Electron spin wave wavelength conversion device, arithmetic device, and electron spin wave phase modulation device

Abstract

The present invention provides an electron spin wave wavelength conversion device that enables easy and accurate control of the wavelength of an electron spin wave, and an arithmetic device equipped with the same. [Solution] The wavelength conversion device 100 of the electron spin wave of the present invention is made of a compound semiconductor and includes a waveguide 101 that propagates electron spin in the X direction, a first barrier layer 102 arranged on one side of the waveguide 101 in the Z direction intersecting with the X direction, and a second barrier layer 103 arranged on the other side of the waveguide 101, the waveguide 101 being formed by connecting a first waveguide 104 and a second waveguide 105, and the width W of the second waveguide 105 in the Y direction intersecting with the X direction and the Z direction. 2 is the width W of the first waveguide 104. 1 The narrower first barrier layer 102 and the second barrier layer 103 have a larger band gap energy than the waveguide 101 .

Description

[Technical field]

[0001] The present invention relates to an electron spin wave wavelength conversion device, an arithmetic device, and an electron spin wave phase modulation device. [Background technology]

[0002] It is known that the spatial pattern drawn by the electron spin polarization can be used as an information carrier having wave properties called electron spin wave (Non-Patent Document 1). The inventors have developed a technology for optically observing electron spin waves, and it is expected that electron spin waves will be used in various materials including semiconductors. Since the wavelength of the electron spin wave is a continuously changing parameter, it is possible to process a huge amount of information by assigning a different wavelength to each information carrier, and for example, parallel calculations can be performed using multiple information carriers simultaneously. In this case, a technology is required to easily and accurately control the wavelength of the electron spin wave to be assigned, but such a technology has not been established at present. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Y. Kunihashi et al., Nat. Commun. 7, 10722 (2016). Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made in consideration of the above circumstances, and aims to provide an electron spin wave wavelength conversion device that enables easy and accurate control of the wavelength of an electron spin wave, an arithmetic device equipped with the same, and an electron spin wave phase modulation device. [Means for solving the problem]

[0005] In order to solve the above problems, the present invention employs the following means.

[0006] (1) An electron spin wave wavelength conversion device according to one aspect of the present invention includes a waveguide made of a compound semiconductor and propagating electron spin in an X direction, a first barrier layer arranged on one side of the waveguide in a Z direction intersecting the X direction, and a second barrier layer arranged on the other side of the waveguide, the waveguide being formed by connecting a first waveguide and a second waveguide, the width of the second waveguide being narrower than the width of the first waveguide in a Y direction intersecting the X direction and the Z direction, and a material forming the first barrier layer and the second barrier layer has a larger band gap energy than a material forming the waveguide.

[0007] (2) In the electron spin wave wavelength conversion device described in (1) above, it is preferable that one of the first barrier layer and the second barrier layer is made of AlGaAs and the other is made of AlAs, the material of the waveguide is GaAs, and the thickness of the waveguide in the Z direction is 50 nm or less.

[0008] (3) In the electron spin wave wavelength conversion device described in (1) above, it is preferable that the material of the first barrier layer and the second barrier layer is AlGaAs, the material of the waveguide is GaAs, and the thickness of the waveguide in the Z direction is 50 nm or less.

[0009] (4) In the electron spin wave wavelength conversion device described in (1) above, it is preferable that the material of the first barrier layer and the second barrier layer is GaAs, the material of the waveguide is InAs, and the thickness of the waveguide in the Z direction is 50 nm or less.

[0010] (5) In the electron spin wave wavelength conversion device described in any one of (1) to (4) above, it is preferable that the thickness of the first barrier layer and the second barrier layer in the Z direction is 10 nm or more and 100 nm or less, and the thickness of the waveguide in the Z direction is 5 nm or more and 50 nm or less.

[0011] (6) An electron spin wave wavelength conversion device according to another aspect of the present invention includes a waveguide formed by heterojunction of two different compound semiconductor layers, which propagates electron spins in an X direction along an interface of the heterojunction, and a first barrier layer and a second barrier layer arranged on one side of the waveguide in a Z direction intersecting the X direction, the waveguide being formed by connecting a first waveguide and a second waveguide, and at the interface of the heterojunction, a width of the second waveguide is narrower than a width of the first waveguide in a Y direction intersecting the X direction.

[0012] (7) In the electron spin wave wavelength conversion device described in (6) above, one of the first barrier layer and the second barrier layer is made of InAs and the other is made of GaAs, and at least the region of the heterojunction interface made of InAs becomes the waveguide.

[0013] (8) In the electron spin wave wavelength conversion device described in any one of (1) to (7) above, the first waveguide and the second waveguide may be connected via a third waveguide, one end of the third waveguide may be connected to the first waveguide and the other end of the third waveguide may be connected to the second waveguide, and the width in the Y direction may change continuously from the one end to the other end.

[0014] (9) In the electron spin wave wavelength conversion device described in any one of (1) to (8) above, the compound semiconductor may be a III-V group semiconductor.

[0015] (10) In the electron spin wave wavelength conversion device according to any one of (1) to (9) above, a plurality of the second waveguides may be connected to the first waveguide.

[0016] (11) A computing device according to one aspect of the present invention includes the electron spin wave wavelength conversion device according to any one of (1) to (10) above.

[0017] (12) An electron spin wave phase modulation device according to one aspect of the present invention includes the electron spin wave wavelength conversion device according to any one of (1) to (10) above. Effect of the Invention

[0018] According to the present invention, it is possible to provide an electron spin wave wavelength conversion device that enables easy and accurate control of the wavelength of an electron spin wave, an arithmetic device equipped with the same, and an electron spin wave phase modulation device. [Brief description of the drawings]

[0019] [Figure 1] 1A is a perspective view of an electron spin wave wavelength converter according to a first embodiment of the present invention, and FIG. 1B is a perspective view of a waveguide constituting the electron spin wave wavelength converter of FIG. [Diagram 2] FIG. 2 is a diagram illustrating an example of a crystal structure of a compound semiconductor that constitutes a waveguide. [Diagram 3] The figure (left) shows a planar view of an electron spin wave wavelength conversion device from the Y direction, and the figure (right) shows the distribution of electron band gap energy in the Z direction within the electron spin wave wavelength conversion device. [Figure 4] (a) A schematic diagram showing an effective magnetic field generated by an electric field caused by the crystal structure of the waveguide. (b) A schematic diagram showing an effective magnetic field generated by an electric field caused by the energy band structure in the Z direction. (c) A schematic diagram showing a composite effective magnetic field obtained by combining the effective magnetic fields of (a) and (b). [Diagram 5] 1A and 1B are diagrams illustrating an electron spin wave propagating through a waveguide. [Figure 6] 1 is a graph illustrating the relationship between the drift velocity of electrons and the wavelength of electron spin waves. [Figure 7] 13 is a plan view of the waveguide of Modification 1 seen from the Z direction. FIG. [Figure 8] 13 is a plan view of a waveguide according to Modification 2, seen from the Z direction. FIG. [Figure 9]FIG. 13 is a diagram showing the change in wavelength of the electron spin wave of electrons propagating through a waveguide that is made up of three parts of different widths, with a relatively thick part, a thin part, and a thick part being connected in sequence. [Figure 10] FIG. 13 is a diagram showing a simulation result of an example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, the wavelength conversion device and the arithmetic device of the electron spin wave according to the embodiment of the present invention will be described in detail with reference to the drawings. Note that the drawings used in the following description may show the characteristic parts enlarged for convenience in order to make the characteristics easier to understand, and the dimensional ratios of each component may not be the same as the actual ones. In addition, the materials, dimensions, etc. exemplified in the following description are only examples, and the present invention is not limited to them, and can be appropriately changed and implemented within the scope that does not change the gist of the present invention.

[0021] First Embodiment 1(a) is a perspective view of an electron spin wave wavelength converter 100 according to a first embodiment of the present invention. The electron spin wave wavelength converter 100 mainly includes a waveguide 101 for propagating an electron spin wave, a first barrier layer 102, and a second barrier layer 103. The waveguide 101 is plate-shaped (flat) having a substantially flat main surface, and extends in one direction (here, the X direction). In a direction (here, the Z direction) intersecting (preferably perpendicular) to the X direction, the first barrier layer 102 is disposed on one side (here, the upper side) of the waveguide 101, and the second barrier layer 103 is disposed on the other side (here, the lower side) of the waveguide 101.

[0022] 1(b) is a perspective view of the waveguide 101. The waveguide 101 is formed by coupling a first waveguide 104 and a second waveguide 105 that extend in one direction (here, the X direction). An end of the first waveguide 104 and an end of the second waveguide 105 in the X direction are coupled. The first waveguide 104 and the second waveguide 105 may be separate from each other, but are preferably integrated from the viewpoint of not interfering with the propagation of electron spin waves.

[0023] In the Y direction intersecting (preferably perpendicular to) the X and Z directions, the first waveguide 104 and the second waveguide 105 have different widths W. Here, the case is illustrated in which the width W2 of the second waveguide is narrower than the width W1 of the first waveguide.

[0024] The thickness T of the waveguide 101 in the Z direction is approximately uniform throughout. The thickness T may be any thickness that allows the material forming the waveguide to form a quantum well, and for example, the thickness T of the waveguide in the Z direction is preferably 50 nm or less, more preferably 25 nm or less, and even more preferably 10 nm or less, and may be 5 nm or more. If the thickness T is within this range, the motion of the propagating electrons can be restricted to approximately within the XY plane, and if it is thicker than 50 nm, the characteristics approach those of a bulk material, and there is a possibility that the problem of the present invention will not be solved.

[0025] The waveguide 101 is made of a compound semiconductor with broken crystal field symmetry. The compound semiconductor is preferably a III-V group semiconductor, such as GaAs, InAs, InP, or InSb. The compound semiconductor may be either magnetic or non-magnetic, and is selected from materials having smaller energy gaps than the first barrier layer 102 and the second barrier layer 103.

[0026] FIG. 2 is a diagram showing a schematic example of a crystal structure of a compound semiconductor constituting the waveguide 101. Here, the case where the compound semiconductor is GaAs is shown as an example. GaAs has a zinc blende type crystal structure as shown in FIG. 2. In the crystal structure of GaAs, each Ga is relatively positively charged and each As is relatively negatively charged, and an electric field is generated in a direction from each Ga to each As, resulting in a break in the symmetry of the crystal field as a whole. In this way, in a compound semiconductor in which the symmetry of the crystal field is broken, an electric field E1 is generated in a specific direction as a whole.

[0027] The waveguide 101 is sandwiched between a first barrier layer 102 and a second barrier layer 103 in the Z direction. The first barrier layer 102 is bonded to one main surface 101a of the waveguide extending in the XY plane, and the second barrier layer 103 is bonded to the other main surface 101b opposite to the one main surface 101a. The first barrier layer 102 may have a shape that covers at least the one main surface 101a of the waveguide. The second barrier layer 103 may have a shape that covers at least the other main surface 101b of the waveguide.

[0028] The material of the first barrier layer 102 and the material of the second barrier layer 103 may be the same or different from each other, and have a larger band gap energy than the compound semiconductor that constitutes the waveguide 101. For example, when the waveguide 101 is made of GaAs, one of the first barrier layer 102 and the second barrier layer 103 can be made of AlGaAs, and the other can be made of AlAs or AlGaAs. Also, when the waveguide 101 is made of InAs, the material of the first barrier layer 102 and the second barrier layer 103 can be selected from, for example, InP, AlAs, and GaAs.

[0029] The thickness of the first barrier layer 102 and the second barrier layer 103 is not particularly limited, but from the viewpoint of miniaturization, it is preferable to select the thickness from 10 nm or more and 100 nm or less.

[0030] 3 shows a plan view of electron spin wave wavelength converter 100 from the Y direction (left diagram) and a distribution diagram of electron band gap energy in the Z direction within electron spin wave wavelength converter 100 (right diagram). The band gap energies of first barrier layer 102 and second barrier layer 103 act as energy barriers, and the wave function of electrons is nearly localized within waveguide 101, and the region of electron motion is restricted to within waveguide 101. An electric field E2 is generated from the first barrier layer 102 or second barrier layer 103, whichever has the relatively smaller band gap energy, toward the one with the larger band gap energy.

[0031] 4(a) is a schematic diagram in momentum space showing the effective magnetic field H1 generated by the electric field E1 caused by the crystal structure of the waveguide 101. The effective magnetic field H1 is affected by the motion of electrons flowing in the waveguide 101 and is generated in a complexly tilted direction at each position of the crystal structure, and acts on the rotation of the electron spin wave. This effect is called the Dresselhaus spin-orbit interaction.

[0032] Figure 4(b) is a schematic diagram in momentum space showing the effective magnetic field H2 generated by the electric field E2 caused by the Z-direction energy band structure (quantum well structure) of the waveguide. The effective magnetic field H2 is generated in a counterclockwise direction around the Z-direction electric field E2, and acts on the rotation of the electron spin wave. This effect is called the Rashba spin-orbit interaction.

[0033] 4(c) is a schematic diagram showing a composite effective magnetic field H (=H1+H2) obtained by combining two effective magnetic fields H1 and H2. When the effective magnetic fields H1 and H2 are combined, a composite effective magnetic field H tilted in one specific direction is obtained as shown in FIG. 4(c). Electron spins in the waveguide 101 perform precession with the direction of the composite effective magnetic field H as the axial direction.

[0034] 5 is a diagram for explaining an electron spin wave S propagating in the X direction in a waveguide 101 constituting an electron spin wave wavelength conversion device 100. Here, the first barrier layer 102 and the second barrier layer 103 are omitted from the illustration. Electrodes 106c and 106d are connected to both ends 101c and 101d of the waveguide 101, respectively, and a voltage V is applied between both ends of the waveguide 101 via the electrodes 106c and 106d to generate an electric field. Each electron in the waveguide 101 moves under the action of this electric field, and the electron spin of each electron precesses with the direction of the effective magnetic field H as the axial direction, so that the distribution of the electron spin directions propagates as an electron spin wave S in the electric field direction.

[0035] The wavelength λ of the electron spin wave S differs when it propagates in the first waveguide 104 and when it propagates in the second waveguide 105. That is, when the electron spin wave S propagates from the first waveguide 104 side toward the second waveguide 105 side, the wavelength λ2 of the electron spin wave S2 propagating in the second waveguide 105 is longer than the wavelength λ1 of the electron spin wave S1 propagating in the first waveguide 104. Conversely, when the electron spin wave S propagates from the second waveguide 105 side toward the first waveguide 104 side, the wavelength λ1 of the electron spin wave S1 propagating in the first waveguide 104 is shorter than the wavelength λ2 of the electron spin wave S2 propagating in the second waveguide 105.

[0036] If the ratio (W2 / W1) is less than 0.1, the number of electrons colliding with the sidewall of the waveguide 101A increases, making it difficult to suppress the scattering of electrons due to the resistance from the sidewall. Also, if the ratio (W2 / W1) is more than 0.9, the difference between the width W1 and the width W2 becomes small, and the effect of converting the wavelength is weakened.

[0037] The effect of the width W of the waveguide on the wavelength λ of the electron spin wave S will be described. The wavelength λ of the electron spin wave is given by the following formula (1). h / (2π), m, α, β1, β3, and V drift , V Fermi respectively represent the following physical quantities: h / (2π): reduced Planck constant (Dirac constant), m: effective mass of the electron, α: Rashba spin-orbit coupling constant, β1, β3: Dresselhaus spin-orbit coupling constants.

[0038]

number

[0039] Figure 6 shows the drift velocity V of an electron moving under the action of an electric field. drift and the wavelength λ of the electron spin wave. The horizontal axis of the graph is the Fermi velocity V Fermi Drift velocity V drift Ratio (Vdrift / V Fermi ) The vertical axis of the graph indicates the wavelength λ of the electron spin wave. In the graph of Figure 6, m is 0.067m0 (m0 is the rest mass of a free electron) and α is -1.75×10 -13 (eVm), β1 is 1.70×10 -13 (eVm), β3 is 0.41×10 -13 (eVm), the wavelength λ of the electron spin wave is the electron drift velocity V drift The curves are plotted as a function of .

[0040] Drift speed V drift is given by the following equation (2). j, e, and n S respectively represent the following physical quantities: j: current density, e: elementary charge, n S : Carrier density.

[0041]

number

[0042] As shown in the above equation (2), the drift velocity V drift is proportional to the current density j. The current density j is inversely proportional to the cross-sectional area of ​​the waveguide 101 through which the current (electrons) flows, and for example, the smaller the width W of the waveguide 101, the larger the current density j. Therefore, the wavelength λ of the electron spin wave is inversely proportional to the width W of the waveguide 101, and in the first waveguide 104 with a large width W, the wavelength λ1 of the electron spin wave is short, and conversely, in the first waveguide 104 with a small width W, the wavelength λ2 of the electron spin wave is long.

[0043] 7 shows a first modified example of the configuration of the waveguide 101. Fig. 7 is a plan view of the waveguide 101A of the first modified example seen from the Z direction. In the waveguide 101A, the first waveguide 104 and the second waveguide 105 are coupled via the third waveguide 107. The configuration is the same as that of the waveguide 101 except for the presence of the third waveguide 107.

[0044] One end 107a of third waveguide 107 is connected to first waveguide 104, and the other end 107b is connected to second waveguide 105. A width W3 in the Y direction of third waveguide 107 changes continuously from one end 107a to the other end 107b. Here, a case is illustrated in which width W3 decreases continuously and linearly with respect to the distance from first waveguide 104 or second waveguide 105 from one end 107a to the other end 107b.

[0045] In addition, although the example here shows a case where the width W3 of one end side 107a coincides with the width W1 of first waveguide 104, the width W3 of one end side 107a may be smaller than the width W1. Similarly, although the example here shows a case where the width W3 of the other end side 107b coincides with the width W2 of second waveguide 105, the width W3 of the other end side 107b may be larger than the width W2.

[0046] In addition, although the case where both side surfaces 107c, 107d in the Y direction of the third waveguide 107 are flat is illustrated here, both side surfaces 107c, 107d may be curved surfaces convex inward or outward as indicated by the dashed lines. That is, the width W3 may change nonlinearly with respect to the distance from the first waveguide 104 or the second waveguide 105.

[0047] In waveguide 101A, the presence of third waveguide 107 whose width changes continuously makes the change in width W between first waveguide 104 and second waveguide 105 gentler. Therefore, at the connection portion between first waveguide 104 and second waveguide 105, the resistance that electrons receive from the sidewall of waveguide 101A can be reduced, and scattering of electrons at the sidewall can be suppressed.

[0048] Modification 2 relating to the configuration of waveguide 101 is shown. Fig. 8 is a plan view of waveguide 101B of modification 2 seen from the Z direction. In waveguide 101B, a plurality of second waveguides 105 are coupled to one first waveguide 104. Here, a case where the number of coupled second waveguides 105 is two is illustrated as an example, but three or more may be used. The configuration other than the number of coupled second waveguides 105 is the same as the configuration of waveguide 101.

[0049] The width W2 of each second waveguide 105 can be set individually so that the electron spin S is converted to a desired wavelength, and may be the same as or different from each other. The configuration of the waveguide 101B is the same as when the second waveguide 105 in the waveguide 101 is divided into multiple parts, and the current density is the same in each of the multiple second waveguides 105. If the total of the widths W2 of all the second waveguides 105 is smaller than the width W1 of the first waveguide 104, the current density in each second waveguide 105 is larger than the current density in the first waveguide 104. Note that the third waveguide 107 of the first modification may be interposed between the first waveguide 104 and the second waveguide 105.

[0050] In the waveguide 101B, for example, the electron spin wave S can be branched into multiple waves by propagating the electron spin wave S from the first waveguide 104 toward the second waveguide 105. Furthermore, the wavelength of each branched electron spin wave S can be made longer than the wavelength of the electron spin wave S before branching.

[0051] In addition, in the waveguide 101B, for example, a plurality of electron spin waves S can be merged by propagating the electron spin waves S from the second waveguide 105 toward the first waveguide 104. Furthermore, the wavelength of the merged electron spin waves S can be made shorter than the wavelengths of the individual electron spin waves S before the merging.

[0052] As described above, the electron spin wave wavelength conversion device 100 of this embodiment is configured to generate a composite effective magnetic field resulting from two spin-orbit interactions within the waveguide, and the electron spins within the waveguide precess with the direction of this composite effective magnetic field as the axial direction.

[0053] Since the waveguide is formed by connecting a first waveguide and a second waveguide with different widths, when a current is passed between both ends, the current density differs between the first waveguide and the second waveguide, and the electron drift velocity also differs accordingly. In the presence of the above-mentioned composite effective magnetic field, there is a proportional relationship between the electron drift velocity and the wavelength of the electron spin wave, as shown in the above formula (1).

[0054] By utilizing these relationships, the electron spin wave wavelength conversion device 100 can convert the wavelength of the electron spin wave propagating through the waveguide. For example, when the electron spin wave of the wider waveguide (first waveguide 104) is propagated to the narrower waveguide (second waveguide 105), the wavelength of the electron spin wave is converted to be longer. Conversely, when the electron spin wave of the narrower waveguide is propagated to the wider waveguide, the wavelength of the electron spin wave is converted to be shorter.

[0055] A computing device equipped with the electron spin wave wavelength conversion device 100 can process huge amounts of information by assigning a different wavelength to each information carrier, and can perform parallel calculations using multiple information carriers simultaneously, for example.

[0056] Second Embodiment The electron spin wave wavelength converter according to the second embodiment of the present invention differs from the electron spin wave wavelength converter of the first embodiment in the method of confining electrons propagating in the waveguide. The electron spin wave wavelength converter of this embodiment is provided with a waveguide that propagates electron spins in the X direction along the interface (heterointerface) of the heterojunction, in which two different compound semiconductor layers are heterojunctioned. The other configurations are the same as those of the electron spin wave wavelength converter of the first embodiment. In this case, the shape of the potential well that confines electrons in the Z direction is triangular rather than rectangular, but the same effect as that of the electron spin wave wavelength converter of the first embodiment can be achieved.

[0057] In the second embodiment, the material of the first barrier layer and the material of the second barrier layer are different from each other. For example, when one of the first barrier layer and the second barrier layer is InAs, the other can be GaAs. In this case, a waveguide is formed in a region on the InAs side, which has a smaller energy gap than GaAs, at the interface of the heterojunction.

[0058] The thicknesses of the first and second barrier layers are not particularly limited, but are preferably selected to be 250 nm or less in total from the viewpoint of miniaturization. EXAMPLES

[0059] The effects of the present invention will be more clearly understood by the following examples. Note that the present invention is not limited to the following examples, and can be modified as appropriate without departing from the spirit and scope of the present invention.

[0060] We created a waveguide consisting of three sections with different widths, with a relatively thick section, a thin section, and a thick section connected in that order. Figure 9 shows the change in wavelength of the electron spin wave of electrons propagating through this waveguide. The wavelength is short in the thick section, and long in the thin section. It is thought that the phase of the electron spin wave at the connecting section is inverted by the overlap of the short-wavelength electron spin wave propagating through the thick section and the long-wavelength electron spin wave propagating through the thin section.

[0061] Figure 10 is an image showing the simulation results that confirm this inversion. The upper image shows the phase of the electron spin wave propagating through a waveguide of constant thickness. The lower image shows the phase of the electron spin wave propagating through a waveguide consisting of three thickness sections, as shown in Figure 9. The upper and lower sides are colored differently at the position of the dashed line indicating the connecting section. From this result, it can be confirmed that the phase of the electron spin wave is inverted at the connecting section where the waveguide thickness changes.

[0062] As described above, by using an electron spin wave wavelength conversion device, phase modulation of an electron spin wave becomes possible, and the device can be used as a phase modulation device for an electron spin wave. [Explanation of symbols]

[0063] 100....Electron spin wave wavelength conversion device 101, 101A, 101B...Waveguide 102...First barrier layer 103...Second barrier layer 104...First waveguide 105...Second waveguide 106c, 106d...electrode 107...Third waveguide W: Width of the waveguide W1: Width of first waveguide W2: Width of second waveguide W3: Width of third waveguide S: Electron spin wave S1: Electron spin wave in the first waveguide S2: Electron spin wave in the second waveguide λ: wavelength of electron spin wave λ1: wavelength of the electron spin wave in the first waveguide λ2: wavelength of the electron spin wave in the second waveguide

Claims

1. a waveguide made of a compound semiconductor and for propagating electron spin in an X-direction; a first barrier layer disposed on one side of the waveguide in a Z direction intersecting the X direction, and a second barrier layer disposed on the other side of the waveguide; the waveguide comprises a first waveguide and a second waveguide connected together, In a Y direction intersecting the X direction and the Z direction, a width of the second waveguide is narrower than a width of the first waveguide, An electron spin wave wavelength conversion device, characterized in that the materials constituting the first barrier layer and the second barrier layer have a band gap energy larger than that of the material constituting the waveguide.

2. one of the first barrier layer and the second barrier layer is made of AlGaAs and the other is made of AlAs; and the material forming the waveguide is made of GaAs; 2. The electron spin wave wavelength conversion device according to claim 1, wherein the thickness of the waveguide in the Z direction is 50 nm or less.

3. the first barrier layer and the second barrier layer are made of AlGaAs, the waveguide is made of GaAs, 2. The electron spin wave wavelength conversion device according to claim 1, wherein the thickness of the waveguide in the Z direction is 50 nm or less.

4. the first barrier layer and the second barrier layer are made of GaAs, and the waveguide is made of InAs; 2. The electron spin wave wavelength conversion device according to claim 1, wherein the thickness of the waveguide in the Z direction is 50 nm or less.

5. The wavelength conversion device of electron spin waves as described in claim 1, characterized in that the thickness of the first barrier layer and the second barrier layer in the Z direction is 10 nm or more and 100 nm or less, and the thickness of the waveguide is 5 nm or more and 50 nm or less.

6. a waveguide formed by heterojunction of two different compound semiconductor layers, which propagates electron spins in an X-direction along an interface of the heterojunction; a first barrier layer disposed on one side of the waveguide in a Z-direction intersecting with the X-direction; and a second barrier layer disposed on the other side of the waveguide, the waveguide comprises a first waveguide and a second waveguide connected together, Electron spin wave wavelength conversion device, characterized in that at the interface of the heterojunction, in a Y direction intersecting with the X direction, the width of the second waveguide is narrower than the width of the first waveguide.

7. The wavelength conversion device for electron spin waves as described in claim 6, characterized in that one of the first barrier layer and the second barrier layer is made of InAs and the other is made of GaAs, and at least the region of the heterojunction interface made of InAs becomes the waveguide.

8. the first waveguide and the second waveguide are coupled via a third waveguide; The wavelength conversion device for electron spin waves as described in claim 1 or 6, characterized in that the third waveguide has one end connected to the first waveguide and the other end connected to the second waveguide, and the width in the Y direction changes continuously from the one end to the other end.

9. 7. The electron spin wave wavelength conversion device according to claim 1, wherein the compound semiconductor is a III-V group semiconductor.

10. 7. The electron spin wave wavelength conversion device according to claim 1, wherein a plurality of the second waveguides are connected to the first waveguide.

11. An arithmetic device comprising the electron spin wave wavelength conversion device according to claim 1 or 6.

12. An electron spin wave phase modulation device comprising the electron spin wave wavelength conversion device according to claim 1 or 6.

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