip of the present application is also provided.

Description

Technical Field

[0001] The present application relates to the field of quantum chip technology, and in particular to a superconducting quantum chip and a processing method thereof, and a method for detecting surface hydrogen bonds. Background Art

[0002] Decoherence in superconducting quantum chips is primarily due to dissipative two-level systems (TLS), which exist in superconducting devices such as Josephson junctions and superconducting quantum devices (SQUIDs). In Josephson junctions, hydrogen bonding generates an electric dipole moment, which in turn produces dielectric losses and leads to decoherence. In superconducting quantum devices, hydrogen bonds attract gas molecules in the environment, inducing magnetization and generating a magnetic dipole moment. This leads to an additional source of flux noise, causing bit energy levels to fluctuate and phase decoherence to occur. The surface of superconducting devices easily forms hydrogen bonds (Al-H, OH…O, OH, CH, etc.) with hydrogen atoms (H) and hydroxyl groups (OH-). Hydrogen bonds are the primary cause of dissipative two-level losses. Therefore, characterizing and eliminating hydrogen bonds on the surface of superconducting quantum chips is crucial for addressing dissipative two-level losses caused by hydrogen bonds. Summary of the Invention

[0003] The purpose of this application is to provide a superconducting quantum chip and its processing method, as well as a method for detecting surface hydrogen bonds, to solve the dissipative two-level loss caused by hydrogen bonds. The specific technical solution is as follows:

[0004] In a first aspect, the present application provides a method for detecting hydrogen bonds on the surface of a superconducting quantum chip, wherein the superconducting quantum chip includes a superconducting device, and the detection method includes:

[0005] Use the TEM mode of a spherical aberration scanning transmission electron microscope to photograph the target superconducting device and obtain an electron microscope image;

[0006] Performing an electron energy loss spectroscopy (EELS) scan on the electron microscope image within a preset energy range using a spherical aberration scanning transmission electron microscope (STEM) mode to obtain energy loss data;

[0007] comparing the energy loss data to a set of energy values ​​for hydrogen bond breakage;

[0008] If the energy loss data have the same energy value in the set, determining that hydrogen bonds exist on the surface of the target superconducting device;

[0009] Wherein, each energy value included in the set is within the preset energy range.

[0010] In some embodiments, before performing EELS scanning within a preset energy range on the electron microscope image using the STEM mode of the spherical aberration scanning transmission electron microscope, the method further comprises:

[0011] The electron microscope image is magnified according to a preset magnification.

[0012] In some embodiments, the preset energy range is 0-500 meV; the energy values ​​of the set are selected from the energy values ​​of breaking Al-H hydrogen bonds, OH...O hydrogen bonds, OH hydrogen bonds and CH hydrogen bonds.

[0013] In some embodiments, before photographing the target superconducting device using the TEM mode of the spherical aberration scanning transmission electron microscope, the method further includes:

[0014] The target superconducting device is cut and thinned.

[0015] In some embodiments, the detection method further comprises:

[0016] The type of hydrogen bonds on the surface of the target superconducting device is determined according to the energy value identical to the energy loss data.

[0017] A second aspect of the present application provides a method for processing a superconducting quantum chip, the method comprising:

[0018] Providing a superconducting quantum chip, wherein the superconducting quantum chip includes a superconducting device;

[0019] The method for detecting hydrogen bonds on the surface of a superconducting quantum chip provided in the first aspect of the present application is used to detect whether hydrogen bonds exist on the surface of a target superconducting device;

[0020] When hydrogen bonds exist on the surface of the target superconducting device, a graphene layer is covered on the surface of the target superconducting device.

[0021] In some embodiments, the method for detecting hydrogen bonds on the surface of a superconducting quantum chip provided in the first aspect of the present application is used to detect whether hydrogen bonds exist on the surface of a target superconducting device, including:

[0022] The method for detecting hydrogen bonds on the surface of a superconducting quantum chip provided in the first aspect of the present application is used to detect multiple times whether hydrogen bonds exist on the surface of a target superconducting device. When the number of times hydrogen bonds are detected on the surface of the target superconducting device is within a threshold range, it is determined that hydrogen bonds exist on the surface of the target superconducting device.

[0023] In some embodiments, the graphene layer is deposited by chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), mechanical exfoliation-dry transfer, or mechanical exfoliation-wet transfer.

[0024] In some embodiments, the process conditions of the chemical vapor deposition include: a flow rate of CH4 of 100 sccm to 300 sccm, a flow rate of Ar of 10 sccm to 30 sccm, a temperature of 400 to 600°C, and a deposition time of 5 to 20 minutes.

[0025] In some embodiments, the graphene layer has a thickness of 30-200 nm.

[0026] The third aspect of the present application provides a superconducting quantum chip obtained according to the processing method of the superconducting quantum chip provided in the second aspect of the present application.

[0027] The present application provides a method for detecting hydrogen bonds on the surface of a superconducting quantum chip, wherein the superconducting quantum chip includes a superconducting device, and the detection method includes: photographing the target superconducting device using the TEM mode of a spherical aberration scanning transmission electron microscope to obtain an electron microscope image; performing an EELS scan on the electron microscope image within a preset energy range using the STEM mode of a spherical aberration scanning transmission electron microscope to obtain energy loss data; comparing the energy loss data with a set consisting of energy values ​​of hydrogen bond breakage; if the energy loss data have the same energy value within the set, determining that hydrogen bonds exist on the surface of the target superconducting device; wherein each energy value contained in the set is within the preset energy range. The detection method can accurately characterize the surface hydrogen bonds of the superconducting quantum chip. The present application further provides a method for processing a superconducting quantum chip, including: using the method for detecting hydrogen bonds on the surface of a superconducting quantum chip provided by the present application to detect whether hydrogen bonds exist on the surface of the target superconducting device; when hydrogen bonds exist on the surface of the target superconducting device, covering the surface of the target superconducting device with a graphene layer. The treatment method covers the surface of a superconducting device with hydrogen bonds with a graphene layer, using the graphene to eliminate the polarization effect induced by hydrogen impurities, thereby solving the TLS loss caused by hydrogen impurities. The present application also provides a superconducting quantum chip obtained by the treatment method of the superconducting quantum chip of the present application. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by those skilled in the art based on the present application are within the scope of protection of the present application.

[0029] In a first aspect, the present application provides a method for detecting hydrogen bonds on the surface of a superconducting quantum chip, wherein the superconducting quantum chip includes a superconducting device, and the detection method includes:

[0030] Use the TEM mode of a spherical aberration scanning transmission electron microscope to photograph the target superconducting device and obtain an electron microscope image;

[0031] Performing EELS scanning on the electron microscope image within a preset energy range using a spherical aberration scanning transmission electron microscope (STEM) mode to obtain energy loss data;

[0032] comparing the energy loss data to a set of energy values ​​for hydrogen bond breakage;

[0033] If the energy loss data have the same energy value in the set, determining that hydrogen bonds exist on the surface of the target superconducting device;

[0034] Wherein, each energy value included in the set is within the preset energy range.

[0035] In this application, the target superconducting device includes a Josephson junction, a superconducting loop, etc. In this application, the energy loss data is determined based on the abscissa (in meV) of the peak position in the EELS spectrum. In this application, the presence of hydrogen bonds on the surface of the target superconducting device is confirmed if the energy loss data have at least one identical energy value within the set.

[0036] At present, the commonly used methods for characterizing hydrogen bonds are infrared spectroscopy and electrochemiluminescence, but they are mainly used for the detection of organic matter, or have requirements on the transmittance of the substrate, and cannot be applied to the detection of superconducting quantum chips. The method for detecting hydrogen bonds on the surface of superconducting quantum chips provided in this application uses a spherical aberration scanning transmission electron microscope TEM mode to shoot the target superconducting device in a small area such as the Josephson junction and superconducting loop of the superconducting quantum chip, and then uses the STEM mode to perform EELS analysis to obtain energy loss data. By comparing the energy loss data with the correspondence of the energy values ​​of the broken hydrogen bonds of Al-H, OH...O, OH, CH, etc., the presence of hydrogen bonds can be accurately judged. The method for detecting hydrogen bonds on the surface of superconducting quantum chips provided in this application can accurately characterize the presence of hydrogen bonds on the surface of superconducting quantum chips, and provide a reliable basis for solving the dissipative two-level loss caused by hydrogen bonds.

[0037] In some embodiments, before performing EELS scanning within a preset energy range on the electron microscope image using the STEM mode of the spherical aberration scanning transmission electron microscope, the method further comprises:

[0038] The electron microscope image is magnified according to a preset magnification.

[0039] This application does not have any special limitation on the preset magnification, as long as the purpose of this application can be achieved. For example, the preset magnification is 4-6 million times, which can make the electron microscope image clearer for EELS scanning and obtain more accurate energy loss data.

[0040] In some embodiments, the preset energy range is 0-500meV; the energy values ​​of the set are selected from the energy values ​​of the breakage of Al-H hydrogen bonds, OH...O hydrogen bonds, OH hydrogen bonds, and C-H hydrogen bonds. In some experimental measurements, the energy values ​​of the breakage of Al-H hydrogen bonds are 139meV and 226meV, the energy value of the breakage of OH...O hydrogen bonds is 218meV, the energy value of the breakage of OH hydrogen bonds is 195meV, 269meV, and 303meV, and the energy value of the breakage of C-H hydrogen bonds is 295meV and 352meV. In the present application, the electron energy loss spectroscopy can accurately measure the energy loss of the order of meV. The energy value of the hydrogen bond breakage is within the preset energy range of the EELS scan. Therefore, the EELS spectrum can characterize the energy loss of the hydrogen bond breakage, and then the presence of the hydrogen bond can be determined.

[0041] In some embodiments, before photographing the target superconducting device using the TEM mode of the spherical aberration scanning transmission electron microscope, the method further includes:

[0042] The target superconducting device is cut and thinned.

[0043] In this application, the cutting and thinning does not involve directly thinning the surface of the target superconducting device. Instead, the cutting and thinning can be performed from the bottom or periphery of the target superconducting device, without damaging the surface of the target superconducting device. This application does not specifically limit the cutting and thinning method, as long as it can achieve the objectives of this application. For example, a focused ion beam (FIB) can be used to thin the target superconducting device. Furthermore, the FIB can be used to thin the target superconducting device to a thickness of 80-120 nm, thereby further enabling accurate analysis of hydrogen bonds on the surface of the target superconducting device.

[0044] In the present application, in the EELS scanning of the electron microscope image within a preset energy range using the STEM mode of the spherical aberration scanning transmission electron microscope, the higher the resolution of the spherical aberration scanning transmission electron microscope used, the more accurate the measured EELS spectrum, and the higher the accuracy of judging the existence of hydrogen bonds; preferably, the resolution of the spherical aberration scanning transmission electron microscope is 50-200pm.

[0045] In some embodiments, the detection method further comprises:

[0046] The type of hydrogen bonds on the surface of the target superconducting device is determined according to the energy value identical to the energy loss data.

[0047] A second aspect of the present application provides a method for processing a superconducting quantum chip, the method comprising:

[0048] Providing a superconducting quantum chip, wherein the superconducting quantum chip includes a superconducting device;

[0049] The method for detecting hydrogen bonds on the surface of a superconducting quantum chip provided in the first aspect of the present application is used to detect whether hydrogen bonds exist on the surface of a target superconducting device;

[0050] When hydrogen bonds exist on the surface of the target superconducting device, a graphene layer is covered on the surface of the target superconducting device.

[0051] The processing method of the superconducting quantum chip provided in this application is to cover the surface of the target superconducting device with a graphene layer. On the one hand, the induced magnetization of hydrogen atoms, hydroxyl groups, etc. is reduced to the graphene through charge transfer, and the graphene is used to eliminate the polarization effect induced by hydrogen impurities; on the other hand, other molecules such as H2O and O2 are prevented from diffusing to the surface of the target superconducting device, thereby solving the TLS loss caused by hydrogen impurities.

[0052] In some embodiments, the method for detecting hydrogen bonds on the surface of a superconducting quantum chip provided in the first aspect of the present application is used to detect whether hydrogen bonds exist on the surface of a target superconducting device, including:

[0053] The method for detecting hydrogen bonds on the surface of a superconducting quantum chip provided in the first aspect of the present application is used to detect multiple times whether hydrogen bonds exist on the surface of a target superconducting device. When the number of times hydrogen bonds are detected on the surface of the target superconducting device is within a threshold range, it is determined that hydrogen bonds exist on the surface of the target superconducting device.

[0054] In this application, the accuracy of the detection results of hydrogen bonds on the surface of the superconducting quantum chip can be further improved by performing multiple detections of hydrogen bonds on the surface of the superconducting quantum chip. This application does not specifically limit the number of such multiple detections, as long as the purpose of this application can be achieved. For example, at least 10 detections of hydrogen bonds on the surface of the superconducting quantum chip can be performed. This application does not specifically limit the threshold range, as long as the purpose of this application can be achieved. Preferably, the threshold range is a value of more than 60% of the number of detections.

[0055] In some embodiments, the graphene layer is deposited by CVD, PECVD, mechanical exfoliation-dry transfer, or mechanical exfoliation-wet transfer.

[0056] In some embodiments, the process conditions of the chemical vapor deposition include: a flow rate of CH4 of 100 sccm to 300 sccm, a flow rate of Ar of 10 sccm to 30 sccm, a temperature of 400 to 600°C, and a deposition time of 5 to 20 minutes.

[0057] In some embodiments, the graphene layer has a thickness of 30-200 nm.

[0058] The third aspect of the present application provides a superconducting quantum chip obtained according to the superconducting quantum chip processing method provided in the second aspect of the present application.

[0059] In this application, the term "about" means within ±5% of a value.

[0060] Hereinafter, embodiments of the present application will be described in more detail with reference to examples.

[0061] Example 1

[0062] A Josephson junction (S (superconductor) - I (insulator) - S (superconductor) structure is Al-Al2O3-Al structure, with thicknesses of 36nm, 2nm, and 97nm, respectively) was thinned to a thickness of about 100nm by FIB cutting. The surface of the Josephson junction was photographed using a spherical aberration scanning transmission electron microscope in TEM mode to obtain an electron microscope image. The electron microscope image was magnified at a magnification of about 5 million times, and the magnified electron microscope image was scanned by EELS using a spherical aberration scanning transmission electron microscope in STEM mode with a resolution of 60pm, with a scanning range of 0-500 meV, the energy loss data is determined according to the abscissa (in meV) of the peak position in the EELS spectrum, as shown in Table 1; the detection is repeated according to the above steps, and the energy loss data obtained by detection 10 times are respectively shown in Table 1; it can be seen that among the energy loss data obtained in 10 times of detection, 3 times are the same as the energy value of 139meV for the breaking of Al-H hydrogen bond, and 4 times are the same as the energy value of 226meV for the breaking of Al-H hydrogen bond. According to Table 1, it can be seen that the presence of hydrogen bonds on the surface of the Josephson junction is detected a total of 6 times, confirming the presence of hydrogen bonds on the surface of the Josephson junction.

[0063] Table 1

[0064]

[0065] A graphene layer is covered on the surface of a Josephson junction where hydrogen bonds exist. Specifically, the Josephson junction is placed in a vacuum tube furnace, argon gas is introduced at a flow rate of 20 sccm, the temperature of the tube furnace is controlled to be 500°C, methane is used as a carbon source, the flow rate is 200 sccm, and the deposition time is 10 minutes. After the graphene deposition is completed, the furnace is cooled to room temperature, the gas is turned off and the furnace is taken out to obtain a Josephson junction covered with a graphene layer. The graphene layer has a thickness of 50 nm.

[0066] The same method as the above-mentioned detection steps of hydrogen bonds on the Josephson junction surface was used to detect that no hydrogen bonds existed on the surface of the Josephson junction covered with the graphene layer.

[0067] In summary, the method for detecting hydrogen bonds on the surface of a superconducting quantum chip of the present application can accurately characterize the hydrogen bonds on the surface of a target superconducting device; the method for treating a superconducting quantum chip of the present application can eliminate the polarization effect induced by hydrogen impurities, thereby solving the TLS loss caused by hydrogen impurities.

[0068] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for detecting hydrogen bonds on the surface of a superconducting quantum chip, wherein the superconducting quantum chip includes a superconducting device, characterized in that: The detection method comprises: Use the TEM mode of a spherical aberration scanning transmission electron microscope to photograph the target superconducting device and obtain an electron microscope image; Performing EELS scanning on the electron microscope image within a preset energy range using a spherical aberration scanning transmission electron microscope (STEM) mode to obtain energy loss data; comparing the energy loss data to a set of energy values ​​for hydrogen bond breakage; If the energy loss data have the same energy value in the set, determining that hydrogen bonds exist on the surface of the target superconducting device; Wherein, each energy value included in the set is within the preset energy range.

2. The detection method according to claim 1, wherein Before performing EELS scanning within a preset energy range on the electron microscope image using the STEM mode of the spherical aberration scanning transmission electron microscope, the method further includes: The electron microscope image is magnified according to a preset magnification.

3. The detection method according to claim 1, wherein The preset energy range is 0-500 meV; the energy value of the set is selected from the energy values ​​of the breakage of Al-H hydrogen bond, OH...O hydrogen bond, OH hydrogen bond and CH hydrogen bond.

4. The detection method according to claim 1, wherein Before photographing the target superconducting device using the TEM mode of the spherical aberration scanning transmission electron microscope, the method further includes: The target superconducting device is cut and thinned.

5. The detection method according to claim 1, wherein The detection method further comprises: The type of hydrogen bonds on the surface of the target superconducting device is determined according to the energy value identical to the energy loss data.

6. A method for processing a superconducting quantum chip, characterized in that: The processing method comprises: Providing a superconducting quantum chip, wherein the superconducting quantum chip includes a superconducting device; The method for detecting hydrogen bonds on the surface of a superconducting quantum chip according to any one of claims 1 to 5 is used to detect whether hydrogen bonds exist on the surface of a target superconducting device; When hydrogen bonds exist on the surface of the target superconducting device, a graphene layer is covered on the surface of the target superconducting device.

7. The processing method according to claim 6, characterized in that The method for detecting hydrogen bonds on the surface of a superconducting quantum chip according to any one of claims 1 to 5 is used to detect whether hydrogen bonds exist on the surface of a target superconducting device, comprising: The method for detecting hydrogen bonds on the surface of a superconducting quantum chip according to any one of claims 1 to 5 is used to detect multiple times whether hydrogen bonds exist on the surface of a target superconducting device. When the number of times hydrogen bonds are detected on the surface of the target superconducting device is within a threshold range, it is determined that hydrogen bonds exist on the surface of the target superconducting device.

8. The processing method according to claim 6, characterized in that The graphene layer is deposited by chemical vapor deposition, plasma enhanced chemical vapor deposition, mechanical exfoliation-dry transfer or mechanical exfoliation-wet transfer.

9. The processing method according to claim 8, characterized in that: The process conditions of the chemical vapor deposition include: a flow rate of CH4 of 100 sccm to 300 sccm, a flow rate of Ar of 10 sccm to 30 sccm, a temperature of 400 to 600° C., and a deposition time of 5 to 20 minutes.

10. A superconducting quantum chip obtained by the method for processing a superconducting quantum chip according to any one of claims 6 to 9.

Images