Signal conditioner and circuit for pulse-driven quantum voltage system

Abstract

The invention discloses a signal conditioner and circuit for a pulse-driven quantum voltage system. The signal conditioner comprises a signal isolation unit, a signal conditioning unit and a power supply unit, the receiving end of the signal isolation unit is connected with a first signal source, and the output end is connected with the first receiving end of the signal conditioning unit; a second receiving end of the signal conditioning unit is connected with a second signal source, and an output end of the signal conditioning unit outputs conditioned signals; the power supply unit is connected to the signal conditioning unit for power supply. The conditioner simultaneously has a signal conditioning function and a quantum step observation interface function, can be used for establishing a broadband, low-noise and electrically isolated signal measurement environment for a pulse type quantum voltage system, and realizes a function of introducing a low-frequency compensation signal generated by a low-frequency signal source into a Josephson junction; and an interface for observing and checking the width of the quantum voltage step can also be provided.

Description

Technical Field

[0001] This invention relates to the fields of precision metrology and quantum technology, and in particular to a signal conditioner and circuitry for pulse-driven quantum voltage systems. Background Technology

[0002] In pulse-driven quantum voltage systems, when generating microvolt-level AC voltages, the low-frequency components of the microwave pulse signal are filtered out and need to be compensated to prevent distortion of the generated microvolt-level AC voltage signal. Existing methods utilize an external signal source to generate a low-frequency AC signal, which is then input to the pulse-driven Josephson junction in the pulse-driven quantum voltage system after passing through a fixed resistor. However, because a ground loop is formed between the external signal source and ground, electromagnetic interference generated by common-impedance circuit coupling may cause output signal distortion, introducing new error factors and increasing the difficulty of adjusting the drive signal and synthesizing high-accuracy micro-AC quantum voltages. This drive signal drives the Josephson junction in the pulse-driven quantum voltage system to generate AC quantum voltage.

[0003] To address the aforementioned issues, there is an urgent need to provide a signal conditioner and circuit for pulse-driven quantum voltage systems. This conditioner should possess both signal conditioning and quantum step observation interface functions. It can be used to establish a broadband, low-noise, and electrically isolated signal measurement environment for pulse-driven quantum voltage systems, enabling the introduction of low-frequency compensation signals generated by low-frequency signal sources into Josephson junctions. Furthermore, it can provide an interface for observing and verifying the width of quantum voltage steps. Summary of the Invention

[0004] The purpose of this invention is to provide a signal conditioner for pulse-driven quantum voltage systems, which establishes a wideband, low-noise, and electrically isolated signal measurement environment for pulse-driven quantum voltage systems. It enables the introduction of low-frequency compensation signals generated by low-frequency signal sources into the Josephson junction. Simultaneously, it provides an interface for observing and verifying the quantum voltage step width. The signal conditioner outputs a drive current to drive the Josephson junction of the pulse-driven quantum voltage system. By simultaneously inputting the drive current and the output voltage generated by the Josephson junction onto an oscilloscope, the IV curve of the Josephson junction can be observed. The quantum voltage step width, i.e., the current variation range where the voltage value remains constant, is the step width.

[0005] The present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a signal conditioner circuit for a pulse-driven quantum voltage system, comprising a signal isolation unit, a signal conditioning unit, and a power supply unit;

[0007] The receiving end of the signal isolation unit is connected to the first signal source, and the output end is connected to the first receiving end of the signal conditioning unit.

[0008] The second receiving end of the signal conditioning unit is connected to the second signal source, and the output end outputs the conditioned signal.

[0009] The power supply unit supplies power to the signal conditioning unit.

[0010] In some possible implementations, the signal isolation unit circuit includes a Josephson junction BNC signal input port, a resistor R5 connected in parallel with the BNC signal input port, and a current transformer connected in parallel with the resistor R5. The output of the current transformer includes a first coil output and a second coil output, which are connected to the first receiving end of the signal conditioning unit.

[0011] In some possible implementations, the current transformer is manufactured as follows:

[0012] The current transformer core adopts a toroidal structure. According to the magnetic flux calculation, the magnet cross-section is required to ensure that the magnetic flux is not saturated under the working current. The core is made of manganese-zinc ferrite material. Multi-core stranded wires are selected to reduce the high-frequency skin effect. The number of turns at the primary input end of the coil is equal to the number of turns at the secondary output end.

[0013] In some possible implementations, the signal conditioning unit includes a first conditioning unit, a second conditioning unit, a signal superposition unit, and a voltage-to-current conversion unit;

[0014] The first conditioning unit, with operational amplifier N1 as its core, conditions the output signal of the signal isolation unit;

[0015] The second conditioning unit, with operational amplifier N4 as its core, conditions the signal output from the second signal source in the preceding stage.

[0016] The signal superposition unit, with operational amplifier N3 as its core, superimposes the signals output by the first conditioning unit and the second conditioning unit.

[0017] The voltage-to-current conversion unit, with operational amplifier N2 as its core, converts the voltage output from the signal superposition unit into a current output.

[0018] In some possible implementations, the output signal of the signal isolation unit is a sinusoidal signal floating on the signal isolation unit, and the signal output by the second signal source in the preceding stage is a low-frequency triangular wave signal.

[0019] In some possible implementations, the first conditioning unit and the second conditioning unit are respectively selected as LM7171 amplifier and TL071 amplifier, and are equipped with multiple matching resistors to suppress common-mode noise introduced at the input signal terminal and achieve impedance matching.

[0020] In some possible implementations, the signal superposition unit and the voltage-to-current conversion unit are respectively selected as LM7171 amplifier and LM6171 amplifier. The voltage-to-current conversion unit is equipped with a resistor R2 to directly control the gain ratio of the output voltage and the converted current, and ultimately determine the magnitude of the output current value.

[0021] In some possible implementations, the voltage-to-current conversion unit is further provided with a combination of resistor R3 and switch S1 for releasing the voltage in the circuit.

[0022] In some possible implementations, the first conditioning unit, the second conditioning unit, the signal superposition unit, and the voltage-current conversion unit are all provided with capacitors, which are used to stabilize the power supply and filter out high-frequency and low-frequency interference waves introduced by the power supply.

[0023] In a second aspect, the present invention also provides a signal conditioner for a pulse-driven quantum voltage system, comprising an external shielding box and an internal circuit, wherein the external shielding box is made of hard aluminum and the internal circuit comprises the signal conditioner circuit for a pulse-driven quantum voltage system described in the first aspect.

[0024] The present invention provides a signal conditioner and circuit for a pulse-driven quantum voltage system, which has the following advantages:

[0025] 1. This invention utilizes a signal conditioner to input a compensation signal into a pulse-driven quantum voltage system. The signal isolation unit solves the problem of electromagnetic interference caused by common-ground impedance circuit coupling in existing technologies, which introduces new errors. The signal isolation unit of the signal conditioner isolates the ground loop introduced by the front-end signal source, greatly reducing the common-ground impedance circuit coupling of the input signal. This avoids the generation of a small additional voltage on the Josephson junction output signal due to common-ground impedance circuit coupling, improving measurement accuracy. The differential amplifier selected in the signal conditioning unit suppresses noise introduced by the front-end signal source, effectively suppressing common-mode noise caused by various environmental noises and enabling the signal to float, thus improving the operational stability of the Josephson junction from noise interference.

[0026] 2. This invention utilizes a signal conditioner to excite the Josephson junction by superimposing a sine wave with a triangular wave, thereby achieving the scanning of the Josephson junction steps. This avoids the complex method of using a current scanning source or other methods to perform step scanning before quantum voltage experiments, which is common in traditional schemes. This reduces the number of instruments, simplifies the operation process, and improves work efficiency.

[0027] 3. This invention provides a new current transformer to solve the problem of the narrow applicable frequency range of existing commercial isolation components. It uses manganese-zinc ferrite as the magnetic core, which has excellent high-frequency characteristics and can achieve low-loss ground isolation of broadband signals from 10Hz to 1MHz. The input resistance design achieves impedance matching with the signal source, which can significantly improve the electromagnetic interference caused by common-ground impedance circuit coupling.

[0028] 4. The power supply unit uses batteries, which can reduce power supply noise, crosstalk between channels, and the impact on the ground loop. Attached Figure Description

[0029] Figure 1 This is a block diagram of a signal conditioner for a pulse-driven quantum voltage system.

[0030] Figure 2 This is the circuit schematic of the signal isolation unit;

[0031] Figure 3 This is a structural diagram of a current transformer;

[0032] Figure 4 This is the circuit schematic of the signal conditioning unit.

[0033] In the diagram: 1-Signal isolation unit, 2-Signal conditioning unit, 3-Power supply unit, 4-Ring structure, 5-50 turns. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. At the same time, in the description of the embodiments of this application, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0035] Example 1

[0036] This embodiment provides a signal conditioner circuit for a pulse-driven quantum voltage system, including a signal isolation unit, a signal conditioning unit, and a power supply unit, such as... Figure 1 As shown;

[0037] Signal isolation unit circuit, such as Figure 2As shown, it includes a Josephson junction BNC signal input port, a resistor R5 connected in parallel with the BNC signal input port, and a current transformer connected in parallel with resistor R5, where R5 = 50Ω. The current transformer can achieve low-loss isolation for signals from 10Hz to 1MHz; the output terminal of the current transformer includes the first coil output terminal ( Figure 2 The coil output 1) and the second coil output terminal ( Figure 2 The coil output 2) is connected to the first receiving end of the signal conditioning unit. Figure 4 (Connected to coil output 1 and coil output 2); the receiving end of the signal isolation unit is connected to the first signal source ( Figure 1 The signal source (input 1) is connected to the signal conditioning unit's first receiver. Figure 4 The first receiving terminal of the signal conditioning unit is connected to coil output 1 and coil output 2; specifically, the input of the signal isolation unit is the voltage signal from the output of the preceding signal source, and the output of the signal isolation unit is the voltage signal output of the current transformer. The input of the signal conditioning unit is connected to the output of the signal isolation unit and the voltage signal from the output of the preceding signal source. Figure 1 The signal source in the input (input 2).

[0038] The signal isolation unit circuit is used to achieve impedance matching between the signal conditioner and the signal source. The input signal of the signal isolation unit is the pre-amplifier signal source (input 1). The pre-amplifier signal source is a general-purpose instrument. To ensure signal stability and reduce signal noise interference, its power supply terminal needs to be grounded. However, the grounding design of the pre-amplifier signal source will cause common-mode interference noise in the pulsed quantum voltage system. Therefore, a signal isolation unit is used to make the signal input to the Josephson junction float, thereby establishing a low-noise and electrically isolated signal measurement environment for the pulsed quantum voltage system.

[0039] The electromagnetic isolator in the signal isolation unit is a self-made current transformer, which can achieve low-loss isolation of signals from 10Hz to 1MHz, enabling the establishment of a broadband signal measurement environment for pulsed quantum voltage systems. The fabrication method of the current transformer is as follows, and its structure is as follows: Figure 3 As shown:

[0040] The current transformer core adopts a toroidal structure with dimensions of 63×38×20. According to the magnetic flux calculation, the magnet cross-section is required to ensure that the magnetic flux is not saturated under the working current. The core is made of manganese-zinc ferrite material. AWG36 Litz wire is selected for the conductor to reduce the high-frequency skin effect. The number of turns at the primary input end and the secondary output end of the coil are equal, which is 50 turns.

[0041] The signal conditioning unit is used to achieve voltage-to-current conversion, input signal superposition, and impedance matching, such as... Figure 4As shown, it mainly includes a first conditioning unit, a second conditioning unit, a signal superposition unit, and a voltage-to-current conversion unit.

[0042] The first conditioning unit, with operational amplifier N1 as its core, conditions the output signal of the signal isolation unit.

[0043] The second conditioning unit, with operational amplifier N4 as its core, conditions the signal output from the second signal source of the preamplifier; the output signal of the signal isolation unit is a sinusoidal signal floating to the signal isolation unit, and the signal output from the second signal source of the preamplifier is a low-frequency triangular wave signal.

[0044] The first conditioning unit and the second conditioning unit are respectively equipped with LM7171 amplifier N1 and TL071 amplifier N4, and have multiple matching resistors. Among them, the matching resistors R1, R4, R6, R9, R11, R13, R14, and R16 are 100kΩ, and the matching resistors R7, R8, and R10 are 10kΩ, which are used to suppress common-mode noise introduced at the input signal terminal and achieve impedance matching.

[0045] The signal superposition unit uses operational amplifier N3 as its core and selects LM7171 to superimpose the two signals output from the first conditioning unit and the second conditioning unit.

[0046] The voltage-to-current conversion unit uses operational amplifier N2 as its core and selects TL071 to convert the voltage output from the signal superposition unit into current output.

[0047] The voltage-to-current conversion unit is equipped with a resistor R2 = 270Ω, which directly controls the gain ratio of the output voltage and the converted current, and ultimately determines the magnitude of the output current. The voltage-to-current conversion unit is also equipped with a resistor R3 = 100Ω and a switch S1 combination, which is used to release the voltage in the circuit and prevent the additional voltage of the signal conditioner from causing the frozen magnetic flux of the Josephson junction during the process of connecting the signal conditioner to the Josephson junction.

[0048] Capacitors are provided in the first conditioning unit, the second conditioning unit, the signal superposition unit, and the voltage-current conversion unit. The capacitors are used to stabilize the power supply and filter out high-frequency and low-frequency interference waves introduced by the power supply.

[0049] The voltage-to-current conversion unit is equipped with a resistor R3, a switch S1, and an output connector X3 (connected to the Josephson junction) to form a Josephson junction protection circuit. After the Josephson junction stops working, the switch S1 is closed to eliminate the residual drive current in the Josephson junction, thus protecting the Josephson junction.

[0050] The second receiver of the signal conditioning unit is connected to the second signal source. Figure 1 The signal source (input 2) in the middle, and the output terminal outputs the conditioned signal ( Figure 1Bias current (output) in the middle;

[0051] The power supply unit supplies power to the signal conditioning unit.

[0052] The working principle of this invention is summarized as follows: (1) Before the pulsed quantum voltage system is working, the signal conditioner is used to provide an interface for observing and verifying the width of the quantum voltage step, thereby ensuring that the pulsed quantum voltage system can work normally. At this time, the low-frequency triangular wave signal output by the front-end signal source (input 2) is added to the low-frequency compensation signal of the front-end signal source (input 1) (the low-frequency compensation signal is a sine wave, used to generate driving current so that the Josephson junction works at the center point of the quantum step) through the signal conditioning unit, thereby realizing the amplitude change of the low-frequency compensation signal, thereby realizing the current scanning function of the quantum step. The triangular wave of the front-end signal source (input 2) is superimposed on the sine wave to realize the width scanning from the start point to the end point of the step near the midpoint of the step. When the step width is adapted to the parameters of the Josephson junction, it indicates that the pulsed quantum voltage system can work normally.

[0053] (2) When the pulsed quantum voltage system is working, the signal conditioner is used to establish a wideband, low-noise and electrically isolated signal measurement environment for the pulsed quantum voltage system: the low-frequency compensation voltage signal (sine wave) output by the front-end signal source (input 1) is isolated and floated to ground by the signal isolation unit. The isolated signal is suppressed by the differential amplifier of the signal conditioning unit to suppress common-mode noise caused by various environmental noises. The signal conditioner is converted from voltage to current signal by the next stage operational amplifier of the signal conditioning unit to generate a driving current to drive the Josephson junction to work. According to the principle that the feedback operational amplifier operates in the linear region with approximate virtual short and virtual open at the two input terminals, the signal conditioning unit converts the low-frequency compensation voltage signal into a current signal to the output port of the operational amplifier to drive the Josephson junction to work.

[0054] Example 2

[0055] This embodiment provides a signal conditioner for a pulse-driven quantum voltage system, including an external shielding box and an internal circuit. The external shielding box is made of hard aluminum, and the internal circuit includes the signal conditioner circuit for a pulse-driven quantum voltage system of Embodiment 1.

[0056] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A signal conditioning circuit for a pulse-driven quantum voltage system, characterized in that, Includes a signal isolation unit, a signal conditioning unit, and a power supply unit; The receiving end of the signal isolation unit is connected to the first signal source, and the output end is connected to the first receiving end of the signal conditioning unit. The second receiving end of the signal conditioning unit is connected to the second signal source, and the output end outputs the conditioned signal. The power supply unit supplies power to the signal conditioning unit.

2. The signal conditioner circuit for a pulse-driven quantum voltage system according to claim 1, characterized in that, The signal isolation unit includes a Josephson junction BNC signal input port, a resistor R5 connected in parallel with the BNC signal input port, and a current transformer connected in parallel with the resistor R5. The output terminals of the current transformer include a first coil output terminal and a second coil output terminal, which are connected to the first receiving terminal of the signal conditioning unit.

3. The signal conditioner circuit for a pulse-driven quantum voltage system according to claim 1 or 2, characterized in that, The current transformer is manufactured as follows: The current transformer core adopts a toroidal structure. According to the magnetic flux calculation, the magnet cross-section is required to ensure that the magnetic flux is not saturated under the working current. The core is made of manganese-zinc ferrite material. Multi-core stranded wires are selected to reduce the high-frequency skin effect. The number of turns at the primary input end of the coil is equal to the number of turns at the secondary output end.

4. The signal conditioner circuit for a pulse-driven quantum voltage system according to claim 1 or 2, characterized in that, The signal conditioning unit includes a first conditioning unit, a second conditioning unit, a signal superposition unit, and a voltage-to-current conversion unit; The first conditioning unit, with operational amplifier N1 as its core, conditions the output signal of the signal isolation unit; The second conditioning unit, with operational amplifier N4 as its core, conditions the signal output from the second signal source in the preceding stage. The signal superposition unit, with operational amplifier N3 as its core, superimposes the signals output by the first conditioning unit and the second conditioning unit. The voltage-to-current conversion unit, with operational amplifier N2 as its core, converts the voltage output from the signal superposition unit into a current output.

5. The signal conditioner circuit for a pulse-driven quantum voltage system according to claim 4, characterized in that, The output signal of the signal isolation unit is a sinusoidal signal floating on the signal isolation unit, and the output signal of the second signal source in the front stage is a low-frequency triangular wave signal.

6. The signal conditioner circuit for a pulse-driven quantum voltage system according to claim 4 or 5, characterized in that, The first conditioning unit and the second conditioning unit are respectively equipped with LM7171 amplifier and TL071 amplifier, and have multiple matching resistors to suppress common-mode noise introduced at the input signal terminal and achieve impedance matching.

7. The signal conditioner circuit for a pulse-driven quantum voltage system according to claim 6, characterized in that, The signal superposition unit and the voltage-to-current conversion unit are respectively equipped with LM7171 amplifier and LM6171 amplifier. The voltage-to-current conversion unit is equipped with resistor R2, which directly controls the gain ratio of the output voltage and the conversion current, and ultimately determines the magnitude of the output current value.

8. The signal conditioner circuit for a pulse-driven quantum voltage system according to claim 7, characterized in that, The voltage-to-current conversion unit is also equipped with a combination of resistor R3 and switch S1 to release the voltage in the circuit.

9. The signal conditioner circuit for a pulse-driven quantum voltage system according to claim 4, characterized in that, The first conditioning unit, the second conditioning unit, the signal superposition unit, and the voltage-current conversion unit are all equipped with capacitors. The capacitors are used to stabilize the power supply and filter out high-frequency and low-frequency interference waves introduced by the power supply.

10. A signal conditioner for a pulse-driven quantum voltage system, characterized in that, It includes an external shielding box and an internal circuit, wherein the external shielding box is made of hard aluminum, and the internal circuit is a signal conditioner circuit for a pulse-driven quantum voltage system as described in any one of claims 1-9.

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