Efficient passive broadband gyrator

Abstract

A gyrator for AC signals comprises a Hall effect material, means for coupling an alternating current (I.sub.1; I.sub.4) into the Hall effect material, means for permeating a Hall effect material with a magnetic field that is perpendicular to the plane or surface of the material, and means far converting a current (I.sub.3; I.sub.2), which was generated by the current I.sub.1 perpendicularly to the electric field generated by I.sub.1 in the Hall effect material, into an output voltage (U.sub.4; U.sub.1). A transformer is provided between at least one conductor loop (1a; 2a) made of a normal-conducting or semi-conducting material and at least one conductor loop (1; 2) made of the Hall effect material for coupling the current (I.sub.1; I.sub.4) into the Hall effect material and/or for converting the current (I.sub.3; I.sub.2) in the Hall effect material into the output voltage (U.sub.4; U.sub.1). It was found that eliminating an inefficient galvanic coupling of the Hall effect material to metallic or semi-conducting conductors minimizes the dissipative losses that occur during the conversion of the input current (I.sub.1; I.sub.4) into the output voltage (U.sub.4; U.sub.1). The gyrator can thus also be used for highly sensitive experiments in quantum information processing at low temperatures.

Claims

1. A gyrator for AC signals, comprising a Hall effect material, means for coupling an alternating current (I.sub.1; I.sub.4) into the Hall effect material, means for permeating the Hall effect material with a magnetic field that is perpendicular to the plane or surface of the material, means for converting a current (I.sub.3; I.sub.2), which was generated by the current I.sub.1 perpendicularly to the electric field generated by I.sub.1 in the Hall effect material, into an output voltage (U.sub.4; U.sub.1), wherein a transformer provided between at least one conductor loop made of a normal-conducting or semi-conducting material and at least one conductor loop made of the Hall effect material for coupling the current (I.sub.1; I.sub.4) into the Hall effect material and/or for converting the current (I.sub.3; I.sub.2) in the Hall effect material into the output voltage (U.sub.4; U.sub.1), and the Hall effect material is disposed in at least two segments such that, when a magnetic field is applied, an electromotive force in one segment produces a current flow primarily in the other segment.

2. The gyrator according to claim 1, comprising a second transformer between at least one other conductor loop made of a normal-conducting or semi-conducting material and at least one other conductor loop made of the Hall effect material for coupling the current (I.sub.1; I.sub.4) into the Hall effect material and/or for converting the current (I.sub.3; I.sub.2) in the Hall effect material into the output voltage (U.sub.4; U.sub.1), wherein the conductor loops of the two transformers, which are made of the normal-conducting or semi-conducting material, are inductively decoupled from each other.

3. The gyrator according to claim 2, wherein the Hall effect material forms at least two conductor loops (1) and (2), which are electrically connected to each other at one point and intersect without electrical connection at least at one other point.

4. The gyrator according to claim 3, wherein the one conductor loop (1; 2) is the secondary winding of one of the two transformers, said one of the two transformers being configured for incoupling the input current (I.sub.1; I.sub.4) and/or the second conductor loop (2; 1) is the primary winding of the transformer other of the two transformers, said other of the two transformers being configured for converting the current (I.sub.3; I.sub.2) in the Hall effect material into the output voltage (U.sub.4; U.sub.1).

5. The gyrator according to claim 3, wherein the one conductor loop (1; 2) is the secondary winding of one of the two transformers, said one of the two transformers being configured for incoupling the input current (I.sub.1; I.sub.4) and/or the second conductor loop (2; 1) is the primary winding of the other of the two transformers, said other of the two transformers being configured for converting the current (I.sub.3; I.sub.2) in the Hall effect material into the output voltage (U.sub.4; U.sub.1).

6. The gyrator according to claim 1, wherein the Hall effect material is a quantum Hall effect material.

7. The gyrator according to claim 6, wherein the quantum Hall effect material comprises graphene and/or a semiconductor heterostructure, which forms a two-dimensional electron gas.

8. The gyrator according to claim 1, wherein the Hall effect material forms at least two conductor loops (1) and (2), which are electrically connected to each other at one point and intersect without electrical connection at least at one other point.

9. The gyrator according to claim 1, wherein the Hall effect material comprises a metalloid, in particular a metalloid from the group arsenic, -tin (gray tin), antimony, bismuth or graphite, and/or a doped semiconductor.

10. The gyrator according to claim 1, wherein the Hall effect material occupies a three-dimensional area, which can be represented by moving a two-dimensional area on a closed path in the space.

11. The gyrator according to claim 10, wherein the Hall effect material is disposed as a layer on an insulating substrate and/or the three-dimensional area forms a hollow body from the Hall effect material.

12. The gyrator according to claim 11, wherein one path in the Hall effect material, along the closed path or parallel to this path, is the secondary winding of the transformer for incoupling the input current (I.sub.1; I.sub.4), or the primary winding of the transformer for converting the current (I.sub.3; I.sub.2) in the Hall effect material into the output voltage (U.sub.4; U.sub.1).

13. The gyrator according to claim 10, wherein one path in the Hall effect material, along the circumference of the two-dimensional area, at a point on the closed path, is the secondary winding of the transformer for incoupling the input current (I.sub.1; I.sub.4), or the primary winding of the transformer for converting the current (I.sub.3; I.sub.2) in the Hall effect material into the output voltage (U.sub.4; U.sub.1).

14. The gyrator according to claim 10, wherein the three-dimensional area is a torus.

15. The gyrator according to claim 10, wherein the Hall effect material has at least one opening for feeding magnetic field lines through the three-dimensional area.

16. The gyrator according to claim 10, comprising a magnetic multipole arrangement for permeating the Hall effect material with the magnetic field.

17. The gyrator according to claim 10, further comprising means for generating a local electric auxiliary field in at least one location in the three-dimensional area.

18. The gyrator according to claim 1, wherein the Hall effect material is a material having a Hall angle .sub.H of at least 80 degrees at a magnetic field strength of 1 T.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: shows an exemplary embodiment of the gyrator according to the invention comprising two conductor loops made of Hall effect material;

(2) FIG. 2: shows an exemplary embodiment of the gyrator according to the invention comprising a Hall effect material on a torus surface (a) having two current paths along the torus surface, which are inductively connected to the outside via coils (b, c); and

(3) FIG. 3: shows a magnetic multipole arrangement for realizing a homogeneous perpendicular field along the torus surface.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(4) FIG. 1 shows a schematic illustration of an exemplary embodiment of the gyrator according to the invention. The Hall effect material is segmented into two conductor loops 1 and 2. The magnetic field, which is not shown for the sake of clarity, is homogenous in this space and located perpendicularly to the drawing plane. Coils 1a and 2a are wound around the conductor loops 1 and 2, respectively. An input current I.sub.1, which is coupled in via the coil 1a, produces an electromotive force E.sub.1 in conductor loop 1. The Hall effect converts this electromotive force into a current I.sub.3 through conductor loop 2. This current induces the output voltage U.sub.4 in the coil 2a. If, conversely, an input current I.sub.4 flows through the coil 2a, this produces an electromotive force E.sub.2 in conductor loop 2. As a result of the right-hand rule, the Hall effect converts this electromotive force E.sub.2 into a current I.sub.2 through conductor loop 1 which is 180 phase-shifted in relation to the input current, at the same magnetic field direction. This current induces the output voltage U.sub.1 in the coil 1a, which is likewise 180 phase-shifted in relation to the input current I.sub.4.

(5) FIG. 2 shows a further exemplary embodiment of the gyrator according to the invention. The Hall effect material is disposed on the surface of a torus here (FIG. 2a). The grid of lines covering this surface is only intended to illustrate the three-dimensional structure for visual purposes; the layer made of the Hall effect material is continuous in the light gray regions. The layer is only interrupted by the regions 3 shown in black, in which no current conduction can take place. These regions are used to allow a magnetic multipole field to pass through the torus surface, so that a magnetic field perpendicular to this surface is present substantially everywhere on this surface. Additionally, these regions are used to form defined regions in which the current I.sub.3 can flow along the circumference of the circle, the movement of which created the torus along a larger circle. In the direction perpendicular thereto, the current I.sub.2 can flow parallel to the larger circle.

(6) FIG. 2b shows a coil 1a for inductively coupling the current path for I.sub.2 shown in FIG. 2a to the outside. When an input current I.sub.1 is coupled into the coil, an electric field E.sub.1 is generated along the current path for I.sub.2, the field being converted via the Hall effect into a current I.sub.3 in the direction perpendicular thereto. If, conversely, an electromotive force acts along the path for the current I.sub.3, the Hall effect produces a current I.sub.2, which induces the output voltage U.sub.1 in the coil. For optimal action of the gyrator, the spatial profile of the coil should be approximated as closely as possible to the spatial distribution of the current I.sub.2. Moreover, a second, identical coil is advantageously connected in series to the coil shown in FIG. 2b on the lower face of the torus. The coil is electrically insulated with respect to the Hall effect material.

(7) FIG. 2c shows a coil 2a for inductively coupling the current path for I.sub.3 shown in FIG. 2a to the outside. The different pieces along the larger one of the two circles defining the torus are connected in series. When, due to an input current a current I.sub.3 flows through the coil 1a, this current is converted into the output voltage U.sub.4 by the coil 2a. When, conversely, the coil 2a is acted on by the input current I.sub.4, an electromotive force E.sub.3 is generated along the path for the current I.sub.3, the force being converted by the Hall effect into a current I.sub.2 and inducing the output voltage U.sub.1 in the coil 1a. The coil 2a is electrically insulated both with respect to the coil 1a and with respect to the Hall effect material. There is also no direct inductive coupling between the coils 1a and 2a. For optimal action of the gyrator, the spatial profile of the coil should be approximated as closely as possible to the spatial distribution of the current I.sub.3. The coil 2a may entirely or partially cover the regions 3 shown in black, in which no current conduction is possible.

(8) The two coils 1a or 2a can each be located on the inner side or on the outer side of the torus surface. It is also immaterial whether coil 1a is located above coil 2a, or vice versa.

(9) FIG. 3 shows a sectional view of a magnetic multipole arrangement, which generates a homogeneous perpendicular magnetic field on the surface of the torus, in the equatorial plane of the torus. The field lines originating from magnetic north pass through the regions 3 in which the Hall effect material is interrupted, enter the torus, and exit the torus again perpendicularly in the direction of the magnetic south through the regions to which the Hall effect material is applied. Advantageously further magnets are provided on the outer surface of the torus, such as above and below the drawing plane, so as to provide further magnetic souths there, so that additional field lines perpendicularly exit the surface there.