In-situ testing device and method for quantum bit chip

Abstract

The invention discloses an in-situ test device and method for a quantum bit chip. The device comprises a laser irradiation unit, a test board, a probe structure and an electrical property detection device, a vacuum cavity is formed in the test board, a window and at least two probe interfaces which are communicated with the vacuum cavity are formed in the side wall of the test board, a sample table is arranged in the vacuum cavity, and the sample table carries a quantum bit chip; the laser irradiation unit is used for generating laser; the probe structure comprises at least two groups of probe arms and probes, the probe arms penetrate through the probe interface, the first ends of the probe arms are located in the vacuum cavity, the second ends of the probe arms are located outside the vacuum cavity, the probes are fixedly installed at the first ends of the probe arms and electrically connected with the probe arms, and the second ends of the probe arms are electrically connected with the electrical property detection device. According to the invention, the problem that the oxidation layer of the quantum bit chip affects the accuracy of the electrical property test can be solved, and the efficiency of the electrical property test of the quantum bit chip can be effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of superconducting quantum computing, and in particular relates to an in-situ testing device and method for a quantum bit chip. Background Art

[0002] The field of superconducting quantum bits based on the Josephson junction is developing rapidly. In order to optimize the interface contact characteristics of the quantum bit, micro-area laser annealing technology is usually used to induce changes in the interface contact of the Josephson junction quantum bit, thereby causing changes in the bit resistance and bit frequency to regulate the bit performance. Testing the electrical properties of the quantum bit chip, such as resistance, has become an effective method for quickly feeding back changes in the characteristics of the quantum bit chip after laser annealing.

[0003] The prior art usually moves the quantum bit chip after laser irradiation modification to a special electrical probe test bench for electrical testing. However, this process exposes the sensitive quantum bit chip to the atmosphere, and oxidation by water and oxygen will cause an ultra-thin oxide layer to form on the outermost surface of the quantum bit chip. This not only brings uncontrollable factors to the function of the quantum bit chip, but also causes the disadvantage of inaccurate probe testing caused by the presence of an ultra-thin oxide layer in electrical testing. Therefore, it is also necessary to use precise micro-force feedback and displacement adjustment components in combination with resistance monitoring modules and processing modules to break the oxide layer, so as to accurately test the electrical properties. The equipment used in this method is usually expensive, complicated to operate, and inconvenient to use. In addition, there are problems such as inaccurate testing, complicated operation, and long testing time during the test process.

[0004] Therefore, in response to the above technical problems, it is necessary to provide an in-situ testing device and method for quantum bit chips. Summary of the invention

[0005] The purpose of the present invention is to provide an in-situ testing device and method for a quantum bit chip, which can solve the problem that the oxide layer of the quantum bit chip affects the accuracy of electrical property testing and effectively improve the efficiency of electrical property testing of the quantum bit chip.

[0006] In order to achieve the above object, a technical solution provided by a specific embodiment of the present invention is as follows:

[0007] An in-situ testing device for a quantum bit chip, the in-situ testing device comprising a laser irradiation unit, a test bench, a probe structure and an electrical characteristic detection device;

[0008] A vacuum cavity is arranged inside the test bench, a window communicating with the vacuum cavity and at least two probe interfaces are arranged on the side wall of the test bench, and a sample stage is arranged inside the vacuum cavity, and the sample stage is used to carry a quantum bit chip;

[0009] The laser irradiation unit is used to generate laser light, which enters the vacuum chamber from the window and irradiates the quantum bit chip on the sample stage;

[0010] The probe structure includes at least two groups of probe arms and probes, the probe arms pass through the probe interface, the first end of the probe arm is located in the vacuum chamber, and the second end is located outside the vacuum chamber, the probe is fixedly installed on the first end of the probe arm and electrically connected to the probe arm, and the second end of the probe arm is electrically connected to the electrical characteristic detection device.

[0011] In one or more embodiments of the present invention, the in-situ testing device further includes a mechanical pump and a molecular pump, the molecular pump is connected to the vacuum chamber, and the mechanical pump is connected to the molecular pump.

[0012] In one or more embodiments of the present invention,

[0013] The probe arm also includes a connecting rod, a bellows, a first connecting piece and a vacuum electrical feedthrough;

[0014] The probe is fixedly mounted on the first end of the connecting rod and is electrically connected to the connecting rod, the vacuum electrical feedthrough is fixedly mounted on the second end of the connecting rod and is electrically connected to the connecting rod, and a portion of the connecting rod is located in the vacuum chamber and a portion is nested in the bellows;

[0015] The first end of the bellows is fixedly connected to the first connecting piece, and the second end is sealedly connected to the vacuum electrical feedthrough, and the vacuum electrical feedthrough is electrically connected to the electrical characteristic detection device.

[0016] In one or more embodiments of the present invention, the probe interface includes a second connecting member fixedly connected to a side wall of the test bench, and the first connecting member and the second connecting member are connected via a fixing member.

[0017] In one or more embodiments of the present invention, the first connection member comprises a first butt welding flange; and / or,

[0018] The second connecting member includes a second welding flange.

[0019] In one or more embodiments of the present invention, the in-situ testing device further comprises a coaxial shielded cable, wherein the coaxial shielded cable is connected between the vacuum electrical feedthrough and the electrical property detector.

[0020] In one or more embodiments of the present invention, the electrical property detector includes a multimeter.

[0021] In one or more embodiments of the present invention, the diameter of the end of the probe away from the probe arm is 15-20 μm.

[0022] In one or more embodiments of the present invention, the laser irradiation unit includes a laser and a lens, wherein the lens is disposed between the laser and the window and is used to collimate and focus the laser.

[0023] Another specific embodiment of the present invention provides a technical solution as follows:

[0024] An in-situ testing method for a quantum bit chip, the method comprising:

[0025] Provide in-situ testing equipment;

[0026] The quantum bit chip to be tested is placed on the sample stage, and one end of the probe is contacted with the Josephine junction on the quantum bit chip to be tested;

[0027] Evacuate the vacuum chamber to an ultra-high vacuum state;

[0028] generating laser light by a laser irradiation unit to irradiate a Josephine junction on a quantum bit chip;

[0029] The electrical characteristic signal of the Josephine junction of the quantum bit chip is obtained through the probe.

[0030] Compared with the prior art, the in-situ testing device and method for quantum bit chips of the present invention provide a vacuum chamber in the test bench, and provide a window and a probe interface on the side wall of the test bench, so that the test bench can simultaneously perform laser irradiation operation and electrical test operation, and does not need to transfer the quantum bit chip, thereby achieving in-situ testing, avoiding the quantum bit chip from being exposed to the atmosphere, and improving the accuracy and convenience of electrical property measurement;

[0031] By setting up interconnected mechanical pumps and molecular pumps, and cooperating with the probe structure connected to the vacuum chamber through the welding flange, the vacuum chamber is kept in a closed state, providing an ultra-high vacuum environment for the quantum bit chip, effectively avoiding the oxidation of the quantum bit chip by water, oxygen, etc., and eliminating the influence of the ultra-thin oxide layer on the electrical measurement of the quantum bit from the root;

[0032] The present invention does not need to construct a complex dedicated probe system, thus saving material costs and reducing operation complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1Schematic diagram of the structure of an in-situ testing device for a quantum bit chip in one embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the probe structure of an in-situ testing device for a quantum bit chip in one embodiment of the present invention;

[0036] Figure 3a is a scanning electron microscope image of a Josephine knot in one embodiment of the present invention;

[0037] Figure 3b is a scanning electron microscope image of a Josephine knot in one embodiment of the present invention;

[0038] Figure 3c is a microscopic magnified image of a Josephine knot in one embodiment of the present invention;

[0039] Figure 3d FIG. 4 is a transmission electron microscope image of a Josephine knot in one embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0041] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0042] "Coupled" or "connected" or "connected" in the specification includes both direct connection and indirect connection. Indirect connection is a connection through an intermediate medium, such as a connection through an electrically conductive medium, which may have parasitic inductance or parasitic capacitance; indirect connection may also include connection through other active or passive devices on the basis of achieving the same or similar functional purposes, such as connection through circuits or components such as switches and follower circuits. In addition, in the present invention, words such as "first" and "second" are mainly used to distinguish one technical feature from another technical feature, and do not necessarily require or imply that there is a certain actual relationship, quantity or order between these technical features.

[0043] In the detailed description of the specification, reference is made to the accompanying drawings forming a part thereof, wherein like reference numerals refer to like parts throughout, and wherein are shown by way of exemplary embodiments that may be implemented. It should be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present application. Therefore, the following detailed description should not be considered in a limiting sense.

[0044] The various operations in the specification may be described in turn as multiple discrete actions or operations in a manner that is most helpful in understanding the claimed subject matter. However, the order of description should not be interpreted as implying that these operations must be order-dependent. Specifically, these operations may not be performed in the order presented. The described operations may be performed in an order different from the described embodiments. Various additional operations may be performed and / or the described operations may be omitted in additional embodiments.

[0045] For purposes of this application, the phrase "A and / or B" means (A), (B), or (A and B). For purposes of this application, the phrase "A, B and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

[0046] Various components and devices may be referred to or shown in the singular form in this document (for example, "MOS tube", "transistor", "switch", etc.), but this is only for convenience of discussion, and any element mentioned in the singular form may include multiple such elements according to the teachings of this document.

[0047] The specification describes the use of phrases "in this embodiment" or "in other embodiments" or "in some embodiments", which can each refer to one or more of the same or different embodiments. In addition, the terms "including", "comprising", "having", etc. used in relation to the embodiments of the present application are synonymous.

[0048] like Figure 1 As shown, an embodiment of the present invention provides an in-situ testing device for a quantum bit chip, and the in-situ testing device includes a laser irradiation unit 20, a test bench 10, a probe structure 30 and an electrical characteristic detection device 40.

[0049] A vacuum chamber 11 is arranged inside the test bench 10 , a window 12 connected to the vacuum chamber 11 and at least two probe interfaces 13 are provided on the side wall of the test bench 10 , and a sample stage 14 is arranged in the vacuum chamber 11 , and the sample stage 14 is used to carry the quantum bit chip.

[0050] The laser irradiation unit 20 is used to generate laser light, which enters the vacuum chamber 11 from the viewing window 12 and irradiates the quantum bit chip on the sample stage 14. In one embodiment, the sample stage 14 is disposed directly below the viewing window 12.

[0051] In one embodiment, the wavelength of the laser is 532 nm. After the laser irradiates the Josephine junction on the quantum bit chip, the Josephine junction on the quantum bit chip is modified.

[0052] The probe structure 30 includes a probe arm 32 and a probe 31, wherein the probe 31 arm passes through the probe interface 13, wherein the first end of the probe arm 32 is located in the vacuum chamber 11, and the second end is located outside the vacuum chamber 11, wherein the probe 31 is fixedly mounted on the first end of the probe arm 32 and electrically connected to the probe arm 32, and wherein the second end of the probe arm 32 is electrically connected to the electrical characteristic detection device 40. It is understood that the probe arm 32 is sealed and connected to the probe interface 13. The probe structure 30 includes at least two groups of probe arms 32 and probes 31, i.e., the number of the probe arms 32 and the number of the probes 31 are equal to the number of the probe interfaces 13.

[0053] In a preferred embodiment of the present application, two probe interfaces 13 are provided on the side wall of the test bench 10, and the two probe interfaces 13 are symmetrically arranged on both sides of the test bench 10. Adaptively, the probe structure 30 includes two probe arms 32 and two corresponding probes 31.

[0054] like Figure 1 As shown, the in-situ test device in one embodiment further includes a mechanical pump 60 and a molecular pump 70. The molecular pump 70 is sealed and connected to the side wall of the test bench 10, and the molecular pump 70 is connected to the vacuum chamber 11. The mechanical pump 60 is connected to the molecular pump 70. The mechanical pump 60 and the molecular pump 70 are used to evacuate the inside of the vacuum chamber 11 to an ultra-high vacuum state. It can be understood that the ultra-high vacuum (UHV) state refers to the pressure in the vacuum chamber 11 being between 10 -9 Below mBar, that is, the number of molecules per unit volume is 1 / 10000000000000 of normal atmospheric pressure.

[0055] like Figure 2 As shown, the probe arm 32 includes a connecting rod 321 , a bellows 322 , a first connecting piece 323 and a vacuum electrical feedthrough 324 .

[0056] The probe 31 is fixedly mounted on the first end of the connecting rod 321 and electrically connected to the connecting rod 321 . The vacuum electrical feedthrough 324 is fixedly mounted on the second end of the connecting rod 321 and electrically connected to the connecting rod 321 . Part of the connecting rod 321 is located in the vacuum chamber 11 , and part of it is nested in the bellows 322 .

[0057] The first end of the bellows 322 is fixedly connected to the first connector 323 , and the second end is sealedly connected to the vacuum electrical feedthrough 324 , and the vacuum electrical feedthrough 324 is electrically connected to the electrical characteristic detection device 40 .

[0058] It can be understood that the first end of the connecting rod 321 is the first end of the probe arm 32, and the vacuum electrical feedthrough 324 is the second end of the probe arm 32. Further, the vacuum electrical feedthrough 324 in one embodiment includes a butt-welded flange structure, thereby achieving a sealed connection with the bellows 322. Connecting rod 321 vacuum chamber 11 It can be understood that the probe 31 is completely placed inside the vacuum chamber 11.

[0059] The probe interface 13 includes a second connection member 131 fixedly connected to the side wall of the test bench 10, and the first connection member 323 is connected to the second connection member 131 via a fixing member. Optionally, the fixing member includes a bolt.

[0060] In one embodiment, the first connection member 323 includes a first butt-weld flange, and the second connection member 131 includes a second butt-weld flange. It can be understood that the sizes of the first butt-weld flange and the second butt-weld flange match each other, and the butt-weld flange sealing docking method can ensure that the bellows 322 of the probe arm 32 is docked with the vacuum chamber 11 according to the ultra-high vacuum standard, so that when the molecular pump and the mechanical pump work in series, the vacuum chamber 11 is pumped to an ultra-high vacuum state, that is, the inside of the probe arm 32 is also in a vacuum state.

[0061] In one embodiment, the in-situ testing device also includes a coaxial shielded cable 50, which is connected between the vacuum electrical feedthrough 324 and the electrical property detector 40. When one end of the probe 31 is in conductive contact with the Josephine junction on the quantum bit chip, the electrical property signal of the Josephine junction (such as resistance, current, voltage, etc.) is obtained, and the coaxial shielded cable 50 transmits the electrical property signal to the electrical property detector 40. Preferably, the electrical property detector 40 includes a multimeter.

[0062] The diameter of one end of the probe 31 away from the probe arm 32 is 15-20 μm. Preferably, the diameter of one end of the probe 31 away from the probe arm 32 is 20 μm.

[0063] like Figure 1 As shown, the laser irradiation unit 20 in one embodiment includes a laser 21 and a lens 22. The laser 21 is used to generate laser light. The lens 22 is disposed between the laser 21 and the window 12 to collimate and focus the laser light.

[0064] Another embodiment of the present invention further provides an in-situ testing method for a quantum bit chip, the method comprising:

[0065] Provide in-situ testing equipment;

[0066] The quantum bit chip to be tested is placed on the sample stage 14, and one end of the probe 31 is contacted with the Josephine junction on the quantum bit chip to be tested;

[0067] Evacuate the vacuum chamber 11 to an ultra-high vacuum state;

[0068] The laser irradiation unit 20 generates laser light to irradiate the Josephine junction on the quantum bit chip;

[0069] The electrical characteristic signal of the Josephine junction of the quantum bit chip is obtained through the probe 31.

[0070] It can be understood that, based on the in-situ testing device proposed in the present invention, the electrical characteristic signal of the Josephine junction of the quantum bit chip can be obtained before, after or during the laser irradiation treatment of the Josephine junction on the quantum bit chip.

[0071] like Figure 3a , Figure 3b and Figure 3c As shown, the Josephine knot in this embodiment is of micron size. Figure 3d As shown, the Josephine junction in this embodiment includes a three-layer structure of Al / AlOx / Al. Before, after or during laser processing of the quantum bit chip, the present invention can in-situ test the electrical properties of the Josephine junction on the quantum bit chip. It can be understood that the nonlinear electrical properties between the two layers of superconducting films of the Josephine junction and the tunneling layer in the middle are directly related to the intrinsic properties of the material. Therefore, the in-situ test of the present application can better reflect the real and effective state of the chip compared to the traditional non-in-situ test. In addition, the present invention effectively avoids the oxidation of the quantum bit chip by water, oxygen, etc., and eliminates the influence of the ultra-thin oxide layer on the electrical measurement of the quantum bit from the root.

[0072] The traditional method requires 10 minutes for a single laser irradiation treatment, 30 minutes for transferring the sample to the probe station under the atmosphere, 50 minutes for the special probe station sample placement, needle pricking, and micro-force feedback to break the ultra-thin oxide layer, and 10 minutes for the final test resistance value. However, the in-situ test device and test method of the present invention do not need to transfer the quantum bit chip sample, avoid atmospheric exposure of the quantum bit chip, and thus avoid oxidation of the sample by water and oxygen, eliminating the step of breaking the ultra-thin oxide layer; so the total test time requires the time for a single laser irradiation treatment and the time required for testing the resistance. Therefore, compared with the traditional probe station, the device of the present invention can increase the efficiency of electrical testing of quantum bit chips by several times.

[0073] It can be seen from the above technical solutions that the present invention has the following beneficial effects:

[0074] The present invention provides a vacuum chamber 11 in the test bench 10, and provides a window 12 and a probe interface 13 on the side wall of the test bench 10, so that the test bench 10 can simultaneously implement laser irradiation operation and electrical test operation, realize in-situ testing, do not need to transfer the quantum bit chip, avoid its exposure to the atmosphere, and improve the accuracy and convenience of electrical property measurement;

[0075] By setting up interconnected mechanical pumps and molecular pumps, and cooperating with the probe structure 30 connected to the vacuum cavity through the welding flange, the vacuum cavity 11 is ensured to be in a closed state, providing an ultra-high vacuum environment for the quantum bit chip, effectively avoiding the oxidation of the quantum bit chip by water, oxygen, etc., and eliminating the influence of the ultra-thin oxide layer on the electrical measurement of the quantum bit from the root;

[0076] The present invention does not need to construct a complex dedicated probe system, thus saving material costs and reducing operation complexity.

[0077] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0078] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An in-situ testing device for a quantum bit chip, characterized in that: The in-situ testing device comprises a laser irradiation unit, a testing platform, a probe structure and an electrical characteristic detection device; A vacuum cavity is arranged inside the test bench, a window communicating with the vacuum cavity and at least two probe interfaces are provided on the side wall of the test bench, and a sample table for carrying a quantum bit chip is arranged inside the vacuum cavity; The laser irradiation unit is used to generate laser light, which enters the vacuum cavity from the window and irradiates the quantum bit chip; The probe structure includes at least two groups of probe arms and probes, the probe arms pass through the probe interface, the first end of the probe arm is located in the vacuum chamber, and the second end is located outside the vacuum chamber, the probe is fixedly installed on the first end of the probe arm and electrically connected to the probe arm, and the second end of the probe arm is electrically connected to the electrical characteristic detection device.

2. The in-situ testing device for a quantum bit chip according to claim 1, characterized in that: The in-situ testing device further comprises a mechanical pump and a molecular pump, wherein the molecular pump is connected to the vacuum chamber, and the mechanical pump is connected to the molecular pump.

3. The in-situ testing device for a quantum bit chip according to claim 1, characterized in that: The probe arm also includes a connecting rod, a bellows, a first connecting piece and a vacuum electrical feedthrough; The probe is fixedly mounted on the first end of the connecting rod and is electrically connected to the connecting rod, the vacuum electrical feedthrough is fixedly mounted on the second end of the connecting rod and is electrically connected to the connecting rod, and a portion of the connecting rod is located in the vacuum chamber and a portion is nested in the bellows; The first end of the bellows is fixedly connected to the first connecting piece, and the second end is sealedly connected to the vacuum electrical feedthrough, and the vacuum electrical feedthrough is electrically connected to the electrical characteristic detection device.

4. The in-situ testing device for a quantum bit chip according to claim 3, characterized in that: The probe interface includes a second connecting member fixedly connected to the side wall of the test bench, and the first connecting member and the second connecting member are connected via a fixing member.

5. The in-situ testing device for a quantum bit chip according to claim 4, characterized in that: The first connecting member comprises a first butt welding flange; and / or, The second connecting member includes a second welding flange.

6. The in-situ testing device for a quantum bit chip according to claim 3, characterized in that: The in-situ testing device further comprises a coaxial shielded cable connected between the vacuum electrical feedthrough and the electrical property detector.

7. The in-situ testing device for a quantum bit chip according to claim 1, characterized in that: The electrical characteristic detector includes a multimeter.

8. The in-situ testing device for a quantum bit chip according to claim 1, characterized in that: The diameter of one end of the probe away from the probe arm is 15-20 μm.

9. The in-situ testing device for a quantum bit chip according to claim 1, characterized in that: The laser irradiation unit comprises a laser and a lens, wherein the lens is arranged between the laser and the window and is used for collimating and focusing the laser.

10. An in-situ testing method for a quantum bit chip, characterized in that: The method comprises: Providing an in-situ testing device as claimed in any one of claims 1 to 9; The quantum bit chip to be tested is placed on the sample stage, and one end of the probe is contacted with the Josephine junction on the quantum bit chip to be tested; Evacuate the vacuum chamber to an ultra-high vacuum state; generating laser light by a laser irradiation unit to irradiate a Josephine junction on a quantum bit chip; The electrical characteristic signal of the Josephine junction of the quantum bit chip is obtained through the probe.

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