Semiconductor quantum dot device and preparation method, signal reading method and manipulation method

Abstract

The application discloses a semiconductor quantum dot device structure and a preparation method, a signal reading method and a control method. The structure comprises: a silicon substrate with a first ion region and a second ion region; a dielectric layer on the silicon substrate, an interface between the silicon substrate and the dielectric layer forming a carrier channel; a first electrode in ohmic contact with the first ion region and a second electrode in ohmic contact with the second ion region; a confinement electrode on the dielectric layer, the confinement electrode being used to confine carriers in the carrier channel to form a quantum dot; and a magnetic electrode, the magnetic electrode being used to form a magnetic field gradient at the interface and to control the quantum dot. The semiconductor quantum dot device of the application has a relatively small magnetic electrode, a structural advantage, easy integration, and a stronger electric field control ability through the application of a microwave signal by the magnetic electrode.

Description

Technical Field

[0001] This invention belongs to the field of quantum computing technology, and specifically relates to a semiconductor quantum dot device and its preparation method, signal reading method, and manipulation method. Background Technology

[0002] With the rapid development of modern large-scale integrated circuit manufacturing technology, the size of integrated components within chips is constantly shrinking, and quantum effects are becoming increasingly significant. Among the many solutions to the crisis of Moore's Law failing, quantum computers, designed based on the principles of quantum mechanics, have become an important strategic focus and priority for countries around the world in the field of science and technology due to their breakthrough performance improvements and excellent quantum algorithm applications (such as cracking key distribution in current classical computers).

[0003] Among various qubit schemes for quantum computing, gate-controlled quantum dots based on semiconductor materials, such as GaAs / AlGaAs, SiO2 / Si, and Si / SiGe, are considered the most promising qubit encoding carriers for quantum computing. Semiconductor quantum dots exhibit good quantum coherence and are easily integrated with existing large-scale integrated circuit micro / nano fabrication processes. Furthermore, because the quantum dot structure is less susceptible to external environmental interference, it facilitates stable manipulation of qubits. Therefore, compared to other quantum computing systems, semiconductor quantum dots possess significant promise and advantages.

[0004] Manipulation methods and performance are important directions in quantum computing research. For single-spin qubits, manipulation methods include electron spin resonance using antennas, spin-orbit coupling, or electric dipole spin resonance using external micromagnets. For silicon-related semiconductor quantum dot devices, their weak hyperfine interactions and spin-orbit coupling can maintain electron spin for a longer decoherence time; however, current electrical manipulation methods for silicon-related semiconductor quantum dot devices are very limited.

[0005] To achieve excellent electrical control performance, obtaining high-quality semiconductor quantum dot devices with superior materials and structures is of paramount importance. These factors decisively influence the qubit properties of semiconductor quantum dot devices and further affect the quality of qubit control. Summary of the Invention

[0006] The purpose of this invention is to provide a semiconductor quantum dot device and its fabrication, manipulation, and readout methods to overcome the shortcomings of existing technologies. It can construct quantum bits through the electron spin-valley level hybrid effect and has strong electric field manipulation capabilities.

[0007] The technical solution adopted in this invention is as follows:

[0008] A semiconductor quantum dot device includes: a silicon substrate having a first ion region and a second ion region formed thereon; a dielectric layer located on the silicon substrate, the interface between the silicon substrate and the dielectric layer forming a carrier channel; a first electrode in ohmic contact with the first ion region, and a second electrode in ohmic contact with the second ion region; a confinement electrode located on the dielectric layer, the confinement electrode being used to confine carriers in the carrier channel to form a quantum dot; and a magnetic electrode being used to form a magnetic field gradient at the interface and to manipulate the quantum dot.

[0009] Furthermore, the dielectric layer includes one of a silicon dioxide layer, a silicon-germanium heterojunction layer, and a nanowire material layer.

[0010] Furthermore, the limiting electrode includes a plurality of overlapping gate electrodes, and an insulating layer is formed between adjacent gate electrodes.

[0011] Furthermore, the limiting electrode includes: a first guiding electrode and a second guiding electrode located between the first electrode and the second electrode; a first pump electrode located between the first guiding electrode and the second guiding electrode and arranged alternately with the first guiding electrode and the second guiding electrode; and a second pump electrode and a third pump electrode, wherein the second pump electrode is located between the first guiding electrode and the first pump electrode, and the third pump electrode is located between the second guiding electrode and the first pump electrode.

[0012] Furthermore, the dielectric layer partially covers the first ion region and the second ion region, and the first guiding electrode extends to cover the portion of the first ion region, and the second guiding electrode extends to cover the portion of the second ion region.

[0013] Furthermore, the magnetic electrode includes an iron electrode and a cobalt electrode.

[0014] Furthermore, it also includes a first channel electrode and a second communication electrode located on the dielectric layer, wherein a one-dimensional channel is formed between the first channel electrode and the second communication electrode, and the limiting electrode, as well as the first electrode and the second electrode, are all located in the one-dimensional channel.

[0015] This invention also proposes a method for fabricating a semiconductor quantum dot device, comprising: forming a first ion region and a second ion region on a silicon substrate; forming a dielectric layer on the silicon substrate, wherein the interface between the silicon substrate and the dielectric layer forms a carrier channel; forming a first electrode in ohmic contact with the first ion region and a second electrode in ohmic contact with the second ion region; forming a confinement electrode on the dielectric layer, wherein the confinement electrode is used to confine carriers in the carrier channel to form a quantum dot; and forming a magnetic electrode, wherein the magnetic electrode is used to form a magnetic field gradient at the interface and receive microwave signals that manipulate the quantum dot.

[0016] Furthermore, it also includes: forming a first channel electrode and a second communication electrode on the dielectric layer, wherein a one-dimensional channel is formed between the first channel electrode and the second communication electrode, and the limiting electrode, as well as the first electrode and the second electrode, are both located in the one-dimensional channel.

[0017] The present invention also proposes a signal readout method for a semiconductor quantum dot device, the signal readout method comprising: applying a magnetic field to the semiconductor quantum dot device; applying a voltage to the first electrode and the confinement electrode; applying a microwave signal to the magnetic electrode; and acquiring an electrical signal output from the second electrode.

[0018] The present invention also proposes a method for manipulating a semiconductor quantum dot device, the method comprising: forming a magnetic field gradient via the magnetic electrode to split the valley energy level of the quantum dot to obtain a split energy level; and applying a microwave signal via the magnetic electrode to adjust the energy level transition between the split energy levels to achieve manipulation of the state of the quantum dot.

[0019] Furthermore, the splitting energy level includes a first valley spin level, a second valley spin level, a third valley spin level, and a fourth valley spin level, wherein the second valley spin level and the third valley spin level are anti-crossed; the frequency of the microwave signal corresponds to the transition energy between the second valley spin level and the third valley spin level.

[0020] The present invention also proposes a quantum computer comprising any of the semiconductor quantum dot devices described in the foregoing features, semiconductor quantum dot devices prepared according to the method described in any of the foregoing features, or semiconductor quantum dot devices manipulated according to the method described in any of the foregoing features.

[0021] Compared with the prior art, the semiconductor quantum dot device provided by the first aspect of the present invention forms a magnetic field gradient at the interface through a magnetic electrode, and the magnetic electrode can change the magnetic field gradient at the interface between the silicon substrate and the dielectric layer according to the magnetic field strength vector applied to the semiconductor quantum dot device, thereby causing the valley energy level of the charge carrier at the quantum dot to split, thereby obtaining a split energy level suitable for electrical manipulation by a microwave signal applied to the magnetic electrode. Compared with structures such as antennas, the magnetic electrode used in the present invention is relatively small, has structural advantages, and is easy to integrate.

[0022] Compared with the prior art, the method for fabricating semiconductor quantum dot devices provided in the second aspect of the present invention can fabricate the semiconductor quantum dot devices provided in the first aspect of the present invention.

[0023] Compared with the prior art, the third aspect of the present invention provides a method for manipulating semiconductor quantum dot devices by forming a magnetic field gradient through magnetic electrodes to split the valley energy level of the quantum dot to obtain a split energy level, and applying a microwave signal through the magnetic electrodes to adjust the transition of the split energy level to achieve manipulation of the state of the quantum dot. Compared with the traditional manipulation between spin energy levels, the state of the quantum dot in the present invention is adjusted between split energy levels, which has the advantage of fast manipulation speed. Therefore, the electric field manipulation capability of the present invention is stronger. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a semiconductor quantum dot device provided in an embodiment of the present invention, wherein, Figure 1 (2) is Figure 1 (1) Schematic diagram of section Aa;

[0025] Figure 2 A flowchart illustrating a method for fabricating a semiconductor quantum dot device according to an embodiment of the present invention;

[0026] Figure 3 To and Figure 2 A structural diagram corresponding to each process step in the flowchart;

[0027] Figure 4 A flowchart illustrating a signal readout method for a semiconductor quantum dot device provided in an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the structure of a signal readout system for a semiconductor quantum dot device provided in an embodiment of the present invention;

[0029] Figure 6 A flowchart illustrating a method for manipulating a semiconductor quantum dot device according to an embodiment of the present invention;

[0030] Figure 7A schematic diagram of energy level splitting in a semiconductor quantum dot device under the action of a magnetic field, provided as an embodiment of the present invention;

[0031] Figure 8 and Figure 9 This is a diagram illustrating the electrical manipulation effect of a semiconductor quantum dot device provided in an embodiment of the present invention.

[0032] Explanation of reference numerals in the attached figures: 101-Silicon substrate, 102-Dielectric layer, 103-First ion region, 104-Second ion region, 201-First electrode, 202-Second electrode, 203-First guiding electrode, 204-Second guiding electrode, 205-First pump electrode, 206-Second pump electrode, 207-Third pump electrode, 208-First channel electrode, 209-Second channel electrode, 210-Second quantum dot, 211-First quantum dot, 212-Third quantum dot, 213-Magnetic electrode, 301-Semiconductor quantum dot device, 302-DC bias voltage source, 303-Microwave source, 304-Signal amplifier, 305-Voltage testing device. Detailed Implementation

[0033] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0034] Example 1

[0035] Figure 1 This is a schematic diagram of the structure of a semiconductor quantum dot device provided in an embodiment of the present invention, wherein, Figure 1 (2) is Figure 1 (1) Schematic diagram of section Aa.

[0036] Combination Figure 1 As shown, this embodiment provides a semiconductor quantum dot device structure, including: a silicon substrate 101 having a first ion region 103 and a second ion region 104 formed thereon; a dielectric layer 102 located on the silicon substrate 101, wherein the interface between the silicon substrate 101 and the dielectric layer 102 forms a carrier channel; a first electrode 201 in ohmic contact with the first ion region 103, and a second electrode 202 in ohmic contact with the second ion region 104; a confinement electrode located on the dielectric layer 102, the confinement electrode being used to confine carriers in the carrier channel to form a quantum dot; and a magnetic electrode 213, the magnetic electrode 213 being used to form a magnetic field gradient at the interface and to manipulate the quantum dot.

[0037] In the field of semiconductor quantum dot fabrication, a stack of silicon substrate 101 and dielectric layer 102 is used, and quantum dots are fabricated at the interface in the middle of the stack. Specifically, a first ion region 103 and a second ion region 104 are fabricated on opposite sides of the silicon substrate 101 for storing and releasing electrons; a first electrode 201 (i.e., source) ohmically connected to the first ion region 103 is fabricated directly above it, and a second electrode 202 (i.e., drain) ohmically connected to the second ion region 104 is fabricated directly above it. The first electrode 201 and the second electrode 202 function the same as the source and drain in a semiconductor chip. By applying a first DC bias voltage, the current required for the directional transport of electrons (i.e., forming a carrier channel current) is generated, thus constraining the direction of electron transport. The first DC bias voltage can be a positive voltage, a negative voltage, etc. Then, a confinement electrode is fabricated on the dielectric layer 102 to constrain the number of electrons in the carrier channel. By applying a set DC bias voltage, only a limited number of electrons (i.e., quantum dots) are left directly below the confinement electrode. A two-level system is designed by taking advantage of the spin characteristics of electrons (spin up and spin down) to form a quantum bit.

[0038] Furthermore, by setting up magnetic electrodes 213, quantum dots can be manipulated. Specifically, the magnetic field signal applied to the magnetic electrodes 213 causes the energy level of electrons to split, forming a two-level system with spin-up (high energy level) and spin-down (low energy level). The energy level difference depends on the magnitude of the applied magnetic field signal. A microwave signal is then applied through the magnetic electrodes 213. When the frequency of the applied microwave signal resonates with the energy level difference of the two-level system, electrons in the energy level system absorb or emit photons due to resonance, resulting in energy level transitions. For example, a spin-up electron will transition to the lower energy level (spin-down) corresponding to a spin-down electron; that is, the spin direction of the electron changes from spin-up to spin-down. Similarly, a spin-down electron, under the resonance of the microwave signal, will absorb photons and transition to a higher energy level (spin-up). Applying microwave signals through the magnetic electrodes 213 enables electrical manipulation of quantum dots. Furthermore, placing the magnetic electrodes 213 in semiconductor quantum dot devices can effectively improve the integration density of semiconductor quantum dot devices.

[0039] The dielectric layer 102 includes one of a silicon dioxide layer, a silicon-germanium heterojunction layer, and a nanowire material layer.

[0040] In the fabrication process of semiconductor quantum dot devices, the dielectric layer 102 material used to fabricate the electrodes that bind quantum dots can typically include solid materials such as gallium arsenide / aluminum gallium arsenide heterojunction, silicon / silicon germanium heterojunction, germanium / silicon germanium heterojunction, and silicon metal oxide semiconductor. It can also be two-dimensional materials such as graphene and molybdenum disulfide, one-dimensional materials such as indium arsenide nanowires, silicon germanium nanowires, silicon nanowires, and carbon nanotubes, or zero-dimensional materials such as germanium crystals.

[0041] The limiting electrode includes a plurality of overlapping gate electrodes, and an insulating layer is formed between adjacent gate electrodes.

[0042] The confinement electrode, disposed on the dielectric layer 102, is an electrode that constrains the number of electrons in the carrier channels. Its function is similar to that of the gate in a semiconductor device. By applying a set DC bias voltage, only a limited number of electrons (i.e., quantum dots) remain directly beneath the confinement electrode. To achieve multiple quantum dot structures, the gate electrodes are overlapped, ensuring that a quantum dot is formed beneath each gate electrode. Furthermore, an insulating layer is placed between the multiple gate electrodes to effectively isolate them from each other, preventing short circuits and leakage.

[0043] The limiting electrode includes: a first guiding electrode 203 and a second guiding electrode 204 located between the first electrode 201 and the second electrode 202; a first pump electrode 205 located between the first guiding electrode 203 and the second guiding electrode 204 and arranged alternately with the first guiding electrode 203 and the second guiding electrode 204; and a second pump electrode 206 and a third pump electrode 207, wherein the second pump electrode 206 is located between the first guiding electrode 203 and the first pump electrode 205, and the third pump electrode 207 is located between the second guiding electrode 204 and the first pump electrode 205.

[0044] like Figure 1 As shown, the limiting electrode includes a first guiding electrode 203 and a second guiding electrode 204, wherein the first guiding electrode 203 and the second guiding electrode 204 are both disposed between the first electrode 201 and the second electrode 202; when the quantum dot device is electrically controlled, a second DC bias voltage can be applied to the first guiding electrode 203 and the second guiding electrode 204 to form a carrier channel, and then a first DC bias voltage can be applied to the first electrode 201 and the second electrode 202 to form a current in the carrier channel.

[0045] After a current is formed in the carrier channel, a pump voltage signal needs to be applied to purge most of the electrons from the current, retaining only a few. The applied pump voltage is equal to the number of quantum dots formed. For example, in this invention, a first pump electrode 205, a second pump electrode 206, and a third pump electrode 207 are provided, such that fewer electrons are retained at the corresponding positions below the pump electrodes, forming three quantum dots. The first pump electrode 205, the second pump electrode 206, and the third pump electrode 207 are alternately arranged between the first and second guiding electrodes.

[0046] Furthermore, the pump voltage signals applied to the first pump electrode 205, the second pump electrode 206, and the third pump electrode 207 are different. Specifically, a second bias voltage, such as a positive voltage, of the same magnitude as the first or second guide electrode needs to be applied to the first pump electrode 205; while a smaller positive voltage relative to the first pump electrode 205 needs to be applied to the second pump electrode 206 and the third pump electrode 207.

[0047] The dielectric layer 102 partially covers the first ion region 103 and the second ion region 104, and the first guiding electrode 203 extends to cover the portion of the first ion region 103, and the second guiding electrode 204 extends to cover the portion of the second ion region 104.

[0048] like Figure 1 As shown, the first ion region 103 and the second ion region 104 are used to store and generate electrons. The number and direction of movement of these electrons are controlled by the first electrode 201 and the second electrode 202. That is, the first electrode 201 is in ohmic contact with the first ion region 103, and the second electrode 202 is in ohmic contact with the second ion region 104. The dielectric layer 102 and the silicon substrate 101 are stacked in layers. When fabricating the first electrode 201 and the second electrode 202 on the dielectric layer 102, the contact areas between the first electrode 201 and the first ion region 103, and the contact areas between the second electrode 202 and the second ion region 104 on the dielectric layer 102 need to be removed by an etching process to ensure the stability of the ohmic contact. That is, the dielectric layer 102 partially covers the first ion region 103 and the second ion region 104. Furthermore, the first guiding electrode 203 and the second guiding electrode 204 in the limiting electrode are used to apply a second bias voltage to form a carrier channel. Therefore, the first guiding electrode 203 extends to cover the first ion region 103, and the second guiding electrode 204 extends to cover the second ion region 104.

[0049] The magnetic electrode 213 includes an iron electrode and a cobalt electrode. The material of the magnetic electrode 213 can be any magnetic material such as iron, cobalt, or nickel. In the fabrication of semiconductor quantum dot devices, it can be formed by electron beam lithography and electron beam evaporation deposition. For example, the magnetic electrode 213 can be formed by depositing a magnetic material onto the surface of the dielectric layer 102 using an electron beam evaporation deposition process. In this invention, the location of the magnetic electrode 213 is not limited to this; it is acceptable as long as a magnetic field gradient can be formed at the interface and microwave signals used to manipulate the quantum dot can be received.

[0050] The semiconductor quantum dot device further includes a first channel electrode 208 and a second communication electrode 209 located on the dielectric layer 102, wherein a one-dimensional channel is formed between the first channel electrode 208 and the second communication electrode 209, and the confinement electrode, as well as the first electrode 201 and the second electrode 202, are all located in the one-dimensional channel.

[0051] like Figure 1 As shown, a one-dimensional channel is also provided on the dielectric layer 102. As is well known in the semiconductor field, a channel refers to the semiconductor layer between the source and drain electrodes in a transistor. In this invention, it is provided along the horizontal direction of the first electrode 201 and the second electrode 202. Specifically, by providing a first channel electrode 208 and a second channel electrode 209 on the dielectric layer 102, a one-dimensional channel is formed between the first channel electrode 208 and the second channel electrode 209.

[0052] The one-dimensional channel corresponds to the carrier channel. The one-dimensional channel is set along the horizontal direction of the first electrode 201 and the second electrode 202. When a first DC bias voltage is applied to the first electrode 201 and the second electrode 202 to form a current in the carrier channel, the carrier channel is located in the one-dimensional channel region, that is, electrons move in the one-dimensional channel. Therefore, the limiting electrode for controlling the electrons in the carrier channel also needs to be set in the one-dimensional channel.

[0053] The semiconductor quantum dot device provided by the first aspect of the present invention forms a magnetic field gradient at the interface through a magnetic electrode 213. The magnetic electrode 213 can change the magnetic field gradient at the interface between the silicon substrate 101 and the dielectric layer 102 according to the magnetic field strength vector applied to the semiconductor quantum dot device, thereby splitting the charge carrier valley energy level at the quantum dot and obtaining a split energy level suitable for electrical manipulation by applying a microwave signal to the magnetic electrode 213. Compared with structures such as antennas, the magnetic electrode 213 used in the present invention is relatively small, has structural advantages, and is easy to integrate.

[0054] Example 2

[0055] Figure 2 This is a flowchart illustrating a method for fabricating a semiconductor quantum dot device according to an embodiment of the present invention. Figure 3 To and Figure 2 A structural diagram of each process step in the flowchart.

[0056] Combination Figure 2 and Figure 3 As shown, this embodiment provides a method for fabricating a semiconductor quantum dot device, including:

[0057] S110: A first ion region 103 and a second ion region 104 are formed on a silicon substrate 101;

[0058] like Figure 3 As shown in (1), the first ion region 103 and the second ion region 104 are formed on the silicon substrate using photolithography and etching processes in semiconductor chip fabrication. The first ion region 103 and the second ion region 104 are symmetrical along the same horizontal line on the silicon substrate 101.

[0059] S120: A dielectric layer 102 is formed on the silicon substrate 101, and a carrier channel is formed at the interface between the silicon substrate 101 and the dielectric layer 102;

[0060] like Figure 3 As shown in (2), after the first ion region 103 and the second ion region 104 are prepared on the silicon substrate 101, a dielectric layer 102 can be formed above the silicon substrate 101, and a carrier channel can be formed at the contact surface between the silicon substrate 101 and the dielectric layer 102.

[0061] S130: A first electrode 201 is formed in ohmic contact with the first ion region 103 ohms, and a second electrode 202 is formed in ohmic contact with the second ion region 104 ohms.

[0062] like Figure 3 As shown in (3), a first electrode 201 with an ohmic contact is formed on the first ion region 103 and a second electrode 202 with an ohmic contact is formed on the second ion region 104 using photolithography, etching, and metal deposition processes. Specifically, the first ion region 103 and the second ion region 104 can be used to store and output electrons. The output of electrons requires a current between the first ion region 103 and the second ion region 104, and the first electrode 201 and the second electrode 202 are used to apply a first DC bias voltage to form a current (i.e., carrier channel current) between the first ion region 103 and the second ion region 104.

[0063] S140: Forming a confinement electrode on the dielectric layer 102, the confinement electrode being used to confine charge carriers in the charge carrier channel to form a quantum dot;

[0064] like Figure 3 (5) and Figure 3As shown in (6), the limiting electrode includes a first guiding electrode 203, a second guiding electrode 204, a first pump electrode 205, a second pump electrode 206, and a third pump electrode 207. Specifically, the first guiding electrode 203 and the second guiding electrode 204 are first fabricated on the dielectric layer 102 between the first electrode 201 and the second electrode 202; the processing method of the first guiding electrode 203 and the second guiding electrode 204 is the same as that used to form the first electrode 201 or the second electrode 202, and then the first pump electrode 205 is fabricated between the first guiding electrode 203 and the second guiding electrode 204 using the same process. The first electrode 201, the second electrode 202, the first guiding electrode 203, the second guiding electrode 204, and the first pump electrode 205 are coaxially arranged along the horizontal direction of the dielectric layer 102.

[0065] Furthermore, after the first guiding electrode 203, the second guiding electrode 204, and the first pump electrode 205 are formed on the dielectric layer 102, an insulating layer needs to be formed on its surface to electrically isolate the electrodes from each other. Specifically, the insulating layer can be formed by in-situ thermal oxidation, plasma oxidation, or electron deposition techniques.

[0066] S150: Form a magnetic electrode 213, which is used to form a magnetic field gradient at the interface and receive microwave signals that manipulate the quantum dot.

[0067] After fabricating a first electrode 201, a second electrode 202 for forming carrier channel current, and a confinement electrode for restricting the movement and quantity of electrons on the dielectric layer 102, a corresponding quantum dot can be generated below the confinement electrode. Manipulating the quantum dot requires an applied external magnetic field, therefore a magnetic electrode 213 needs to be formed on the quantum dot device. Specifically, the magnetic electrode 213 can be shaped using electron beam lithography and formed using electron beam evaporation deposition. The magnetic electrode 213 can be fabricated on the dielectric layer 102 or on the silicon substrate 101; the fabrication process is simple and easy to integrate.

[0068] The method for fabricating a semiconductor quantum dot device provided in the second aspect of the present invention is capable of fabricating the semiconductor quantum dot device provided in the first aspect of the present invention.

[0069] Example 3

[0070] Figure 4 This is a flowchart illustrating a signal readout method for a semiconductor quantum dot device provided in an embodiment of the present invention. Figure 5 This is a schematic diagram of the structure of a signal readout system for a semiconductor quantum dot device provided in an embodiment of the present invention.

[0071] Combination Figure 4 and Figure 5 As shown, this embodiment provides a signal readout method for a semiconductor quantum dot device, specifically including:

[0072] Step S210: Apply voltage to the first electrode 201, the second electrode 202 and the limiting electrode.

[0073] Specifically, a second DC bias voltage is first applied to the first guiding electrode 203 and the second guiding electrode 204 to form carrier channels. Then, a first DC bias voltage is applied to the first electrode 201 and the second electrode 202, causing current to flow through the carrier channels. Next, a third DC bias voltage is applied to the gate electrode 206 and the gate electrode 207, causing a second quantum dot 210, a first quantum dot 211, and a third quantum dot 212 to form directly below the pump electrode 205, the gate electrode 206, and the gate electrode 207. Each of the formed second quantum dot 210, first quantum dot 211, and third quantum dot 212 has multiple energy levels (called valley levels), and the energy levels can be selected. The first, second, and third DC bias voltages can be adjusted in real time according to the performance parameters of the quantum dots during implementation.

[0074] Step S220: Apply a vector magnetic field to the magnetic electrode 213.

[0075] After forming the second quantum dot 210, the first quantum dot 211, and the third quantum dot 212 on the substrate through step S210, they can be manipulated by applying a magnetic field signal. Specifically, any valley level of each quantum dot is in a degenerate state, i.e., it has electrons with spin-up and spin-down. Combining the energy level splitting principle in quantum physics, when a magnetic field signal is applied to the quantum dot, the valley level of the quantum dot will undergo Zeeman splitting, that is, a valley level splits into a high energy level composed of spin-up electrons and a low energy level composed of spin-down electrons. Each energy level can be set as an eigenstate of the quantum dot (such as the ground state and excited state).

[0076] It is foreseeable that when a quantum dot has multiple valley levels, under the influence of a suitable magnetic field, each valley level will undergo Zeeman splitting, splitting into two energy levels (i.e., a high energy level and a low energy level). Both the high and low energy levels formed by this splitting have a single spin direction. By using two quantum dots and combining this with the Pauli exclusion principle, it is possible to measure a single quantum dot. The Pauli exclusion principle can be simply summarized as follows: an atom cannot accommodate electrons with identical spin states (spin up and spin down); that is, two electrons with the same spin-up or spin-down orientation cannot coexist in a single energy level.

[0077] Figure 7 This is a schematic diagram of energy level splitting in a semiconductor quantum dot device under the influence of a magnetic field, provided as an embodiment of the present invention. (Refer to...) Figure 7 As shown, taking the second quantum dot 210 as an example, 403 and 404 in the figure are the valley levels of the second quantum dot 210 itself. When a changing magnetic field signal is applied, both valley levels 403 and 404 undergo Zeeman splitting. Specifically, valley level 403 undergoes Zeeman splitting to form 407 (spin down) and 408 (spin up), while valley level 404 undergoes Zeeman splitting to form 405 (spin down) and 406 (spin up). Therefore, the second quantum dot 210 now has four energy levels (i.e., 405, 406, 407, and 408).

[0078] With the help of Figure 7 It can be seen that there are energy level differences between adjacent energy levels. Specifically, the energy level difference between energy levels 405 and 406 is the energy level difference generated by the Zeeman splitting of quantum dot 410; the energy level difference between 407 and 408 is the valley energy level difference of quantum dot 410; and there are two energy level differences 411 and 412 between energy levels 406 and 407. It can be found that energy level differences 411 and 412 are energy level differences after the mixing of valley energy levels and spin energy levels, also known as a mixed energy level system. As the applied magnetic field increases, energy level differences 410, 411, and 412 will also change accordingly.

[0079] Among them, energy levels 407 (spin down) and 406 (spin up) can interact, and electrons in these energy levels can interconvert to each other if the energy requirement is met, thus resulting in… Figure 7 In the case where energy levels 407 and 406 do not cross (which can be understood as anti-crossing), especially in the anti-crossing region, energy levels are more likely to interact and transition. This can be further understood as the mixed energy level system being easier to control; that is, spin resonance can be efficiently achieved through electrical manipulation, thus enabling the corresponding qubit to respond.

[0080] Step S230: Apply a microwave signal to the magnetic electrode 213.

[0081] When a quantum dot's energy levels are split by applying a magnetic field signal, creating multiple energy levels, there are energy level differences between them, such as the energy level differences 410, 411, and 412 of the second quantum dot 210 in the example above. In physics, electron spin can be manipulated by applying a microwave electric field. Taking the mixed energy level systems 411 and 412 as examples, the mixed valley energy level differences each consist of energy level 407 occupied by spin-up electrons and energy level 406 occupied by spin-down electrons. When a microwave signal is applied, and the frequency of the applied microwave signal is the same as or close to that of the mixed energy level systems 411 and 412, resonance occurs, causing a change in the spin direction of electrons in energy levels 406 and 407. This principle can be referenced to the manipulation of electron spin using electric dipole spin resonance.

[0082] Among them, the manipulation of a single quantum dot can be achieved by using electric dipole spin resonance. In practical applications, the state of the controlled quantum dot can be read by adding auxiliary quantum dots, i.e., the state reading of the qubit, which is of great significance in the field of quantum computing.

[0083] As an example, taking the second quantum dot 210 and the first quantum dot 211 as examples, the first quantum dot 211 can be used as an auxiliary quantum dot, where the electron spin direction in the auxiliary quantum dot is set to be known (e.g., spin down). Referring to steps S20 and S30, by applying a magnetic field signal to split the energy levels of the first quantum dot 210, and by applying a microwave signal through the magnetic electrode 213, the spin of the electrons in the first quantum dot 210 is modulated. Using the Pauli exclusion principle, the original spin state of the electrons in the first quantum dot 210 can be measured. Simply put, when the electron spin direction in the first quantum dot 210 is downward, the electric dipole spin resonance caused by applying a microwave signal changes its spin direction to upward. Meanwhile, the electron spin direction in the auxiliary quantum dot (first quantum dot 211) is downward, meaning the change in output current can be measured. Conversely, when the electron spin direction in the second quantum dot 210 is upward, the electric dipole spin resonance caused by applying a microwave signal changes its spin direction to downward. In this case, electrons cannot pass through the energy level of the first quantum dot 211, meaning the output current remains unchanged.

[0084] Step S240: Obtain the electrical signal output by the second electrode 202.

[0085] Referring to the measurement described in step S230, the change in the output current of the auxiliary quantum dot can be tested using a signal testing device. In a specific quantum dot device, the current at the drain (the second electrode 202 in this invention) can be measured using an ammeter or voltmeter.

[0086] By employing two quantum dots and applying magnetic field and microwave signals using magnetic electrode 213, it is possible to read out a single quantum dot. When designed as a qubit, the quantum state of the qubit can be effectively read out.

[0087] Example 4

[0088] Figure 6 This is a flowchart illustrating a method for manipulating a semiconductor quantum dot device according to an embodiment of the present invention. Figure 7 This is a schematic diagram of energy level splitting in a semiconductor quantum dot device under the action of a magnetic field, provided as an embodiment of the present invention.

[0089] Combination Figure 6 and Figure 7 As shown, this embodiment provides a method for manipulating a semiconductor quantum dot device, specifically including:

[0090] Step S310: Apply a magnetic field via the magnetic electrode 213 to cause the energy levels of the quantum dot to split, thus obtaining split energy levels;

[0091] The splitting energy level includes a first valley spin energy level, a second valley spin energy level, a third valley spin energy level and a fourth valley spin energy level, wherein the second valley spin energy level and the third valley spin energy level are anti-crossed;

[0092] Specifically, the splitting effect is as follows: Figure 7 As shown, quantum dots possess spin energy levels and valley energy levels. Valley energy levels are natural energy levels of silicon-based quantum dots and can have multiple levels, such as... Figure 7 In the quantum dot, 403 and 404 are valley levels. Spin levels, on the other hand, require a magnetic field to be applied, causing them to split into two levels (spin-up and spin-down). After Zeeman splitting occurs in the quantum dot, the valley and spin levels mix, forming split levels 405 (first valley spin level), 406 (second valley spin level), 407 (third valley spin level), and 408 (fourth valley spin level).

[0093] Taking the second quantum dot 210 as an example, valley level 403 is a high energy level and valley level 404 is a low energy level. Valley level 403 undergoes Zeeman splitting under the influence of a magnetic field to form split energy levels 408 (electron spin up) and 407 (electron spin down); valley level 404 undergoes Zeeman splitting under the influence of a magnetic field to form split energy levels 406 (electron spin up) and 405 (electron spin down).

[0094] Specifically, the energy difference between valley levels 403 and 404 is an inherent property of silicon-based quantum dots, influenced by their own properties. However, the Zeeman splitting energy level formed after Zeeman splitting occurs under the influence of an applied external magnetic field is related to the magnitude of the applied external magnetic field. For example... Figure 7The energy difference 410 between the splitting energy levels 405 and 406 in the magnetic field increases with the increase of the magnetic field.

[0095] Not only does a split energy level difference 410 form between split energy levels 405 and 406, but there are also split energy level differences 411 and 412 (mixed energy level system) between split energy levels 406 and 407. These energy level differences 411 and 412 are the result of mixing valley and spin energy levels. Furthermore, there is also an energy level difference 409 between split energy levels 407 and 408. This energy level difference 409 is a valley energy level difference and is related to the inherent properties of the silicon substrate 101.

[0096] Among them, spin energy level 407 and spin energy level 406 can be used as the eigenstates (excited state and ground state) of the qubit. Therefore, the mixed energy level system 411 and 412 between spin energy level 407 and spin energy level 406 is the object of qubit manipulation. Specifically, the electrons between the mixed energy level system 411 and 412 can generate spin resonance by applying a microwave signal.

[0097] Step S320: Apply a microwave signal via the magnetic electrode 213 to adjust the splitting energy level corresponding to the state of the quantum dot.

[0098] The frequency of the microwave signal corresponds to the transition energy between the second valley spin level and the third valley spin level.

[0099] After the mixed energy level systems 411 and 412 are formed, they can be controlled by applying a microwave signal through the magnetic electrode 213. Specifically, this is achieved using electric dipole spin resonance, as mentioned earlier. When the frequency of the microwave signal applied through the magnetic electrode 213 corresponds to the transition energy between the second valley spin level (406) and the third valley spin level (407), i.e., when it resonates with the mixed energy level systems 411 and 412, electrons will transition between spin levels 406 and 407. Correspondingly, for a qubit, applying a microwave signal causes a change in the quantum state of the qubit.

[0100] In semiconductor quantum dot devices, both valley levels and electron spin levels can be designed as qubits by selecting the two lowest energy levels, thus representing the eigenstates of the qubit. However, using valley levels as eigenstates results in a shorter decoherence time compared to using electron spin levels, which limits the manipulation time of the qubit and significantly restricts the efficiency of quantum computing. Therefore, valley levels are generally not used as eigenstates for qubit design; in current technologies, electron spin levels are typically chosen.

[0101] However, while the decoherence time of qubits designed using electron spin energy levels is relatively long, the spin energy level difference after Zeeman splitting under the influence of a magnetic field is very large. This means that the microwave signal required to resonate with the spin energy level difference also increases accordingly, significantly increasing the difficulty of manipulation. Using a hybrid energy level system can quickly respond to the applied microwave signal, which is beneficial for improving the efficiency of electrical manipulation.

[0102] Example 5

[0103] Figure 8 and Figure 9 This is a diagram illustrating the electrical manipulation effect of a semiconductor quantum dot device provided in an embodiment of the present invention.

[0104] Combination Figure 8 and Figure 9 As shown, this embodiment provides an example of the electrical manipulation effect of a semiconductor quantum dot device based on valley spin hybrid energy levels. The semiconductor quantum dot device is the semiconductor quantum dot device in Example 1, or a semiconductor quantum dot device prepared according to the method of Example 2.

[0105] Using the second quantum dot 210 as an example, the current signal is measured through the second electrode 202. Specifically, the horizontal axis represents the magnetic field gradient applied through the micromagnet, the vertical axis represents the frequency of the microwave signal applied through the micromagnet, and the depth (brightness) in the figure represents the magnitude of the current.

[0106] Among them, dashed line 603 represents the current change curve obtained by measuring the second electrode 202 under the control of magnetic field and microwave signal in hybrid energy level system 411; dashed line 605 represents the current change curve obtained by measuring the second electrode 202 under the control of magnetic field and microwave signal in hybrid energy level system 412; in addition, dashed line 604 represents the current change curve obtained by measuring the second electrode 202 when the spin energy level and valley energy level difference are the same.

[0107] like Figure 9 As shown, for comparison, 610 is the current change curve obtained by measuring the second electrode 202 under the control of the spin energy level difference 410 in the presence of a magnetic field and microwave signal. The microwave signal required to be applied is much larger than the control range of the mixed energy level systems 411 and 412. It can be understood that the control effect of the spin energy level difference 410 by the microwave signal is very poor. Furthermore, it can be understood that if the spin energy level difference 410 is used as the eigenstate of the qubit, a very large microwave signal is required to read the quantum state of the qubit, which increases the difficulty of control.

[0108] Conversely, when hybrid energy level systems 411 and 412 are used, their ability to control microwave signals is strong, meaning that when used as eigenstates of qubits, they are easy to manipulate during quantum computing.

[0109] The third aspect of the present invention provides a method for manipulating a semiconductor quantum dot device. A magnetic field gradient is formed by a magnetic electrode 213 to split the valley energy level of the quantum dot to obtain a split energy level. A microwave signal is applied via the magnetic electrode 213 to adjust the split energy level corresponding to the state of the quantum dot. Compared with the conventional manipulation between spin energy levels, the state of the quantum dot in the present invention is adjusted between split energy levels, which has the advantage of fast manipulation speed. Therefore, the electric field manipulation capability of the present invention is strong.

[0110] Implementation 6

[0111] like Figure 5 As shown, this embodiment provides a signal readout system based on a hybrid energy level semiconductor quantum dot device. The system includes a semiconductor quantum dot device 301, a DC bias voltage source 302, a microwave source 303, a signal amplifier 304, and a voltage testing device 305. The semiconductor quantum dot device is the semiconductor quantum dot device in Embodiment 1, or a semiconductor quantum dot device prepared according to the method of Embodiment 2.

[0112] A DC bias voltage source 302 connects the first electrode 201, the second electrode 202, the first guiding electrode 203, the second guiding electrode 204, and each confinement electrode of the semiconductor quantum dot. It is used to provide a DC bias voltage, specifically including a DC bias voltage applied to the first electrode 201 and the second electrode 202 of the semiconductor quantum dot device for generating carrier channels; a forward bias voltage applied to the first guiding electrode 203 and the second guiding electrode 204 for forming current in the carrier channels; and a bias voltage applied to the confinement electrode for forming the quantum dot.

[0113] The microwave source 303 is connected to the magnetic electrode 213 of the semiconductor quantum dot device and is used to provide a microwave signal whose frequency resonates with the mixed energy level system 411 and 412, thereby enabling the control of the semiconductor quantum dot device 301.

[0114] Signal amplifier 304 is connected to the second electrode 202 (drain) of the semiconductor quantum dot device and is used to amplify the signal output from the drain of the semiconductor quantum dot device. Specifically, the semiconductor quantum dot outputs a current signal, which is first converted into a voltage signal, then amplified, and finally output as an amplified voltage signal for testing.

[0115] A voltage testing device 305 is connected to a signal amplifier 304 to test the amplified voltage signal. The test results are then used to analyze the quantum states of the semiconductor quantum dot device.

[0116] Furthermore, this embodiment also proposes a quantum computer, including the semiconductor quantum dot device described in the above embodiments, or a semiconductor quantum dot device prepared according to the method described in the above embodiments, or a semiconductor quantum dot device manipulated by the method described in the above embodiments, or a semiconductor quantum dot device for signal reading according to the signal reading method described in the above embodiments.

[0117] Compared with the prior art, the semiconductor quantum dot device provided by the first aspect of the present invention forms a magnetic field gradient at the interface through a magnetic electrode 213. The magnetic electrode 213 can change the magnetic field gradient at the interface between the silicon substrate and the dielectric layer according to the magnetic field strength vector applied to the semiconductor quantum dot device, thereby splitting the charge carrier valley energy level at the quantum dot and obtaining a split energy level suitable for electrical manipulation by applying a microwave signal to the magnetic electrode 213. Compared with structures such as antennas, the magnetic electrode 213 used in the present invention is relatively small, has structural advantages, and is easy to integrate.

[0118] Compared with the prior art, the method for fabricating semiconductor quantum dot devices provided in the second aspect of the present invention can fabricate the semiconductor quantum dot devices provided in the first aspect of the present invention.

[0119] Compared with the prior art, the third aspect of the present invention provides a method for manipulating a semiconductor quantum dot device by forming a magnetic field gradient through a magnetic electrode 213 to split the valley energy level of the quantum dot to obtain a split energy level, and applying a microwave signal through the magnetic electrode 213 to adjust the split energy level corresponding to the state of the quantum dot. Compared with the traditional control between spin energy levels, the state of the quantum dot in the present invention is adjusted between split energy levels, which has the advantage of fast manipulation speed. Therefore, the electric field manipulation capability of the present invention is stronger.

[0120] The above description, based on the embodiments shown in the figures, details the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the figures. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, that do not exceed the spirit covered by the specification and figures, should be within the protection scope of the present invention.

Claims

1. A semiconductor quantum dot device, characterized in that, include: A silicon substrate having a first ion region and a second ion region; A dielectric layer located on the silicon substrate, wherein the interface between the silicon substrate and the dielectric layer forms a carrier channel; A first electrode that is in ohmic contact with the first ion region, and a second electrode that is in ohmic contact with the second ion region; A confinement electrode located on the dielectric layer, the confinement electrode being used to confine charge carriers in the charge carrier channel to form a quantum dot; And a magnetic electrode, which is used to form a magnetic field gradient at the interface and to manipulate the quantum dot so that the quantum dot has a split energy level difference after the valley energy level and spin energy level are mixed.

2. The semiconductor quantum dot device according to claim 1, characterized in that, The dielectric layer includes one of a silicon dioxide layer, a silicon-germanium heterojunction layer, and a nanowire material layer.

3. The semiconductor quantum dot device according to claim 1, characterized in that, The limiting electrode includes a plurality of overlapping gate electrodes, and an insulating layer is formed between adjacent gate electrodes.

4. The semiconductor quantum dot device according to claim 1 or 3, characterized in that, The limiting electrode includes: A first guiding electrode and a second guiding electrode located between the first electrode and the second electrode; A first pump electrode is located between the first guide electrode and the second guide electrode, and is arranged alternately with the first guide electrode and the second guide electrode; The device also includes a second pump electrode and a third pump electrode, wherein the second pump electrode is located between the first guide electrode and the first pump electrode, and the third pump electrode is located between the second guide electrode and the first pump electrode.

5. The semiconductor quantum dot device according to claim 4, characterized in that, The dielectric layer partially covers the first ion region and the second ion region, and the first guiding electrode extends to cover the portion of the first ion region, and the second guiding electrode extends to cover the portion of the second ion region.

6. The semiconductor quantum dot device according to claim 1, characterized in that, The magnetic electrodes include iron electrodes and cobalt electrodes.

7. The semiconductor quantum dot device according to claim 1, characterized in that, It also includes a first channel electrode and a second communication electrode located on the dielectric layer, wherein a one-dimensional channel is formed between the first channel electrode and the second communication electrode, and the limiting electrode, as well as the first electrode and the second electrode, are all located in the one-dimensional channel.

8. A method for fabricating a semiconductor quantum dot device, characterized in that, include: A first ion region and a second ion region are formed on a silicon substrate; A dielectric layer is formed on the silicon substrate, and a carrier channel is formed at the interface between the silicon substrate and the dielectric layer. A first electrode is formed that is in ohmic contact with the first ion region, and a second electrode is in ohmic contact with the second ion region; A confinement electrode is formed on the dielectric layer, the confinement electrode being used to confine charge carriers in the charge carrier channel to form a quantum dot; A magnetic electrode is formed to create a magnetic field gradient at the interface, so that the quantum dot has a splitting energy level difference after the valley level and spin level are mixed.

9. The preparation method according to claim 8, characterized in that, Also includes: A first channel electrode and a second communication electrode are formed on the dielectric layer, a one-dimensional channel is formed between the first channel electrode and the second communication electrode, and the limiting electrode, as well as the first electrode and the second electrode, are all located in the one-dimensional channel.

10. A signal readout method for a semiconductor quantum dot device, characterized in that, The semiconductor quantum dot device is the semiconductor quantum dot device according to any one of claims 1-3, 5-7, or the semiconductor quantum dot device prepared by the method according to any one of claims 8-9, and the signal readout method includes: A magnetic field is applied to the semiconductor quantum dot device; A voltage is applied to the first electrode and the limiting electrode; A microwave signal is applied to the magnetic electrode; And to acquire the electrical signal output by the second electrode.

11. A method for manipulating a semiconductor quantum dot device, characterized in that, The semiconductor quantum dot device is the semiconductor quantum dot device according to any one of claims 1-3, 5-7, or the semiconductor quantum dot device prepared by the method according to any one of claims 8-9, wherein the manipulation method includes: A magnetic field gradient is formed via the magnetic electrodes to cause the valley level of the quantum dot to split, resulting in a split energy level formed by the mixing of the valley level and the spin level; The state of the quantum dot can be manipulated by applying a microwave signal via the magnetic electrode to regulate the energy level transitions between the split energy levels.

12. The control method according to claim 11, characterized in that, The splitting energy level includes a first valley spin energy level, a second valley spin energy level, a third valley spin energy level, and a fourth valley spin energy level, wherein the second valley spin energy level and the third valley spin energy level are anti-crossed; The frequency of the microwave signal corresponds to the transition energy between the second valley spin level and the third valley spin level.

13. A quantum computer, characterized in that, The semiconductor quantum dot device includes any one of claims 1-3 and 5-7, or a semiconductor quantum dot device prepared by the method according to any one of claims 8-9, or a semiconductor quantum dot device manipulated by the method according to any one of claims 11-12.

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