Magnetic components, especially quantum components

Abstract

The present invention relates to a magnetic component comprising a substrate (6) supporting at least a pair of permanent magnets (2) extending in a first direction (X), each magnet (2) having interacting ends (21 a, 21 b) arranged opposite each other, the pair of magnets (2) being arranged such that, under the influence of a magnetic field generated by external magnetic means, they exert an antisymmetric magnetic field having a high magnetic field gradient along a second direction (Z) orthogonal to the first direction (X).

Description

Detailed Description of the Invention

[0001] The present invention relates to magnetic components in the field of micro and nanoelectronics, and more particularly to quantum components. The quantum components are particularly, but not limited to, intended for manufacturing quantum computers. They may also be of interest in the fields of spintronics, topological superconductivity, magnetic operation of nano-devices and nano-beads, or near-field magnetic detection using scanning probes.

[0002] In the field of micro and nanoelectronics, there are devices designed to generate a magnetic field in a specific direction through magnets, which are called micro-magnets by those skilled in the art.

[0003] One object of the present invention is to propose a new quantum component architecture that can significantly reduce the quantum inconsistencies observed in conventional quantum components, thereby enabling the improvement of the performance of these components.

[0004] 〔Object of the Invention〕 For this purpose, according to a first aspect, the present invention proposes a magnetic component comprising a substrate supporting at least a pair of permanent magnets extending in a first direction, each magnet having an interaction end, the interaction ends being arranged opposite to each other, and the pair of magnets being arranged to exert an anti-symmetric magnetic field with respect to the X = 0 plane having a high magnetic field gradient along a second direction orthogonal to the first direction and a symmetric magnetic field with respect to the X = 0 plane along a first direction (X) orthogonal to the Y and Z directions under the influence of a magnetic field generated by external magnetic means.

[0005] For the above and the remaining part of the description, the following terms have the following definitions.

[0006] - Quantum components: assemblies of electronic circuits and / or devices that use nanotubes as their conductive or semiconducting elements, the circuits having single, dual or multiple quantum dots in series or parallel, using a single nanoobject having selected properties as channel elements, or multiple separately selected nanoobjects.

[0007] - Quantum dots: These are parts of nanomaterials in which electrons are trapped / confined in three dimensions and can only occupy discrete energy levels.

[0008] -Nano-object: An object whose external dimensions (typically its height, width, thickness, and length) are 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, for example, a hollow single-walled or multi-walled nanotube that can be closed at at least one end, or a solid fiber. Conductive or semi-conductive nanofibers are hereafter referred to as nanowires. If its external dimensions (typically its thickness) are less than 100 nm, it is a nanosheet.

[0009] - Electrode: The end of a conductor arranged to discharge or capture electric current.

[0010] - Gate electrode: An electrode that allows for the transmission of microwave signals or the setting of potential (volts).

[0011] - Microwave gate electrode: A gate electrode that transports and emits microwave signals, enabling interaction between a microwave cavity and nanomaterials.

[0012] - Low-frequency gate electrodes: Gate electrodes that allow setting an electrostatic potential to generate dual quantum dots.

[0013] -Magnet: A magnetic element that becomes magnetized under the influence of a magnetic field.

[0014] - Electrostatic potential enabling the formation of two quantum dots: The electrostatic potential modulates the potential energy barrier, making it possible to generate a double quantum dot.

[0015] -Spin-photon coupling: A controllable interaction or "coupling" between the magnetic appearance of a qubit, i.e., its spin, and the microwave electric field emanating from a microwave cavity. Since the electric field is composed of photons, the inventors refer to this as spin-photon coupling.

[0016] - Quantum gate: A logical operation that can change the superposition state of a qubit. For example, a qubit may have a 50 / 50 chance of being in one or the other of two states.

[0017] - Non-uniform magnetic field: A magnetic field generated to produce a magnetic dipole, preferably by any variation in the magnetic field around and / or along at least one nanomaterial element. For example, the vertical and / or horizontal components of the magnetic field change sign along or around at least one nanomaterial element, preferably at or perpendicular to at least one magnetic gate electrode. In a particular example, a magnetic field gradient horizontal to or along at least one nanomaterial element, preferably a component of the magnetic field along the axis or direction of at least one nanomaterial, changes sign along at least one nanomaterial element, making the entire magnetic field non-uniform along that nanomaterial element.

[0018] - Spatial extent: A zone located along and / or around at least one nanomaterial element, preferably radially, preferably between suspension electrodes, which, according to one embodiment, corresponds to the distance between two quantum dots.

[0019] - Substrate: An element of a component that has a high resistivity, for example, a higher dielectric constant than air, especially at low temperatures.

[0020] According to a second aspect of the present invention, a quantum component comprising the following is proposed:

[0021] At least two suspension electrodes: a source electrode connected to an electron source and a drain electrode connected to a reference potential, designed to accept a quantum element integrating dual quantum dots. At least three gate electrodes positioned between two suspension electrodes, wherein the two suspension electrodes are raised relative to at least three gate electrodes, A magnetic component according to the present invention, designed to exert an antisymmetric magnetic field having a high magnetic field gradient along a second direction perpendicular to a first direction, under the influence of a magnetic field generated by an external magnetic means, wherein the antisymmetric magnetic field is applied to the quantum element.

[0022] According to a third aspect of the present invention, a method for manufacturing a quantum component according to the present invention is proposed, which includes the following steps.

[0023] - A process of etching the substrate to receive the magnetic element, - A step of depositing at least one pair of magnets extending in a first direction (X), wherein each magnet has an interacting end, and the interacting ends are arranged facing each other. - A step of performing low-angle etching on a substrate on which at least one pair of magnets are deposited, - A process of depositing an oxide layer on a processed substrate, - A process of depositing suspension electrodes and gate electrodes on an oxide layer.

[0024] Preferably, according to any of the aforementioned embodiments, the components or methods may include one or more of the following features:

[0025] - The pair of magnets themselves generate an antisymmetric magnetic field (z-axis component) between the two dots (with respect to the x=0 plane), and the applied external magnetic field generates a symmetric field between the two dots.

[0026] Between quantum dots separated by distances between -60 and 120 nanometers, these gradients result in an asymmetric field component that can reach about 30 mT or 40 mT (millitesla).

[0027] When considering dots arranged symmetrically with respect to the field distribution, the fields at the two dots of a double quantum dot consist of a symmetric part and an antisymmetric part.

[0028] For each field component, it is possible to define i = u, v, w.

[0029]

Number

[0030] Here, L;R refer to the left (L) and right (R) quantum dots, respectively. This definition of the symmetric / antisymmetric magnetic field for each vector component i, where u, v, w equally refer to directions in space x, y, z. This definition makes sense in the context of a double quantum dot.

[0031] The influence of the drift field on the energy in the left and right parts of a double quantum dot can be expressed as follows.

[0032]

Number

[0033] Here,[[]]

[0034]

Number

[0035] is the probability density of the presence of an electron at dot p (left or right), the prefactor 2 represents the Landé factor of the electron spin, and μB is the Bohr magneton.

[0036] This corresponds to the mathematical definition of the magnetic coupling constant between the electrons in the quantum dots and symmetric and anti-symmetric magnetic fields respectively. What is considered to be the quantity to be optimized (maximized) will be described later.

[0037] Therefore, the gradient must be considered as the non-uniformity between two quantum dots of the field averaged over each dot.

[0038] Next, consider a pair of dots with linear confinement, such as seen in double quantum dots in a nanowire. The dots are aligned along the x-axis, defined between -250 nm and -150 nm for dot L and between 150 nm and 250 nm for dot R.

[0039] The nanowire is suspended at z = 200 nm above a magnetic layer extending from -100 nm < z < 100 nm.

[0040] The external magnetic field is preferably applied along the nanowire. Since a lateral gradient is required, assume a uniform magnetization along +x.

[0041] Here, since we are considering dots located above the magnetic system, the following is used.

[0042]

Equation

[0043] Here, L and R are interchanged with respect to the above. The definition of Q is the quantity to be optimized (refer to the previous coupling constant between the magnetic field and the dots). <000015​​​​​​Therefore, this optimization involves determining the presence or absence of magnets in each cell or one or more cells or elements along the Z axis at all X and Y positions. This method of optimizing quantity Q is linear for individual magnetic elements / cells.

[0046] A higher magnetic saturation MS directly favors higher parasitic fields and gradients. It also facilitates the formation of magnetic domains in nanomagnets and therefore requires a higher external field to reach saturation.

[0047] Let this external field be a term

[0048]

number

[0049] From the symmetrical part of the parasitic field in the formation of the dot energy level

[0050]

number

[0051] Add it.

[0052] The heterogeneity of the boundary acting on the dot is defined as follows:

[0053]

number

[0054] This performance index decreases when a strong external field is used.

[0055] Therefore, in order to optimize heterogeneity, it is necessary to identify the following pairs of MS and Bext values ​​that provide the highest values.

[0056]

number

[0057] This last point corresponds to the definition of the contribution of the external magnetic field to the symmetric component.

[0058] [Brief explanation of the drawing] Other features and advantages of the present invention will become apparent from the following detailed description of the invention with reference to the accompanying drawings.

[0059] [Figure 1] Figure 1 is a schematic diagram of a quantum component according to one embodiment, comprising electrodes extending substantially perpendicularly to two series of magnets.

[0060] [Figure 2] Figure 2 shows two series of magnets extending parallel to each other within the same series and between the two series, with the magnet ends of the first series facing the magnet ends of the second series, and the magnets of both series lying in the same plane.

[0061] [Figure 3] Figure 3 is a schematic diagram of a nanotube connecting two opposing magnetic ends and the two ends, according to one embodiment of a quantum component, and this diagram is positioned in a three-dimensional reference frame.

[0062] [Figure 4] Figure 4 is a nanoscale depiction of magnetic field saturation at the ends of two magnets.

[0063] [Figure 5] Figure 5 shows the curve of the magnetic field component along a carbon nanotube, in particular the magnetic field distribution along a carbon nanotube obtained using the micromagnet shown in Figure 2.

[0064] [Figure 6] Figure 6 shows the effect of an external magnetic field on various physical quantities using three different magnetic materials.

[0065] For clarity, identical or similar elements of various embodiments are indicated by the same reference numerals in all figures.

[0066] [Detailed description of the invention] In relation to Figures 1 and 2, one embodiment of the quantum component is shown. For example, a substrate 6 made of a high-resistivity material, A magnetic device 2 comprises two comb-shaped portions 2A and 2B, which act as magnetic electrodes, are arranged to generate a magnetic field on the quantum component 1, are positioned opposite each other, and are separated by a central gap 22 that generates a dedicated magnetic field for each portion. A pair of gate electrodes 8 positioned above the central gap 22, these gate electrodes are surrounded by a source electrode 9.1, a cut source electrode 9.2, a cut drain electrode 9.3, and a drain electrode 9.4, and The device comprises a nanotube or nanowire (not visible in Figure 1) connected to a suspension electrode, wherein the nanotube or nanowire is linearly suspended above the gate electrode and preferably above a pair of substantially parallel magnets made of carbon.

[0067] The source and drain electrodes are arranged on the conductive layer with an insulating layer in between. They act as suspension electrodes for the nanotube or nanowire, and are raised above the gate electrode. This arrangement is specific to quantum components, including carbon nanotubes.

[0068] Referring to Figure 2, the magnetic device 8 comprises permanent magnets arranged in the form of two opposing combs 2A, 2B, i.e., a first comb and a second comb. Each comb 2A, 2B comprises a plurality of substantially rectangular magnets 20A, 21A. 21A, 21B are arranged parallel to each other. The series of magnets in each comb are connected along the Z-axis to the two opposing ends of the corresponding ones.

[0069] According to the illustrated embodiment, each comb 2A, 2B comprises 15 magnets. Each magnet is 1.5 micrometers wide and 8.5 micrometers long. The width is selected so that the magnetic moment, due to the internal dipole energy, is parallel to the boundary. Preferably, each magnet is spaced laterally by a distance of 0.75 micrometers along the Y-axis. Preferably, each comb 2A, 2B has a thickness of 400 nanometers. Preferredly, each magnet contains iron and cobalt, which preferably have high persistence.

[0070] Referring to Figures 2 and 3, each magnet 21A of the first comb 2A has an interaction end or magnetic pole 41A positioned to face the interaction end or pole 41B of the magnet 21B of the second comb 2B. Each cross-section faces the cross-section of the magnet on the second comb. Preferably, the distance between the two interaction ends or magnetic poles is 0.4 to 1 micrometer. The spacing is measured between the distal points of the interaction ends.

[0071] Preferably, each interaction end has a rounded shape when viewed along the two-dimensional plane or longitudinal plane indicated by the XY plane in Figure 2. In addition, Figures 3, 4, and 5 show the optimal shape of a saturated nanomagnet in the case of a finitely extended quantum dot, in particular, uniform magnetization imposed along x, maximizing the field difference Bz. Preferably, a rounded distal portion, especially a three-dimensional oval shape, contributes most to magnetic field optimization. The shape of the interaction end aligns the magnetic moment in a single direction.

[0072] In addition, each magnet 21A has a connecting end 31A facing the interacting end 41A. Each comb 2A, 2B further comprises magnet connecting pieces 200A, 200B, so that each magnet in comb 2A, 2B is connected to the connecting pieces 200A, 200B of the comb 2A, 2B via the connecting end. According to the shown embodiment, the connecting pieces 200A, 200B are 4 micrometers wide.

[0073] This embodiment provides an anisotropic shape and generates a uniform magnetic field in the Y direction relative to the nanotube. The reduced dimensions of the magnet result in shape anisotropy, and the magnetic moment tends to be parallel to the boundary due to the internal dipole energy.

[0074] Preferably, the two magnetic combs 2A and 2B are fitted into the substrate 6.

[0075] Furthermore, the quantum component includes external magnetic means (not shown) arranged to exert a magnetic field along the X direction. For example, a toroid (not shown) surrounds the electrodes and comb. Preferably, this toroid generates a magnetic field of 200 to 500 millitesla.

[0076] Therefore, we propose that the quantum components exert an antisymmetric magnetic field with a strong magnetic field gradient along the Z direction perpendicular to the X direction, under the influence of a magnetic field generated by an external magnetic means. For example, according to the tests performed, the antisymmetric field constant reaches 26.8 microeV and the symmetric field constant reaches 29 microeV, making it possible to optimize spin-photon coupling.

[0077] The quantum components optimize the distribution of magnetic moments around the quantum dots, the magnetic field gradient, and thus the interaction between the magnet and the nanomaterial or nanotube containing at least two quantum dots. Preferably, the nanomaterial or nanotube is located about 100 nanometers above the magnet pair under consideration.

[0078] Figure 6 shows the results of a micromagnetic simulation of a shape optimized for a heterogeneous component Bz, with magnetization along the external field Bext and x. Based on the external magnetic field, (a) magnetization mx, (b) symmetry (alpha s), (c) antisymmetric (alpha as) coupling constant due to the nanomagnet, and (d) ratio between the antisymmetric and total symmetric fields.

[0079]

number

[0080] The different colors correspond to CoFe (square lines), Co (triangular lines), and NiFe (circular lines). [Brief explanation of the drawing]

[0081] [Figure 1] This is a schematic diagram of a quantum component according to one embodiment, comprising electrodes extending substantially perpendicularly to two series of magnets. [Figure 2] The image shows two series of magnets extending parallel to each other within the same series and between the two series, with the magnet ends of the first series facing the magnet ends of the second series, and both series of magnets lying in the same plane. [Figure 3] This is a schematic diagram of a nanotube connecting two opposing magnetic ends and one end of a quantum component, arranged in a three-dimensional reference frame. [Figure 4] This is a nanoscale depiction of magnetic field saturation at the ends of two magnets. [Figure 5] This figure shows the curve of the magnetic field component along a carbon nanotube, in particular the magnetic field distribution along the carbon nanotube obtained using a micromagnet as shown in Figure 2. [Figure 6] This study demonstrates the effect of an external magnetic field on various physical quantities using three different magnetic materials.

Claims

1. A substrate (6) and A pair of permanent magnets extending in a first direction (X), wherein each permanent magnet has an interaction end, and the interaction ends are arranged facing each other. External magnetic means configured to generate a magnetic field, A magnetic component comprising, At least one pair of the permanent magnets are configured to generate a composite magnetic field under the influence of the magnetic field generated by the external magnetic means, The first component of the composite magnetic field along the second direction (Z) perpendicular to the first direction (X) is an antisymmetric magnetic field with respect to the X=0 plane and has a non-zero gradient with respect to X at X=0. A magnetic component in which the second component of the composite magnetic field along the first direction (X) is a magnetic field symmetric with respect to the X=0 plane.

2. The magnetic component according to claim 1, comprising several pairs of permanent magnets facing each other to form two combs.

3. The magnetic component according to claim 1, wherein each permanent magnet has a linear shape.

4. The magnetic component according to claim 1, wherein each permanent magnet interaction end has a rounded shape.

5. The magnetic component according to claim 4, characterized in that the rounded shape is a curve having a predetermined radius of curvature.

6. The magnetic element according to claim 4, wherein each permanent magnet end is rounded in three dimensions.

7. The magnetic component according to claim 1, wherein each permanent magnet interaction end has a shape without protrusions.

8. The magnetic component according to claim 1, wherein at least one pair of the permanent magnets are embedded in the substrate.

9. The magnetic component according to claim 1, wherein at least one pair of the permanent magnets are deposited on the substrate.

10. Quantum constituent elements, - A quantum device integrating dual quantum dots, with a source electrode connected to an electron source and a drain electrode connected to a reference potential, - At least three gate electrodes disposed between the source electrode and the drain electrode, - A magnetic component (1) according to claim 1, which is designed to generate a first component of the composite magnetic field along a second direction (Z) perpendicular to the first direction (X), under the influence of a magnetic field generated by the external magnetic means, the first component of the composite magnetic field being antisymmetric with respect to the X=0 plane and having a non-zero gradient with respect to X at X=0, and this antisymmetric magnetic field is applied to the quantum element, A quantum component that possesses these features.

11. The quantum component according to claim 10, characterized in that the source electrode and drain electrode constitute a suspension electrode that is raised relative to the at least three gate electrodes.

12. The quantum element further comprises at least a nanomaterial element (11) suspended between the source electrode and the drain electrode and electrically connected to the source electrode and the drain electrode, The quantum element according to claim 11, wherein at least one of the nanomaterial elements is positioned above the at least three gate electrodes.

13. The quantum element according to claim 10, further comprising a two-dimensional electron gas located in a substrate disposed between the source electrode and the drain electrode as a quantum element.

14. The quantum element according to claim 10, wherein the quantum element is arranged at a distance of 100 nm above at least one pair of permanent magnets.

15. The quantum element according to claim 10, wherein a plurality of the permanent magnets among at least one pair of permanent magnets are arranged symmetrically with respect to a plane perpendicular to the direction of the quantum element.

16. A method for manufacturing a quantum component according to claim 10, - The process of etching the substrate to receive the magnetic element, - A step of depositing at least one pair of magnets extending in a first direction (X), wherein each magnet has an interacting end, and the interacting ends are arranged facing each other. - A step of performing low-angle etching of the substrate on which at least one pair of magnets are deposited, - A step of depositing an oxide layer on the substrate on which the low-angle etching has been performed, A method comprising the step of depositing a suspension electrode and a gate electrode on the oxide layer.

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