Quantum device

Abstract

A quantum device includes a transistor structure portion having a source, a drain, and a gate; one or more quantum dot structure portions in which electric charges can locally exist; and a quantum bit control current line that changes a state of the electric charges in the quantum dot structure portion.

Description

Technical Field

[0001] This invention relates to a quantum device.

[0002] This application claims priority to Japan Patent Application No. 2020-102530, filed on June 12, 2020, the contents of which are incorporated herein by reference. Background Technology

[0003] Research and development on quantum computers and quantum annealing machines are underway. For example, Non-Patent Documents 1 and 2 report examples of fabricating more than fifty qubits using superconductors. Furthermore, Non-Patent Document 3 presents an experimental example of a quantum annealing machine, a technology that has already been commercialized.

[0004] As a technology related to quantum computing, as illustrated in this example, the use of superconductors is under development. This is because, in experiments, a superconducting state with zero resistance is relatively easy to achieve, allowing for the time (coherence time) required to maintain the quantum state. However, in superconducting devices, integration has historically been difficult.

[0005] On the other hand, current computers are made of semiconductors such as silicon. The gate length of transistors used in current smartphones and other devices is already below 15nm, and a technology roadmap to reach below 5nm is underway. If qubits can be fabricated using semiconductor technology, decades of accumulated integration technology can be utilized, thus raising hopes for the realization of quantum computer technologies that combine high reliability and versatility.

[0006] Specifically, in order to fabricate qubits using semiconductors, one proposal is to use a method that utilizes the spin of electrons or holes (Non-Patent Document 4) and another proposal is to use the amount of charge itself (Non-Patent Document 5).

[0007] Figure 22 The paper presents a schematic diagram of a simple spin qubit. It defines the spin-up state |↑> and spin-down state |↓> of the spin qubit relative to an external magnetic field, and demonstrates a general quantum superposition state |Ψ>=a|↑>+b|↓> (where a and b are arbitrary complex numbers) through arbitrary rotations around this axis. However, since maintaining the coherence of spin and charge states is generally difficult, future advancements in this field compared to superconductivity are anticipated.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: U.S. Patent Application Publication No. 2019 / 0393328

[0011] Patent Document 2: Japanese Patent Publication No. 2011-512525

[0012] Non-patent literature

[0013] Non-patent literature 1: M.Veldhorst, CHYang, JCCHwang, W.Huang, JPDehollain, JTMuhonen, S.Simmons, A.Laucht, FEHudson, KMItoh, A.Morello & A.S.Dzurak "Atwo-qubit logic gate in silicon" Nature volume 526, pages410-414 (2015)

[0014] Non-patent literature 2: Frank Arute, Kunal Arya et al., “Quantum supremacy using a programmable superconducting processor”, Nature, volume 574, pages 505-510 (2019).

[0015] Non-patent literature 3: MW Johnson et al., “Quantum annealing with manufactured spins”, Nature vol 473, pp. 194-198 (2011).

[0016] Non-patent literature 4: Guido Burkard, Daniel Loss, and David P. DiVincenzo, “Coupled quantum dots as quantum gates”, Physical Review B59, p. 2070 (1999).

[0017] Non-patent document 5: T Tanamoto, Y Higashi, J Deguchi "Calculation of acapacitively-coupled floating gate array toward quantum annealing machine" Journal of Applied Physics Vol.124,154301(2018)

[0018] Non-patent document 6: Ruoyu Li, Luca Petit1, David P. Franke, Juan Pablo Dehollain1, Jonas Helsen, Mark Steudtner, Nicole K. Thomas, Zachary R. Yoscovits, Kanwal J. Singh, Stephanie Wehner, Lieven MK Vandersypen, James S. Clarke and Menno Veldhorst "A crossbar network for silicon quantum dot qubits"ScienceAdvances 06Jul 2018:Vol.4,no.7,eaar3960:DOI:10.1126 / sciadv.aar3960

[0019] Non-patent literature 7: R. Xia, T. Bian, and Sabre Kais, “Electronic Structure Calculations and the Ising Hamiltonian”, arXiv:1706.00271

[0020] Non-patent literature 8: Yoshiaki Rikitake and Hiroshi Imamura, “Decoherence of localized spins interacting via RKKY interaction”, Phys. Rev. B 72, 033308 (2005). Summary of the Invention

[0021] (The technical problem the invention aims to solve)

[0022] The purpose of this invention is to provide a quantum device that expands existing transistors into the basic building blocks of a quantum computer or a quantum annealing machine.

[0023] In detail, the object of the present invention is to provide a quantum device that can be manufactured using existing transistor structures and existing factory facilities as much as possible, and can be easily measured.

[0024] (Technical means used to solve technical problems)

[0025] One embodiment of the present invention is a quantum device comprising: a transistor structure having a source, a drain, and a gate; one or more quantum dot structures in which charge can be locally present; and a quantum bit control current line that changes the state of charge within the quantum dot structures, wherein the length of the gate is 30 nm or less.

[0026] One embodiment of the present invention is a quantum device comprising: a transistor structure having a source, a drain, and a gate, and having a plurality of channel structures between the source and drain; one or more quantum dot structures, wherein the quantum dot structures are sandwiched by the plurality of channel structures, and electrons or holes can be stored in the quantum dot structures; the quantum device further comprises a quantum bit control current line, through which a quantum bit control current generating a magnetic field flows, and the magnetic field controls the spin state of the electrons or holes.

[0027] In a quantum device according to one embodiment of the present invention, the transistor structure having the plurality of channel structures that hold the quantum dot structure can be a multi-gate transistor.

[0028] In a quantum device according to one embodiment of the present invention, the gate may be disposed on any of the upper, lateral, and lower sides of the channel structure.

[0029] In a quantum device according to one embodiment of the present invention, the transistor structure may have two or more gates as gates.

[0030] In a quantum device according to one embodiment of the present invention, the transistor structure may have a substrate, and the quantum bit control current line may be configured closer to the substrate than the quantum dot structure.

[0031] In a quantum device according to one embodiment of the present invention, the quantum device may include at least a first quantum dot structure and a second quantum dot structure as the quantum dot structure. The first channel structure is included among the plurality of channel structures. The first channel structure is disposed between the first quantum dot structure and the second quantum dot structure. By utilizing the magnetic field generated by causing a quantum bit control current to flow through the quantum bit control current line, the quantum state of the charge spin in the first quantum dot structure is changed, and the interaction between the charge spin in the first quantum dot structure and the charge spin in the second quantum dot structure becomes an indirect interaction via the charge in the first channel structure.

[0032] In one embodiment of the present invention, the quantum device has an operating mode in which the current of the qubit control current line is set to a non-zero value, the voltage of the gate is set to a value greater than zero, the voltage of the source is set to a non-zero value, the voltage of the drain is set to a non-zero value, and at least the magnetic field generated by the qubit control current line is set to a non-zero value, and RKKY (Ruderman-Kittel-Kasuya-Yosida) interaction is utilized.

[0033] In a quantum device according to one embodiment of the present invention, the quantum device has a measurement mode in which the main current of the qubit control current line is set to zero, the gate voltage is set to a value greater than zero, the source voltage is set to a value lower than the drain voltage, and the state of charge spin within the quantum dot structure is inferred based on the source / drain current. Furthermore, when a high frequency is continuously applied, the main current of the qubit control current line can be set to a non-zero value.

[0034] In a quantum device according to one embodiment of the present invention, the state of the charge spin within the quantum dot structure is inferred based on the measured value of the current flowing through the source / drain of the first channel structure, which is sandwiched between the first channel structure and the second channel structure included in the plurality of channel structures, by utilizing the fact that the charge spin within the quantum dot structure has different energy levels depending on the state of the charge within the quantum dot structure.

[0035] In a quantum device according to one embodiment of the present invention, the quantum dot structure is naturally or artificially made, and the energy level of the quantum dot structure is a trap energy level.

[0036] (The effect of the invention)

[0037] According to the present invention, a quantum device can be provided that can be manufactured using existing transistor structures and existing factory facilities as much as possible, and can be easily measured. Attached Figure Description

[0038] Figure 1 A diagram illustrating an example of the basic structure of the quantum device according to the first embodiment.

[0039] Figure 2 This is a cross-sectional view used to illustrate the differences between the existing FINFET structure and the quantum device 1 of the first embodiment.

[0040] Figure 3 A diagram illustrating an example of a portion of a quantum device according to a second embodiment.

[0041] Figure 4 This is a diagram illustrating an example of a quantum device according to a third embodiment.

[0042] Figure 5 This is a diagram illustrating an example of a storage mode for qubits.

[0043] Figure 6 This is a diagram illustrating an example of RKKY interactions and decoherence relations.

[0044] Figure 7 A diagram illustrating the principle of the spin filter effect.

[0045] Figure 8 A graph showing simulation results, etc.

[0046] Figure 9 This diagram illustrates an example of a measurement method in the case of multiple conductive channels.

[0047] Figure 10 A diagram illustrating an example of controlling six qubits (N=5).

[0048] Figure 11 A diagram illustrating a first example of a quantum device according to the eighth embodiment.

[0049] Figure 12 A diagram illustrating a second example of the quantum device according to the eighth embodiment.

[0050] Figure 13 A diagram illustrating a first example of a quantum device according to the ninth embodiment.

[0051] Figure 14 A diagram illustrating a second example of a quantum device according to the ninth embodiment.

[0052] Figure 15 A diagram illustrating a third example of the quantum device according to the ninth embodiment.

[0053] Figure 16 A diagram illustrating an example of a quantum device according to the tenth embodiment.

[0054] Figure 17 A diagram illustrating a first example of a quantum device according to the eleventh embodiment.

[0055] Figure 18 A diagram illustrating a third example of a quantum device according to the eleventh embodiment, etc.

[0056] Figure 19 A diagram illustrating an example of a quantum device according to the twelfth embodiment.

[0057] Figure 20 A diagram illustrating an application example of the quantum device according to the thirteenth embodiment.

[0058] Figure 21 A diagram illustrating an application example of the quantum device according to the fourteenth embodiment.

[0059] Figure 22 This is a schematic diagram of a simple spin qubit.

[0060] Figure 23 A diagram illustrating an example of a nanowire transistor to which the quantum device of the present invention can be applied.

[0061] Figure 24 A diagram illustrating an example of a quantum device according to the fifteenth embodiment.

[0062] Figure 25 A diagram illustrating an example of the equivalent circuit of the sixteenth embodiment.

[0063] Explanation of reference numerals in the attached figures

[0064] 1…Quantum Device

[0065] 11… Transistor Structure Section

[0066] 1S, 1S-1, 1S-2, 1S-3… source poles

[0067] 1SC, 1SC-1, 1SC-2, 1SC-3… Source Electrode

[0068] 1D, 1D-1, 1D-2, 1D-3… Drain

[0069] IDC…Drain electrode

[0070] 1G…gate

[0071] 1C, 1C-0, 1C-1, 1C-2, 1C-3, 1C-4, 1C-5, 1C-6… Channel structure section 1T… Substrate section

[0072] 12, 12-1, 12-2, 12-3, 12-4, 12-5, 12-6… Quantum dot structure

[0073] 13, 13-1, 13-2, 13-3, 13-4, 13-5, 13-6… Quantum bit control current lines. Detailed Implementation

[0074] Before describing embodiments of the quantum device of the present invention, prior art concerning the structure, measurement, etc., of quantum devices will be explained.

[0075] (Prior art related to the structure)

[0076] Research and development of qubits using electron spin or hole spin has progressed slowly. This is because the interaction between spins is short-range, requiring the spins to be brought close together. On the other hand, the structures that generate the magnetic field (the magnetic field required for spin state changes) cannot be extremely close together. Therefore, while experiments with up to two qubits can be conducted, progress has not been made with more than three qubits. For example, in the structure of Non-Patent Document 1, it is difficult to bring more than three qubits close together. This hinders the integration of multiple qubits.

[0077] (Existing techniques related to measurement)

[0078] Furthermore, measuring the spin state in spin-based quantum devices presents challenges. Measuring the spin state requires electronic circuitry, but spin is a magnetic property, and conventional electronic circuits lack mechanisms for directly measuring quantities related to magnetization. Therefore, it is necessary to convert the magnetic property into a charge state.

[0079] Specifically, there are methods known as spin blocking. This method utilizes the technique that when a quantum dot is added and the spin direction of the electrons within it is fixed, the electrons are blocked or allowed to flow by the spin direction of the electrons entering from the quantum bit, either upwards or downwards. This is based on the Pauli exclusion principle, which states that electrons with the same spin direction cannot occupy two identical energy levels.

[0080] In existing methods, additional electrodes and current lines are required to measure this spin blocking. For example, in Non-Patent Document 1, measuring two qubits requires more than five electrodes, which remains undesirable for integrated qubits.

[0081] (Manufacturing costs)

[0082] Furthermore, the novel device structure presents significant challenges in manufacturing. Non-patent documents such as Non-patent Document 1 and Non-patent Document 6 require novel microstructures. Currently, the gate length of silicon transistors used in smartphones is less than 16nm, and manufacturing a chip costs over one trillion yen. Even 40nm would require approximately four hundred billion yen. As a novel microstructure, qubits are expected to require enormous development costs, thus posing a significant obstacle to industrialization. Therefore, it is desirable to utilize existing structures as much as possible.

[0083] (Quantum annealing technology)

[0084] Quantum annealing technology is related to artificial intelligence, and research on it as a means of solving optimization problems is underway. First, Nishimura et al. developed the physical theory, and the development / sales of D-wave in Canada accelerated the research (non-patent literature 3). Quantum annealing is a quantum extension of the traditional annealing computation method, and it is expected to shorten the computation time in so-called NP-hard problems such as the traveling salesman problem. First, the problem is mapped to the Ising Hamiltonian. At this time, it is expressed as the traditional Ising Hamiltonian as shown in the following equation (1).

[0085] [Mathematical Expression 1]

[0086]

[0087] In equation (1), the first term is the spin-spin interaction term, and the second term is the magnetic field term (Zeeman term). The variable s i It is a binary value (s) i =±1).

[0088] In the model of the quantum annealing machine, as shown in equation (2), a tunneling term is added.

[0089] [Mathematical Expression 2]

[0090]

[0091] In the case of quantum annealing machines, variables are not binary values, but rather Pauli matrices σ. x , σ z The final tunneling term is adjusted to Δ(t→∞)→0 according to the schedule, and the calculation result is obtained. The Hamiltonian equation (2) is in a simple form and has been discussed in various physical systems, but in order to be used as a quantum annealing machine, it is necessary to be able to freely manipulate the Hamiltonian. That is, it needs to be formed into a J that can freely change the interaction. ij and magnetic field term h j The composition of.

[0092] Furthermore, the interaction part of the Hamiltonian is not the Ising model shown in Equation (2), but rather the Heisenberg model shown in Equation (3). However, as shown in Non-Patent Document 7, it can be mapped to the ordinary Ising Hamiltonian. As shown in Non-Patent Document 7, it can also be used for quantum chemical calculations.

[0093] [Mathematical Expression 3]

[0094]

[0095] The embodiments of the quantum device of the present invention will be described below.

[0096] [First Implementation Method]

[0097] Figure 1 A diagram illustrating an example of the basic structure of the quantum device 1 according to the first embodiment.

[0098] exist Figure 1 In the example shown, the quantum device 1 of the first embodiment uses, for example, a FINFET (Fin Field-Effect Transistor) structure as its basic structure. The quantum device 1 has a transistor structure 11 (e.g., a FINFET structure configured in the same way as a conventional FINFET structure), a quantum dot structure 12 in which charge can be locally present, and a quantum bit control current line 13.

[0099] The transistor structure 11 has a substrate 1T and a structure extending from the substrate 1T towards... Figure 1 The FIN-shaped portion extends upwards. Additionally, the transistor structure 11 has a source 1S, a drain 1D, and a gate 1G. The transistor structure 11 has... Figure 1 The current flows through the channel structure 1C between the source and drain in the direction indicated by the middle arrow. The length of the gate 1G is less than 30 nm.

[0100] exist Figure 1 In the example shown, the channel structure 1C includes six channel structure sections 1C-0, 1C-1, 1C-2, 1C-3, 1C-4, and 1C-5.

[0101] In other examples, the channel structure 1C may also contain any number (but more than six) of channel structure sections.

[0102] exist Figure 1 In the example shown, electrons or holes can be stored within the quantum dot structure 12. The material of the quantum dot structure 12 can be a material capable of storing charge, such as polycrystalline silicon. Furthermore, the quantum dot structure 12 can be artificially made or naturally formed, such as with defects, and its energy levels can be trap levels.

[0103] exist Figure 1 In the example shown, the quantum dot structure 12 includes five quantum dot structures 12-1, 12-2, 12-3, 12-4, and 12-5.

[0104] In other examples, the quantum dot structure 12 may contain any number of quantum dot structures other than five.

[0105] exist Figure 1In the example shown, quantum dot structure 12-1 is held by channel structures 1C-0 and 1C-1, quantum dot structure 12-2 is held by channel structures 1C-1 and 1C-2, quantum dot structure 12-3 is held by channel structures 1C-2 and 1C-3, quantum dot structure 12-4 is held by channel structures 1C-3 and 1C-4, and quantum dot structure 12-5 is held by channel structures 1C-4 and 1C-5.

[0106] The quantum bit control current line 13, formed of materials such as Cu, can alter the charge state within the quantum dot structure 12. Specifically, a quantum bit control current flows through the quantum bit control current line 13, generating a magnetic field that controls electrons or holes.

[0107] exist Figure 1 In the example shown, the qubit control current line 13 includes five qubit control current lines 13-1, 13-2, 13-3, 13-4, and 13-5 corresponding to the five quantum dot structures 12-1, 12-2, 12-3, 12-4, and 12-5. Qubit control current line 13-1 primarily changes the charge state within quantum dot structure 12-1; qubit control current line 13-2 primarily changes the charge state within quantum dot structure 12-2; qubit control current line 13-3 primarily changes the charge state within quantum dot structure 12-3; qubit control current line 13-4 primarily changes the charge state within quantum dot structure 12-4; and qubit control current line 13-5 primarily changes the charge state within quantum dot structure 12-5.

[0108] In other examples, multiple quantum dot structures 12 can be sandwiched between two channel structures 1C, and the charge state within the multiple quantum dot structures 12 sandwiched between the two channel structures 1C can be changed by a single quantum bit controlling a current line 13 (see reference). Figure 19 ).

[0109] exist Figure 1 In the example shown, Figure 1 The part that does not record the constituent elements (i.e., Figure 1 The spatial portion of the structure is composed of insulators such as SiO2.

[0110] exist Figure 1 In the example shown, the gate 1G is disposed on the upper part of the channel structure portion 1C, but in other examples, the gate 1G may also be disposed on either the lateral or lower side of the channel structure portion 1C.

[0111] exist Figure 1In the example shown, a qubit with added charge spin is configured as a qubit, or it is configured with a channel structure. The spins of countable electrons or holes accumulated within the quantum dot are used as the basic unit of the quantum device 1, namely the qubit. A gate electrode (gate 1G) is provided in the conduction channel between the source and drain via an insulating film. On the upper part of this gate electrode structure, a line (qubit control current line 13) for controlling each qubit is provided via an insulating film. Furthermore, charge refers to electrons or holes. In the case of holes, the polarity of the applied electrode is opposite to that of electrons, etc., but the explanation is the same; therefore, it will be mainly described as charge below.

[0112] What constitutes a qubit is the spin of an electric charge. The direction of the charge spin corresponds to a quantum state (|↑> and |↓>). An external magnetic field changes the quantum state of the charge spin. Two types of external magnetic fields are used: a static magnetic field applied across the entire quantum device 1, and a dynamic magnetic field generated by flowing current through the qubit control current line 13. When a static external magnetic field is applied, the spin causes Zeeman splitting depending on its direction. For example, when an upward magnetic field is applied, the spin tends to align upwards along the field. Therefore, the energy of upward spins decreases, and the energy of downward spins increases. This allows the distinction between spin states. Experimentally, magnetic fields ranging from approximately 1 T (Tesla) to several T are used. The magnitude of the dynamic magnetic field can be estimated using Ampere's law.

[0113] exist Figure 1 In the example shown, quantum dot structures 12 (quantum dot or trap levels) are embedded between the channel structures 1C of the FINFET structure (transistor structure 11) (between channel structures 1C-0, 1C-1, between channel structures 1C-1, 1C-2, between channel structures 1C-2, 1C-3, between channel structures 1C-3, 1C-4, and between channel structures 1C-4, 1C-5).

[0114] As Figure 1 The method for fabricating the quantum device 1 shown involves, when the quantum dot structure portion 12 is a quantum dot, forming an existing FIN structure (FIN-shaped portion) on a substrate (substrate portion 1T) such as silicon, and then forming the quantum dot structure portion 12 by embedding and etching in polysilicon or the like. The formation of the quantum dot structure portion utilizes, for example, a side-wall patterning technique.

[0115] When trap energy levels are used as quantum dot structure 12, after the existing FIN structure (FIN shape portion) is generated on a substrate such as silicon (substrate portion 1T), before the gate electrode material for gate 1G is injected between the FIN structure (FIN shape portion), an interlayer insulating film layer is generated, and traps that can be generated naturally are used as quantum dot structure 12.

[0116] Alternatively, P (phosphorus), B (boron), etc., can be directly implanted between the FIN structure (FIN-shaped portion) to generate the quantum dot structure 12. After generating the gate insulating film, a gate electrode (gate 1G) common to the FIN structure (FIN-shaped portion) is generated. After generating the interlayer insulating film layer, the quantum bit control current line 13 (current line structure) for controlling the dynamic magnetic field is formed. The subsequent process is the same as the conventional FINFET structure fabrication process.

[0117] Figure 2 This is a cross-sectional view used to illustrate the differences between the existing FINFET structure and the quantum device 1 of the first embodiment. Figure 2 (A) is a cross-sectional view of an existing FINFET structure. Here, although the number of FINs (FIN-shaped portions) is set to 6, the number of FINs can be more or less. Figure 2 (B) shows a cross-sectional view of the quantum device 1 according to the first embodiment. Figure 2 The difference in (A) (the existing example) lies in the use of a quantum dot structure 12 (which may also be a trap level) that maintains the charge spin of a quantum bit between the FIN (FIN-shaped portion) (channel structure 1C) and a quantum bit control current line 13 that generates a magnetic field on the upper part of the common electrode (gate 1G). Since the quantum bit control current line 13 changes the charge spin state within the quantum dot structure 12, it is preferable that its number is equal to that of the quantum dot structure 12, but it may also be slightly less. Hereinafter, the term "quantum dot structure 12" will be used, including the trap level.

[0118] exist Figure 2 In the example shown in (B), since the gate 1G is located on the upper and lateral sides (left and right sides) of the channel structure 1C, the transistor structure 11 is a tri-gate (multi-gate) transistor.

[0119] Although this invention primarily illustrates cases where the FIN structure has a certain height, it is also applicable to cases such as… Figure 23 The nanowire transistor shown.

[0120] Figure 23 A diagram illustrating an example of a nanowire transistor to which the quantum device 1 of the present invention can be applied.

[0121] exist Figure 23 In the example shown, quantum device 1 includes a transistor structure 11 and one or more quantum dot structures 12 in which charge can be locally present. Figure 23 (not shown in the image) and quantum bit control current lines ( Figure 23(Not shown in the figure). The transistor structure 11 has a source 1S, a drain 1D, and a gate 1G. The quantum bit control current line can change the state of the charge within the quantum dot structure.

[0122] In detail, Figure 23 In the example shown, quantum device 1 includes a transistor structure 11 and a quantum dot structure 11. Figure 23 (Not shown in the figure). The transistor structure 11 has a source 1S, a drain 1D, and a gate 1G, and has multiple channel structures 1C-1, 1C-2 between the source and drain. The quantum dot structure is sandwiched between the channel structures 1C-1, 1C-2. Electrons or holes can be stored in the quantum dot structure. The quantum device 1 also includes a quantum bit control current line ( Figure 23 (Not shown in the figure), a quantum bit control current that generates a magnetic field to control electrons or holes flows through the quantum bit control current line.

[0123] exist Figure 23 In the example shown, since the gate 1G can surround all the surfaces of the nanowire, the transistor structure 11 is a full-circuit transistor.

[0124] [Second Implementation]

[0125] Hereinafter, a second embodiment of the quantum device of the present invention will be described.

[0126] Except for the aspects described later, the quantum device 1 of the second embodiment is constructed in the same manner as the quantum device 1 of the first embodiment described above. Therefore, according to the quantum device 1 of the second embodiment, except for the aspects described later, the same effects as the quantum device 1 of the first embodiment described above can be achieved.

[0127] Figure 3 A diagram illustrating an example of a portion of the quantum device 1 according to the second embodiment.

[0128] exist Figure 3 In the example shown, the quantum device 1 includes at least quantum dot structures 12-1 and 12-2 as quantum dot structure 12. In addition, the channel structure 1C includes a channel structure 1C-1 disposed between the quantum dot structures 12-1 and 12-2.

[0129] In a FINFET structure, when a voltage is applied to the gate 1G, due to the electric field effect of the gate 1G, charge accumulates on the channel structure 1C-1 (the charge conduction path) between the source and drain, forming an inversion layer. Due to the interaction between the qubits (the interaction between quantum dot structures 12-1 and 12-2), charge accumulates in the portion of the channel structure 1C-1 near the gate 1G, forming an inversion layer.

[0130] The interaction between qubits (the interaction between quantum dot structures 12-1 and 12-2) utilizes the charge accumulated near the surface within the channel. The insulator between quantum dot structure 12-1 and channel structure 1C-1, and between quantum dot structure 12-2 and channel structure 1C-1, is sufficiently thin. For example, in the case of a silicon oxide film as the insulator, the thickness is less than 2 nm. In this case, quantum mechanical tunneling occurs between quantum dot structure 12-1 and channel structure 1C-1, and between quantum dot structure 12-2 and channel structure 1C-1. Through tunneling, the charge spins within the two quantum dot structures 12-1 and 12-2 located on either side of channel structure 1C-1 interact. This is called the RKKY (Ruderman Kittel Kasuya Yosida) interaction. RKKY The relationship between the spin operator S1 of the quantum dot structure 12-1 and the spin operator S2 of the quantum dot structure 12-2 is shown in equation (4).

[0131] [Mathematical Expression 4]

[0132] H RKKY =J RKKY S1·S2, (4)

[0133] Tunneling through the thin film occurs between the spin in quantum dot structure 12-1 and the charge in the conduction channel (channel structure 1C-1). Similarly, tunneling also occurs between the spin in quantum dot structure 12-2 and the charge in the conduction channel (channel structure 1C-1). Because the charge in quantum dot structure 12-1 interacts with the charge in the conduction channel (channel structure 1C-1) through this tunneling, and because the conduction charge can move within the conduction channel (channel structure 1C-1), it struggles to reach the opposite side of channel structure 1C-1. Here, it also interacts with the spin in another quantum dot structure 12-2 through tunneling.

[0134] Thus, the interaction of charges in quantum dot structures 12-1 and 12-2, i.e., qubits, through the movement of charges within the conduction channel (channel structure 1C-1), becomes a specific explanation of the RKKY interaction. Here, the strength of the interaction is shown in Non-Patent Document 8.

[0135] Table 2 shows its parameter dependencies.

[0136] [Table 2]

[0137]

[0138] J in Table 2d RKKY The strength of the RKKY interaction in equation (4) above, d = 1, indicates the conduction channel (channel structure) as shown above. Figure 23 The one-dimensional electronic state of nanowires, etc., is shown, with d=2, as in a typical FINFET structure. Figure 1 The case of a two-dimensional electronic state (as shown in the FINFET structure shown in the example). As shown in Non-Patent Document 8, it is demonstrated that the coherence of the qubit is sufficiently maintained.

[0139] Figure 6 This is a diagram illustrating an example of the relationship between RKKY interactions and decoherence. In detail, Figure 6 This is a graph depicting the strength of the two-dimensional RKKY interaction divided by the coherence strength as a function of the gate width W and the square root of the electron density n. Since the vertical axis is logarithmic, therefore, according to... Figure 6 This demonstrates, for example, using W = 10 nm and 10 electrons. 18 pcs / cm 3 It can perform more than 1000 calculations. In addition, RKKY interaction sometimes competes with Kondo effect, but if the design value is selected, RKKY interaction can be utilized.

[0140] That is to say, in the quantum device 1 of the second embodiment, such as Figure 3 As shown, by utilizing the quantum bit control current flowing through quantum bit control current line 13 (refer to...) Figure 1 and Figure 2 The magnetic field generated by (B) can change the quantum state of the charge spin within the quantum dot structure 12-1. Furthermore, the interaction between the charge spin within the quantum dot structure 12-1 and the charge spin within the quantum dot structure 12-2 is considered as an indirect interaction via the charge within the channel structure 1C-1.

[0141] [Third Implementation Method]

[0142] The third embodiment of the quantum device of the present invention will be described below.

[0143] Except for the aspects described later, the quantum device 1 of the third embodiment is constructed in the same manner as the quantum device 1 of the first embodiment described above. Therefore, according to the quantum device 1 of the third embodiment, except for the aspects described later, the same effects as the quantum device 1 of the first embodiment described above can be achieved.

[0144] Figure 4 This is a diagram illustrating an example of the quantum device 1 according to the third embodiment. In detail, Figure 4(A) shows the FIN structure (channel structure 1C-1) between the two quantum dot structures 12-1 and 12-2. Figure 4 (B) and Figure 4 (C) shows the use of energy bands. Figure 4 (A) shows an example of the operation of quantum device 1. In detail, Figure 4 (B) shows the operation mode (RKKY interaction is ON). Figure 4 (C) shows the measurement mode.

[0145] Table 1 shows the comparison with Figure 4 (B) Operating Mode Figure 4 An example of the operation (mode) corresponding to the measurement mode of (C).

[0146] [Table 1]

[0147] Table 1 Operation in QD-FINFET

[0148]

[0149] In the example shown in Table 1, under the manipulation mode of the qubits (quantum dot structures 12-1, 12-2), the qubit control current lines 13-1, 13-2 (refer to...) Figure 1 The current I ctrl Set to a non-zero value, and set gate 1G (reference) Figure 1 The voltage V G Set to a value greater than zero, and set the source 1S (reference) Figure 1 The voltage V S Set to a non-zero value, and set the drain 1D (reference) Figure 1 The voltage V D The transverse magnetic field generated by the qubit control current lines 13-1, 13-2, etc., is set to a non-zero value. Additionally, the magnetic field B generated by the magnetic field generating unit (not shown) other than qubit control current line 13 is also set to a non-zero value. Z Set to a non-zero value.

[0150] In the measurement mode of the qubits (quantum dot structure parts 12-1, 12-2), the current I of the qubit control current lines 13-1, 13-2 is... ctrl Set to zero, and set the voltage V of gate 1G to zero. G Set to a value greater than zero, and set the source voltage V for 1 second. SSet as the voltage V of drain 1D D A low value. As a result, current flows between the source and drain. Furthermore, the state of charge spin within the quantum dot structure 12 is inferred from the current between the source and drain. Additionally, due to the symmetry of the circuit, the voltage V... S It can also be compared to voltage V D High. Additionally, the magnetic field B generated by the magnetic field generating unit (not shown) other than the quantum bit control current line 13 will be... Z Set to a non-zero value.

[0151] In the memory mode of the qubits (quantum dot structure parts 12-1 and 12-2), the current I of the qubit control current lines 13-1 and 13-2 is... ctrl Set to zero, and set the voltage V of gate 1G to zero. G Set to a value greater than zero, and set the source voltage V for 1 second. S Set to a non-zero value, and set the voltage V at drain 1D to... D Set to a non-zero value. Additionally, the magnetic field B generated by the magnetic field generating unit (not shown) other than the quantum bit control current line 13 will be... Z Set to a non-zero value.

[0152] like Figure 4 As shown, under a static magnetic field, the electron spin has different energy levels in the up and down directions. Figure 4 In the example shown, as an illustration, it is assumed that the gate length is less than 30 nm and the size of the quantum dots (quantum dot structure parts 12-1, 12-2) is also less than 20 nm. In such miniaturized quantum dots, the Coulomb force between charges cannot be ignored if more electrons are to enter the quantum dots. Figure 4 (B) and Figure 4 In (C), "U" represents the magnitude of the Coulomb energy. In a quantum dot, the second electron has an energy level that is U higher than the energy level of the qubit.

[0153] exist Figure 4 In the examples shown, the operating modes of quantum device 1, as shown in Table 1, include the manipulation mode of the qubits (quantum dot structures 12-1, 12-2), the measurement mode of the quantum states of the qubits, and the memory mode of not performing any operation on the qubits. The differences in modes are distinguished by the position of the energy levels within the quantum dot used.

[0154] First, with the state of the qubit controlled, the Fermi surface of the channel is located near the energy level of the lower qubit. This allows the use of the aforementioned RKKY interaction between electrons passing through the inversion layer of the channel. Figure 4 (Operation mode shown in (B)).

[0155] exist Figure 4 In the measurement mode shown in (C), a gate voltage is further applied, and the amount of charge in the channel is increased, thereby raising the position of the Fermi level and utilizing the potential at the top of the quantum dot. Since the two upper energy levels within the quantum dot behave differently depending on their spin states, the spin state of the qubit can be measured.

[0156] exist Figure 4 In the middle, △ Z The difference in Zeeman energy caused by the magnetic field is shown. Figure 4 (B) and Figure 4 The portion between quantum dot structures 12-1 and 12-2 in (C) shows the FIN structure (channel structure 1C-1). Figure 4 In (B), QD1 (quantum dot structure part 12-1) is an upward spin state, and QD2 (quantum dot structure part 12-2) is an upward spin state.

[0157] exist Figure 4 In the example shown in (B), the current of the control electrode (qubit control current line 13-1) used for QD1 (quantum dot structure part 12-1) and the current of the control electrode (qubit control current line 13-2) used for QD2 (quantum dot structure part 12-2) are in opposite directions.

[0158] exist Figure 4 In the example shown in (B), V is performed not only in the FIN portion between QD1 and QD2. S =V D The control, and in the FIN part on the left side of QD1 ( Figure 4 (B) (not shown in the diagram) V S =V D The control is located in the FIN section to the right of QD2. Figure 4 (B) (not shown in the diagram) V S =V D Control.

[0159] exist Figure 4 In the example shown in (C), V is performed in the FIN portion between QD1 and QD2. S <V D Control.

[0160] exist Figure 4In the example shown, the Fermi level differs in both the measurement and interaction modes. Furthermore, during measurement, a quantum level different from the energy level possessed by the qubit is utilized.

[0161] Figure 5 This is a diagram illustrating an example of a storage mode for qubits.

[0162] When the gate voltage V is applied G The channel (channel structure 1C (refer to) Figure 1 A qubit is formed on both sides of the qubit, but the qubits on both sides always interact with each other. Figure 5 The image shows an example of a situation where one wants to keep a qubit separate.

[0163] exist Figure 5 In the example shown, the qubits held are QD1 and QD4. To hold the qubits independently, quantum dots such as QD2 and QD3 need to be placed between them.

[0164] The RKKY interaction between qubits through the channel simultaneously reduces coherence. Based on formula 8 of Non-Patent Document, the relationship between the magnitude of the RKKY interaction and the magnitude of the coherence ratio was calculated, and it is as described above. Figure 6 As mentioned above, in Figure 6 In this context, W represents the gate width, and n is the number of electrons in the inversion layer. This ratio indicates the number of calculations that can be performed while maintaining coherence.

[0165] The orientation of a qubit can be changed using a magnetic field control line. For example, if the distance from the qubit to the magnetic field control line is set to 20 nm, to generate a magnetic field of 1 mT (Tesla) at the location of the qubit, it is only necessary to make the current I shown in equation (6) flow. In equation (6), μB = 1.256563 * 10⁻⁴ 6 mkgs- 2 A- 2 ρ is the permeability of silicon.

[0166] [Mathematical Expression 6]

[0167] I = 2πrB / μ B ~10μA (6)

[0168] [Fourth Implementation Method]

[0169] The fourth embodiment of the quantum device of the present invention will be described below.

[0170] Except for the aspects described later, the quantum device 1 of the fourth embodiment is configured in the same way as the quantum device 1 of the first embodiment described above. Therefore, according to the quantum device 1 of the fourth embodiment, except for the aspects described later, the same effects as the quantum device 1 of the first embodiment described above can be achieved.

[0171] (Operation of the quantum annealing machine)

[0172] The operation of the quantum annealing machine is as follows. First, in the case of the quantum annealing machine, it is used in a strong magnetic field (e.g., 10T (Tesla)) instead of as a quantum computer. At this time, the RKKY interaction is as shown in equation (3), with components in the three directions of x, y, and z. By performing a transformation as shown in non-patent document 7, mapping to the Ising Hamiltonian as in equation (3), the combinatorial optimization problem can be solved. Here, J ij The value needs to be changed depending on the specific problem. J ij The magnitude of the wavenumber k can be controlled by the Fermi energy of each channel, as shown in Table 2. Since each channel can be controlled independently, even if the gate electrode is common, the position of the Fermi energy of the electrons can be changed by lowering the source / drain potential. In other words, as shown in Table 2, the Fermi wavenumber k changes due to the change in the position of the Fermi energy. F Including in the Bessel function, its relationship with the Fermi energy E, as shown in equation (5), is... F Related.

[0173] [Mathematical Expression 5]

[0174]

[0175] The transverse magnetic field in equation (2) is controlled by the magnetic field generated by the current flowing through the control current line (qubit control current line 13). That is, quantum tunneling occurs during the current flow, and when the current is zero, it becomes the Hamiltonian of equation (3), thus the answer can be obtained.

[0176] [Fifth Implementation Method]

[0177] The fifth embodiment of the quantum device of the present invention will be described below.

[0178] Except for the aspects described later, the quantum device 1 of the fifth embodiment is configured in the same way as the quantum device 1 of the first embodiment described above. Therefore, according to the quantum device 1 of the fifth embodiment, except for the aspects described later, the same effects as the quantum device 1 of the first embodiment described above can be achieved.

[0179] (Measurement Process 1)

[0180] Finally, it is necessary to read whether the electron spin is up or down. In this invention, this is read using the typical channel current of a FINFET structure. In this invention, the quantum dot (quantum dot structure 12) is connected to the channel (channel structure 1C) via quantum tunneling. The charge entering from the source 1S of the channel (channel structure 1C) is influenced by the energy levels within the quantum dot (quantum dot structure 12) due to electrical interaction with them. Since the energy levels within the quantum dot (quantum dot structure 12) differ according to the spin direction due to the magnetic field, the spin direction within the quantum dot (quantum dot structure 12) can be measured using the current (source / drain current) in the channel (channel structure 1C). This is referred to here as the spin filtering effect.

[0181] Figure 7 A diagram illustrating the principle of spin filtering effect.

[0182] exist Figure 7 (A) Figure 7 (B) Figure 7 (C) and Figure 7 In (D), the quantum dot QD (quantum dot structure 12) is shown on the left, and the channel (channel structure 1C) is shown on the right. In this case, an energy level that is higher than the spin level of the qubit by a corresponding amount of Coulomb energy is used. This mitigates the direct change in the qubit state caused by measurement. To change the current flowing through the channel by altering the spin state of the qubit, such as... Figure 7 As shown, the Fermi level E of the channel F Preferably, the charge energy levels are further separated by the magnetic field within the quantum dot (quantum dot structure 12).

[0183] Figure 7 (A) and (B) show the state of the spin qubit when it is in the up state |↑>. The charge within the channel (channel structure 1C) has both up and down spin. Figure 7 (A) shows the case where the channel charge is upward. In this case, due to the energy level E S↓ (Its charge is higher than that within the quantum dot (quantum dot structure 12) at the Fermi level E in the channel. F Therefore, the downward-spinning charge in the channel easily enters the quantum dot. On the other hand, as... Figure 7 As shown in (B), in order for an upward spin to enter the quantum dot, it can only be located at an energy level above the quantum dot. However, since this energy level is higher than the Fermi level of the channel, it is difficult for the charge to enter the quantum dot.

[0184] Figure 7 (B) and Figure 7(C) shows the case where the qubits within the quantum dot are in the down state |↓>. In this case, since these energy levels are higher than the Fermi level of the channel, as shown in these figures, it is difficult for charges to enter the channel regardless of whether the spin is up or down. In summary, according to Figure 7 (A) to Figure 7 (D) shows that the current (current between the source and drain) changes depending on whether the state of the qubit is upward (|↑>) or downward (|↓>).

[0185] Figure 8 A graph showing the conductivity under this condition, derived from the Kubo formula based on the theory of linear response, and simulated. In detail, Figure 8 (A) is a graph showing the simulation results. As a model, the general tunneling Hamiltonian is used, as expressed in equation (7) (where y represents the channel direction). In equation (7), E2 and E4 represent the energy levels of the quantum dot, E... ki (i = 1, 3, 5) represents three channels.

[0186] [Mathematical Expression 7]

[0187]

[0188] The conductivity formula derived from the Kubo formula is shown in equation (8).

[0189] [Mathematical Expression 8]

[0190]

[0191] In Equation 8, k1 = 1 and k2 = πnW 2 The diagrams show the one-dimensional and two-dimensional conduction of the channel (n is the number of electrons). e1, e3, and e5 are the effective electron energies within the channel, and s... ij For intrinsic energy, Γ i This represents the tunneling strength of the quantum dot and the channel. (From...) Figure 8 (A) It can be seen that as the difference between E2 and E4 increases, the conductance σ yy This is because, when using a FINFET in a measurement device, the two quantum dots (quantum dot structure sections 12-1 and 12-2) happen to become floating gates, and the differential amplification circuit of these two floating gates has a similar shape. The above describes the case with three conduction channels, but the same principle applies even with multiple conduction channels.

[0192] In other words, in the quantum device 1 of the fifth embodiment, the charge spin within the quantum dot structure 12 has different energy levels depending on the state of the charge within the quantum dot structure 12. Based on, for example, the measured value of the current flowing through the source / drain of the channel structure 1C-1, the state of the charge spin within the quantum dot structure 12, which is included by a plurality of channel structures 1C, such as channel structure 1C-1 and channel structure 1C-2, is inferred.

[0193] [Sixth Implementation Method]

[0194] The sixth embodiment of the quantum device of the present invention will be described below.

[0195] Except for the aspects described later, the quantum device 1 of the sixth embodiment is configured in the same manner as the quantum device 1 of the first embodiment described above. Therefore, according to the quantum device 1 of the sixth embodiment, except for the aspects described later, the same effects as the quantum device 1 of the first embodiment described above can be achieved.

[0196] (Measurement Process 2)

[0197] Figure 9 An example of a measurement method in the presence of multiple conductive channels is described. To allow current to flow through the conductive channel (channel structure 1C), a potential difference is simply applied between the source and drain (Table 1). In the presence of multiple conductive channels (channel structures 1C-0, 1C-1, 1C-2, ...), measurements can be taken one by one, and... Figure 8 The measurement shows the energy difference within adjacent quantum dots (quantum dot structure 12), and as shown... Figure 9 As shown, measurement efficiency can be achieved by simultaneously measuring conductive channels spaced one apart (VS < VD). Of course, measurements can also be performed every two channels, or even simultaneously measuring conductive channels with larger intervals. Alternatively, conductive channels can be measured continuously one after another, with intervals of several nanoseconds or similar, before the measurement of one channel is completed.

[0198] When you only want to measure two specific qubits, you can achieve various measurement methods, such as comparing the current when the conduction channel between the qubits is set to ON and the current when the conduction channel of the outermost qubit is set to ON.

[0199] [Seventh Implementation Method]

[0200] The seventh embodiment of the quantum device of the present invention will be described below.

[0201] Except for the aspects described later, the quantum device 1 of the seventh embodiment is configured in the same way as the quantum device 1 of the first embodiment described above. Therefore, according to the quantum device 1 of the seventh embodiment, except for the aspects described later, the same effects as the quantum device 1 of the first embodiment described above can be achieved.

[0202] (crosstalk)

[0203] Because the distance between qubits (e.g., the distance between quantum dot structures 12-1 and 12-2) is relatively close, a problem arises that crosstalk between qubits may occur. To prevent this, as shown in Non-Patent Document 6, there is a method to make the direction of the current flowing through adjacent current lines opposite. In the case of N+1 magnetic field control lines (qubit control current lines 13-1, 13-2, ...), and each with a current Ii (0≤i≤N), a qubit located at a distance r relative to the substrate (substrate section 1T) can generate the magnetic field shown in Equation (9). In Equation (9), p = r / (r 2 +W 2 ) 1 / 2 .

[0204] [Mathematical Expression 9]

[0205]

[0206]

[0207] In the case of only wanting to generate a magnetic field up to the nth qubit, the magnetic field needs to be related to the relationship shown in equation (10), but this condition can be achieved under the current condition shown in equation (11).

[0208] [Mathematical Expression 10]

[0209] h0 = h1 = ... = h n-1 =h n+1 =...h N =0 (10)

[0210] [Mathematical Expression 11]

[0211] I0 = pI1, I N =pI N-1 ,

[0212] I i =p(I i-1 +I i+1 ), (i≠n)

[0213]

[0214] Figure 10A diagram illustrating an example of controlling six qubits (N=5) (quantum dot structure parts 12-1 to 12-6).

[0215] exist Figure 10 In the example shown, in order to generate a magnetic field only in the fourth qubit, it is sufficient to have the current shown in equation (12) flowing through it.

[0216] [Mathematical Expression 12]

[0217]

[0218]

[0219] In this case, the magnitude of the magnetic field received by the fourth qubit is as shown in equation (13). Typically, np is required. 2 ≠1 (n=1,2,…) and L≠r(n-1) 1 / 2 .

[0220] [Mathematical Expression 13]

[0221]

[0222] [Eighth Implementation Method]

[0223] Hereinafter, an eighth embodiment of the quantum device of the present invention will be described.

[0224] Except for the aspects described later, the quantum device 1 of the eighth embodiment is configured in the same way as the quantum device 1 of the first embodiment described above. Therefore, according to the quantum device 1 of the eighth embodiment, except for the aspects described later, the same effects as the quantum device 1 of the first embodiment described above can be achieved.

[0225] Figure 11 A diagram illustrating a first example of the quantum device 1 according to the eighth embodiment.

[0226] exist Figure 11 In the example shown, the qubit control lines (qubit control current lines 13-1, 13-2, 13-3) are added to the typical FINFET structure. Therefore, they need to be set up to avoid conventional source / drain vias and other structures.

[0227] exist Figure 11 In the example shown, the quantum device 1 includes a transistor structure 11 (e.g., a FINFET structure configured similarly to a conventional FINFET structure) and a quantum dot structure where charge can be locally present. Figure 11 (Not shown in the diagram), qubit control current lines 13-1, 13-2, and 13-3.

[0228] The transistor structure 11 has a substrate portion ( Figure 11 (Not shown in the diagram) and a FIN-shaped portion. Additionally, the transistor structure 11 includes source electrodes 1S-1, 1S-2, 1S-3, source electrodes 1SC-1, 1SC-2, 1SC-3, drain electrodes 1D-1, 1D-2, 1D-3, and gate electrode 1G. The transistor structure 11 also includes a channel structure between source electrodes 1S-1 and drain electrodes 1D-1, a channel structure between source electrodes 1S-2 and drain electrodes 1D-2, and a channel structure between source electrodes 1S-3 and drain electrodes 1D-3.

[0229] exist Figure 11 In the example shown, quantum device 1 includes three channel structures. Additionally, quantum device 1 includes quantum dot structures corresponding to qubit control current lines 13-1, 13-2, and 13-3.

[0230] exist Figure 11 In the example shown, the quantum dot structure corresponding to the quantum bit control current line 13-1 is sandwiched between the channel structure between the source 1S-1 and the drain 1D-1 and the channel structure between the source 1S-2 and the drain 1D-2.

[0231] The quantum dot structure corresponding to the quantum bit control current line 13-2 is sandwiched between the channel structure between the source 1S-2 and the drain 1D-2 and the channel structure between the source 1S-3 and the drain 1D-3.

[0232] exist Figure 11 In the example shown, the current flowing between source 1S-1 and drain 1D-1, the current flowing between source 1S-2 and drain 1D-2, and the current flowing between source 1S-3 and drain 1D-3 can be different from each other.

[0233] Figure 12 A diagram illustrating a second example of the quantum device 1 according to the eighth embodiment.

[0234] exist Figure 12 In the example shown, with Figure 11 As shown in the example, the qubit control lines (qubit control current lines 13-1, 13-2, 13-3) are added to the typical FINFET structure. Therefore, they need to be set up to avoid conventional source / drain vias and other structures.

[0235] exist Figure 12 In the example shown, because the quantum bit control current lines 13-1, 13-2, and 13-3 are bent, interference with the source electrodes 1SC-1, 1SC-2, and 1SC-3 can be avoided.

[0236] exist Figure 12 In the example shown, with Figure 11 As shown in the example, the quantum device 1 includes a transistor structure 11 (e.g., a FINFET structure configured similarly to a conventional FINFET structure) and a quantum dot structure where charge can be locally present. Figure 12 (Not shown in the diagram), qubit control current lines 13-1, 13-2, and 13-3.

[0237] Transistor structure 11 and Figure 11 The transistor structure 11 shown is similarly constructed.

[0238] exist Figure 12 In the example shown, the quantum dot structure corresponding to quantum bit control current line 13-1 and the quantum dot structure corresponding to quantum bit control current line 13-2 are both... Figure 11 The example shown is constructed in the same way.

[0239] exist Figure 12 In the example shown, with Figure 11 The example shown is the same, but it is possible to make the current flowing between source 1S-1 and drain 1D-1, the current flowing between source 1S-2 and drain 1D-2, and the current flowing between source 1S-3 and drain 1D-3 different from each other.

[0240] [Ninth Implementation Method]

[0241] The ninth embodiment of the quantum device of the present invention will be described below.

[0242] Except for the aspects described later, the quantum device 1 of the ninth embodiment is configured in the same way as the quantum device 1 of the first embodiment described above. Therefore, according to the quantum device 1 of the ninth embodiment, except for the aspects described later, the same effects as the quantum device 1 of the first embodiment described above can be achieved.

[0243] Figure 13 A diagram illustrating a first example of the quantum device 1 according to the ninth embodiment.

[0244] Figure 13The portions P (space) and Q (space) shown exist between the source / drain and gate electrodes (gate 1G) of the via (hole) connected to the upper electrode. This portion has an electrical parasitic capacitance with the electrodes controlling the magnetic field (qubit control current lines 13-1, 13-2). Therefore, when the potential of the electrodes controlling the magnetic field (qubit control current lines 13-1, 13-2) moves up or down, the potential of the channel (channel structure 1C between the source and drain) also moves up or down accordingly. Since current flows through the channel (channel structure 1C) by lowering the potential of the drain 1D, if the potential of this portion Q is increased, the current cannot flow. Thus, since the channel current can be ON / OFF by adjusting the potential of the electrodes controlling the magnetic field (qubit control current lines 13-1, 13-2), therefore, in Figure 13 In the example shown, with Figure 11 and Figure 12 The example shown is different; the source 1S and drain 1D are common. This allows for a significant reduction in the manufacturing cost of the quantum device 1.

[0245] exist Figure 13 In the example shown, the source electrode 1SC is connected to the source electrode 1S, and the drain electrode 1DC is connected to the drain electrode 1D.

[0246] Figure 14 A diagram illustrating a second example of the quantum device 1 according to the ninth embodiment.

[0247] exist Figure 14 In the example shown, the parasitic capacitance between the qubit control current line 13-1 and the channel structure 1C-0 is utilized, as are the parasitic capacitances between the qubit control current line 13-1 and the channel structure 1C-1, the qubit control current line 13-2 and the channel structure 1C-1, the qubit control current line 13-3 and the channel structure 1C-2, the qubit control current line 13-3 and the channel structure 1C-2, the qubit control current line 13-4 and the channel structure 1C-3, the qubit control current line 13-5 and the channel structure 1C-4, and the qubit control current line 13-5 and the channel structure 1C-5.

[0248] exist Figure 14In the example shown, qubit control current lines 13-1, 13-2, and 13-5 are set to low, and qubit control current lines 13-3 and 13-4 are set to high. Additionally, channel structures 1C-0, 1C-1, 1C-4, and 1C-5 are set to off, and channel structures 1C-2 and 1C-3 are set to on.

[0249] Figure 15 A diagram illustrating a third example of the quantum device 1 according to the ninth embodiment.

[0250] exist Figure 13 In the example shown, the qubit control current lines 13-1, 13-2, and 13-3 are straight lines, but... Figure 15 In the example shown, the qubit control current lines 13-1, 13-2, and 13-3 are bent. Figure 15 In the example shown, the potential of FIN (the channel structure of transistor structure 11) can also be increased and the current cut off by using the magnetic field to generate electrodes (qubit control current lines 13-1, 13-2, 13-3).

[0251] [Tenth Implementation Method]

[0252] Hereinafter, a tenth embodiment of the quantum device of the present invention will be described.

[0253] Except for the aspects described later, the quantum device 1 of the tenth embodiment is configured in the same way as the quantum device 1 of the first embodiment described above. Therefore, according to the quantum device 1 of the tenth embodiment, except for the aspects described later, the same effects as the quantum device 1 of the first embodiment described above can be achieved.

[0254] Figure 16 This diagram illustrates an example of the quantum device 1 according to the tenth embodiment. In detail, Figure 16 For use such Figure 1 A top view (two-dimensional configuration diagram) of an example structure consisting of multiple quantum devices 1.

[0255] For qubits to interact via RKKY interaction, they need to be positioned close to each other. To arrange qubits in a two-dimensional configuration, besides arranging them under a common gate as described above, other methods include... Figure 16 As shown in the example, a common channel is provided between different gates, connecting the vertically aligned qubits. However, if the qubits are connected via a common channel, the method is not limited to this example; more than two qubits can be connected and quantum operations performed. Furthermore, a three-dimensional structure can also be formed.

[0256] exist Figure 16In the example shown, the transistor structure 11 having multiple channel structures 1C that hold the quantum dot structure 12 is a multi-gate transistor.

[0257] In other words, Figure 16 In the example shown, transistor structure 11 has two or more gates as gate 1G.

[0258] [Eleventh Implementation Method]

[0259] Hereinafter, an eleventh embodiment of the quantum device of the present invention will be described.

[0260] Except for the aspects described later, the quantum device 1 of the eleventh embodiment is configured in the same way as the quantum device 1 of the first embodiment described above. Therefore, according to the quantum device 1 of the eleventh embodiment, except for the aspects described later, the same effects as the quantum device 1 of the first embodiment described above can be achieved.

[0261] Figure 17 The diagram illustrates a first example of the quantum device 1 according to the eleventh embodiment. In detail, Figure 17 (A) An example of a quantum device 1 according to the first embodiment is shown (with) Figure 2 (The example shown in (B) is the same). Figure 17 (B) shows a first example of the quantum device 1 according to the eleventh embodiment. Figure 17 (C) shows a second example of the quantum device 1 according to the eleventh embodiment.

[0262] Regarding the electrode structure of quantum device 1 (qubit control current lines 13-1, 13-2, 13-3, 13-4, 13-5), the electrodes are located on the common gate (gate 1G). Figure 17 (A) is the basic system, and can also be like... Figure 17 (B) shows the embedding beneath the quantum dots (quantum dot structure parts 12-1, 12-2, 12-3, 12-4, 12-5). In this case, it is easier to control the quantum bits via the quantum bit control current lines 13-1, 13-2, 13-3, 13-4, 13-5. Furthermore, as shown... Figure 17As shown in (C), the qubit control current lines 13-1, 13-2, 13-3, 13-4, and 13-5 can be embedded on top of the quantum dots (quantum dot structures 12-1, 12-2, 12-3, 12-4, and 12-5). In this case, instead of reducing the influence of the gate electrode (gate 1G) on the quantum dots (quantum dot structures 12-1, 12-2, 12-3, 12-4, and 12-5), the electrons in the inversion layer of the channels (channel structures 1C-1, 1C-2, 1C-3, and 1C-4) and the tunneling strength of the quantum dots (quantum dot structures 12-1, 12-2, 12-3, 12-4, and 12-5) are slightly weakened.

[0263] exist Figure 17 In the example shown in (B), the quantum bit control current lines 13 (13-1, 13-2, 13-3, 13-4, 13-5) are positioned closer to the substrate 1T than the quantum dot structure 12 (12-1, 12-2, 12-3, 12-4, 12-5).

[0264] Figure 18 The figure illustrates a third example of the quantum device 1 according to the eleventh embodiment. In detail, Figure 18 (A) shows a third example of the quantum device 1 according to the eleventh embodiment. Figure 18 (B) shows a fourth example of the quantum device 1 according to the eleventh embodiment. Figure 18 (C) shows a fifth example of the quantum device 1 according to the eleventh embodiment.

[0265] Figure 18 This describes an implementation used in the case of nanowire structures as a developmental form of FINFET structures. A two-level nanowire structure is described here, but the same principle applies even to structures with three or more nanowires.

[0266] In other words, Figure 18 (A) to Figure 18 In the example shown in (C), the channel structure 1C-0 is composed of a two-level nanowire structure, the channel structure 1C-1 is composed of a two-level nanowire structure, the channel structure 1C-2 is composed of a two-level nanowire structure, the channel structure 1C-3 is composed of a two-level nanowire structure, the channel structure 1C-4 is composed of a two-level nanowire structure, and the channel structure 1C-5 is composed of a two-level nanowire structure.

[0267] exist Figure 18 In the example shown in (A), a portion (the upper level) of the two-level nanowire structure is combined with a qubit. Figure 18 In the example shown in (B), the current lines (qubit control current lines 13-1, 13-2, 13-3, 13-4, 13-5) are positioned next to the lower-level nanowire structure. Figure 18 In the example shown in (C), the wiring of the magnetic field control lines (qubit control current lines 13-1, 13-2, 13-3, 13-4, 13-5) is set in the same layer as the upper-level nanowire structure. Figure 18 (C) at the same height), quantum dots (quantum dot structure parts 12-1, 12-2, 12-3, 12-4, 12-5) are mainly embedded between the lower nanowire structures.

[0268] [Twelfth Implementation Method]

[0269] Hereinafter, a twelfth embodiment of the quantum device of the present invention will be described.

[0270] Except for the aspects described later, the quantum device 1 of the twelfth embodiment is configured in the same way as the quantum device 1 of the first embodiment described above. Therefore, according to the quantum device 1 of the twelfth embodiment, except for the aspects described later, the same effects as the quantum device 1 of the first embodiment described above can be achieved.

[0271] Figure 19 A diagram illustrating an example of the quantum device 1 according to the twelfth embodiment.

[0272] exist Figure 1 In the example shown, a quantum dot structure 12-1 is held by channel structures 1C-0 and 1C-1, a quantum dot structure 12-2 is held by channel structures 1C-1 and 1C-2, a quantum dot structure 12-3 is held by channel structures 1C-2 and 1C-3, a quantum dot structure 12-4 is held by channel structures 1C-3 and 1C-4, and a quantum dot structure 12-5 is held by channel structures 1C-4 and 1C-5.

[0273] On the other hand, Figure 19 In the example shown, two quantum dot structures 12-1 are held by channel structures 1C-0 and 1C-1, two quantum dot structures 12-2 are held by channel structures 1C-1 and 1C-2, two quantum dot structures 12-3 are held by channel structures 1C-2 and 1C-3, two quantum dot structures 12-4 are held by channel structures 1C-3 and 1C-4, and two quantum dot structures 12-5 are held by channel structures 1C-4 and 1C-5.

[0274] exist Figure 19In the example shown, two quantum dots (quantum dot structures 12-1, 12-2, 12-3, 12-4, 12-5) of the qubit portion are arranged along the channel (channel structures 1C-0, 1C-1, 1C-2, 1C-3, 1C-4, 1C-5). When two quantum dots are arranged, the energy levels between the two quantum dots acquire bonding and antibonding orbitals, similar to those of a molecule composed of two elements. In this case, since the aforementioned external magnetic field is not required, a more easily controlled quantum computer can be built.

[0275] [Thirteenth Implementation Method]

[0276] The thirteenth embodiment of the quantum device of the present invention will be described below.

[0277] Except for the aspects described later, the quantum device 1 of the thirteenth embodiment is configured in the same way as the quantum device 1 of the first embodiment described above. Therefore, according to the quantum device 1 of the thirteenth embodiment, except for the aspects described later, the same effects as the quantum device 1 of the first embodiment described above can be achieved.

[0278] Figure 20 A diagram illustrating an application example of the quantum device 1 according to the thirteenth embodiment.

[0279] exist Figure 20 In the example shown, the quantum bit chip (qubit portion) of the quantum device 1 as the 13th embodiment is placed in an ultra-low temperature freezer. Figure 20 The example shown illustrates a scenario where the computer ultimately operates at room temperature (typically LSI), while the intermediate low-temperature LSI section (intermediate LSI) serves as a bridge between the qubit section (qubit chip) and the typical computer section (typically LSI). Here, low temperature refers to, for example, around 4K to 77K.

[0280] [Fourteenth Implementation]

[0281] Hereinafter, the fourteenth embodiment of the quantum device of the present invention will be described.

[0282] Except for the aspects described later, the quantum device 1 of the fourteenth embodiment is configured in the same way as the quantum device 1 of the first embodiment described above. Therefore, according to the quantum device 1 of the fourteenth embodiment, except for the aspects described later, the same effects as the quantum device 1 of the first embodiment described above can be achieved.

[0283] Figure 21 A diagram illustrating an application example of the quantum device 1 according to the fourteenth embodiment.

[0284] exist Figure 21In the example shown, the quantum computer portion and the control circuit LSI portion (control LSI) of the quantum device 1, as in the 14th embodiment, are connected via a bus. The qubits (quantum device 1) of the present invention utilize conventional transistors used in smartphones such as FINFETs. Therefore, as... Figure 21 As shown, since it is possible to mix with a general LSI and the quantum computer part (quantum device 1) is mostly controlled by a general LSI circuit, the circuits are connected to each other via a bus.

[0285] In the examples above, the methods (sequences) for fabricating multiple FIN parts and the insulators and quantum dots (polysilicon) between them include, for example, the following methods: a method of fabricating the insulators and quantum dots (polysilicon) after fabricating the entirety of the multiple FIN parts; a method of fabricating the insulators and quantum dots (polysilicon) while fabricating the multiple FIN parts (i.e., while extending the FIN); and a method of combining them, etc.

[0286] [Fifteenth Implementation]

[0287] The fifteenth embodiment of the quantum device of the present invention will be described below.

[0288] Except for the aspects described later, the quantum device 1 of the fifteenth embodiment is configured in the same way as the quantum device 1 of the first embodiment described above. Therefore, according to the quantum device 1 of the fifteenth embodiment, except for the aspects described later, the same effects as the quantum device 1 of the first embodiment described above can be achieved.

[0289] Figure 24 A diagram illustrating an example of the quantum device 1 according to the fifteenth embodiment.

[0290] exist Figure 24 In the example shown, quantum device 1 and Figure 1 The quantum device 1 shown in the example is more miniaturized. Specifically, in... Figure 1 In the example shown, quantum device 1 uses a conventional FINFET, in contrast to... Figure 24 In the example shown, the conductive channel portion of a typical FINFET is used as a novel quantum device.

[0291] In other words, Figure 24 In the example shown, the conductive channel IC becomes smaller than a typical FINFET, and the portion surrounded by the source and drain of the channel is also called a quantum dot.

[0292] Figure 24 The image shows two quantum dots and three conduction channels surrounding the two quantum dots.

[0293] exist Figure 24 In the example shown, with Figure 23 The nanowires shown have been further miniaturized.

[0294] exist Figure 24 In the diagram, (Source 1, Quantum Dot 1, Drain 1), (Source 3, Quantum Dot 3, Drain 3), and (Source 5, Quantum Dot 5, Drain 5) represent the smaller states of a typical FINFET.

[0295] [Sixteenth Implementation]

[0296] Hereinafter, a sixteenth embodiment of the quantum device of the present invention will be described.

[0297] Except for the aspects described later, the quantum device 1 of the sixteenth embodiment is configured in the same way as the quantum device 1 of the first embodiment described above. Therefore, according to the quantum device 1 of the sixteenth embodiment, except for the aspects described later, the same effects as the quantum device 1 of the first embodiment described above can be achieved.

[0298] Figure 25 A diagram illustrating an example of the quantum device 1 according to the sixteenth embodiment.

[0299] exist Figure 25 In the example shown, Figure 4 The channel portion and two quantum dot portions shown are described as a circuit simulator. Specifically, the quantum dot portions are described as floating gates, and the channel portion is described as two transistors.

[0300] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the specific configuration is not limited to the above-described embodiments, and appropriate modifications can be made without departing from the spirit of the present invention. The configurations described in the above embodiments and examples can also be combined.

Claims

1. A quantum device, characterized in that, It possesses: A transistor structure having a source, a drain, and a gate, and having multiple channel structures between the source and drain; More than one quantum dot structure, The quantum dot structure is held between the plurality of channel structures. Electrons or holes can be stored within the quantum dot structure. The quantum device also includes a qubit control current line, through which a qubit control current that generates a magnetic field flows, and the magnetic field controls the spin state of the electron or the hole. The thickness of the insulating film between the quantum dot structure and the channel structure is less than 2 nm. The gate length is less than 30nm. The size of the quantum dot structure is less than 20 nm.

2. The quantum device according to claim 1, characterized in that, The transistor structure having the plurality of channel structures that hold the quantum dot structure is a multi-gate transistor.

3. The quantum device according to claim 1, characterized in that, The gate is disposed on any one of the upper, lateral, and lower sides of the channel structure.

4. The quantum device according to claim 1, characterized in that, The transistor structure has two or more gates as gates.

5. The quantum device according to claim 1, characterized in that, The transistor structure includes a substrate portion. The quantum bit control current line is positioned closer to the substrate than the quantum dot structure.

6. The quantum device according to claim 1, characterized in that, The quantum device includes at least a first quantum dot structure and a second quantum dot structure as the quantum dot structure. The plurality of channel structures includes a first channel structure, which is disposed between the first quantum dot structure and the second quantum dot structure. By utilizing the magnetic field generated by allowing a quantum bit control current to flow through the quantum bit control current line, the quantum state of the charge spin within the first quantum dot structure is altered, and the interaction between the charge spin within the first quantum dot structure and the charge spin within the second quantum dot structure becomes an indirect interaction via the charge within the first channel structure.

7. The quantum device according to claim 6, characterized in that, The quantum device has operating modes. In the operating mode, the current of the qubit control current line is set to a non-zero value, the voltage of the gate is set to a value greater than zero, the voltage of the source is set to a non-zero value, the voltage of the drain is set to a non-zero value, and at least the magnetic field generated by the qubit control current line is set to a non-zero value, and RKKY (Ruderman-Kittel-Kasuya-Yosida) interaction is utilized.

8. The quantum device according to claim 7, characterized in that, The quantum device has a measurement mode. In the measurement mode, the voltage of the gate is set to a value greater than zero, the voltage of the source is set to a value lower than the voltage of the drain, and the state of charge spin within the quantum dot structure is inferred based on the current between the source and drain.

9. The quantum device according to claim 1, characterized in that, The quantum dot structure is either naturally formed or artificially created. The energy levels of the quantum dot structure are trap energy levels.

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