Acoustic cavity-based carbon nanotube quantum dot regulation and control device and method

Abstract

The invention relates to the field of quantum architecture design, quantum dots and photonic crystals, in particular to a carbon nano tube quantum dot regulation and control device and method based on a vocal cavity, the device comprises a photonic cavity, a gate electrode, a metal coating, a carbon nano tube and a groove, and the regulation and control method is characterized in that quantum bits are regulated and controlled by inputting signals from the outside through coupling of the photonic cavity and the quantum dots; and the cat-state codes in the phonon cavity are used for quantum state storage, so that the reliability of information storage is improved, the retention time of quantum information is prolonged, the stability of regulation and control is enhanced, and errors in regulation and control are reduced. According to the design, the size of a single quantum bit is remarkably reduced to a micron order, so that a foundation is laid for realizing chip integration of millions of quantum bits. The design based on the acoustic cavity not only improves the density and expandability of quantum bits in quantum calculation, but also provides a brand new thought for the development of large-scale quantum calculation in the future by introducing the phonon cavity to efficiently regulate and control the quantum dots.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, quantum architecture design, quantum dots, and phononic crystals, and in particular to a carbon nanotube quantum dot control device and method based on an acoustic cavity. Background Art

[0002] Quantum computing is a new computing model based on the principles of quantum mechanics. It uses phenomena such as quantum superposition and quantum entanglement to perform complex computing tasks that traditional computers cannot handle. Since its proposal in the early 1980s, the development of quantum computing has made significant progress and has gradually become a research focus for governments, technology companies and academia around the world. Quantum computing not only has the potential to bring revolutionary breakthroughs in fields such as cryptography, materials science, drug design and optimization problems, but also has a far-reaching impact on the promotion of cutting-edge technologies such as artificial intelligence and machine learning. Globally, governments and companies are increasing their investment in quantum computing research. Competition in the field of quantum computing is particularly fierce among countries and regions such as China, the United States and the European Union. The key to manufacturing a general-purpose quantum computer with quantum advantage lies in a large number (on the order of millions) of mutually coupled quantum bits, so the integrability of quantum bits is very important. Our solution can control the area of ​​each bit on the quantum chip to 4 square microns, and achieve stable regulation of the quantum state, which can realize large-scale integration of quantum chips. Summary of the invention

[0003] To achieve the above-mentioned purpose of the invention, the technical solution of the present invention is as follows:

[0004] A carbon nanotube quantum dot control device based on an acoustic cavity includes a phonon cavity, a gate electrode, a metal coating, a carbon nanotube, and a groove.

[0005] The phonon cavity is formed by connecting multiple cells, made of piezoelectric material, and located between two electrode plates, with one end receiving external input electrical signal control and the other end connected to the gate electrode;

[0006] Groove: Made of silicon dioxide, the middle of the groove is concave, and the surfaces of the convex parts on both sides of the concave are respectively provided with a grounded first metal coating and a second metal coating;

[0007] Gate electrode: Made of metal, located at the bottom of the groove, used to control the quantum dots on the carbon nanotubes;

[0008] Carbon nanotube: the middle part is suspended above the depression, and the two ends span the groove and are in contact with the first metal coating and the second metal coating respectively.

[0009] As a preferred method, the quantum bit is controlled by inputting a signal from the outside through the coupling of the phonon cavity and the quantum dot.

[0010] As a preferred method, the phonon cavity is prepared using piezoelectric material LiNbO3 crystal.

[0011] As a preferred embodiment, the cross-sectional area of ​​the phonon cavity is 1 square micrometer, and the total length of the phonon cavity is 20 micrometers.

[0012] As a preferred embodiment, the phonon cavity is arranged perpendicular to the bottom of the groove.

[0013] Preferably, the area occupied by each quantum bit is 4 square microns.

[0014] As a preferred embodiment, the electrode at one end of the phonon cavity receiving the external input electrical signal is separated from the outside by a capacitor, and the end of the capacitor connected to the phonon cavity is grounded.

[0015] As a preferred embodiment, the first metal coating, the second metal coating and the gate electrode are all made of noble metals.

[0016] As a preferred embodiment, the first metal coating, the second metal coating and the gate electrode are made of platinum, gold or silver.

[0017] The second object of the present invention is to provide a carbon nanotube quantum dot control method based on an acoustic cavity, using the control device to control the quantum bit by inputting signals from the outside through the coupling of the phonon cavity and the quantum dot, and using the cat state coding inside the phonon cavity to store the quantum state, thereby improving the reliability of information storage, extending the retention time of quantum information, enhancing the stability of control and reducing errors in control.

[0018] The beneficial effects of the present invention are as follows: the present invention replaces the traditional microwave cavity with a phonon cavity made of piezoelectric material (such as LiNbO3 crystal) to couple with quantum dots and regulate quantum bits. This design significantly reduces the size of a single quantum bit to the micron level, thus laying the foundation for chip integration of millions of quantum bits. This acoustic cavity-based design not only improves the density and scalability of quantum bits in quantum computing, but also provides a new idea for the development of large-scale quantum computing in the future by introducing efficient regulation of quantum dots by phonon cavities. In addition, the cat-state coding based on the acoustic cavity realizes the stable storage of quantum states. Compared with the traditional microwave cavity solution, the acoustic cavity is more flexible and has more potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Illustration of a single quantum bit and its control unit.

[0020] Figure 2 A detailed circuit diagram of the connection between the acoustic cavity and the gate electrode.

[0021] Figure 3 This is the equivalent circuit diagram for storing quantum states. The external circuit is on the right side of the dotted line, and the phonon cavity on the left is connected to the gate electrode.

[0022] Among them, 1-phonon cavity, 2-gate electrode, 3-first metal coating, 4-second metal coating, 5-groove, 6-carbon nanotube, 7-capacitor, 8-grounding and ATS, 9-phononic crystal cavity, 10-recess, 11-filter, 12-grounding, 13-ATS. DETAILED DESCRIPTION

[0023] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0024] Example 1

[0025] like Figure 1 As shown, a carbon nanotube quantum dot control device based on an acoustic cavity includes a phonon cavity 1, a gate electrode 2, a metal coating, a carbon nanotube 6, and a groove 5.

[0026] The phonon cavity 1 is formed by connecting multiple cells, made of piezoelectric material, and located between two electrode plates, with one end receiving external input electrical signal control and the other end connected to the gate electrode 2;

[0027] Groove 5: Made of silicon dioxide, the middle of the groove is a depression 10, and the surfaces of the raised parts on both sides of the depression 10 are respectively provided with a grounded first metal coating 3 and a second metal coating 4;

[0028] Gate electrode 2: made of metal, located at the bottom of the recess 10 of the groove, used to control the quantum dots on the carbon nanotubes 6;

[0029] The carbon nanotube 6 has a middle portion suspended above the depression 10 , and two ends spanning over the groove 5 and contacting the first metal coating 3 and the second metal coating 4 respectively.

[0030] Specifically, the quantum bit is controlled by inputting a signal from the outside through the coupling between the phonon cavity 1 and the quantum dot.

[0031] Specifically, the phonon cavity 1 is prepared using piezoelectric material LiNbO3 crystal.

[0032] Specifically, the cross-sectional area of ​​the phonon cavity 1 is 1 square micron, and the total length of the phonon cavity is 20 microns. The phonon cavity 1 of the present invention is not a single structure, but is composed of multiple acoustic cavity units. This modular acoustic cavity design makes the entire control system more scalable and flexible, and can adapt to quantum computing needs of different scales. In addition, the distance on both sides of the groove is controlled at about 0.5 microns, ensuring the close coupling between the quantum dots and the electrodes. This design makes the conduction path of the electric field and the acoustic field shorter, the response time faster, and effectively improves the computing speed and energy efficiency of the entire quantum bit system.

[0033] Specifically, the phonon cavity 1 is arranged perpendicular to the bottom of the groove 5 .

[0034] Specifically, the area occupied by each quantum bit is 4 square microns.

[0035] Specifically, the electrode at one end of the phonon cavity 1 that receives the external input electrical signal is separated from the outside by a capacitor 7, and the end of the capacitor 7 connected to the phonon cavity 1 is grounded. Figure 2 Detailed circuit diagram of the connection between the phonon cavity 1 and the gate electrode 2.

[0036] The capacitor 7, in order to prevent the external interference signal from adversely affecting the control process of the quantum dots in the phonon cavity 1, the present invention designs an electrode at one end of the acoustic cavity that receives external electrical signals to be isolated from the outside world by capacitor 7. This capacitor not only protects the acoustic cavity and quantum dots, but also screens input signals to ensure the quality of signals entering the system. This design greatly enhances the anti-interference ability of the system, making the quantum bit control process more stable and reliable. In addition, the electrode connected to the phonon cavity 1 needs to be grounded, which further ensures the electric field stability and anti-electromagnetic interference ability of the entire system.

[0037] Specifically, the first metal coating 3, the second metal coating 4 and the gate electrode 2 are all made of noble metals, which have high electrical conductivity.

[0038] The selection of precious metals is mainly based on their high electrical conductivity and antioxidant ability. These properties ensure that the electrodes will not experience conductivity degradation or material loss during long-term operation. In addition, the application of precious metals further enhances the electric field control effect between the electrodes and carbon nanotube quantum dots, making the regulation process of quantum bits more precise. Through the optimized design of precious metal electrodes, the entire system not only has efficient electrical signal transmission capabilities, but also maintains stable performance under different temperature, pressure and environmental conditions. This provides important technical support for fields such as quantum computing that are sensitive to environmental changes.

[0039] Specifically, the first metal coating 3, the second metal coating 4 and the gate electrode 2 are made of platinum, gold or silver.

[0040] This embodiment also provides a carbon nanotube quantum dot control method based on an acoustic cavity, using the control device, the quantum bit is controlled by inputting signals from the outside through the coupling of the phonon cavity 1 and the quantum dot, and the cat state coding inside the phonon cavity 1 is used to store the quantum state, thereby improving the reliability of information storage, extending the retention time of quantum information, enhancing the stability of control and reducing errors in control.

[0041] The phononic crystal cat state encoding is used to store quantum states as a quantum storage unit. Cat state encoding is a way to generate physical quantum bits, and a quantum bit is encoded by multiple phonons. Doing so will actually increase the distance between the 0 state and the 1 state in the physical space, forming two potential barriers in the potential energy space, thereby greatly reducing the probability of bit reversal errors and maintaining stability in the noisy environment. Cat states are less sensitive to phase noise, which makes them better able to resist the problem of quantum coherence loss and help extend the storage time of quantum information. Cat state encoding of quantum bits can reduce the coherence decay caused by environmental interference, thereby improving the storage quality of quantum states. In addition, in quantum algorithms, noise or errors are easily introduced when operating quantum bits. Cat state encoding helps to stabilize the phase relationship of quantum bits, so that quantum gate operations are more accurate, which is very important for improving the execution reliability of quantum algorithms. In summary, after using cat state encoding, the stability of various operations of quantum bits is greatly improved, thereby providing a more solid foundation for the regulation of quantum bits, helping to improve the reliability of quantum storage and quantum computing, and lowering the practical threshold.

[0042] The phonon cavity 1 is coupled with the quantum dots. The present invention uses the phonon cavity 1 as a control unit coupled with the quantum dots, and uses the piezoelectric material LiNbO3 crystal to prepare the acoustic cavity. The acoustic cavity structure can replace the traditional microwave cavity, realize more precise quantum bit control, and the size of a single quantum bit is greatly reduced to the micron level. Through this design, the quantum bit density on the quantum chip has been greatly improved, which makes it possible to integrate millions of quantum bits in the future. This coupling method guides the interaction between phonons and quantum dots through the acoustic cavity, thereby realizing efficient control of the quantum bit state.

[0043] Example 2

[0044] The difference between this embodiment and embodiment 1 is that:

[0045] (1) Preparation of Phonon Cavity 1

[0046] The preparation process of phononic crystals is a precise nanofabrication process, using lithium niobate (LiNbO3) thin films as phononic crystal materials, with a typical film thickness of 200 nanometers, deposited on a high-resistance silicon substrate (resistivity greater than 3kΩ·cm). Lithium niobate is a piezoelectric material that can efficiently couple between mechanical vibrations and electric fields, making it very suitable for use in this device.

[0047] First, the film needs to be thinned. The LiNbO3 film is thinned from its original thickness (such as 500 nanometers) to the required 200 nanometers by argon ion etching. This is to ensure that the thickness of the film is suitable for the propagation of high-frequency sound waves and the manufacture of phononic crystal structures. Then, in order to create one-dimensional or two-dimensional periodic structures on the film, electron beam lithography is used. These structures are usually sub-micron in size. In this process, the lattice constant is 1 micron to ensure that a phononic band gap can be formed near the target frequency (such as 6GHz).

[0048] Through periodic patterning, the phononic crystal can form a complete band gap in a certain frequency range (such as 6.0-6.5GHz), that is, no sound waves will propagate in this frequency range. A defect area with a size of 1.6 microns (length) and 500 nanometers (width) is introduced in the center of the lattice. This helps to localize the mechanical vibration and form a resonant mode that can confine the sound waves to the defect and achieve an ultra-small mode volume (<1 cubic micron).

[0049] Aluminum (Al) is deposited on the film, and the superconducting Josephson junction is made using the "Dolan bridge double angle evaporation process". The thickness of the electrode is usually 200 nanometers, and the electrode is arranged at a distance of 200 nanometers from the defect point to couple the phonon mode and the microwave circuit to achieve control and readout of the electrical signal.

[0050] To eliminate the clamping loss of phonons, the phononic crystal structure is suspended by selectively removing the silicon substrate (e.g., by etching with XeF2 gas), thereby preventing the phonons from being lost into the substrate.

[0051] (2) Cat-state coding and quantum state storage

[0052] The phononic crystal cat state encoding is used to store quantum states as a quantum storage unit. Cat state encoding is a multi-particle entangled state, which is an important encoding method in quantum computing and quantum information. In it, the quantum bit can be in a superposition of two extreme states, which has the significance of anti-noise and enhanced entanglement. In the present invention, the storage unit is divided into three parts, one is the phononic crystal, the second is the reservoir, and the third is the read-out and write unit of the phonon state. The phononic crystal serves as a storage medium for the phonon state, and the reservoir serves as a regulating unit for regulating the phonon state, which is used to assist in cat state encoding. The key components of the reservoir are ATS and filters, and the filter here is set to filter out waves of specific frequencies.

[0053] Among them, ATS is an asymmetrically threaded superconducting quantum interference device, which is usually composed of two Josephson junctions and an inductor. Its characteristic is that the magnetic flux passing through it is asymmetrically distributed. This asymmetric structure is usually achieved by applying different currents or different geometric designs to the two Josephson junctions. The quantization of ATS electromagnetic excitation manifests as "photons", which can absorb noise in the acoustic cavity quantum dots and filter out unnecessary frequency components to a certain extent, helping to maintain the coherence and stability of the cat-state quantum bits. Therefore, ATS, as a buffer, plays a role in stabilizing the system and prolonging the lifetime of the quantum state through interaction with the cat-state quantum bits.

[0054] In the process of storing quantum states, the circuit diagram is as follows Figure 3 As shown. The electrical signal input from the external circuit or waveguide enters the parallel circuit of the capacitor and ATS after passing through the filter, and after filtering out unnecessary frequency components, it acts on the phononic crystal. A quantum vibration mode of the corresponding frequency is generated in the phononic crystal, and a cat state is obtained. When the phonons in the cat state are converted into photons in the circuit due to nonlinear interactions and transferred to the buffer (ATS), it can temporarily store the energy to avoid premature decoherence of the cat state.

[0055] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A carbon nanotube quantum dot control device based on an acoustic cavity, characterized in that: Including phonon cavity, gate electrode, metal coating, carbon nanotube, groove, The phonon cavity is formed by connecting multiple cells, made of piezoelectric material, and located between two electrode plates, with one end receiving external input electrical signal control and the other end connected to the gate electrode; Groove: Made of silicon dioxide, the middle of the groove is concave, and the surfaces of the convex parts on both sides of the concave are respectively provided with a grounded first metal coating and a second metal coating; Gate electrode: Made of metal, located at the bottom of the groove, used to control the quantum dots on the carbon nanotubes; Carbon nanotube: the middle part is suspended above the depression, and the two ends span the groove and are in contact with the first metal coating and the second metal coating respectively.

2. The acoustic cavity-based carbon nanotube quantum dot control device according to claim 1, characterized in that: The quantum bit is controlled by inputting signals from the outside through the coupling of the phonon cavity and the quantum dot.

3. The acoustic cavity-based carbon nanotube quantum dot control device according to claim 1, characterized in that: The phonon cavity is prepared using piezoelectric material LiNbO3 crystal.

4. The acoustic cavity-based carbon nanotube quantum dot control device according to claim 1, characterized in that: The cross-sectional area of ​​the phonon cavity is 1 square micron, and the total length of the phonon cavity is 20 microns.

5. The acoustic cavity-based carbon nanotube quantum dot control device according to claim 1, characterized in that: The phonon cavity is arranged perpendicular to the bottom of the groove.

6. The acoustic cavity-based carbon nanotube quantum dot control device according to claim 1, characterized in that: Each quantum bit occupies an area of ​​4 square microns.

7. The acoustic cavity-based carbon nanotube quantum dot control device according to claim 1, characterized in that: The electrode at one end of the phonon cavity receiving the external input electrical signal is separated from the outside by a capacitor, and the end of the capacitor connected to the phonon cavity is grounded.

8. The acoustic cavity-based carbon nanotube quantum dot control device according to claim 1 is characterized in that: The first metal coating layer, the second metal coating layer and the gate electrode are all made of noble metals.

9. The acoustic cavity-based carbon nanotube quantum dot control device according to claim 1 is characterized in that: The first metal coating, the second metal coating and the gate electrode are made of platinum, gold and silver.

10. A method for controlling carbon nanotube quantum dots based on an acoustic cavity, using the control device according to any one of claims 1 to 8, characterized in that: By coupling the phonon cavity with the quantum dots, external signals are input to control the quantum bits, and the cat state coding inside the phonon cavity is used to store the quantum state, thereby improving the reliability of information storage, extending the retention time of quantum information, enhancing the stability of control and reducing errors in control.

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