Probe device, superconducting qubit junction resistance measurement system and method

Abstract

The present invention discloses a probe device, a superconducting qubit junction resistance measurement system and method. The probe device includes a first probe, a second probe, a third probe, a probe manipulation mechanism, a resistance monitoring module and a chip displacement stage; the probe manipulation mechanism is used to manipulate the first probe to lower the needle to at least one side of the Josephson junction, so that the first probe contacts the oxide layer on the surface of the electrode of the Josephson junction, and is also used to manipulate the second probe and the third probe to lower the needle to both sides of the Josephson junction respectively, so that the second probe and the third probe just penetrate through the oxide layer on the surface of the electrode of the Josephson junction; the probes are all connected to the resistance monitoring module to obtain the resistance value between two probes; the chip displacement stage is used to carry the superconducting quantum chip. By monitoring the change of the resistance between the probes, the probes can accurately penetrate to the interface between the oxide layer and the electrode of the Josephson junction electrode, realize good electrical connection without damaging the electrode, and improve the measurement accuracy.

Description

Technical Field

[0001] The present invention belongs to the field of quantum information, especially the field of quantum chip detection, and particularly relates to a probe device, a superconducting qubit junction resistance measurement system and method. Background Art

[0002] The key structure on a superconducting quantum chip is a superconducting qubit, and the key structure of a superconducting qubit is a Josephson junction. A Josephson junction is a special device formed by isolating two electrodes with a thin insulator in the middle. To ensure the performance of the superconducting quantum chip, the frequency parameters of the superconducting qubit must be strictly controlled. The room-temperature resistance characterization of the superconducting qubit is important information reflecting the frequency parameters, and the resistance of the Josephson junction is the key to the room-temperature resistance characterization of the superconducting qubit. Therefore, it is necessary to accurately measure the resistance of the Josephson junction.

[0003] Currently, there is no dedicated resistance measurement scheme for superconducting quantum chips. At present, the resistance measurement of superconducting quantum chips adopts the resistance measurement scheme of traditional semiconductor chips, that is, using a probe to penetrate into the internal structure of the device to form a direct contact method to measure the resistance. This is mainly because an oxide layer will form on the electrodes of the Josephson junction. This oxide layer is not desired to be generated but is difficult to remove. Therefore, it is necessary to penetrate the oxide layer to obtain the resistance between the electrodes more accurately. Otherwise, the existence of the oxide layer will interfere with the measurement results. However, when the electrodes of the Josephson junction are penetrated by the probe, it will cause performance loss of the superconducting qubit. But using the resistance measurement scheme of semiconductor chips will inevitably cause the probe to penetrate into the electrodes, and in severe cases, the probe will even penetrate through the electrodes, directly damaging the Josephson junction. Therefore, the traditional resistance measurement scheme of semiconductor chips is not applicable to superconducting quantum chips. Summary of the Invention

[0004] The purpose of the present invention is to provide a probe device, a superconducting qubit junction resistance measurement system and method to solve the problem that the probe will penetrate into the electrodes of the Josephson junction in the prior art, which can avoid the probe from damaging the electrodes, thus not causing performance loss of the superconducting qubit, and can achieve accurate measurement of the resistance of the Josephson junction.

[0005] To achieve the above purpose and other related purposes, the present invention provides the following examples:

[0006] 1. Example 1 provided by the present invention: A probe device for measuring a superconducting quantum chip, which includes a first probe, a second probe, a third probe, a probe manipulation mechanism, a resistance monitoring module, and a chip displacement stage;

[0007] The probe manipulation mechanism is used to manipulate the first probe to move downward to at least one side of the Josephson junction on the superconducting quantum chip, and make the first probe contact the oxide layer on the electrode surface of the Josephson junction. The probe manipulation mechanism is also used to manipulate the second probe and the third probe to move downward to both sides of the Josephson junction on the superconducting quantum chip respectively, and make the second probe and the third probe just pierce through the oxide layer on the electrode surface of the Josephson junction;

[0008] The first probe, the second probe and the third probe are all connected to the resistance monitoring module to obtain the resistance value between the first probe and the second probe, and the resistance value between the first probe and the third probe;

[0009] The chip displacement stage is used to carry the superconducting quantum chip.

[0010] 2. Example 2 provided by the present invention: including Example 1, wherein, it further includes a fourth probe. The probe manipulation mechanism is also used to manipulate the fourth probe to move downward to the side of the Josephson junction on the superconducting quantum chip that has not been penetrated by the first probe, and make the fourth probe contact the oxide layer on the electrode surface of the Josephson junction. The fourth probe is connected to the resistance monitoring module.

[0011] 3. Example 3 provided by the present invention: including Example 2, wherein, the shank diameters of the first probe and the fourth probe are between 10 - 500 μm, and the tip diameters are between 0.5 - 15 μm. The shank diameters of the second probe and the third probe are between 5 - 50 μm, and the tip diameters are between 0.2 - 1 μm.

[0012] 4. Example 4 provided by the present invention: including Example 2, wherein, the probe manipulation mechanism includes a displacement adjustment component and a micro-force sensor fixed on the displacement adjustment component. The first probe and the fourth probe are respectively fixed on the corresponding micro-force sensors, and the second probe and the third probe are fixed on the displacement adjustment component.

[0013] 5. Example 5 provided by the present invention: including Example 2, wherein, it further includes: a processing module. The processing module receives in real time the pressure detected by the micro-force sensor, and at least monitors the pressure value when the pressure suddenly changes. The processing module also controls the movement of the displacement adjustment component according to the pressure value when the sudden change occurs.

[0014] 6. Example 6 provided by the present invention: a superconducting qubit junction resistance measurement system, wherein, it includes:

[0015] The probe device as described in any one of Examples 1 - 5, and

[0016] The junction resistance measurement module, and the junction resistance measurement module is respectively connected to the second probe and the third probe.

[0017] 7. Example 7 provided by the present invention: A method for measuring the junction resistance of a superconducting qubit, wherein a probe device as described in any one of Examples 1-5 is adopted, including:

[0018] Respectively lower the second probe and the third probe to the opposite sides of the Josephson junction on the superconducting quantum chip, and make both the second probe and the third probe exactly pierce through the oxide layer on the electrode surface of the Josephson junction;

[0019] Apply an electrical signal to the second probe and the third probe to measure the resistance of the Josephson junction.

[0020] 8. Example 8 provided by the present invention: including Example 7, wherein the step of lowering the second probe to the superconducting quantum chip and exactly piercing through the oxide layer on the electrode surface of the Josephson junction includes:

[0021] Contact the first probe with the first oxide layer on one side of the Josephson junction;

[0022] Move the second probe towards the first oxide layer on one side of the Josephson junction, and monitor the resistance value between the first probe and the second probe in real time;

[0023] Monitor the first mutation of the resistance value, and continue to move the second probe;

[0024] Monitor the second mutation of the resistance value, and stop moving the second probe when the second mutation occurs. At this time, the second probe is in contact with the first electrode of the Josephson junction.

[0025] 9. Example 9 provided by the present invention: including Example 8, wherein the step of lowering the third probe to the superconducting quantum chip and exactly piercing through the oxide layer on the electrode surface of the Josephson junction includes:

[0026] Contact the first probe or the fourth probe with the second oxide layer on the other side of the Josephson junction;

[0027] Move the third probe towards the second oxide layer on the other side of the Josephson junction, and monitor the resistance value between the first probe or the fourth probe and the third probe in real time;

[0028] Monitor the first mutation of the resistance value, and continue to move the third probe;

[0029] Monitor the second mutation of the resistance value, and stop moving the third probe when the second mutation occurs. At this time, the third probe is in contact with the second electrode of the Josephson junction.

[0030] Example 10 provided by the present invention: It includes Example 8, wherein the first oxide layer is a native oxide layer.

[0031] Example 11 provided by the present invention: It includes Example 9, wherein the second oxide layer is a native oxide layer.

[0032] Example 12 provided by the present invention: It includes Example 9, wherein the needle insertion position of the first probe is farther from the Josephson junction than that of the second probe, and the needle insertion position of the first probe or the fourth probe is farther from the Josephson junction than that of the third probe.

[0033] Example 13 provided by the present invention: It includes Example 9, wherein the pressure received by the first probe or the fourth probe is monitored to cause the first probe or the fourth probe to penetrate into the interface between the first film layer and the second film layer.

[0034] Example 14 provided by the present invention: It includes Example 8 or 9, wherein the first mutation is that the resistance value decreases from above 10 MΩ to 10 KΩ - 10 MΩ.

[0035] Example 15 provided by the present invention: It includes Example 8 or 9, wherein the second mutation is that the resistance value becomes 10 Ω - 1000 Ω.

[0036] In the above examples provided by the present invention, the probe device just penetrates through the oxide layer on the surface of the electrode of the Josephson junction by manipulating the probe, so that the probe forms a conductive connection with the electrode of the Josephson junction. Compared with the way of directly inserting the probe into the electrode of the Josephson junction in the prior art, the present invention can avoid the direct and rough contact between the probe and the electrode, thus not causing the loss of the performance of the superconducting qubit. For example, the coherence time and the qubit frequency of the superconducting qubit will not be affected, and it is very suitable for superconducting quantum chips.

[0037] In the above examples provided by the present invention, the superconducting qubit junction resistance measurement system adopts the probe device in some examples, so that probes form conductive connections with both electrodes on both sides of the Josephson junction. By using the junction resistance measurement module to connect the probes on both sides of the Josephson junction respectively, the resistance measurement can be realized. Since the probe just penetrates through the oxide layer on the surface of the electrode of the Josephson junction, it can accurately measure the resistance of the Josephson junction while avoiding the loss of the performance of the superconducting qubit.

[0038] In the above examples provided by the present invention, during the measurement of the superconducting qubit junction resistance, by monitoring the change in the resistance between the probes in real time, the probes can be accurately inserted to the interface between the oxide layer of the Josephson junction electrode and the electrode, enabling the probes to achieve good electrical connection with the electrodes of the Josephson junction without damaging the electrodes. On this basis, the measurement of the Josephson junction resistance can effectively improve the measurement accuracy.

[0039] In the above examples provided by the present invention, during the measurement of the superconducting qubit junction resistance, the number of probes used can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 FIG. is a schematic structural diagram of a qubit of a superconducting quantum chip;

[0041] Figure 2 FIG. is a schematic structural diagram of another qubit of a superconducting quantum chip;

[0042] Figure 3 FIG. is a schematic structural diagram of a Josephson junction;

[0043] Figure 4 FIG. is a flowchart of the electrical contact connection method provided in an embodiment of the present invention; Figure 1 ;

[0044] Figure 5 FIG. is a flowchart of the electrical contact connection method provided in an embodiment of the present invention; Figure 2 ;

[0045] Figure 6 FIG. is a schematic diagram of the needle insertion position provided in an embodiment of the present invention; Figure 1 ;

[0046] Figure 7 FIG. is a schematic structural diagram of the probe device provided in an embodiment of the present invention;

[0047] Figure 8 FIG. is a schematic structural diagram of the superconducting qubit junction resistance measurement system provided in an embodiment of the present invention;

[0048] Figure 9 FIG. is a flowchart of the superconducting qubit junction resistance measurement method provided in an embodiment of the present invention;

[0049] Figure 10 FIG. is a schematic diagram of the needle insertion position provided in an embodiment of the present invention; Figure 2 ;

[0050] Figure 11 FIG. is a schematic diagram of the needle insertion position provided in an embodiment of the present invention; Figure 3 。 DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] The specific embodiments of the present invention will be described in more detail below in conjunction with the schematic diagrams. The advantages and features of the present invention will be clearer according to the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise scales, only for the purpose of facilitating and clearly assisting in explaining the purpose of the embodiments of the present invention.

[0052] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0053] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0054] According to different physical systems used to construct qubits, qubits include superconducting quantum circuits, semiconductor quantum dots, ion traps, diamond vacancies, topological qubits, photons, etc. in terms of physical implementation methods.

[0055] Superconducting quantum computing is currently the fastest and best solid-state quantum computing implementation method. For a superconducting quantum chip, the structure of a qubit can use a single capacitor to ground, that is, 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, as shown in Figure 1 shown, the capacitor plate C q is surrounded by a ground plane (GND), and there is a gap between the capacitor plate C q and the ground plane (GND). One end of the superconducting quantum interference device Squid is connected to the capacitor plate C q , and the other end is connected to the ground plane (GND). In addition, the structure of a qubit can also use two capacitors to ground, and superconducting quantum interference devices respectively connected to the two capacitors to ground, as shown in Figure 2 shown, the first capacitor plate C q1 , the second capacitor plate C q2 , and the superconducting quantum interference device Squid are surrounded by a ground plane (GND), and the first capacitor plate C q1 , the second capacitor plate C q2There is a gap between each and the ground plane (GND). One end of the superconducting quantum interference device Squid is connected to the first capacitor plate C q1 and the other end is connected to the second capacitor plate C q2 .

[0056] The key structure on the superconducting quantum chip is the superconducting quantum bit. The key structure of the superconducting quantum bit is the Josephson junction, and the performance quality of the Josephson junction directly affects the performance of the quantum bit. The Josephson junction is a special device formed by isolating a thin insulator between two electrodes. For example, Figure 3 in, the Josephson junction 41 includes a first electrode 4011 and a second electrode 4012, and an insulator between the first electrode 4011 and the second electrode 4012. Among them, the first electrode 4011 can extend from the Josephson junction 41 to one side, and the second electrode 4012 can extend from the Josephson junction 41 to the opposite side. In order to ensure the performance of the superconducting quantum chip, the frequency parameters of the superconducting quantum bit must be strictly controlled. The room-temperature resistance characterization of the superconducting quantum bit is important information reflecting the frequency parameters, and the resistance of the Josephson junction is the key to the room-temperature resistance characterization of the superconducting quantum bit. Therefore, it is necessary to accurately measure the resistance of the Josephson junction to confirm whether it is qualified, and there is currently no dedicated resistance measurement scheme for superconducting quantum chips. In the present invention, the measurement of the junction resistance of the Josephson junction is mainly at the position where the electrode extends from the Josephson junction when the needle is inserted.

[0057] Embodiment 1

[0058] In order to test the Josephson junction, it is necessary to achieve electrical connection with the electrodes of the Josephson junction. An oxide layer will be formed on the surface of the electrodes of the Josephson junction. In order to form a good electrical connection with the electrodes of the Josephson junction, a feasible solution is to contact the electrodes by piercing the oxide layer with a probe. However, how to make the probe form a good electrical connection with the electrodes of the Josephson junction without damaging the Josephson junction is a very important link.

[0059] Embodiment 1 of the present invention provides an electrical contact connection method. Using this method, it is possible to more precisely achieve that the probe exactly reaches the interface between the two film layers, for example, the interface between the electrode and the oxide layer.

[0060] Please refer to the following Figure 4 . This embodiment includes the following content:

[0061] In the embodiment of the present invention, the electrical contact connection method includes:

[0062] S1001, move the probe towards the first film layer and monitor the pressure on the probe in real time;

[0063] S1002, monitor the first mutation of the pressure and continue to move the probe;

[0064] S1003, monitor the second mutation of the pressure and stop the movement of the probe when the second mutation occurs. At this time, the probe is in contact with the second film layer.

[0065] In a specific implementation, the second film layer is an electrode of a Josephson junction, and the first film layer is an oxide layer on the surface of the electrode.

[0066] For example, the electrode can be made of materials such as aluminum and niobium. In addition, other superconducting material layers can also be applied in the present invention.

[0067] The thickness of the first film layer can be between 0.1 nm and 5 nm, such as 0.3 nm, 0.5 nm, 0.8 nm, 1 nm, 1.2 nm, 1.5 nm, 1.7 nm, 2 nm, 2.3 nm, 2.6 nm, 2.9 nm, 3 nm, 3.1 nm, 3.4 nm, 3.6 nm, 3.8 nm, 4 nm, 4.3 nm, 4.5 nm, 4.8 nm, etc.

[0068] In order to reduce the influence of the external environment, in the embodiments of the present invention, it can be carried out in a dust-free room with a vibration isolation platform and a sound insulation box.

[0069] In S1001, under normal circumstances, the probe is not initially in contact with other external objects, so it is not under pressure, and the monitoring result should be 0.

[0070] As an example, in S1002, the first mutation is that the pressure changes from 0 to 0.1 - 10 μN, denoted as a μN. When the first mutation occurs, it means that the probe changes from a non-contact state to a contact state with the first film layer.

[0071] The limiting factors for the first pressure mutation include the probe shape, material, film layer thickness, etc. Generally, the softer the probe material, the blunter the tip, and the thicker the film layer, the greater the pressure. Obviously, it can be understood that the hardness of the probe is at least greater than the hardness of the first film layer.

[0072] When the first mutation occurs, the probe will continue to move, that is, continue to penetrate into the first film layer. During this process, the detected pressure usually continues to increase.

[0073] As the probe continues to penetrate, when the pressure undergoes a second mutation, it is considered that the probe just penetrates through the first film layer and is in contact with the second film layer.

[0074] As an example, in S1003, the second mutation is that the pressure becomes 10 - 100 times the first mutation.

[0075] The multiple of the second pressure mutation will vary according to the actual material and the thickness of the oxide layer. For example, for an aluminum film, a possible multiple is 10 - 12 times; however, for niobium, a possible multiple is 50 - 60 times.

[0076] For example, for an aluminum film, the first mutation is that the pressure changes from 0 to 5 μN. As the probe continues to move, for example, when the pressure becomes 6 μN, it can be considered that the probe is still in the first film layer. When the pressure becomes 50 μN (for example, a mutation occurs from 6.2 μN), and the changed pressure at this time is 10 times that of the first mutation, it can be considered that the probe just penetrates the first film layer and contacts the second film layer.

[0077] In the embodiment of the present invention, the multiple of the second pressure mutation can be obtained through multiple experiments and characterizations to obtain a multiple suitable for the relevant hardware and the device under test.

[0078] In S1003, when the second pressure mutation is detected, the probe immediately stops moving to avoid further penetration into the second film layer.

[0079] Verified by experiments, the method of the embodiment of the present invention can achieve the electrical connection between the probe and the electrode. At this time, the probe only penetrates the oxide layer and does not damage the electrode, or the probe only leaves a very small pit on the surface of the electrode, with minimal damage (usually acceptable at this time), and hardly affects the performance of the Josephson junction.

[0080] In addition, in the embodiment of the present invention, the probe moves at a slow and uniform speed. On the one hand, since the oxide layer itself is relatively thin, the speed of the probe is not easy to be too high. On the other hand, it is also convenient to immediately stop moving when reaching the target position.

[0081] For example, the moving speed of the probe ranges from 10 nm / s to 1 μm / s.

[0082] The electrical contact connection method proposed in this embodiment can make the probe just penetrate the oxide layer and contact the electrode as much as possible, and reduce the damage to the electrode of the Josephson junction as much as possible.

[0083] Embodiment 2

[0084] In order to test the Josephson junction, it is necessary to achieve electrical connection with the electrode of the Josephson junction. An oxide layer is formed on the surface of the electrode of the Josephson junction. In order to form a good electrical connection with the electrode of the Josephson junction, a feasible solution is to contact the electrode by penetrating the oxide layer with a probe. However, how to make the probe form a good electrical connection with the electrode of the Josephson junction without damaging the Josephson junction is a very important step.

[0085] Based on this, in this embodiment, a method for electrical contact connection is specifically proposed. This method can ensure that the probe precisely penetrates the oxide layer and contacts the electrode as much as possible, and reduces the damage to the electrode of the Josephson junction electrode as much as possible.

[0086] In the embodiment of the present invention, please refer to Figure 5 , the method for electrical contact connection includes:

[0087] S1901, bringing the first probe into contact with the first film layer;

[0088] S1902, moving the second probe towards the first film layer and monitoring the resistance value between the first probe and the second probe in real time;

[0089] S1903, monitoring the first mutation of the resistance value and continuing to move the second probe;

[0090] S1904, monitoring the second mutation of the resistance value and stopping the movement of the second probe when the second mutation occurs. At this time, the second probe is in contact with the second film layer.

[0091] In S1901, the contact between the first probe and the first film layer may include several situations such as contacting on the surface of the first film layer, penetrating into the first film layer, and precisely penetrating through the first film layer.

[0092] In a specific implementation, the second film layer is the electrode of the Josephson junction electrode, and the first film layer is the oxide layer of the electrode.

[0093] For example, the electrode can be made of materials such as aluminum and niobium. In addition, other superconducting material layers can also be applied in the present invention.

[0094] The thickness of the first film layer can be between 0.1 nm and 5 nm, such as 0.3 nm, 0.5 nm, 0.8 nm, 1 nm, 1.2 nm, 1.5 nm, 1.7 nm, 2 nm, 2.3 nm, 2.6 nm, 2.9 nm, 3 nm, 3.1 nm, 3.4 nm, 3.6 nm, 3.8 nm, 4 nm, 4.3 nm, 4.5 nm, 4.8 nm, etc.

[0095] To reduce the influence of the external environment, in the embodiment of the present invention, it can be carried out in a clean room with a vibration isolation platform and a sound insulation box.

[0096] In a better choice, as Figure 6 shown, the needle insertion position of the first probe is farther from the Josephson junction than the needle insertion position of the second probe. For example, the needle insertion position of the first probe is 20 - 200 μm away from the junction area. Thus, the position where the first probe is inserted is far from the junction area, and the influence on the junction can be ignored.

[0097] In addition, the first probe can be a relatively thick probe, which can easily penetrate or pierce through the oxide layer on the surface of the electrode.

[0098] In one embodiment, in S1901, the first probe is made to contact the first film layer by monitoring the pressure received by the first probe.

[0099] For example, the first probe can be made to contact the first film layer in the manner described in Embodiment 1.

[0100] In S1902, when the second probe is just started, since it has not yet contacted the first film layer, the resistance value between the first probe and the second probe tends to infinity (above 10 MΩ).

[0101] As an example, in S1903, the first mutation is that the resistance value drops to 10 KΩ - 10 MΩ. When the first mutation occurs, it means that the second probe changes from a non-contact state to a contact state with the first film layer.

[0102] The limiting factors for the first mutation include probe material, film layer material, etc.

[0103] When the first mutation occurs, the second probe will continue to move, that is, it will continue to penetrate into the first film layer. During this process, the resistance value usually shows a continuous downward trend.

[0104] As the second probe continues to penetrate, when the second mutation of the resistance value occurs, it is considered that the second probe just penetrates through the first film layer and contacts the second film layer.

[0105] As an example, in S1904, the second mutation is that the resistance value becomes 10 Ω - 1000 Ω, for example, 40 - 150 Ω.

[0106] In S1904, when it is detected that the second mutation of the resistance value occurs, the second probe immediately stops moving to avoid continuing to penetrate into the second film layer.

[0107] Through experimental verification, the method of the embodiment of the present invention can achieve the electrical connection between the second probe and the electrode. At this time, the second probe only penetrates through the oxide layer and does not damage the electrode, or the probe only leaves a very small pit on the surface of the electrode, with extremely small damage and hardly affecting the performance of the Josephson junction.

[0108] In addition, in the embodiment of the present invention, the second probe moves at a slow and uniform speed. On the one hand, since the oxide layer itself is relatively thin, the probe speed is not easy to be too high. On the other hand, it is also convenient to immediately stop moving when reaching the target position.

[0109] For example, the moving speed of the second probe ranges from 10 nm / s to 1 μm / s.

[0110] In the electrical contact connection method proposed in this embodiment, the probe can penetrate the oxide layer exactly to contact the electrode as much as possible, and the damage to the electrode of the Josephson junction electrode is reduced as much as possible.

[0111] Embodiment III

[0112] Embodiment III of the present invention provides a probe device, which can make the probe penetrate the oxide layer exactly to contact the electrode as much as possible, thereby reducing the damage to the electrode of the Josephson junction electrode as much as possible.

[0113] In one embodiment, please refer to Figure 7 , a probe device for measuring a superconducting quantum chip is provided, including a first probe 11, a second probe 12, a third probe 13, a probe manipulation mechanism, a resistance monitoring module 33, and a chip displacement stage 7;

[0114] The probe manipulation mechanism is used to manipulate the first probe 11 to lower the needle to at least one side of the Josephson junction on the superconducting quantum chip 4, and make the first probe 11 contact the oxide layer on the electrode surface of the Josephson junction. The probe manipulation mechanism is also used to manipulate the second probe 12 and the third probe 13 to lower the needles to both sides of the Josephson junction on the superconducting quantum chip respectively, and make the second probe 12 and the third probe 13 exactly penetrate the oxide layer on the electrode surface of the Josephson junction;

[0115] The first probe 11, the second probe 12, and the third probe 13 are all connected to the resistance monitoring module 33 to obtain the resistance value between the first probe and the second probe, and the resistance value between the first probe and the third probe;

[0116] The chip displacement stage 7 is used to carry the superconducting quantum chip 4.

[0117] Furthermore, a fourth probe 14 is further included. The probe manipulation mechanism is also used to manipulate the fourth probe 14 to lower the needle to the side of the Josephson junction on the superconducting quantum chip 4 that has not been lowered by the first probe 11, and make the fourth probe 13 contact the oxide layer on the electrode surface of the Josephson junction. The fourth probe 14 is connected to the resistance monitoring module 33.

[0118] As an example, the shank diameters of the first probe 11 and the fourth probe 14 range from 10 - 500 μm, the tip diameters range from 0.5 - 15 μm, the shank diameters of the second probe 12 and the third probe 13 range from 5 - 50 μm, and the tip diameters range from 0.2 - 1 μm.

[0119] In one implementation, the probe manipulation mechanism includes a displacement adjustment component 21 and a micro-force sensor 23 fixed on the displacement adjustment component 21. The first probe 11 and the fourth probe 14 are respectively fixed on one of the micro-force sensors 23, and the second probe 12 and the third probe 13 are fixed on the displacement adjustment component 21.

[0120] Further, it further includes: a processing module 331. The processing module 331 receives in real time the pressure detected by the micro-force sensor 23 and monitors at least the pressure value when the pressure undergoes a sudden change. The processing module 331 also controls the movement of the displacement adjustment component 21 according to the pressure value at the time of the sudden change.

[0121] Embodiment Four

[0122] Embodiment Four of the present invention provides a superconducting qubit junction resistance measurement system. This system can make the probe just penetrate the oxide layer and contact the electrode as much as possible, thereby reducing the damage to the Josephson junction electrode as much as possible and improving the measurement accuracy.

[0123] Please refer to Figure 8 , this embodiment provides a superconducting qubit junction resistance measurement system, including:

[0124] A probe device, and

[0125] A junction resistance measurement module 32, and the junction resistance measurement module 32 is respectively connected to the second probe 12 and the third probe 13.

[0126] Among them, the probe device may be the probe device provided in Embodiment Three of the present invention, which will not be described repeatedly here, and its corresponding technical effects are also applicable in this embodiment.

[0127] Further, in this embodiment, the junction resistance measurement module 32 can be replaced by a test instrument unit 34, so that the oxide layer can also be broken down in this embodiment.

[0128] Based on the superconducting qubit junction resistance measurement system of this embodiment, since the probe can be in place as precisely as possible, the measurement result accuracy of the Josephson junction resistance is relatively high.

[0129] Embodiment Five

[0130] Embodiment Five of the present invention provides a superconducting qubit junction resistance measurement method, and this measurement method can obtain relatively high measurement accuracy.

[0131] Please refer to Figure 8 - Figure 9 , this embodiment provides a superconducting qubit junction resistance measurement method, including:

[0132] S2601. Respectively lower the second probe 12 and the third probe 13 to the opposite side of the Josephson junction on the superconducting quantum chip 4, and make both the second probe 12 and the third probe 13 exactly pierce through the oxide layer on the electrode surface of the Josephson junction;

[0133] S2602. Apply an electrical signal to the second probe 12 and the third probe 13 to measure the resistance of the Josephson junction.

[0134] Specifically, in S2601, the steps of lowering the second probe 12 to the superconducting quantum chip 4 and exactly piercing through the oxide layer on the electrode surface of the Josephson junction include:

[0135] S2601A1. Contact the first probe 11 with the first oxide layer on one side of the Josephson junction;

[0136] S2601A2. Move the second probe 12 towards the first oxide layer on one side of the Josephson junction, and monitor the resistance value between the first probe and the second probe 12 in real time;

[0137] S2601A3. Monitor the first mutation of the resistance value, and continue to move the second probe 12;

[0138] S2601A4. Monitor the second mutation of the resistance value, and stop the movement of the second probe 12 when the second mutation occurs. At this time, the second probe 12 is in contact with the first electrode of the Josephson junction.

[0139] Among them, the needle insertion position of the first probe 11 is farther from the Josephson junction than the needle insertion position of the second probe 12, as Figure 6 schematically shows the relative positions when using the first probe and the second probe for needle insertion.

[0140] Specifically, in S2601, the steps of lowering the third probe 13 to the superconducting quantum chip and exactly piercing through the oxide layer on the electrode surface of the Josephson junction include:

[0141] S2601B1. Contact the first probe 11 or the fourth probe 14 with the second oxide layer on the other side of the Josephson junction;

[0142] S2601B2. Move the third probe 13 towards the second oxide layer on the other side of the Josephson junction, and monitor the resistance value between the first probe 11 or the fourth probe 14 and the third probe 13 in real time;

[0143] S2601B3. Monitor the first mutation of the resistance value, and continue to move the third probe 13;

[0144] S2601B4, monitor the second mutation of the resistance value and stop the movement of the third probe 13 when the second mutation occurs. At this time, the third probe 13 is in contact with the second electrode of the Josephson junction.

[0145] Wherein, the needle insertion position of the first probe or the fourth probe is farther from the Josephson junction than that of the third probe, as Figure 10 schematically shows the relative positions when the first probe and the third probe are used for needle insertion, as Figure 11 schematically shows the relative positions when the third probe and the fourth probe are used for needle insertion.

[0146] Among them, the operation processes of S2601A1 - S2601A4 and S2601B1 - S2601B4 are basically the same, and all can be carried out in the manner described in the above Embodiment 2.

[0147] In this embodiment, a simple and accurate resistance measurement method is provided. During the measurement process, by monitoring the change of the resistance between the probes in real time, the probe can accurately penetrate to the interface between the oxide layer of the Josephson junction electrode and the electrode, enabling the probe to achieve good electrical connection with the electrode of the Josephson junction without damaging the electrode. On this basis, the measurement of the Josephson junction resistance can effectively improve the measurement accuracy.

[0148] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example" or "specific example" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0149] The above are only the preferred embodiments of the present invention and do not impose any limitation on the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification and other changes to the technical solution and technical content disclosed in the present invention, all of which belong to the content of the technical solution of the present invention and are still within the protection scope of the present invention.

Claims

1. A probe device for measuring a superconducting quantum chip, characterized in that, It includes a first probe, a second probe, a third probe, a probe manipulation mechanism, a resistance monitoring module, and a chip displacement stage; The probe manipulation mechanism is used to manipulate the first probe to lower the needle to at least one side of the Josephson junction on the superconducting quantum chip, and make the first probe contact the oxide layer on the electrode surface of the Josephson junction. The probe manipulation mechanism is also used to manipulate the second probe and the third probe to lower the needles to both sides of the Josephson junction on the superconducting quantum chip respectively, and make the second probe and the third probe just pierce through the oxide layer on the electrode surface of the Josephson junction; The first probe, the second probe, and the third probe are all connected to the resistance monitoring module to obtain the resistance value between the first probe and the second probe, and the resistance value between the first probe and the third probe; The chip displacement stage is used to carry the superconducting quantum chip.

2. The probe device according to claim 1, wherein It further includes a fourth probe. The probe manipulation mechanism is also used to manipulate the fourth probe to lower the needle to the side of the Josephson junction on the superconducting quantum chip where the first probe does not lower the needle, and make the fourth probe contact the oxide layer on the electrode surface of the Josephson junction. The fourth probe is connected to the resistance monitoring module.

3. The probe device according to claim 2, characterized in that The shank diameters of the first probe and the fourth probe are between 10 - 500 μm, and the tip diameters are between 0.5 - 15 μm. The shank diameters of the second probe and the third probe are between 5 - 50 μm, and the tip diameters are between 0.2 - 1 μm.

4. The probe device according to claim 2, wherein The probe manipulation mechanism includes a displacement adjustment component and a micro - force sensor fixed on the displacement adjustment component. The first probe and the fourth probe are respectively fixed on the corresponding micro - force sensors, and the second probe and the third probe are fixed on the displacement adjustment component.

5. The probe device according to claim 4, characterized in that, It further includes: A processing module, which receives in real time the pressure detected by the micro - force sensor, and at least monitors the pressure value when the pressure undergoes a sudden change. The processing module also controls the movement of the displacement adjustment component according to the pressure value when the sudden change occurs.

6. A superconducting qubit junction resistance measurement system, characterized in that, It includes: The probe device according to any one of claims 1 - 5, and A junction resistance measurement module, which is respectively connected to the second probe and the third probe.

7. A method for measuring the junction resistance of a superconducting qubit, characterized in that, Using the probe device according to any one of claims 1 - 5, it includes: Respectively making the second probe and the third probe lower the needles to the opposite sides of the Josephson junction on the superconducting quantum chip, and making the second probe and the third probe both just pierce through the oxide layer on the electrode surface of the Josephson junction; Applying an electrical signal to the second probe and the third probe to measure the resistance of the Josephson junction.

8. The superconducting qubit junction resistance measurement method according to claim 7, characterized in that The step of making the second probe lower the needle to the superconducting quantum chip and just pierce through the oxide layer on the electrode surface of the Josephson junction includes: Contacting the first probe with the first oxide layer on one side of the Josephson junction; Moving the second probe towards the first oxide layer on one side of the Josephson junction, and monitoring in real time the resistance value between the first probe and the second probe; Monitoring the first sudden change in the resistance value, and continuing to move the second probe; Monitor the second mutation of the resistance value, and stop the movement of the second probe when the second mutation occurs. At this time, the second probe is in contact with the first electrode of the Josephson junction.

9. The superconducting qubit junction resistance measurement method according to claim 8, characterized in that The step of lowering the third probe onto the superconducting quantum chip and just piercing through the oxide layer on the surface of the electrode of the Josephson junction includes: Bring the first probe or the fourth probe into contact with the second oxide layer on the other side of the Josephson junction; Move the third probe towards the second oxide layer on the other side of the Josephson junction, and monitor the resistance value between the first probe or the fourth probe and the third probe in real time; Monitor the first mutation of the resistance value, and continue to move the third probe; Monitor the second mutation of the resistance value, and stop the movement of the third probe when the second mutation occurs. At this time, the third probe is in contact with the second electrode of the Josephson junction.

10. The superconducting qubit junction resistance measurement method according to claim 9, wherein The needle insertion position of the first probe is farther from the Josephson junction than the needle insertion position of the second probe, and the needle insertion position of the first probe or the fourth probe is farther from the Josephson junction than the needle insertion position of the third probe.

11. The superconducting qubit junction resistance measurement method according to claim 9, characterized in that By monitoring the pressure received by the first probe or the fourth probe, the first probe or the fourth probe is inserted into the interface between the first film layer and the second film layer.

12. The method for measuring the resistance of a superconducting qubit junction according to claim 8 or 9, characterized in that, The first mutation is that the resistance value decreases from above 10 MΩ to 10 KΩ - 10 MΩ.

13. The superconducting qubit junction resistance measurement method according to claim 8 or 9, characterized in that, The second mutation is that the resistance value becomes 100 Ω - 1000 Ω.

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