Superconducting quantum bit device with long-lifetime phonon storage structure and preparation method thereof

Abstract

The present application provides a superconducting quantum bit device with a long-life phonon storage structure and a preparation method thereof, and relates to the technical field of semiconductor device preparation. The superconducting quantum bit device includes: an upper substrate substrate; a high tensile stress film, part of which is suspended; a capacitor and a junction area of ​​the quantum bit; a lower substrate substrate; a microwave resonant metal layer; a connection module, which is grown around the lower substrate substrate and connected to the capacitor and the junction area of ​​the quantum bit; the capacitor and the junction area of ​​the quantum bit form a spatial capacitance structure with the microwave resonant metal layer, and when the high tensile stress film vibrates, the spatial capacitance structure changes, and the coupling of the thin film mechanical oscillator formed by the high tensile stress film and the microwave resonant metal layer is realized, so as to realize the storage of the quantum state of the quantum bit in the long-life phonon mode of the thin film mechanical oscillator or the reading back of the quantum state in the long-life phonon mode to the quantum bit, which is conducive to the large-scale integration of the long-life quantum state storage structure and the superconducting quantum bit.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor device preparation, and in particular to a superconducting quantum bit device with a long-lifetime phonon storage structure and a preparation method thereof. Background Art

[0002] Superconducting quantum computing is currently considered by the quantum computing field to be the most likely quantum computing system to be scaled and integrated, and superconducting quantum bits are the core structure of superconducting quantum computing systems.

[0003] The coherent lifetime of the current superconducting quantum bit's own quantum state is only on the order of 1ms. In order to store quantum states for a longer time, the superconducting quantum bit needs to be coupled to other types of quantum systems with long coherent lifetimes, such as natural atomic systems. These coupled long coherent lifetime quantum systems and superconducting quantum systems are incompatible in terms of preparation process and structure, and therefore are two separate structures.

[0004] In order to realize universal fault-tolerant quantum computing, the number of superconducting qubits needs to continue to increase, which will make it difficult to continue to expand this independent structure storage system. Therefore, it is necessary to find a superconducting qubit that has its own long-life storage structure. Summary of the invention

[0005] In order to solve at least one of the above problems, the present application proposes a superconducting quantum bit device with a long-lifetime phonon storage structure and a preparation method thereof.

[0006] According to the first aspect of the present application, at least one embodiment of the present application provides a superconducting quantum bit device with a long-life phonon storage structure, comprising: an upper substrate substrate, a first portion of the upper substrate substrate being hollowed out; a high tensile stress film grown on the upper substrate substrate, and the high tensile stress film corresponding to the first portion being suspended; a capacitor and a junction region of the quantum bit, grown on the high tensile stress film; a lower substrate substrate; a microwave resonant metal layer grown on the front side of the lower substrate substrate; a connecting module grown around the front side of the lower substrate substrate to be connected to the capacitor and the junction region of the quantum bit; wherein the capacitor and the junction region of the quantum bit form a spatial capacitor structure with the microwave resonant metal layer, and when the high tensile stress film vibrates, the spatial capacitor structure changes, thereby realizing the coupling of the thin film mechanical oscillator formed by the high tensile stress film and the microwave resonant metal layer, so as to realize storing the quantum state of the quantum bit in the long-life phonon mode of the thin film mechanical oscillator or reading the quantum state in the long-life phonon mode back to the quantum bit.

[0007] For example, in some embodiments of the present application, when the quantum state of the quantum bit is stored in the long-lived phonon mode of the thin film mechanical oscillator, the quantum state of the quantum bit is mapped to the microwave resonant metal layer by applying a microwave field of a first frequency, so that the microwave resonant metal layer generates cavity field photons and transfers them to the vibration mode of the thin film mechanical oscillator formed by the high tensile stress film, so as to realize the storage of the quantum state of the quantum bit in the long-lived phonon mode of the thin film mechanical oscillator.

[0008] For example, in some embodiments of the present application, when the quantum state in the long-lived phonon mode is read back to the quantum bit, the phonons in the vibration mode on the high tensile stress film are transferred to microwave photons of the microwave resonant metal layer by applying a microwave field of a second frequency, and a photon number selection flip pulse is applied to the quantum bit to transfer the microwave photons to the quantum bit, thereby realizing the reading back of the quantum state in the long-lived phonon mode to the quantum bit.

[0009] For example, in some embodiments of the present application, the upper substrate substrate and the lower substrate substrate include silicon wafers.

[0010] For example, in some embodiments of the present application, the high tensile stress film includes silicon nitride and / or silicon carbide.

[0011] For example, in some embodiments of the present application, the capacitor and junction region of the quantum bit are made of metal materials, including aluminum, niobium and / or tantalum.

[0012] For example, in some embodiments of the present application, the microwave resonant metal layer is a metal material including aluminum, niobium and / or tantalum.

[0013] For example, in some embodiments of the present application, the connection module is a chip flip-chip connection metal, including metal indium.

[0014] According to the second aspect of the present application, at least one embodiment of the present application provides a preparation method for preparing a superconducting quantum bit device as described in any one of the first aspects, the preparation method comprising: depositing the high tensile stress film on the front and back sides of the upper substrate substrate; removing the high tensile stress film on the back side of the upper substrate substrate by windowing to expose the upper substrate substrate window; etching the exposed upper substrate substrate window to make the high tensile stress film corresponding to the upper substrate substrate window suspended; preparing the capacitor and junction area of ​​the quantum bit on the suspended high tensile stress film; depositing the microwave resonant metal layer on the front side of the lower substrate substrate; depositing the connection module around the front side of the lower substrate substrate; and flip-chip bonding the front side of the lower substrate substrate to the capacitor and junction area of ​​the quantum bit through the connection module.

[0015] For example, in some embodiments of the present application, the front side of the lower substrate substrate is flip-chip bonded to the capacitor and junction area of ​​the quantum bit through the connection module, including: controlling the distance between the capacitor and junction area of ​​the quantum bit and the microwave resonant metal layer to be less than or equal to a preset distance, and aligning the capacitor metal part of the capacitor and junction area of ​​the quantum bit with the capacitor metal part of the microwave resonant metal layer.

[0016] Through the above-mentioned example embodiments, the present application provides a superconducting quantum bit device with a long-lifetime phonon storage structure and a preparation method thereof, which adopts semiconductor processing technology to prepare a superconducting quantum bit with a long-lifetime phonon storage structure, realizes the compatible integration of the long-lifetime phonon storage structure and the superconducting quantum bit, and directly grows the capacitor and junction structure of the superconducting quantum bit on the vibrating film with the long-lifetime phonon storage structure, which is conducive to the large-scale integration of the long-lifetime quantum state storage structure and the superconducting quantum bit.

[0017] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By describing in detail exemplary embodiments thereof with reference to the accompanying drawings, the above and other objects, features and advantages of the present application will become more apparent. The accompanying drawings described below are only some embodiments of the present application, and are not intended to limit the present application.

[0019] Figure 1 A schematic diagram of a superconducting quantum bit device with a long-lifetime phonon storage structure according to an exemplary embodiment is shown;

[0020] Figure 2 A schematic diagram showing a method for preparing a capacitor and a junction region of a quantum bit on a high tensile stress thin film structure in a superconducting quantum bit device according to an exemplary embodiment;

[0021] Figure 3 A schematic diagram showing a method for preparing a microwave resonant metal layer and a connection module of a lower substrate base in a superconducting quantum bit device according to an exemplary embodiment;

[0022] Figure 4 A schematic diagram showing a method for preparing a flip-chip connection between an upper substrate substrate and a lower substrate substrate in a superconducting quantum bit device according to an exemplary embodiment;

[0023] Figure 5 A schematic diagram showing the capacitance and junction region of a quantum bit on a high tensile stress film of an exemplary embodiment;

[0024] Figure 6 A schematic diagram showing a microwave resonant metal layer and a connection module on a lower substrate substrate according to an exemplary embodiment. DETAILED DESCRIPTION

[0025] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this application will be comprehensive and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0026] The described features, structures or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced without one or more of these specific details, or other modes, components, materials, devices, etc. may be adopted. In these cases, known structures, methods, devices, implementations, materials or operations will not be shown or described in detail.

[0027] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0028] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0029] Those skilled in the art will appreciate that the drawings are merely schematic diagrams of example embodiments, and the modules or processes in the drawings are not necessarily necessary for implementing the present application, and therefore cannot be used to limit the scope of protection of the present application.

[0030] Figure 1 A schematic diagram of a superconducting quantum bit device with a long-lifetime phonon storage structure according to an exemplary embodiment is shown.

[0031] like Figure 1As shown, the superconducting quantum bit device with a long-life phonon storage structure includes: an upper substrate substrate 1, a high tensile stress film 2, a capacitor and junction area 3 of the quantum bit, a lower substrate substrate 4, a microwave resonant metal layer 5 and a connection module 6.

[0032] The first part of the upper substrate substrate 1 is hollowed out. The high tensile stress film 2 is grown on the upper substrate substrate, and the high tensile stress film corresponding to the first part is suspended. The capacitor and junction area 3 of the quantum bit are grown on the high tensile stress film 2. The microwave resonant metal layer 5 is grown on the front side of the lower substrate substrate 4. The connection module 6 is grown around the front side of the lower substrate substrate 4 to connect with the capacitor and junction area 3 of the quantum bit.

[0033] Among them, the suspended high tensile stress film 2 can be in a taut state due to its own in-plane tensile stress, forming a vibration structure with a high quality factor. For example, a film with an in-plane stress of 1GPa and an area of ​​0.5mm*0.5mm can form a vibration mode with a basic resonance frequency of about 750kHz, which will vibrate the capacitance and junction area 3 of the quantum bit on the surface of the film. The capacitance and junction area 3 of the quantum bit form a spatial capacitance structure with the microwave resonant metal layer 5, and the capacitance structure C forms a capacitive coupling between the capacitance and junction area 3 of the quantum bit and the microwave resonant metal layer 5. When the high tensile stress film 2 vibrates, the spatial capacitance structure changes, that is, the coupling of the thin film mechanical oscillator formed by the high tensile stress film 2 and the microwave resonant metal layer 5 is realized, so as to store the quantum state of the quantum bit in the long-lived phonon mode of the thin film mechanical oscillator or read the quantum state in the long-lived phonon mode back to the quantum bit.

[0034] For example, the vibration mode frequency formed by the high tensile stress film 2 is , the operating frequency of the quantum bit is , the resonant frequency of the microwave resonant metal layer 5 is For example.

[0035] At present, the quality factor Q of the vibration mode formed by high tensile stress films can generally reach above 1E8. When the system is cooled to the operating temperature T = 10mK, the resonant frequency F m The number of phonons of ambient thermal noise at the vibration mode of about 750kHz ,in is Planck's constant, is the Boltzmann constant, and the calculation can be obtained About 280. The single phonon thermalization time of the vibration mode in a certain ambient thermal noise is , when Q=1E8, the single phonon thermalization time is calculated to be About 57ms, that is, when this vibration mode performs single-phonon storage, its quantum coherence lifetime is about 57ms, which is much higher than the coherence lifetime of the current superconducting quantum bit itself.

[0036] In the case where it is necessary to store the quantum state of the quantum bit in the long-lived phonon mode of the thin film mechanical oscillator: by applying a microwave field of a first frequency, the microwave pulse of the microwave field will realize the cavity field induced enhanced coupling between the vibration mode of the high tensile stress film 2 and the microwave resonant metal layer 5, and at the same time map the quantum state of the quantum bit to the microwave resonant metal layer 5. The mapping method can be selected to directly adjust the quantum bit frequency to resonate with the microwave resonant metal layer 5, so that the quantum state of the superconducting quantum bit is directly transferred to the microwave resonant metal layer 5, so that the microwave resonant metal layer 5 generates cavity field photons. Due to the existence of the microwave field, the cavity field photons of the microwave resonant metal layer 5 will be transferred to the vibration mode of the thin film mechanical oscillator formed by the high tensile stress film 2, thereby realizing the storage of the quantum state of the quantum bit in the long-lived phonon mode of the thin film mechanical oscillator.

[0037] When it is necessary to read the quantum state in the long-lived phonon mode back to the quantum bit, a microwave field of a second frequency is applied. At this time, there are no microwave photons in the microwave resonant metal layer 5, so the microwave field can transfer the phonons in the vibration mode on the high tensile stress film 2 to microwave photons in the microwave resonant metal layer 5, and apply a photon number selection flip pulse to the quantum bit. The state of the superconducting quantum bit will change according to the state of the microwave photons in the microwave resonant metal layer 5, that is, the microwave photons are transferred to the quantum bit, thereby realizing the read-back of the quantum state in the long-lived phonon mode to the quantum bit.

[0038] The first frequency and the second frequency are the same, for example, the frequencies are both of microwave fields.

[0039] Figure 2 A schematic diagram showing a method for preparing the capacitance and junction region of a quantum bit on a high tensile stress thin film structure in a superconducting quantum bit device according to an exemplary embodiment.

[0040] like Figure 2 As shown, the method for preparing the capacitor and junction region of the quantum bit on the high tensile stress film structure includes:

[0041] 1. Deposit high tensile stress films on the front and back sides of the top substrate.

[0042] According to some embodiments, the upper substrate substrate is a 500um silicon wafer.

[0043] According to some embodiments, a thin film layer with a thickness of 1 um and high in-plane prestress is deposited on the upper substrate substrate 1 by a low pressure chemical vapor deposition (LPCVD) process.

[0044] According to some embodiments, the material of the high tensile stress film 2 is silicon nitride or silicon carbide, the film thickness is 1 um, and the maximum in-plane tensile stress can reach more than 2 GPa.

[0045] According to some embodiments, a high tensile stress film refers to a film material having high tensile stress inside itself, and the tensile stress is generally above 1 GPa.

[0046] 2. Windowing is performed to remove the high tensile stress film on the back of the upper substrate to expose the upper substrate window.

[0047] According to some embodiments, the high tensile stress film 2 on the back side of the upper substrate base 1 is removed by windowing through a dry etching process such as reactive ion etching to expose a silicon substrate window.

[0048] 3. Etch the exposed upper substrate window to make the high tensile stress film corresponding to the upper substrate window suspended.

[0049] According to some embodiments, a wet etching process such as KOH solution or a dry etching process such as reactive ion etching is used to remove the middle portion of the upper substrate substrate 1 using the silicon substrate window exposed in the previous step to form a suspended high tensile stress film 2 with an area of ​​0.5mm*0.5mm.

[0050] 4. Prepare the capacitor and junction region of the quantum bit on the suspended high tensile stress film.

[0051] According to some embodiments, the capacitor and junction region 3 of the quantum bit are prepared on the front surface of the high tensile stress film 2 by evaporation or sputtering process, with a thickness of 120nm, such as Figure 5 shown.

[0052] According to some embodiments, the metal materials commonly used in the capacitor and junction region 3 of the quantum bit can be selected from metals such as aluminum, niobium, and tantalum.

[0053] Figure 3 A schematic diagram showing a method for preparing a lower substrate microwave resonant metal layer and a connection module in a superconducting quantum bit device of an exemplary embodiment.

[0054] like Figure 3 As shown, the method for preparing the microwave resonant metal layer and the connection module of the lower substrate substrate in the superconducting quantum bit device includes:

[0055] 1. Deposit a microwave resonant metal layer on the front side of the lower substrate.

[0056] According to some embodiments, a microwave resonant metal layer 5 with a thickness of 100 nm is deposited on the surface of the lower substrate 4 by evaporation or sputtering process, and the material of the microwave resonant metal layer 5 can be selected from metals such as aluminum, niobium, and tantalum.

[0057] 2. Deposit the connection module around the front side of the lower substrate.

[0058] According to some embodiments, at the corners of the four edges of the surface of the lower substrate 4, a connection module 6 with a thickness of 1 um is deposited by an evaporation process, such as Figure 6 shown.

[0059] According to some embodiments, the connection module 6 is a flip-chip connection metal, such as metal indium.

[0060] Figure 4 A schematic diagram showing a method for preparing a flip-chip connection between an upper substrate substrate and a lower substrate substrate in a superconducting quantum bit device according to an exemplary embodiment.

[0061] like Figure 4 As shown, the method for preparing the flip-chip connection between the upper substrate substrate and the lower substrate substrate includes:

[0062] By connecting the modules, the front side of the substrate is flip-chip bonded to the capacitor and junction area of ​​the quantum bit.

[0063] According to some embodiments, an upper substrate substrate 1 with a structure is flip-chip welded to a lower substrate substrate 4 through a flip-chip welding process, and the thickness of the indium column after welding is controlled by controlling the pressure of the flip-chip welding, thereby controlling the distance between the upper substrate substrate 1 and the lower substrate substrate 4, so that the distance between the capacitor and junction area 3 of the quantum bit and the microwave resonant metal layer 5 is less than or equal to a preset distance, for example, the distance from the capacitor and junction area 3 of the quantum bit to the microwave resonant metal layer 5 is controlled within 500nm, and the capacitor metal part of the capacitor and junction area 3 of the quantum bit is aligned with the capacitor metal part of the microwave resonant metal layer 5 over a large area.

[0064] The present application provides a superconducting quantum bit device with a long-lifetime phonon storage structure and a preparation method thereof. A superconducting quantum bit device with a long-lifetime phonon storage structure is prepared by using semiconductor processing technology to achieve compatible integration of the long-lifetime phonon storage structure and the superconducting quantum bit. The capacitor and junction structure of the superconducting quantum bit are directly grown on a vibrating film with a long-lifetime phonon storage structure, which is beneficial to the large-scale integration of the long-lifetime quantum state storage structure and the superconducting quantum bit.

[0065] It should be clearly understood that the present application describes how to form and use specific examples, but the present application is not limited to any details of these examples. On the contrary, based on the teaching of the content disclosed in the present application, these principles can be applied to many other embodiments.

[0066] In addition, it should be noted that the above figures are only schematic illustrations of the processes included in the method according to the exemplary embodiments of the present application, and are not intended to be limiting. It is easy to understand that the processes shown in the above figures do not indicate or limit the time sequence of these processes. In addition, it is also easy to understand that these processes can be performed synchronously or asynchronously, for example, in multiple modules.

[0067] The exemplary embodiments of the present application are specifically shown and described above. It should be understood that the present application is not limited to the detailed structures, configurations or implementations described herein; on the contrary, the present application is intended to cover various modifications and equivalent configurations included in the spirit and scope of the appended claims.

Claims

1. A superconducting quantum bit device with a long-lifetime phonon storage structure, characterized in that: include: An upper substrate substrate, wherein a first portion of the upper substrate substrate is hollowed out; A high tensile stress film is grown on the front and back sides of the upper substrate, and the high tensile stress film located on the front side of the upper substrate and corresponding to the first portion is suspended; The capacitor and junction regions of the quantum bit are grown on a suspended high-tensile stress film; A lower substrate substrate; A microwave resonant metal layer is grown on the front surface of the lower substrate; A connection module, grown around the front side of the lower substrate, to connect with the capacitor and junction area of ​​the quantum bit; The capacitor and the junction region of the quantum bit form a spatial capacitor structure with the microwave resonant metal layer. When the high tensile stress film vibrates, the spatial capacitor structure changes, so as to achieve coupling between the thin film mechanical oscillator formed by the high tensile stress film and the microwave resonant metal layer, so as to store the quantum state of the quantum bit in the long-lived phonon mode of the thin film mechanical oscillator or read the quantum state in the long-lived phonon mode back to the quantum bit, including: In the case of storing the quantum state of the quantum bit in the long-lived phonon mode of the thin film mechanical oscillator, the quantum state of the quantum bit is mapped to the microwave resonant metal layer by applying a microwave field of a first frequency, so that the microwave resonant metal layer generates cavity field photons, and the cavity field photons are transferred to the vibration mode of the thin film mechanical oscillator formed by the high tensile stress film, so as to realize the storage of the quantum state of the quantum bit in the long-lived phonon mode of the thin film mechanical oscillator; When the quantum state in the long-lived phonon mode is read back to the quantum bit, the phonons in the vibration mode on the high tensile stress film are transferred to microwave photons of the microwave resonant metal layer by applying a microwave field of a second frequency, and a photon number selection flip pulse is applied to the quantum bit to transfer the microwave photons to the quantum bit, thereby realizing the reading back of the quantum state in the long-lived phonon mode to the quantum bit.

2. The superconducting quantum bit device according to claim 1, characterized in that: The upper substrate wafer and the lower substrate wafer include silicon wafers.

3. The superconducting quantum bit device according to claim 1, characterized in that: The high tensile stress film includes silicon nitride and / or silicon carbide.

4. The superconducting quantum bit device according to claim 1, characterized in that: The capacitor and junction region of the quantum bit are made of metal materials, including aluminum, niobium and / or tantalum.

5. The superconducting quantum bit device according to claim 1, characterized in that: The microwave resonant metal layer is made of metal material, including aluminum, niobium and / or tantalum.

6. The superconducting quantum bit device according to claim 1, characterized in that: The connection module is a chip flip-chip connection metal, including metal indium.

7. A preparation method, characterized in that: For preparing a superconducting quantum bit device according to any one of claims 1 to 6, the preparation method comprising: Depositing the high tensile stress film on the front and back sides of the upper substrate substrate; Windowing to remove the high tensile stress film on the back side of the upper substrate substrate to expose the upper substrate substrate window; Etching the exposed upper substrate window to make the high tensile stress film corresponding to the upper substrate window suspended; Fabricate the capacitor and junction region of the quantum bit on a suspended high tensile stress film; Depositing the microwave resonant metal layer on the front side of the lower substrate substrate; Depositing the connection module around the front side of the lower substrate; The front side of the lower substrate substrate is flip-chip bonded to the capacitor and junction area of ​​the quantum bit through the connection module.

8. The preparation method according to claim 7, characterized in that: The method of flip-chip bonding the front side of the lower substrate substrate to the capacitor and junction area of ​​the quantum bit through the connection module comprises: The distance between the capacitor and the junction region of the quantum bit and the microwave resonant metal layer is controlled to be less than or equal to a preset distance, and the capacitor metal part of the capacitor and the junction region of the quantum bit is aligned with the capacitor metal part of the microwave resonant metal layer.

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