Spin isolation apparatus, spin asymmetric material producing method, current source, and signal processing method   

Abstract: A spin isolation apparatus comprising a particle source for emitting particles having spins, a receiving section for receiving the particles emitted by the particle source, a magnet for separating the particles into first particles having positive spins and second particles having negative spins, and a trajectory restricting section for isolating the first and the second particles received by the receiving section through restricting trajectories of the first particles and/or the second particles is provided. By applying this apparatus, particles having spins whose every sign is either one of the two signs can be mass-produced.

This is a Continuation of application Ser. No. 12/087,152 filed Jun. 27, 2008, which in turn is a National Phase of Application No. PCT/JP2006/326127 filed Dec. 27, 2006, which claims the benefit of International Application No. PCT/JP2005/024266 filed Dec. 28, 2005. The disclosures of the prior applications are hereby incorporated by reference herein in their entirety.

TECHNICAL FIELD

This invention relates to an apparatus for dividing individual particles having spins into two groups each of which contains particles having spins whose every sign is plus or minus, a method for producing a material including particles having spins whose every sign is plus or minus more than particles having spins of another sign different from the sign of spins of the former particles, a current source supplying electrons having spins whose every sign is plus or minus, and a method for processing electric signals comprised of electrons having spins whose every sign is plus or minus.

BACKGROUND ART

It is well known that spins of individual material particles are involved with magnetic characteristics of substances. Those substances having magnetic characteristics such as various magnets are used as raw materials for producing devices and apparatuses indispensable for industry. Further, a new field of electronics called spin electronics or spintronics has been remarked in recent years. In these fields, it is intended to develop new magnetic materials and semiconductors by applying technologies for controlling not only charges but also spins of electrons. As an example of such technologies, it can be mentioned that a giant magneto-resistance effect is obtained by applying an artificial lattice structure of a metal in which atomic deposition in the normal direction to the stratified layers is artificially controlled. This technology has been applied in producing a GMR head as a magnetic head. Recently, development of MRAM as a nonvolatic magnetic memory is energetically advanced. [Non-patent Reference 1] W. Gerlach and O. Stern, Z. Phys. Vol. 9, 349 (1922). [Non-patent Reference 2] ibid. 353 (1922). [Non-patent Reference 3] Ann. Phys. Vol. 74, 673 (1924) [Non-patent Reference 4] D. Bohm, Quantum Theory (Prentice-Hall, Englewood Cliffs, N.J., 1951). [Non-patent Reference 5] H. Ezawa, “Chap. 10 The development of the quantum theory and paradoxes” in Quantum Mechanics and New Technology, ed. by Physical Society of Japan (Baifukan, Tokyo, 1987) (in Japanese).

DISCLOSURE OF THE INVENTION

When ultimately going ahead with the above technologies for controlling spins, we get a technology, as an unprecedented idea, for producing particles having spins of only either one of the plus and minus signs separately from each other. When isolation of each individual particle with the spin of every specified sign becomes possible, it also becomes possible to create a new material that has never existed in the natural world by applying particles having spins of only either one of the two signs.

According to a first aspect of the present invention, there is provided a spin isolation apparatus which isolates particles each having a spin based on a sign of the spin of each of the particles, the apparatus comprising a particle source which emits the particles; a receiving section which receives the particles emitted by the particle source, a magnet which has two magnet poles arranged apart from each other with a prescribed gap and which is placed between the particle source and the receiving section and which separates the particles into first particles each having a spin of a positive sign and second particles each having a spin of a negative sign, and a trajectory restricting section which is placed between the particle source and the receiving section which restricts the trajectories of at least one of the first particles and the second particles to isolate the first and second particles received by the receiving section.

According to the first aspect of this invention, individual particles having spins can be separated and isolated based on the sign of each spin and the isolated particles each having the spin of a specific sign do not mix with other isolated particles each having the spin of the other sign. Accordingly, each of isolated particles can be independently extracted as a particle having the spin of the plus sign or of the minus sign. A particle source in this invention means an apparatus that emits particle beam such as, for example, silver atomic beam or neutron beam. Moreover, placing, for example, a slit-collimator comprised of two slit apertures separated from each other with a certain distance between the magnet and the particle source, the particle beam can be adjusted like parallel rays of light. Further, the magnet in this invention may be an electromagnet (like, for example, an electromagnet used in the Stern-Gerlach experiment) or a permanent magnet. When particles are for instance silver atoms, an insulator plate can be used as the receiving section. Incidentally, in this invention, “to isolate individual particles” does not restricted only to the case when two types of particles can be completely separated without any mixing with each other. For example, if the two types of particles could not be completely separated, these particles can be regarded as “divided into two” provided that the number of particles of one type is larger than the number of particles of the other type.

In the spin isolation apparatus of this invention, the trajectory restricting section may be a screen having a predetermined aperture and may be placed between the magnet and the receiving section. In this case, since the first particles and the second particles arrived at the receiving section can certainly be separated, there is no fear that these two types of particles may mix with each other.

In the spin isolation apparatus of this invention, the trajectory restricting section may be such a conductive wire, which connects the particle source and the receiving section, which is placed in the gap between the magnet poles, and which branches into two wires at the gap between the magnet poles. In this case, when the particles should be charged particles such as, for example, electrons, since there is no fear that the trajectories may be turned toward the outside of the magnet due to Lorentz forces, the first particles and the second particles can be surely separated.

In the spin isolation apparatus of this invention, the particles each having the spin may be electrons, the receiving section may include storage devices and the magnet can be an electromagnet. In this case, one of the electrons having positive spins and the electrons having negative spins can be stored more than another of the electrons in each storage device.

In the spin isolation apparatus of this invention, the particles each having the spin may be neutrons, the receiving section may be formed by a neutron absorber. In this case, since only neutrons having spins of positive signs or negative signs can be absorbed in the neutron absorber, a spin characteristic (e.g., a magnetic characteristic) of the material that has absorbed neutrons can be altered.

According to the second aspect of this invention, there is provided a method for producing a spin asymmetric substance in which a number of particles each having a positive spin and a number of particles each having negative spins are different, the method including: arranging, side by side, a particle source which emits a beam of particles each having a spin, a magnet having two magnet poles arranged with a predetermined gap, and a substance; emitting the particles having the spin from the particle source; separating the particles each having the spin into the particles each having the positive spin and the particles each having the negative spin by making the particles each having the spin pass through the gap of defined in the magnet; and injecting, into the substance, one of the particles each having the positive spin and the particles each having the negative spin such that the one of the particles is injected more than the other of the particles.

According to the second aspect of this invention, injecting particles having positive spins or particles having negative spins into a material can easily alter physical properties (e.g., magnetic properties) of this material. And it is also possible to produce a condenser containing one of the two types of electrons, that is, the electrons having positive spins and the electrons having negative spins, more than another type of the electrons by injecting one of the two types of the electrons more than another type of the electrons into a capacitor included in the condenser as the material in this invention.

According to the third aspect of this invention, there is provided a current source comprising a plurality of first electrons each having a positive spin; a plurality of second electrons each having a negative spin; a storage section which stores the first and second electrons; and electrodes which output the first and second electrons, wherein a number of the first electrons stored in the storage section and a number of the second electrons stored in the storage section are different from each other.

According to the third aspect of this invention, for example, applying the current source supplying electrons having either one of the positive spins or negative spins as the particle source in the second aspect of this invention, it becomes possible to supply electrons having either one of the higher purity positive spins or negative spins.

According to the fourth aspect of this invention, there is provided a signal processing method comprising: forming the first electric signal with a first electron having a positive spin and forming a second electric signal with a second electron having negative spins.

According to the fourth aspect of this invention, an electric signal provided by the signal processing method of this invention can deal with a large quantity of information simultaneously, because this electric signal includes information of spins in addition to information of whether or not electrons exist.

The signal processing method of this invention may further include forming a compound signal that is compounded from the first electric signal and the second electric signal and decomposing the compound signal into the first electric signal and the second electric signal. In this case, since compounding and/or decomposing signals are freely carried out, these two signals can be dealt with by compressing into one signal.

According to this invention, since particles having positive spins and/or particles having negative spins can be injected into a material, magnetic characteristics of the material can easily be altered.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a situation of a silver atomic beam splitting into two in the gap of magnet poles in an apparatus for the Stern-Gerlach experiment.

FIG. 2A is a diagram illustrating a mask having a rectangular aperture placed just before the glass plate in the Stern-Gerlach experimental apparatus and FIG. 2B is a diagram illustrating an example of the positional relationship between the rectangular aperture and the evaporation pattern.

FIG. 3 is a schematic diagram illustrating an apparatus for mass production of electrons having either one of the positive spins or negative spins associated with magnetic moment.

FIG. 4A illustrates a circuit for compounding a signal comprised of electrons having positive spins and another signal comprised of electrons having negative spins together (dual-spin electron signal compounding circuit) and FIG. 4B illustrates a circuit for dividing the compounded signal into signals each comprised of electrons having either one of the positive spins and negative spins.

FIGS. 5A and 5B are diagrams each illustrating an assembly in which a conductive branched wire shown in FIG. 3 and a magnet are assembled together on a substrate. FIG. 5A shows the case in which a permanent magnet is utilized and FIG. 5B shows the case in which an electromagnet is applied.

FIG. 6 is a schematic diagram illustrating the Stern-Gerlach experimental apparatus.

When we call an apparatus, for producing individual particles each having a spin of the positive sign and individual particles each having a spin of the negative sign separately, as a spin isolation apparatus in short, an apparatus used in the Stern-Gerlach experiment can be reminded as an existent apparatus similar to the spin isolation apparatus (Refer to FIG. 6). Before describing the spin isolation apparatus of this invention in detail, the Stern-Gerlach experiment and the apparatus used in the experiment will be shortly explained below.

FIG. 6 is a schematic diagram illustrating the apparatus used in the Stern-Gerlach experiment (Refer to Non-patent References 1 through 3). Since the shapes of pole tips of the N and S poles are extremely different from each other, a strongly inhomogeneous magnetic field is generated. With regard to silver atomic beams emitted from an electric furnace 50, tracks of the silver atomic beam traveling on the x axis were illustrated according to the drawings by Bohm in the Non-patent Reference 4 (Refer to FIG. 1 in page 593 and FIG. 2 in page 598). However, according to the same Non-patent Reference 4, a trajectory of each individual microscopic particle in motion has been considered not possible to exist like in classical mechanics because of the uncertainty principle (In pages 100-101 in the Non-patent Reference 4, the following description stating that the momentum and position of every particle cannot even exist with simultaneously and perfectly defined values is seen. If so, it turns out that every particle has no trajectory.)

A silver atomic beam 106 emitted from an aperture of an electric furnace (particle source) 50 is collimated by passing through slit apertures of the same shape each cut in two screens 101 and 102 both placed with a certain separation and the resulted atomic beam of a cross section that is laterally long (in the direction of the y axis) impinges on an electromagnet. The aperture opened in each of the individual screens 101 and 102 has the length s=0.8 mm in the direction along the y axis and the width w=0.03˜0.04 mm in the direction along the z axis. Since the shapes of magnet poles (103a and 103b) of an electromagnet 103 extremely lack the symmetry with respect to the xy plane, silver atoms arrived at a glass plate 104 (observation plane) draw a specific evaporation pattern. That is, this evaporation pattern extremely lacks, as shown in FIG. 2B, the symmetry with respect to the y axis although that is symmetric with respect to the z axis. The separation between the pattern drawn by the silver atomic rays each having − spin and the pattern drawn by the silver atomic rays each having + spin in the direction of the z axis becomes maximum (Δz=z−−z+˜0.20 mm) on the z axis getting narrower with larger distance from the z axis and, finally, these two patterns are overlapped with each other.

According to Non-patent Reference 4, since each individual silver atom passes through the region between the two magnet poles instantaneously, the force working to the atom in this region is assumed to be neglected. Further, the x motion of the atom is dealt with by assuming as having the velocity v in accordance with classical mechanics, while the z motion parallel to the magnetic field is assumed to be dealt with quantum mechanically. According to the figure shown in the paper by Stern and Gerlach (FIG. 1 in Non-patent Reference 3), the magnet pole length l in the direction along the x axis is about 10 times longer than the distance d (supposed to be ˜3 mm), that is, the distance from the magnet poles to the observation plane shown in FIG. 6. Although the track of the silver atomic beam drawn according to the figure by Bohm does not split while the beam passes through the electromagnet, it splits into two tracks towards different directions as soon as it gets out of the electromagnet. Because each silver atom should rather be affected by the magnetic field only during its passing through the gap between the magnet poles, the track of the silver atomic beam shown in FIG. 6 is unnatural. However, since Bohm\'s textbook for quantum mechanics is the first one that has dealt with the Stern-Gerlach experiment, the behavior of each silver atom in this experiment will be described according to Bohm for the time being. For simplicity, we deal with only the motion in the xz plane in the following. As for the initial condition, each individual silver atom is assumed to exist at the entrance of the electromagnet when t=0. This means that the origin of a local coordinate system exists on the x axis at the entrance of the electromagnet.

The Hamiltonian of the interaction between a silver atom and the magnetic flux density B in this experiment can be expressed as follows:

H 1 = μ  ( σ · B ) = μ  ( B z B x -    B y B x +    B y - B z ) [ Eq .  1 ]

where σ represents a spin operator (Refer to Non-patent Reference 4, p. 405, Eq. (75)).

Here, let the absolute value of electronic charge, the mass of an electron, Planck\'s constant, and the velocity of light be e, m, h, and c respectively, the magnetic moment μ of the electron is written as follows:

μ = - e   ℏ 2  mc < 0 [ Eq .  2 ]

where the reduced Planck\'s constant is defined by the following Eq. 3:

ℏ = h 2  π

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