Quantum components

Abstract

The invention relates to a quantum component comprising: a substrate (6); two suspended electrodes (4); a plurality of gate electrodes (1, 2, 3) arranged between the two suspended electrodes, the two suspended electrodes being elevated with respect to the gate electrodes; at least one nano object element (8) suspended between the two suspended electrodes, in particular at least one nano object element (8) being a nanowire or a nanotube, the at least one nano object element being arranged above the gate electrode, the electrodes of the quantum component comprising a plurality of low frequency gate electrodes (1, 2) for defining an electrostatic potential within the nano object element such that at least two quantum dots are formed in the nano object element; and at least one microwave gate electrode (3), the at least one electrode comprising a magnetic material, preferably a ferromagnetic material, configured to apply a non-uniform magnetic field to the nano object element over the spatial extent of the nano object element.

Description

Technical Field

[0001] The present invention relates to quantum components.

[0002] More specifically, the present invention relates to quantum computing architectures, and more specifically, to examples of exemplary semiconductor quantum dot device embodiments and methods for forming scalable arrays of quantum dots.

[0003] Quantum components are intended, inter alia, without limitation, for manufacturing quantum computers.

Background Art

[0004] The integration density of transistors in integrated circuits has followed Moore's Law since its conception. However, as the size of transistors approaches that of a single atom, the laws of quantum physics are playing an increasingly dominant role in computing architectures, making it difficult to continue this trend for much longer. Nevertheless, the prospect of using quantum mechanical phenomena in information processing offers an opportunity to improve the computing power of computers beyond what is known to be possible with the most ideal conventional computers. Similar to how conventional computers rely on the robustness of transistors, functional quantum computers may require physical components on a chip with reproducible properties that can be incorporated into large-scale structures.

[0005] One of the main candidates for a quantum analog of a transistor is a semiconductor quantum dot defined by a gate electrode. The spin state of an electron trapped in a quantum dot can be a useful physical system for storing quantum information. In particular, silicon ("Si:Silicon") forms a "semiconductor vacuum" for spin states because the ultra-fine field is weak, the spin-orbit coupling is weak, and there is no piezoelectric electron-phonon coupling, and supports electron spin coherence times of several seconds. However, it has been found that the fabrication of reliable and scalable Si-based quantum dots is difficult. Irrespective of the need for a pure spin environment, quantum dots must have reproducible electrical properties for scaling. Due to the large effective mass of electrons in Si and the generally low mobility of two-dimensional ("2D:two-dimensional") Si electron gas Si, it is difficult to fabricate quantum dots that are tightly confined to a small number of electrons with reproducible properties.

[0006] The first quantum dot gate architectures were fabricated on substrates doped with gallium arsenide / aluminum gallium arsenide ("GaAs / AlGaAs"), where conduction electrons are supplied by the overall doped layer and confined to the GaAs / AlGaAs quantum well ("QW:quantum well") interface that forms a two-dimensional electron gas ("2DEG:two-dimensional electron gas"). In these doped structures, by default, the 2DEG is filled with conduction electrons. Thus, in gate design, attempts have been made to separate a single conduction electron by fabricating gate electrodes in a surrounding gate model where a circular barrier can be potentially generated by applying a negative voltage to the gate to deplete the 2DEG directly below the gate. Devices that use this type of gate pattern are called depletion mode devices.

[0007] Depletion-mode devices have been very successful in demonstrating quantum computing benchmarks and are still widely used throughout the quantum dot community. However, depletion-mode devices have major drawbacks regarding confinement potential and scaling control. In depletion-mode devices, the gate pattern most likely controls the electrostatic potential surrounding the dots rather than having direct control over the region of space where the electron wave function exists. The inability to control the electron wave function in this way leads to a wide variety of depletion-mode gate designs, most of which do not provide a straightforward path for scaling to tens or hundreds of quantum dots.

[0008] The use of quantum points / dots in a quantum computing architecture generally depends on the ability to control the confinement potential of the quantum dots, and more specifically, on the ability to control the physically relevant parameters of the quantum dots (e.g., tunnel couplings and electrochemical potentials). However, depletion-mode devices have very limited control over the confinement potential. Simulations of depletion-mode quantum dot devices have shown that the resulting confinement potential can be much smaller than the gate dimensions. Due to such circumstances, adjacent gates generally have similar effects on the dot's tunnel couplings and electrochemical potential, and in depletion-mode devices, it is often impossible to adjust the tunnel couplings and electrochemical potential to the desired values without reaching extreme voltages where breakdown may occur within the device.

[0009] By integrating nano-objects onto electronic components, it becomes possible to fabricate devices that can reach the quantum limit. Since quantum behavior is highly sensitive to their environment, it is important to have high-purity materials for the engineering of quantum technologies. Carbon nanotubes are materials with extremely excellent crystallinity, enabling them to have excellent electron conductivity, an electron mobility more than 100 times that in silicon, and mechanical resistance equivalent to that of diamond. Information can be encoded in a quantum form in the spin of electrons, and due to their high crystal purity, carbon nanotubes are ideal host materials for these electrons. Carbon nanotubes also have an optical response that covers the visible spectrum up to near-infrared light, depending on the size of their diameter. Therefore, they are also incorporated into optical devices or optoelectronic devices.

[0010] However, these properties are degraded by defects or contamination on the nanotubes. Carbon nanotubes also have diverse crystal structures during their growth and tend to aggregate. The ability to separate and manipulate a single object without degrading it enables high control over the behavior of the devices using it. Also, in the fabrication of electronic circuits using inks or thin layers, it does not allow optimal control of the properties of the fabricated components. Inks also have problems found in carbon nanotubes in solutions, which are chemical additives that modify the environment of the nanotubes. Similarly, integration by electron lithography techniques degrades the crystal structure of carbon nanotubes due to the use of resins and electron microscopes.

[0011] By integrating a single carbon nanotube without contamination or defects and with known crystal properties, it becomes possible to preserve the properties of the nanotube, ensuring reproducibility and better control of the device. In addition, the presence of nanotube degradation and contamination affects the success rate of integration, and the success rate of integration depends on the quality of the contact between the nanotube and the target substrate.

[0012] Also, there is known in European Patent No. 3066701 a transistor structure comprising at least two raised electrodes each including at least one source electrode and a drain electrode, an electrode arrangement including one or more gate electrodes located between the source electrode and the drain electrode, and one or more separate nanotubes bridging between at least two of the raised electrodes of the electrode arrangement. The one or more separate nanotubes are suspended between the source electrode and the drain electrode above the one or more gate electrodes, the electrode configuration is mounted on a cantilever-like tip, and at least one or more separate nanotubes are disposed at an end of the cantilever-like tip.

[0013] U.S. Patent Application Publication No. 2021 / 0028344 discloses a quantum device comprising at least one magnetic field source configured to supply a non-uniform magnetic field. Electrons perform reciprocating motion between at least two quantum states within at least one silicon semiconductor layer in the presence of the non-uniform magnetic field. The motion of the electrons between the at least two quantum states generates an oscillating magnetic field for driving a quantum transition between a spin-up state, also known as the 1 / 2 spin of the electron, and a spin-down state, also known as spin-1 / 2, thereby enabling implementation of a quantum bit gate on the spin state of the electrons. This document proposes a system comprising a signal generator for generating an electrical microwave frequency signal. In conventional electron spin resonance, a magnetic field oscillating at a microwave frequency (e.g., 10 - 40 GHz) can be used to control the spin. The oscillating magnetic field is difficult to position specifically on a small scale and is generated using a milliampere current (e.g., the current refers to one quantum dot and the current passes through a wire close to the dot), but it is difficult to scale up to a large number of quantum bits in an extremely low temperature environment because of the large power dissipated by the current. The disclosed process for driving single spin rotation is based on shifting the position of the electrons in the magnetic field gradient, thereby resulting in an effective oscillating magnetic field (e.g., lower power loss).

[0014] Previous approaches to inducing magnetic oscillations used unique quantum dots, where the amount of electron movement was small (e.g., about 1 pm), and a high electric field was required to obtain such movement. The described methods include electrically driven spin resonance in double quantum dots. In double quantum dots, electrons can be moved over a greater distance, leading to a higher effective oscillating magnetic field and a faster spin rotation speed. The faster spin rotation speed enables the spin to be driven with a low microwave output that is beneficial in an extremely low temperature environment. Additionally, a quantum computing architecture is disclosed that combines an electron spin resonance process with a two-qubit gate based on exchange coupling or cavity coupling, and an interaction with an ancilla quantum dot for reading spin states with microwaves.

[0015] Finally, the document T. Cubaynes, M. R. Delbecq, M. C. Dartiailh, R. Assouly, M. M. Desjardins, L. C. Contamin, L. E. Bruhat, Z. Leghtas, F. Mallet, A. Cottet and T. Kontos, "Highly coherent spin states in carbon nanotubes coupled to cavity photons", npj Quantum Information discloses an electron-photon coupling based on two non-collinear Zeeman fields on each quantum dot in a double quantum dot resulting from a zigzag-shaped ferromagnetic contact, and the coupling is performed using carbon nanotubes. These non-collinear Zeeman fields can be obtained by an interfacial exchange field or magnetic flux leakage, both of which give a similar Hamiltonian.

[0016] One object of the present invention is to propose a new quantum component architecture that can significantly reduce the quantum incoherence observed in prior art quantum components, thereby enabling improvement of the performance of these components.

Summary of the Invention

[0017] For this purpose, according to a first aspect, the present invention provides - a substrate, - at least two suspension electrodes, namely, a source electrode connected to an electron source and a drain electrode connected to a reference potential, - at least one gate electrode disposed between the two suspension electrodes, wherein the two suspension electrodes are raised with respect to the at least one gate electrode, - at least one nano-object element suspended between the two suspension electrodes and electrically connected to the two suspension electrodes, wherein the at least one nano-object element is disposed above the at least one gate electrode and the nano-object element encloses or includes at least two quantum dots, - at least one microwave gate electrode connected to a microwave circuit arranged to carry a microwave signal, characterized in that at least one electrode includes a magnetic material referred to as at least one magnetic electrode and is arranged and configured to apply a non-uniform magnetic field to the nano-object element over the spatial extent of the nano-object element, and proposes a quantum component.

[0018] For the above and the remaining part of the description, the following terms have the following definitions.

[0019] - Quantum component: An assembly of electronic circuits and / or devices that uses nanotubes as its conductive or semiconductive elements, and the circuit has single, double, or multiple quantum dots in series or parallel that use a single nano-object having characteristics selected as a channel element, or multiple separately selected nano-objects.

[0020] - Quantum dot: Electrons are trapped / confined in three dimensions and can occupy only discrete energy levels.

[0021] - Nano-object: An object with at least one of its external dimensions (typically, its height, width, thickness, length) less than 100 nanometers. If its three external dimensions (defined along three orthogonal axes) are less than 100 nanometers, it is a nanoparticle. If two of its external dimensions (preferably, defined along two orthogonal axes) are less than 100 nanometers, it is a nanofiber, such as a hollow single- or multi-layer nanotube that can be closed at at least one end, or a solid fiber. Conductive or semiconductive nanofibers are hereinafter referred to as nanowires. If the external dimension (typically its thickness) is less than 100 nm, it is a nanosheet.

[0022] - Electrode: The end of a conductor arranged to emit or capture an electric current.

[0023] - Gate electrode: An electrode that can transmit a microwave signal or set a potential (voltage).

[0024] - Microwave gate electrode: A gate electrode that transports and radiates a microwave signal enabling interaction between a microwave cavity and a nano-object.

[0025] - Low-frequency gate electrode: A gate electrode that can set an electrostatic potential to generate a double quantum dot.

[0026] - Electrostatic potential enabling formation of two quantum dots: The electrostatic potential modulates a potential energy barrier and enables generation of a double quantum dot.

[0027] - Spin-photon coupling: A controllable interaction or "coupling" between the magnetic aspect of a qubit, i.e., its spin, and the microwave electric field coming from a microwave cavity. Since the electric field is composed of photons, the inventors refer to it as spin-photon coupling.

[0028] - Quantum gate: A logical operation capable of changing the superposition state of qubits. For example, a qubit can have a 50% chance of being in one of two states.

[0029] - Inhomogeneous magnetic field: A magnetic field generated to create magnetic dipoles, preferably by any variation of the magnetic field around and / or along at least one nano-object element. For example, the vertical and / or horizontal components of the magnetic field change their signs along and / or around at least one nano-object element, preferably at and / or perpendicular to at least one magnetic gate electrode. According to a specific example, a magnetic field gradient that makes the total magnetic field inhomogeneous along at least one nano-object element, which is horizontal to or along the at least one nano-object element, preferably, the component of the magnetic field along the axis or direction of at least one nano-object changes its sign along at least one nano-object element.

[0030] - Spatial extent: An extent along and / or around at least one nano-object element, preferably radially, preferably in a zone located between suspension electrodes. According to one embodiment, it corresponds to the distance between two quantum dots.

[0031] - Purification combined with nano-objects: Nano-objects that can be composed of a metal material having a purity higher than 90%, for example, a purity of 99.9%.

[0032] - Substrate: An element of a component having a high resistivity, for example, a dielectric constant higher than that of air, especially at low temperatures.

[0033] Preferably, at least one gate electrode includes at least one microwave gate electrode.

[0034] Preferably, at least one gate electrode includes at least one low-frequency gate electrode provided to define an electrostatic potential enabling the formation of two quantum dots. Preferably, the low-frequency gate electrode is superconducting.

[0035] According to one embodiment, the magnetic material is a ferromagnetic material, preferably cobalt or palladium-nickel.

[0036] Preferably, at least one electrode including the magnetic material is a gate electrode.

[0037] Preferably, at least one gate electrode including the magnetic material is a low-frequency gate electrode. The low-frequency gate electrode is provided to define an electrostatic potential that enables the formation of two quantum dots.

[0038] According to one embodiment, at least one low-frequency gate electrode has a height higher than the height of an adjacent low-frequency gate electrode.

[0039] According to various embodiments that can be combined with one or more of the foregoing embodiments, at least one electrode, preferably at least one suspension electrode, and / or preferably at least one gate electrode, and / or preferably at least one low-frequency gate electrode can be in the form of a pad or a layer.

[0040] According to one embodiment of the quantum component, a distance called the microwave distance that separates at least one microwave gate electrode from at least one nano-object element is different from a distance called the low-frequency distance that separates at least one low-frequency gate electrode from at least one nano-object element.

[0041] According to one embodiment, the microwave distance is at least 20% shorter than the low-frequency distance.

[0042] Preferably, the microwave distance and the low-frequency distance are vertical distances and / or are measured in parallel. They are measured from the same nano-object element.

[0043] Preferably, at least one microwave gate electrode has a relative height with respect to at least one nano-object element that is different from the height of at least one low-frequency gate electrode. In the above and following descriptions, the height is measured in the vertical direction.

[0044] According to one embodiment, at least one microwave gate electrode has a height that is at least 20% higher than the height of at least one low-frequency gate electrode, and the height is measured from the surface on which at least one low-frequency gate electrode is placed.

[0045] The quantum components can be fabricated or provided on a semiconductor substrate. For example, the substrate can be selected from (i) a silicon / silicon-germanium (Si / SiGe) substrate, (ii) silicon dioxide on a silicon substrate, and / or (iii) a GaAs / AlGaAs heterostructure, and / or (iv) sapphire, (v) quartz, or a mixture thereof.

[0046] Preferably, the substrate is a high-resistivity or insulating substrate, especially at low temperatures.

[0047] According to one embodiment, the quantum components comprise at least one conductive layer disposed on the substrate and under at least one gate electrode, and each gate electrode is separated from the conductive layer by an insulating layer.

[0048] According to one alternative embodiment, the conductive layer is disposed under at least one gate electrode and under the suspension electrode, and each electrode is separated from the at least one conductive layer by an insulating layer. The at least one conductive layer, also referred to as a conductive return layer, is a conductive layer. It may be superconducting. It enables the microwave electromagnetic field to be pushed back towards the nano-object element.

[0049] Preferably, the quantum components comprise at least one trench formed in at least the conductive layer, and at least one microwave gate electrode is separated from at least one adjacent gate electrode by the at least one trench.

[0050] According to one alternative embodiment, the quantum component comprises at least one trench fabricated within the at least one conductive layer, and at least one microwave gate electrode is disposed on a first substrate and is separated by the at least one trench from at least one adjacent gate electrode disposed on the conductive layer.

[0051] Preferably, the substrate is partially hollowed out so as to extend the at least one trench.

[0052] According to the two foregoing embodiments, the height of the trench may be equal to the height of the at least one microwave gate electrode. The height of the electrode is measured between the external horizontal planes on which the microwave electrode is disposed. The height of the trench is measured from the external horizontal plane on which the gate electrode is disposed to the bottom of the trench.

[0053] According to the two foregoing embodiments, the trench can have a rectangular cross-section.

[0054] The trench makes it possible to enhance the electromagnetic field scattered by the microwave gate electrode and sensed by the nano-object.

[0055] Preferably, the conductive layer is made of, for example, a ferromagnetic or non-ferromagnetic electrical material so as to push back the microwave electromagnetic field towards the nano-object element.

[0056] According to one embodiment, the at least one nano-object element is a two-dimensional or one-dimensional element. Preferably, the at least one nano-object element is at least one nanotube or at least one nanowire. For example, the at least one nano-object element is at least one carbon nano-object element. The carbon nano-object allows electrons to diffuse over a longer distance than in the semiconductor layer.

[0057] Preferably, the nanotubes and nanowires can also generate correlated fundamental electronic states, enable spin positioning and individual control, and thus have a set of properties such as strong electron - electron interactions that enable the generation of quantum information chains or charge / spin pumps, and the interaction of electronic states with the mechanical motion of nanotubes or other correlated materials.

[0058] In this context, it should be noted that the term nanotubes as used herein refers to single - layer and bilayer carbon nanotubes, as well as other types of nanotubes such as semiconductor nanowires (e.g., silicon, GaAs, etc.) and other inorganic nanowires (e.g., molybdenum disulfide - MoS2).

[0059] It should be noted that the above - described technology can also provide an electronic device that uses any number of separate nanotubes (e.g., 1 to dozens, hundreds, thousands, or any number of separate nanotubes) separately arranged at desired positions along a single electrode arrangement. The nanotubes may be arranged in parallel between at least two raised electrodes and / or associated with different sets of electrodes to provide two or more quantum dot structures within a single electronic device. In addition, the electrode arrangement can include multiple sets of raised electrodes arranged parallel to each other, thus making it possible to attach a single nanotube to multiple pairs of raised electrodes. This provides multiple transistor structures composed of the same nanotube and has channels with similar characteristics and cleanliness.

[0060] Thus, the technology of the present invention enables the manufacture of an electronic device comprising one or more transistor structures such that each transistor structure uses one or more separate nanotubes that are channel elements suspended between a source electrode and a drain electrode. One or more gate electrodes can be arranged between the source electrode and the drain electrode, as a result of which the nanotube is suspended over the gate electrode.

[0061] The nanotubes can be suspended at a height between several microns or as low as several nanometers above the gate electrode. For example, the nanotubes can be suspended at a height of 50 nanometers above the gate electrode.

[0062] The parameters of the nanotubes can be selected to give the desired electrical properties to the transistor structure.

[0063] Thus, this assembly technique offers the possibility of generating electronic devices with excellent electronic cleanliness compared to commercially available electronic semiconductor devices. By suitably selecting nanotubes with the desired properties, the resulting device can significantly remove or reduce electronic obstacles within the device.

[0064] In addition, the device can be configured to have one or more local gates disposed under the suspended nanotubes.

[0065] This enables the formation of various transistor structures, including a transistor structure having an active element located on a sub - portion of the suspended nanotube and thus away from the contact metal. This significantly improves the electronic characteristics compared to conventional devices, as it eliminates or at least significantly reduces noise and capacitive coupling from nearby metals. When functioning as a transistor structure, the electronic device can operate as a single electron transistor (SET) and / or a field effect transistor (FET) depending on the ambient temperature. Additionally, the transistor structure can use an electrical trigger to an adjustable barrier device localized along the suspended nanotube. Further, the transistor structure can use an electrical trip to generate a single electron quantum dot, or at least two electron quantum dots, on the order of tens of nanometers in length along the suspended nanotube, as well as multiple quantum dots connected in series or in parallel. Additionally, the nanotube channel allows for high currents along the suspended nanotube.

[0066] Preferably, at least one nano - object element comprises an isotopically purified or enriched material. For example, the material is obtained by chemical vapor deposition (CVD) from an isotopically purified or enriched gas source.

[0067] According to one embodiment, at least one gate electrode is arranged and configured to generate a polarization of the spin of electrons that is non - collinear between two quantum dots formed within the nano - object element. Preferably, at least one low - frequency gate electrode is arranged and configured to generate a polarization of the spin of electrons that is non - collinear between two quantum dots formed within the nano - object element.

[0068] At least one gate electrode further comprises means for generating a polarization of the spins of electrons that is non-collinear between two quantum dots formed within the nano-object element. Preferably, at least one low-frequency gate electrode further comprises means for generating a polarization of the spins of electrons that is non-collinear between two quantum dots formed within the nano-object element.

[0069] The quantum component can further have the following characteristics.

[0070] - The distance separating at least one gate electrode from at least one suspended nano-object element is 100 nanometers.

[0071] - The height of at least one gate electrode, preferably at least one low-frequency gate electrode, is greater than the distance separating at least one gate electrode from at least one suspended nano-object element.

[0072] - The distance separating two gate electrodes horizontally is 200 nanometers, and the end points are located at the centers of the respective electrodes.

[0073] - At least one gate electrode comprises or is made of a high-magnetization material.

[0074] - At least one gate electrode comprises or consists of a single layer or multiple layers of material.

[0075] - The material comprises or consists of a material selected from the following list, namely cobalt, nickel, palladium, or a mixture thereof, preferably a mixture of palladium and nickel, or a mixture of palladium and cobalt.

[0076] According to another optional embodiment, which may or may not be combined with the aforementioned features in particular, the quantum component comprises the following.

[0077] - At least one gate electrode is made of a ferromagnetic or antiferromagnetic or magnetic multilayer material, preferably, at least one low-frequency gate electrode is made of a ferromagnetic or antiferromagnetic or magnetic multilayer material, preferably, at least one microwave gate electrode is made of a ferromagnetic or antiferromagnetic or magnetic multilayer material.

[0078] - At least one gate electrode and / or at least two suspension electrodes are made of a ferromagnetic or antiferromagnetic or magnetic multilayer material.

[0079] - At least one magnetic electrode that can be further configured to generate a polarization of the spin of electrons that is non-collinear between two quantum dots formed within the nano-object.

[0080] - At least one magnetic gate electrode that can be further configured to generate a polarization of the spin of electrons that is non-collinear between two quantum dots formed within the nano-object.

[0081] - Means for applying a uniform magnetic field that enables polarization of at least one magnetic electrode, preferably at least one low-frequency gate electrode.

[0082] - Means for applying a uniform magnetic field that enables polarization of at least one magnetic gate electrode, preferably at least one low-frequency gate electrode.

[0083] - According to one embodiment, the means preferably comprises at least one coil disposed around at least one gate electrode, and advantageously, the quantum component is disposed at the center of the coil to apply a uniform magnetic field.

[0084] - Control means for controlling the quantum component, wherein the at least one microwave gate electrode is connected to a microwave circuit arranged to carry a microwave signal.

[0085] - According to one alternative embodiment, at least one microwave gate electrode comprises means, called control means, for controlling the quantum component, and the at least one microwave gate electrode is connected to a microwave circuit arranged to carry a microwave signal.

[0086] - Preferably, the control means are capacitive coupling means for electromagnetically coupling the component to the microwave circuit.

[0087] - At least one microwave gate electrode enabling the control of a quantum component, the microwave electrode being connected to a microwave circuit arranged to carry a microwave signal, such as a quantum or non-quantum signal, at least one microwave gate electrode.

[0088] - Coupling means for coupling a plurality of quantum components, the at least one microwave gate electrode being connected to a microwave circuit arranged to carry a microwave signal, coupling means.

[0089] - According to one alternative embodiment, at least one microwave gate electrode comprises means, called coupling means, for coupling a plurality of quantum components, and the microwave gate electrode is connected to a microwave circuit arranged to carry a coupling microwave signal.

[0090] - Preferably, the coupling means are capacitive coupling means for electromagnetically coupling the component to the microwave circuit.

[0091] - At least one electrode may comprise a material selected from the following list, namely cobalt, iron, nickel, palladium, their alloys, multiferroic materials or combinations thereof, preferably cobalt or a palladium-nickel alloy. Any other suitable magnetic material can be used.

[0092] The microwave circuit is, for example, a microwave resonator.

[0093] According to a second aspect, the present invention proposes an electronic device comprising at least one quantum component according to one or more features of the first aspect.

[0094] According to a third aspect, the present invention is a method for controlling a quantum component, comprising: - defining at least two quantum states within at least one nano-object using one or more nano-object elements, wherein the at least two quantum states are within a non-uniform magnetic field; - causing a reciprocating motion of electrons between at least two quantum states in the presence of the non-uniform magnetic field based on a microwave oscillating electrical signal carried by a microwave electrode, wherein the motion of the electrons generates an oscillation of the magnetic field and drives a quantum transition between a spin state oriented in one direction of the electrons and a spin state oriented in the opposite direction, and thus implements a qubit gate on the spin state of the electrons.

[0095] Preferably, the method controls the quantum component in accordance with one or more of the features of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0096] Other features and advantages of the present invention will become apparent from the following detailed description of the present invention with reference to the accompanying drawings.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0097] For clarity, identical or similar elements of various embodiments are denoted by the same reference numerals in all figures.

Best Mode for Carrying Out the Invention

[0098] With reference to FIG. 1, an embodiment of a quantum component is shown, - A substrate 6 made of a high-resistivity material, such as silicon or silicon, and - A layer 5 of an electrical material made of a conductive material, such as niobium, disposed on the substrate 6, and - Gate electrodes 1, 2 (by way of example, five gate electrodes: four low-frequency gate electrodes and one magnetic electrode 2 are shown), wherein the gate electrodes are disposed on the conductive layer 5 via an insulating layer, the gate electrodes 1, 2, and - Two suspension electrodes 4 (by way of example, two suspension electrodes are shown), namely a source electrode connected to an electron source and a drain electrode connected to a reference potential, wherein the suspension electrodes are disposed on the conductive layer 5 via an insulating layer, on both sides of the gate electrode group, the suspension electrodes are raised with respect to the gate electrodes, the suspension electrodes, and - A nanotube or nanowire 8 connected to the two suspension electrodes 4, wherein the nanotube or nanowire is linearly suspended above the gate electrodes, and the nanotube or nanowire is preferably made of carbon, the nanotube or nanowire 8, and - A gate electrode called a microwave gate electrode 3, which is connected to a microwave circuit (not shown) configured to carry a microwave read signal intended to be processed and supply the state of a quantum component, is disposed on a substrate 6 and separated by a trench 7 from an adjacent gate electrode called a low-frequency gate electrode.

[0099] According to one embodiment, the width of the electrode 2 has a distance or dimension that is half or less of the distance separating the electrode 2 from the adjacent electrode 1. Preferably, the width of the electrode 2 is 50 to 250 nanometers.

[0100] According to other embodiments not shown, the quantum component can include a plurality of electrodes 2, for example at least two electrodes 2. For example, at least two electrodes 2 can be alternately arranged with respect to the gate electrode 1.

[0101] Preferably, the trench 7 penetrates the thickness of the conductive layer 5, and as a result, the total depth of the trench is substantially equal to the height of the microwave gate electrode 3.

[0102] According to an alternative embodiment shown in FIG. 2, the trench 7 penetrates only the thickness of the conductive layer 5. The microwave gate electrode 3 is disposed on the conductive layer 5 via an insulating layer.

[0103] According to yet another alternative embodiment shown in FIG. 3, the quantum component does not include a trench.

[0104] According to a simplified alternative embodiment shown in FIG. 4, the quantum component includes a single substrate 6, does not include a trench, and in particular includes a magnetic gate electrode 2 made of or covered with a ferromagnetic material, preferably cobalt. Further, the electrode 2 has a height higher than that of the low-frequency gate electrode 1 disposed in its vicinity. Optionally, this feature can be combined with the embodiments shown in the preceding figures. This feature enables the polarization of the nano-object by the dipole field and the magnetization of the spin of the nano-object.

[0105] Referring to FIG. 5, the wave functions and magnetic field profiles of double quantum wells generated by pads or gate electrodes of quantum components according to one embodiment are shown.

[0106] Referring to the upper or topmost graph, the two-state wave function, in particular the electrostatic potential of the nanotube as a function of the axis x in nanometers, is shown by the double quantum dots. The electrostatic potential (shown by the gray solid line) enables the formation of these two quantum dots. The potential profile is the result of the voltage applied to the gate electrode. According to the case shown in the figure, particularly FIG. 1, the high voltages at the center and the ends are generated by the central gate electrode 2 and the two outermost gate electrodes 1. The low voltage is generated by the two gate electrodes 1 on both sides of the gate electrode 2. This potential profile generates the double quantum dots indicated by the gray regions. The black lines indicate the two bonding (solid lines) and antibonding (dotted lines) states of the electrons in the double quantum dots hosted, for example, in a carbon nanotube (not shown).

[0107] Referring to the lower or bottommost graph, the magnetic field profile generated by the cobalt ferromagnetic gate electrode is shown. The magnetic simulation was performed for a cobalt electrode with a height of 100 nanometers and a width of 200 nanometers. The profiles of the two magnetic field components correspond to the leakage magnetic field generated 100 nanometers above the cobalt electrode, which corresponds to the height of the nano-object relative to this electrode. The cobalt electrode is polarized in the x direction (the axis of the double quantum dots and the nanotube) by a uniform magnetic field of 300 mT. The component Bz (dashed line) generates a non-uniform magnetic field (magnetic field gradient), for example, the component Bz is strictly greater than 15 mT.

[0108] The convolution of this non-uniform field with the shape of the wave function of the quantum state (upper graph) gives the value of the non-collinear polarization that enables the coupling of the spin to the microwave. Preferably, the suspension material is pure and the central gate electrode is a cobalt bar. Furthermore, in order to generate non-collinear polarization, it is preferable not to use ferromagnetic drain-source electrodes. Thereby, the quantum dots can be kept away from the source and drain electrodes, and the noise generated from these electrodes can be reduced. This makes it possible to approach an ideal system of suspended nano-objects. This example makes it possible to propose quantum components that outperform the components of the prior art.

Claims

1. A quantum component, comprising: - a substrate (6); - at least two suspension electrodes (4), namely, a source electrode connected to an electron source and a drain electrode connected to a reference potential; - at least one gate electrode (1, 2, 3) disposed between the two suspension electrodes, wherein the two suspension electrodes protrude with respect to the at least one gate electrode; - at least one nano-object element (8) suspended between the two suspension electrodes and electrically connected to the two suspension electrodes, wherein the at least one nano-object element is disposed above the at least one gate electrode and the nano-object element includes at least two quantum dots. The quantum component further comprises: - at least one microwave gate electrode (3) connected to a microwave circuit arranged to carry a microwave signal. At least one electrode includes a magnetic material referred to as at least one magnetic electrode, and is arranged and configured to apply a non-uniform magnetic field to the nano-object element over the spatial extent of the nano-object element. A quantum component characterized by this.

2. The quantum component according to claim 1, wherein the magnetic material is a ferromagnetic material, preferably cobalt, palladium-nickel.

3. The quantum component according to claim 1 or 2, wherein the at least one electrode including a magnetic material is at least one low-frequency gate electrode (1, 2).

4. The quantum component according to claim 3, wherein at least one low-frequency gate electrode (2) has a height higher than that of an adjacent low-frequency gate electrode.

5. The quantum component according to claim 3, wherein a distance, referred to as a microwave distance, separating the at least one microwave gate electrode (3) from the at least one nano-object element (8) is different from a distance, referred to as a low-frequency distance, separating the at least one low-frequency gate electrode (1, 2) from the at least one nano-object element (8).

6. The quantum component according to claim 5, wherein the microwave distance is at least 20% shorter than the low-frequency distance.

7. A quantum component according to any one of claims 1 to 6, comprising at least one conductive layer (5) disposed on the substrate (6) and under the at least one gate electrode, each gate electrode being separated from the conductive layer by an insulating layer.

8. At least one conductive layer (5) disposed on the substrate (6) and under the at least one gate electrode, and at least one trench (7) formed at least in the conductive layer (5), wherein the at least one microwave gate electrode (3) is separated from the at least one adjacent gate electrode by the trench (7). A quantum component according to any one of claims 1 to 6.

9. At least one conductive layer (5) disposed on the substrate (6), and at least one trench (7) formed at least in the conductive layer (5), wherein the at least one microwave gate electrode (3) is disposed on the substrate (6) and separated from the at least one adjacent gate electrode disposed on the conductive layer (5) by the trench (7). A quantum component according to any one of claims 1 to 6.

10. The quantum component according to claim 9, wherein the substrate (6) is partially hollowed out so as to extend the trench (7).

11. The quantum component according to any one of claims 8 to 10, wherein the height of the trench (7) is equal to the height of the at least one microwave gate electrode (3).

12. The quantum component according to any one of claims 1 to 11, wherein the at least one nano-object element (8) is at least one nanotube or at least one nanowire.

13. The quantum component according to any one of claims 1 to 12, wherein the at least one nano-object element (8) contains an isotopically purified or enriched material.

14. The quantum component according to any one of claims 1 to 13, wherein the at least one magnetic electrode is arranged and configured to generate polarization of the spin of electrons that is non-collinear between two quantum dots formed in the nano-object element.

15. The quantum component according to any one of claims 1 to 14, further comprising means for applying a uniform magnetic field that enables polarization of the at least one magnetic electrode.

16. The at least one microwave gate electrode further comprises means for controlling the quantum component, and the at least one microwave gate electrode is connected to a microwave circuit arranged to carry a microwave signal. The quantum component according to any one of claims 1 to 15.

17. The at least one microwave gate electrode further comprises means for coupling a plurality of quantum components, and the at least one microwave gate electrode is connected to a microwave circuit arranged to carry a microwave signal. The quantum component according to any one of claims 1 to 16.

18. An electronic device comprising at least one quantum component according to any one of claims 1 to 17.

19. A method for controlling a quantum component, comprising: - Defining at least two quantum states in at least one nano-object using one or more nano-object elements, wherein the at least two quantum states are in a non-uniform magnetic field; - Causing a reciprocating motion of electrons between the at least two quantum states in the presence of the non-uniform magnetic field based on a microwave oscillating electrical signal carried by a microwave gate electrode, wherein the reciprocating motion of the electrons generates oscillations of the non-uniform magnetic field and drives a quantum transition between a spin state oriented in one direction of the electrons and a spin state oriented in the opposite direction, thereby implementing a quantum bit gate on the spin state of the electrons.

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