Superconducting quantum interference device current amplification unit, amplifier and chip

Abstract

This invention provides a current amplification unit, amplifier, and chip for a superconducting quantum interference device (SQUID), comprising: a superconducting ring series structure, including a series conductor and at least two SQUID superconducting rings; each SQUID superconducting ring is connected in series on the series conductor and alternately distributed on both sides of the series conductor, with adjacent SQUID superconducting rings symmetrically distributed about the midpoint of the series conductor between them; the series conductor provides a first bias current to each SQUID superconducting ring; a first conductor, located on a first side of the superconducting ring series structure, receives a second bias current; a second conductor, located on a second side of the superconducting ring series structure, receives a third bias current; and a current conductor, located between at least two adjacent SQUID superconducting rings, receives the current to be measured. This invention offers high amplification, high signal-to-noise ratio, low interference between adjacent SQUIDs, suitability for high-speed current signal detection, and is more suitable for integrated circuit design and fabrication.

Description

Technical Field

[0001] This invention relates to the field of superconducting technology, and in particular to a current amplification unit, amplifier, and chip for a superconducting quantum interference device. Background Technology

[0002] Superconducting quantum interference devices (SQUIDs) are currently the most sensitive flux-to-voltage conversion devices available for practical use. They convert sensed magnetic flux into voltage signals that can be detected by circuits and instruments. SQUIDs are widely used in systems for detecting extremely weak magnetic signals, such as magnetocardiography, magnetoencephalography, and geophysical magnetic detection. The most commonly used SQUID is the DC SQUID, abbreviated as dc SQUID, hereinafter referred to as SQUID.

[0003] A SQUID is a superconducting ring consisting of two Josephson junctions, J1 and J2, connected in parallel, such as... Figure 1 As shown, signal leads are drawn out at both ends of the junction, P1 and P2; J1 and J2 are typical SIS junctions, with a conventional resistor R0 connected in parallel across their ends; the so-called SIS (superconducting-insulator-superconducting) junction is composed of two superconductors separated by an insulating film of several to tens of nanometers, and its superconducting critical current is I0. SQUIDs are broadband response elements that can respond to input magnetic flux from DC to GHz (109 Hz). Therefore, SQUID amplifiers are particularly suitable for broadband, high-sensitivity current detection, such as low-frequency detection of biocurrents in the heart and brain, high-frequency detection of chip current anomalies, and radio frequency current amplification.

[0004] like Figure 2 As shown, when a DC bias current is injected through the leads, and the DC current flows through Josephson junctions J1 and J2, exceeding the critical current I0, a voltage fluctuation occurs across the junctions. Therefore, a DC voltage Vs can be detected across the SQUID. If an external input magnetic flux Φ is coupled into the superconducting loop formed by the two junctions J1 and J2... i Due to flux quantization and the Josephson effect, the voltage Vs across the SQUID will change with the input magnetic flux Φ coupled to the superconducting ring. i The flux-voltage conversion characteristic changes with the bias current I, resulting in a periodic flux-voltage conversion characteristic. b Below, the SQUID output voltage Vs changes with the input magnetic flux Φ i The changing curve is as follows Figure 3 As shown, Vs / R0I0 is the normalized value, and Φ0 is a magnetic flux quantum.

[0005] Due to its flux-voltage characteristics, a SQUID device is a flux-voltage converter, which can be used not only for magnetic field detection but also for current detection, such as... Figure 4 As shown. As long as a coil Lf is coupled to a SQUID, the current I flowing into Lf... f It is then converted into magnetic flux Φ i The current is sensed by the squid and converted into a voltage Vs, thus achieving current-to-voltage conversion. For example... Figure 5 As shown, although the flux-voltage transfer characteristic of SQUID is nonlinear, it is quasi-linear near the operating point W1 (or W2 or W3). Utilizing this monotonically quasi-linear transfer characteristic, SQUID devices can convert minute changes in magnetic flux into voltage changes, thereby achieving… Figure 4 The weak current I shown f Magnification.

[0006] However, 1) the measured current needs to be input into the SQUID through coil Lf. The more turns the coil has, the more sensitive it is, but the inductance of the coil is proportional to the square of the number of turns, and the reactance increases with increasing inductance. A large-inductance input coil Lf is unsuitable for high-speed signal detection. 2) The output voltage of a single SQUID is relatively small, resulting in low amplification efficiency. 3) Due to... Figure 5 It is known that the linear amplification range of SQUID is only 0.5Φ0, so the range of magnetic flux change generated by the measured current is less than 0.5Φ0, thus limiting the measurement range.

[0007] Therefore, how to improve the efficiency of SQUID current amplifiers, expand their measurement range, and make them suitable for high-speed signal detection has become one of the problems that urgently need to be solved by those skilled in the art.

[0008] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Summary of the Invention

[0009] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a superconducting quantum interference device current amplification unit, amplifier and chip to solve the problems of low efficiency, small measurement range and unsuitability for high-speed signal detection of SQUID current amplifiers in the prior art.

[0010] To achieve the above and other related objectives, the present invention provides a superconducting quantum interference device (QFID) current amplification unit, the superconducting quantum interference device current amplification unit comprising:

[0011] A superconducting ring series structure, a first conductor, a second conductor, and a current conductor;

[0012] The superconducting ring series structure includes a series conductor and N SQUID superconducting rings, where N is a natural number greater than or equal to 2; each SQUID superconducting ring is connected in series on the series conductor and is alternately distributed on both sides of the series conductor, with adjacent SQUID superconducting rings being symmetrically distributed about the midpoint of the series conductor between them; the series conductor provides a first bias current to each SQUID superconducting ring.

[0013] The first conductor is located on the first side of the superconducting ring series structure and receives a second bias current for applying magnetic flux bias to the SQUID superconducting ring on the first side of the series conductor; the second conductor is located on the second side of the superconducting ring series structure and receives a third bias current for applying magnetic flux bias to the SQUID superconducting ring on the second side of the series conductor.

[0014] The current conductor is located between at least two adjacent SQUID superconducting rings and receives the measured current.

[0015] Optionally, the current conductor is a straight structure and passes through the series conductor.

[0016] Optionally, the current conductor is a broken line or a curve, and the current conductor bends sequentially along the outer contour of each SQUID superconducting ring and passes between two adjacent SQUID superconducting rings; one end of the current conductor is located on the first side of the superconducting ring series structure, and the other end is located on the second side of the superconducting ring series structure.

[0017] Optionally, the current conductor is a broken line or a curve, and the current conductor bends sequentially along the outer contour of each SQUID superconducting ring and passes between two adjacent SQUID superconducting rings; the two ends of the current conductor are located on the same side of the superconducting ring series structure.

[0018] To achieve the above and other related objectives, the present invention also provides a superconducting quantum interference device (QFID) current amplification unit, the superconducting quantum interference device current amplification unit comprising:

[0019] A superconducting ring series structure, a first conductor, a second conductor, and (N-1) current conductors;

[0020] The superconducting ring series structure includes a series conductor and N SQUID superconducting rings; each SQUID superconducting ring is connected in series on the series conductor and is alternately distributed on both sides of the series conductor, with adjacent SQUID superconducting rings being symmetrically distributed about the midpoint of the series conductor between them; the series conductor provides a first bias current for each SQUID superconducting ring;

[0021] The first conductor is located on the first side of the superconducting ring series structure and receives a second bias current for applying magnetic flux bias to the SQUID superconducting ring on the first side of the series conductor; the second conductor is located on the second side of the superconducting ring series structure and receives a third bias current for applying magnetic flux bias to the SQUID superconducting ring on the second side of the series conductor.

[0022] Each current conductor is a straight structure, located between two adjacent SQUID superconducting rings, and passes through the series conductors. The current directions of the current conductors on both sides of the same SQUID superconducting ring are opposite.

[0023] Where N is a natural number greater than or equal to 3.

[0024] Optionally, the first conductor and the second conductor are arranged parallel to the series conductor.

[0025] Optionally, the superconducting ring series structure, the first conductor, the second conductor, and the current conductor are located in the same plane.

[0026] To achieve the above and other related objectives, the present invention also provides a chip, which includes at least the superconducting quantum interference device current amplification unit described above.

[0027] To achieve the above and other related objectives, the present invention also provides a superconducting quantum interference device (QFID) current amplifier, the superconducting quantum interference device (QFID) current amplifier comprising:

[0028] The system comprises a first current source, a second current source, a third current source, a measured current generation module, and a superconducting quantum interference device current amplification unit as described in any one of claims 1-7.

[0029] The first current source, the second current source, and the third current source respectively generate a first bias current, a second bias current, and a third bias current;

[0030] One end of the series conductor is connected to the first current source, and the other end is grounded; the connection node between the series conductor and the first current source outputs a detection voltage.

[0031] One end of the first conductor is connected to the second current source, and the other end is grounded;

[0032] One end of the second conductor is connected to the third current source, and the other end is grounded;

[0033] The measured current generating module is used to generate the measured current; one end of the current conductor is connected to the output terminal of the measured current generating module, and the other end is grounded.

[0034] To achieve the above and other related objectives, the present invention also provides a superconducting quantum interference device (QFID) current amplifier, the superconducting quantum interference device (QFID) current amplifier comprising:

[0035] The system comprises a first current source, a second current source, a third current source, a measured current generation module, and at least two superconducting quantum interference device current amplification units cascaded in sequence.

[0036] The first current source, the second current source, and the third current source respectively generate a first bias current, a second bias current, and a third bias current;

[0037] One end of the series-connected wire structure is connected to the first current source, and the other end is grounded; the connection node between the series-connected wire structure and the first current source outputs a detection voltage.

[0038] One end of the first conductor series structure is connected to the second current source, and the other end is grounded;

[0039] One end of the second conductor series structure is connected to the third current source, and the other end is grounded;

[0040] The measured current generation module is used to generate the measured current; one end of each current conductor is connected to the output terminal of the measured current generation module, and the other end is grounded.

[0041] As described above, the superconducting quantum interference device current amplifier, amplifier, and chip of the present invention have the following beneficial effects:

[0042] 1. The superconducting quantum interference device current amplification unit, amplifier and chip of the present invention have high amplification factor and high signal-to-noise ratio; since at least two SQUIDs are used in series, the output voltage amplitude is proportional to the number of SQUIDs in series, and the noise is inversely proportional to the square root of the number of SQUIDs in series.

[0043] 2. The superconducting quantum interference device current amplification unit, amplifier and chip of the present invention adopt a rotationally symmetrical distribution to minimize the interference between adjacent SQUIDs (when the SQUID is working, radio frequency current is excited in the superconducting ring, and when the two SQUID superconducting rings are close to each other, there is radio frequency interference).

[0044] 3. The superconducting quantum interference device current amplification unit, amplifier and chip of the present invention have various input methods for the measured current, and can realize the amplification of single and multi-strand current signals; especially when the bidirectional wiring method is used, the inductance of the current input lead is small, which is suitable for the detection of high-speed current signals.

[0045] 4. The superconducting quantum interference device current amplification unit, amplifier and chip of the present invention adopt a planar wiring method, which is more suitable for integrated circuit design and fabrication. Attached Figure Description

[0046] Figure 1 The diagram shows the structure of a SQUID device with two ends.

[0047] Figure 2 The diagram shows the structure of a SQUID device driven by a bias current source.

[0048] Figure 3 The diagram shows the flux-voltage conversion curves of the SQUID under different bias currents.

[0049] Figure 4 The diagram shows the principle of current detection achieved by coupling a SQUID and a feedback coil.

[0050] Figure 5 The diagram shows the transmission characteristic curve of SQUID as a locally linear curve.

[0051] Figure 6 The diagram shown is a schematic diagram of the first structure of the superconducting quantum interference device current amplification unit of the present invention.

[0052] Figure 7 The diagram shown is a second structural schematic of the current amplification unit of the superconducting quantum interference device of the present invention.

[0053] Figure 8 The diagram shown is a schematic of the third structure of the superconducting quantum interference device current amplification unit of the present invention.

[0054] Figure 9 The diagram shown is a schematic diagram of the fourth structure of the superconducting quantum interference device current amplification unit of the present invention.

[0055] Figure 10 The diagram shown is a fifth structural schematic of the superconducting quantum interference device current amplification unit of the present invention.

[0056] Figure 11 The diagram shown is a sixth structural schematic of the superconducting quantum interference device current amplification unit of the present invention.

[0057] Figure 12 The diagram shown is a seventh structural schematic of the superconducting quantum interference device current amplification unit of the present invention.

[0058] Figure 13 The diagram shown is a structural schematic of a superconducting quantum interference device current amplifier according to the present invention.

[0059] Figure 14 This is a schematic diagram of another structure of the superconducting quantum interference device current amplifier of the present invention.

[0060] Figure 15 The diagram shows the current-voltage transfer characteristic curve of the superconducting quantum interference device current amplification unit of the present invention.

[0061] Figure 16 The diagram shown is another structural schematic of the superconducting quantum interference device current amplifier of the present invention.

[0062] Component designation explanation

[0063] 1. Current Amplification Unit of Superconducting Quantum Interference Device

[0064] 11 Superconducting ring series structure

[0065] 111 Series wires

[0066] 112 SQUID superconducting ring

[0067] 12 First Conductor

[0068] 13 Second conductor

[0069] 14 Current-carrying wires

[0070] 141 First Current Conductor

[0071] 142 Second Current Conductor

[0072] 2 First Current Source

[0073] 3 Second Current Source

[0074] 4. Third Current Source

[0075] 5. Current generation module Detailed Implementation

[0076] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0077] Please see Figures 6 to 16 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0078] Example 1

[0079] like Figure 6As shown, this embodiment provides a superconducting quantum interference device (QFID) current amplification unit 1, which includes:

[0080] The superconducting ring series structure 11, the first wire 12, the second wire 13, and the current wire 14 are arranged in the same plane. In actual use, the superconducting ring series structure 11, the first wire 12, the second wire 13, and the current wire 14 are arranged in the same plane. In actual use, the arrangement can be adjusted as needed to amplify the current to be measured.

[0081] like Figure 6 As shown, the superconducting ring series structure 11 includes a series conductor 111 and N SQUID superconducting rings 112, where N is a natural number greater than or equal to 2. Each SQUID superconducting ring 112 is connected in series on the series conductor 111 and is alternately distributed on both sides of the series conductor 111. Adjacent SQUID superconducting rings 112 are symmetrically distributed about the midpoint of the series conductor between them. The series conductor 111 provides a first bias current I to each SQUID superconducting ring 112. b1 .

[0082] Specifically, the series conductor 111 connects each SQUID superconducting ring 112 in series to form the superconducting series structure 11, and terminals P1 and P2 are respectively led out from both ends of the superconducting series structure 11. The series conductor 111 receives the first bias current I. b1 The center line of the superconducting series structure 11 is used as the center line. In this embodiment, N is set to 2, and is denoted as the first SQUID superconducting ring SQ1 and the second SQUID superconducting ring SQ2, respectively. The first SQUID superconducting ring SQ1 and the second SQUID superconducting ring SQ2 are arranged left and right in a rotationally symmetrical manner with the center line as the reference line (i.e., symmetrical about the midpoint of the series conductor between them). The first SQUID superconducting ring SQ1 is located on one side of the series conductor 111 (left side in the figure as an example), and the second SQUID superconducting ring SQ2 is located on the other side of the series conductor 111 (right side in the figure as an example).

[0083] Specifically, each SQUID superconducting ring 112 includes two Josephson junctions connected in parallel, with both ends connected in series on the series conductor 111. In this embodiment, each SQUID superconducting ring 112 is configured as a quadrilateral structure. The first SQUID superconducting ring SQ1 is composed of four sides a1, b1, c1, and d1. The Josephson junction J12 is connected (in series) in a1, and the Josephson junction J11 can be connected in any of the sides b1, c1, and d1. As an example, the Josephson junction J11 is connected in b1. Similarly, the second SQUID superconducting ring SQ2 is composed of four sides a2, b2, c2, and d2. The Josephson junction J22 is connected (in series) in a2, and the Josephson junction J21 can be connected in any of the sides b2, c2, and d2. In this example, in order to ensure that the first SQUID superconducting ring SQ1 and the second SQUID superconducting ring SQ2 are centrally symmetrical (that is, the first SQUID superconducting ring SQ1 coincides with the second SQUID superconducting ring SQ2 after rotating 180° around the center of symmetry, and the center of symmetry is the midpoint of the series wire between the two), the Josephson junction J21 is connected in b2.

[0084] It should be noted that in actual use, the shape of each SQUID superconducting ring 112 can be set as needed, including but not limited to polygons, circles, ellipses or irregular shapes, and any shape that can form a ring structure is applicable; at the same time, the position of each Josephson junction can also be determined as needed, not limited to this embodiment.

[0085] like Figure 6 As shown, the first conductor 12 is located on the first side of the superconducting ring series structure 11 and receives the second bias current I. b2 The first conductor 111 is used to apply magnetic flux bias to the SQUID superconducting ring 112 on the first side of the series conductor 111; the second conductor 13 is located on the second side of the superconducting ring series structure 11 and receives the third bias current I. b3 It is used to apply magnetic flux bias to the SQUID superconducting ring 112 on the second side of the series conductor 111.

[0086] More specifically, in this embodiment, the first conductor 12 is located on the left side of the superconducting ring series structure 11, close to the c1 side of the first SQUID superconducting ring SQ1, and far from the second SQUID superconducting ring SQ2. Terminals P3 and P4 are respectively led out from both ends of the first conductor 12, and a second bias current I is applied to both ends of the first conductor 12. b2 Then, a magnetic flux bias will be added to the left SQUID superconducting ring (the first SQUID superconducting ring SQ1) (to generate a magnetic flux offset, thereby adjusting the operating zero point), with a mutual inductance of M. 11The effect on the right-side SQUID superconducting ring (the second SQUID superconducting ring SQ2) is negligible. As an example, the second bias current I... b2 The second bias current I flows in from terminal P3 and flows out from terminal P4. b2 A magnetic flux (according to the right-hand rule) will be generated in the first SQUID superconducting ring SQ1, passing through the plane of the ring from the inside out. This magnetic flux is M. 11 I b2 .

[0087] More specifically, in this embodiment, the second conductor 13 is located on the right side of the superconducting ring series structure 11, close to the c2 side of the second SQUID superconducting ring SQ2, and far from the first SQUID superconducting ring SQ1. Terminals P5 and P6 are respectively led out from both ends of the second conductor 13, and a third bias current I is applied to both ends of the second conductor 13. b3 Then, a magnetic flux bias will be added to the right-side SQUID superconducting ring (generating a magnetic flux offset, thereby adjusting the operating zero point), with a mutual inductance of M. 21 The effect on the left-side SQUID superconducting ring is negligible. As an example, the third bias current I... b3 The third bias current I flows in from terminal P5 and flows out from terminal P6. b3 A magnetic flux will be generated in the second SQUID superconducting ring SQ2, flowing from the outside in and passing through the plane of the ring (according to the right-hand rule), and this magnetic flux will be M. 21 I b3 .

[0088] Specifically, in this embodiment, the first conductor 12 and the second conductor 13 are arranged parallel to the series conductor 111, and both are straight structures. In actual use, the first conductor 12 and the second conductor 13 are not necessarily arranged parallel to the series conductor 111. The first conductor 12 and the second conductor 13 are located on both sides of the superconducting ring series structure 11, and can respectively adjust the working zero point of the SQUID superconducting ring 112 on both sides. This embodiment is not the limitation.

[0089] like Figure 6 As shown, the current conductor 14 is located between at least two adjacent SQUID superconducting rings 112 and receives the measured current If.

[0090] Specifically, in this embodiment, the current conductor 14 has a straight structure and passes through the series conductor 111. For example... Figure 6As shown in the example, the series conductor 111 is a straight structure, and the current conductor 14 is perpendicular to the series conductor 111, and the current conductor 14 is located between the first SQUID superconducting ring SQ1 and the second SQUID superconducting ring SQ2. Terminals P7 and P8 are led out from both ends of the current conductor 14. After the current to be measured, If, is applied to both ends of the current conductor 14, it will generate a mutual inductance M with the first SQUID superconducting ring SQ1. 12 Mutual inductance M is generated with the second SQUID superconducting ring SQ2. 22 As an example, the measured current I f Flowing in from terminal P7 and out from terminal P8, a magnetic flux of M is generated from the inside to the outside in the first SQUID superconducting ring SQ1. 12 I f A magnetic flux of M is generated from the outside to the inside in the second SQUID superconducting ring SQ2. 22 I f The magnetic flux is induced by the superconducting ring, and the measured current I is read on the series conductor 111. f The amplified voltage signal Vs.

[0091] It should be noted that, in this embodiment, the first bias current I b1 The second bias current I b2 and the third bias current I b3 The current directions are consistent. In actual use, the direction of each bias current can be set as needed, and is not limited to this embodiment.

[0092] It should be noted that the superconducting quantum interference device current amplification unit 1 in this embodiment may also include at least one SQUID superconducting ring (i.e., N is a natural number greater than or equal to 3), which is connected in series with the first SQUID superconducting ring and the second SQUID superconducting ring. Other structures and principles are the same as those of the superconducting quantum interference device current amplification unit described above, and will not be described in detail here.

[0093] Example 2

[0094] like Figure 7 As shown, this embodiment provides a superconducting quantum interference device current amplification unit 1. The difference from the first embodiment is that the current conductor 14 in this embodiment is a broken line.

[0095] Specifically, the current conductor 14 is bent sequentially along the outer contour of each SQUID superconducting ring 112 and passes between two adjacent SQUID superconducting rings 112; one end of the current conductor 14 is located on the first side of the superconducting ring series structure 11, and the other end is located on the second side of the superconducting ring series structure 11. In this embodiment, the current conductor 14 is wound sequentially along the b1, c1, and d1 sides of the first SQUID superconducting ring SQ1 and the d2, c2, and b2 sides of the second SQUID superconducting ring SQ2, forming an S-shaped bent trace. The two ends of the current conductor 14 are located on both sides of the superconducting ring series structure 11; as an example, the current to be measured I... f The current is input from the right side of the superconducting ring series structure 11 and output from the left side; in actual use, the current direction can be interchanged and is not limited to this embodiment.

[0096] It should be noted that the current conductor 14 can also be configured as a curve, that is, to roughly match the outer contour of each SQUID superconducting ring, but not necessarily to be exactly the same, which will not be elaborated here.

[0097] Compared to the superconducting quantum interference device current amplification unit in Embodiment 1, the mutual inductance M of the current amplification unit in this embodiment is increased. 12 and M 22 This allows for the generation of more magnetic flux within the two superconducting rings. For example... Figure 8 As shown, the number of SQUID superconducting rings can also be increased. For example, N is set to 4, which includes a third SQUID superconducting ring SQ3 and a fourth SQUID superconducting ring SQ4, thereby generating more magnetic flux. The measured current I... f The magnetic flux generated in the third SQUID superconducting ring SQ3 is M 32 I f The magnetic flux generated in the fourth SQUID superconducting ring SQ4 is M. 42 I f The second bias current I b2 The magnetic flux generated on the third SQUID superconducting ring SQ3 is M 31 I b2 The magnetic flux generated by the third bias current Ib3 on the fourth SQUID superconducting ring SQ4 is M. 41 I b32 This will not be elaborated upon in detail.

[0098] Example 3

[0099] like Figure 9 As shown, this embodiment provides a superconducting quantum interference device current amplification unit 1. The difference from embodiment two is that N is set to 3 in this embodiment, and the two ends of the current conductor are located on the same side of the superconducting ring series structure.

[0100] Specifically, the third SQUID superconducting ring SQ3 is located on the same side as the first SQUID superconducting ring SQ1 (i.e., on the left side of the series conductor 111), and the second SQUID superconducting ring SQ2 is located on the other side (i.e., on the right side of the series conductor 111). The third SQUID superconducting ring SQ3 and the second SQUID superconducting ring SQ2 are centrally symmetrical. The third SQUID superconducting ring SQ3 is composed of four sides a3, b3, c3, and d3. A Josephson junction J32 is connected (in series) in a3. a3 is centrally symmetrical with a2, b3 is centrally symmetrical with b2, c3 is centrally symmetrical with c2, and d3 is centrally symmetrical with d2.

[0101] Specifically, the current conductor 14 is wound sequentially along the b1, c1, and d1 sides of the first SQUID superconducting ring SQ1, the d2, c2, and b2 sides of the second SQUID superconducting ring SQ2, and the b3, c3, and d3 sides of the third SQUID superconducting ring SQ3; and the two ends of the current conductor 14 are located on the same side of the superconducting ring series structure 11; as an example, the current to be measured I f The current is input from the right side of the superconducting ring series structure 11 and output from the right side. In actual use, the superconducting quantum interference device current amplification unit 1 of this embodiment can be flipped left and right along the series wire 111. At this time, the current is input from the left side and output from the left side, which is not limited to this embodiment.

[0102] It should be noted that N can be set to a natural number greater than or equal to 4. Following the principle of rotational symmetry between adjacent SQUID superconducting rings, the number of SQUID superconducting rings is increased to improve the series order of the SQUIDs, and the current conductor 14 is wound around them to achieve identical magnetic flux coupling between the input current and each SQUID superconducting ring. When both ends of the current conductor 14 are located on the same side of the superconducting ring series structure 11, the current conductor 14 needs to be wound around the outside of an odd number of SQUID superconducting rings; when both ends of the current conductor 14 are located on opposite sides of the superconducting ring series structure 11, the current conductor 14 needs to be wound around the outside of an even number of SQUID superconducting rings; these details will not be elaborated further here.

[0103] Example 4

[0104] like Figure 10 As shown, this embodiment provides a superconducting quantum interference device current amplification unit 1. The difference between this embodiment and embodiments one to three is that the current conductors 14 are set to N-1, where N is a natural number greater than or equal to 3. By adjusting the arrangement of the current conductors, bidirectional multi-current input detection is achieved.

[0105] like Figure 10As shown, the superconducting quantum interference device current amplification unit 1 includes a superconducting ring series structure 11, a first wire 12, a second wire 13, and M current wires.

[0106] Specifically, in this embodiment, the superconducting ring series structure 11 includes a series conductor 111 and three SQUID superconducting rings (112), respectively denoted as the first SQUID superconducting ring SQ1, the second SQUID superconducting ring SQ2, and the third SQUID superconducting ring SQ3. The first SQUID superconducting ring SQ1, the second SQUID superconducting ring SQ2, and the third SQUID superconducting ring SQ3 are sequentially connected in series on the series conductor 111, and the first SQUID superconducting ring SQ1 and the second SQUID superconducting ring SQ2 are centrally symmetrically distributed, and the second SQUID superconducting ring SQ2 and the third SQUID superconducting ring SQ3 are centrally symmetrically distributed. The first conductor 12 and the second conductor 13 are respectively disposed on both sides of the superconducting ring series structure 11; these will not be described in detail here.

[0107] Specifically, each current conductor is a straight structure, located between two adjacent SQUID superconducting rings and passing through the series conductor. The current directions of the current conductors on both sides of the same SQUID superconducting ring are opposite. In this embodiment, the number of DC conductors is set to two, denoted as the first DC conductor 141 and the second DC conductor 142. As an example, the first DC conductor 141 is perpendicular to the series conductor 111 and is located between the first SQUID superconducting ring SQ1 and the second SQUID superconducting ring SQ2. The second DC conductor 142 is perpendicular to the series conductor 111 and is located between the second SQUID superconducting ring SQ2 and the third SQUID superconducting ring SQ3. Terminals P11 and P12 are led out from both ends of the first current conductor 141, and a first measured current I is applied to both ends of the first current conductor 141. f1 Subsequently, the magnetic flux generated in the first SQUID superconducting ring SQ1 is M. 12 I f1 The magnetic flux generated in the second SQUID superconducting ring SQ2 is M. 22 I f1 Terminals N11 and N12 are respectively led out from the two ends of the second current conductor 142, and a second current to be measured, I, is applied to the two ends of the second current conductor 142. f2 Subsequently, the magnetic flux generated in the second SQUID superconducting ring SQ2 is M. 23 I f2 The magnetic flux generated in the third SQUID superconducting ring SQ3 is M. 33 I f2The magnetic flux is sensed by the superconducting ring, and the first measured current I is read on the series conductor 111. f1 and the second current to be measured I f2 The amplified voltage signal Vs.

[0108] It should be noted that the first current conductor 141 and the second current conductor 142 flow in opposite directions. In this embodiment, the first measured current I... f1 The current flows in from terminal P11 and out from terminal P12; the second measured current I f2 It flows in from terminal N11 and flows out from terminal N12.

[0109] In practical applications, the number of SQUID superconducting rings and current conductors can be further increased to enable the detection and amplification of the sum of measured currents from more circuits. For example, such as... Figure 11 As shown, the superconducting ring series structure 11 includes four SQUID superconducting rings, with three current conductors arranged adjacent to each other, and the current flows in opposite directions between adjacent current conductors; the magnetic flux generated by the third current conductor in the third SQUID superconducting ring SQ3 is M. 32 I f3 The magnetic flux generated in the fourth SQUID superconducting ring SQ4 is M. 42 I f3 As an example, such as Figure 12 As shown, the superconducting ring series structure 11 includes five SQUID superconducting rings, with four current conductors arranged adjacent to each other, and adjacent current conductors flowing in opposite directions; the magnetic flux generated by the fourth current conductor in the fourth SQUID superconducting ring SQ4 is M. 43 I f4 The magnetic flux generated in the fifth SQUID superconducting ring SQ5 is M. 53 I f4 .

[0110] Example 5

[0111] This embodiment provides a chip, which includes at least one of the superconducting quantum interference device current amplification units from Embodiment 1 to Embodiment 4.

[0112] Example 6

[0113] like Figure 13 As shown, this embodiment provides a superconducting quantum interference device (QFID) current amplifier, which includes:

[0114] A superconducting quantum interference device includes a current amplification unit 1, a first current source 2, a second current source 3, a third current source 4, and a measured current generation module 5.

[0115] The first current source 2, the second current source 3, and the third current source 4 respectively generate a first bias current Ib1, a second bias current Ib2, and a third bias current Ib3.

[0116] One end (P1) of the series conductor 111 is connected to the first current source 2, and the other end (P2) is grounded to A-GND; the connection node between the series conductor 111 and the first current source 2 outputs a detection voltage Vs.

[0117] One end (P3) of the first conductor 12 is connected to the second current source 3, and the other end (P4) is grounded to A-GND.

[0118] One end (P5) of the second conductor 13 is connected to the third current source 4, and the other end (P6) is grounded to A-GND.

[0119] The measured current generating module 5 is used to generate the measured current If. One end (P7) of the current conductor 14 is connected to the output terminal of the measured current generating module 5, and the other end (P8) is grounded to S-GND.

[0120] Specifically, in this embodiment, such as Figure 13 As shown, if the superconducting quantum interference device current amplification unit 1 adopts any one of Embodiments 1 to 3, then the measured current generation module 5 generates one current I to be measured. f As another example, such as Figure 14 As shown, the superconducting quantum interference device (SQI) current amplification unit 1 adopts the SQI current amplification unit of Embodiment 4. Therefore, the measured current generation module 5 generates a corresponding number of measured currents I. f Each current to be measured flows into a current conductor (i.e., the number of currents to be measured is the same as the number of current conductors), which will not be elaborated here.

[0121] It should be noted that in actual use, the direction of current flow can be changed, and the corresponding connection relationship of each port can be adjusted accordingly, and is not limited to this embodiment.

[0122] like Figure 13 As shown, a detection voltage Vs can be obtained at both ends of the series conductor; I f The current-voltage characteristic curve of -Vs is as follows: Figure 15 As shown, this can be obtained through scanning. This is achieved by adjusting the second bias current I. b2 and the third bias current I b3The value of can shift the center point b of the characteristic curve to 0, while simultaneously maximizing the voltage difference Vspp between points a (peak) and c (valley) on the characteristic curve. At this point, the superconducting quantum interference device's current amplifier enters its optimal amplification state, utilizing its monotonic amplification curve between points a and c to amplify the measured current signal I. f The amplitude range is determined by the maximum value IL and the minimum value IH of the input current corresponding to points a and c, that is, IL f <IH。

[0123] Example 7

[0124] like Figure 16 As shown, this embodiment provides a superconducting quantum interference device (SQI) current amplifier. The difference between this embodiment and Embodiment 6 is that the superconducting quantum interference device (SQI) current amplifier is obtained by cascading at least two superconducting quantum interference device (SQI) current amplification units 1 as described in Embodiments 1 to 3, so as to realize the summation amplification of multiple currents.

[0125] Specifically, in this embodiment, two superconducting quantum interference device current amplification units cascaded together are used. For example... Figure 16 As shown, the series conductors of the first and second superconducting quantum interference device (SQI) current amplification units are cascaded (connected in series) to form a series conductor structure. The first conductor is cascaded to form a first conductor series structure, and the second conductor is cascaded to form a second conductor series structure, each receiving a corresponding bias current. The first SQI current amplification unit detects the first measured current If1, and the second SQI current amplification unit detects the second measured current If2. The detected voltage Vs outputs the sum of the voltages after amplification of the two currents.

[0126] It should be noted that the first and second superconducting quantum interference device (SQI) current amplification units can be configured with the same structure or different structures. The number of SQI current amplification units can be configured to be more than two, and the SQI current amplification units can be cascaded, which will not be elaborated here.

[0127] It should be noted that, with Figure 14 Compared to the bidirectional wiring scheme of the superconducting quantum interference device (SQID) current amplifier, the bidirectional current detection method has a shorter current line distance, smaller inductance, and faster response to high-speed signals. Furthermore, using the same number of SQUID devices, the bidirectional wiring scheme can connect more current lines, resulting in higher SQUID utilization. However, a drawback is that the current reference direction of the bidirectional current detection method must change from left to right. In contrast, the unidirectional wiring scheme of the superconducting quantum interference device current amplifier in this embodiment has a consistent current reference direction, eliminating the need for strict left-right alternation and simplifying its use. ​

[0128] In summary, this invention provides a current amplification unit, amplifier, and chip for a superconducting quantum interference device (SQUID), comprising: a superconducting ring series structure, a first wire, a second wire, and a current wire; the superconducting ring series structure includes a series wire and N SQUID superconducting rings, where N is a natural number greater than or equal to 2; each SQUID superconducting ring is connected in series on the series wire and is alternately distributed on both sides of the series wire, with adjacent SQUID superconducting rings symmetrically distributed about the midpoint of the series wire between them; the series wire provides a first bias current to each SQUID superconducting ring; the first wire is located on the first side of the superconducting ring series structure and receives a second bias current for applying magnetic flux bias to the SQUID superconducting rings on the first side of the series wire; the second wire is located on the second side of the superconducting ring series structure and receives a third bias current for applying magnetic flux bias to the SQUID superconducting rings on the second side of the series wire; the current wire is located between at least two adjacent SQUID superconducting rings and receives the measured current. The superconducting quantum interference device (SQUID) of this invention features a high amplification factor and a high signal-to-noise ratio in its current amplification unit, amplifier, and chip. It employs a rotationally symmetric distribution to minimize interference between adjacent SQUIDs. The measured current input can be varied, enabling amplification of single-strand and multi-strand current signals. In particular, the bidirectional wiring method results in low inductance of the current input leads, making it suitable for high-speed current signal detection. Furthermore, the planar wiring method is well-suited for integrated circuit design and fabrication. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and possesses high industrial applicability.

[0129] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A current amplification unit for a superconducting quantum interference device, characterized in that, The superconducting quantum interference device current amplification unit includes: A superconducting ring series structure, a first conductor, a second conductor, and a current conductor; The superconducting ring series structure includes a series conductor and N SQUID superconducting rings, where N is a natural number greater than or equal to 2; each SQUID superconducting ring is connected in series on the series conductor and is alternately distributed on both sides of the series conductor, with adjacent SQUID superconducting rings being symmetrically distributed about the midpoint of the series conductor between them; the series conductor provides a first bias current to each SQUID superconducting ring. The first conductor is located on the first side of the superconducting ring series structure and receives a second bias current for applying magnetic flux bias to the SQUID superconducting ring on the first side of the series conductor; the second conductor is located on the second side of the superconducting ring series structure and receives a third bias current for applying magnetic flux bias to the SQUID superconducting ring on the second side of the series conductor. The current conductor is located between at least two adjacent SQUID superconducting rings and receives the measured current.

2. The superconducting quantum interference device current amplification unit according to claim 1, characterized in that: The current conductor is a straight structure and passes through the series conductor.

3. The superconducting quantum interference device current amplification unit according to claim 1, characterized in that: The current conductor is a broken line or a curve. The current conductor bends sequentially along the outer contour of each SQUID superconducting ring and passes between two adjacent SQUID superconducting rings. One end of the current conductor is located on the first side of the superconducting ring series structure, and the other end is located on the second side of the superconducting ring series structure.

4. The superconducting quantum interference device current amplification unit according to claim 1, characterized in that: The current conductor is a broken line or a curve, and the current conductor bends sequentially along the outer contour of each SQUID superconducting ring and passes between two adjacent SQUID superconducting rings; the two ends of the current conductor are located on the same side of the superconducting ring series structure.

5. A current amplification unit for a superconducting quantum interference device, characterized in that, The superconducting quantum interference device current amplification unit includes: A superconducting ring series structure, a first conductor, a second conductor, and (N-1) current conductors; The superconducting ring series structure includes a series conductor and N SQUID superconducting rings; each SQUID superconducting ring is connected in series on the series conductor and is alternately distributed on both sides of the series conductor, with adjacent SQUID superconducting rings being symmetrically distributed about the midpoint of the series conductor between them; the series conductor provides a first bias current for each SQUID superconducting ring; The first conductor is located on the first side of the superconducting ring series structure and receives a second bias current for applying magnetic flux bias to the SQUID superconducting ring on the first side of the series conductor; the second conductor is located on the second side of the superconducting ring series structure and receives a third bias current for applying magnetic flux bias to the SQUID superconducting ring on the second side of the series conductor. Each current conductor is a straight structure, located between two adjacent SQUID superconducting rings, and passes through the series conductors. The current directions of the current conductors on both sides of the same SQUID superconducting ring are opposite. Where N is a natural number greater than or equal to 3.

6. The superconducting quantum interference device current amplification unit according to any one of claims 1-5, characterized in that: The first and second conductors are arranged parallel to the series conductors.

7. The superconducting quantum interference device current amplification unit according to any one of claims 1-5, characterized in that: The superconducting ring series structure, the first conductor, the second conductor, and the current conductor are located in the same plane.

8. A chip, characterized in that, The chip includes at least: a superconducting quantum interference device current amplification unit as described in any one of claims 1-7.

9. A superconducting quantum interference device current amplifier, characterized in that, The superconducting quantum interference device current amplifier includes: The system comprises a first current source, a second current source, a third current source, a measured current generation module, and a superconducting quantum interference device current amplification unit as described in any one of claims 1-7. The first current source, the second current source, and the third current source respectively generate a first bias current, a second bias current, and a third bias current; One end of the series conductor is connected to the first current source, and the other end is grounded; the connection node between the series conductor and the first current source outputs a detection voltage. One end of the first conductor is connected to the second current source, and the other end is grounded; One end of the second conductor is connected to the third current source, and the other end is grounded; The measured current generating module is used to generate the measured current; one end of the current conductor is connected to the output terminal of the measured current generating module, and the other end is grounded.

10. A superconducting quantum interference device current amplifier, characterized in that, The superconducting quantum interference device current amplifier includes: The system comprises a first current source, a second current source, a third current source, a measured current generation module, and at least two superconducting quantum interference device current amplification units as described in any one of claims 1-4 and 6-7, which are cascaded in sequence. The first current source, the second current source, and the third current source respectively generate a first bias current, a second bias current, and a third bias current; One end of the series-connected wire structure is connected to the first current source, and the other end is grounded; the connection node between the series-connected wire structure and the first current source outputs a detection voltage. One end of the first conductor series structure is connected to the second current source, and the other end is grounded; One end of the second conductor series structure is connected to the third current source, and the other end is grounded; The measured current generation module is used to generate the measured current; one end of each current conductor is connected to the output terminal of the measured current generation module, and the other end is grounded.

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