Semiconductor quantum dot measurement method, measurement and control system and quantum computer

Abstract

The invention discloses a semiconductor quantum dot measurement method, a measurement and control system and a quantum computer. The method comprises the following steps: adjusting an impedance matching circuit in a measurement link to enable the impedance of an induction quantum dot to be matched with the characteristic impedance of the measurement link; applying a first direct-current voltage signal, a first radio frequency reading signal and a second direct-current voltage signal to the grid electrode of the induction quantum dot to obtain a coulomb peak phase diagram of the induction quantum dot; determining a first target voltage of the first direct-current voltage signal and a second target voltage of the second direct-current voltage signal according to a change value of a reflection voltage in the coulomb peak phase diagram; and applying a second direct-current voltage signal to the grid electrode of the bit quantum dot, and respectively applying a first direct-current voltage signal of which the voltage value is the first target voltage, a second direct-current voltage signal of which the voltage value is the second target voltage and a first radio frequency reading signal to the grid electrode of the sensing quantum dot to read information of the sensing quantum dot. According to the invention, the measurement efficiency of the semiconductor quantum chip is improved.

Description

Technical Field

[0001] The present application relates to the field of quantum computer technology, and in particular to a semiconductor quantum dot measurement method, a measurement and control system, and a quantum computer. Background Art

[0002] Among the many quantum computing physical systems, silicon-based spin qubits (also known as semiconductor quantum dots) are internationally recognized as one of the physical systems that are expected to achieve scalable, large-scale, practical general quantum computing in the future due to their unique advantages such as compatibility with traditional CMOS industrial manufacturing processes, ultra-long quantum coherence characteristics, and potential for application in temperature ranges above 1.5K.

[0003] The spin state of silicon-based spin qubits is difficult to obtain through direct measurement. The more common measurement scheme internationally is to utilize the coupling between charge detectors and qubits, and adopt the charge-spin conversion mechanism to convert the change information of the electron spin state in the quantum dot into the change of transport resistance in the neighboring charge detector, thereby realizing the spin state information detection of silicon-based spin qubits.

[0004] However, this solution also has obvious drawbacks. For example, using amplifiers and high-precision signal acquisition equipment at room temperature to measure the charge detector usually requires an integration time of 30μs-1ms; the RC filter circuit composed of the DC measurement link's own parasitic capacitance and the charge detector's large transport resistance limits the system's measurement bandwidth to the order of 0-10kHz, and the lower system measurement bandwidth cannot effectively reduce the impact of 1 / f noise on the measurement and control system and quantum chip. The initialization and manipulation of spin quantum bits are both in the nanosecond or microsecond scale, and the above-mentioned slow reading method greatly limits the readout speed of silicon-based spin quantum bits. Summary of the invention

[0005] The present application provides a semiconductor quantum dot measurement method, a measurement and control system, and a quantum computer, which solve the problem of low measurement efficiency of spin quantum dots in the prior art and improve the measurement efficiency.

[0006] On one hand, the present application provides a method for measuring semiconductor quantum dots. Bit quantum dots and sensing quantum dots having mutual coupling are formed on a semiconductor quantum chip. The state of the sensing quantum dots is read through a measurement link to obtain information of the bit quantum dots. The method comprises:

[0007] Adjusting an impedance matching circuit in the measurement link so that the impedance of the sensing quantum dot matches the characteristic impedance of the measurement link;

[0008] Applying a first DC voltage signal, a first radio frequency reading signal and a second DC voltage signal to the gate of the sensing quantum dot to obtain a Coulomb peak phase diagram of the sensing quantum dot;

[0009] Determine a first target voltage of the first DC voltage signal and a second target voltage of the second DC voltage signal according to a change value of the reflected voltage in the Coulomb peak phase diagram;

[0010] The second DC voltage signal is applied to the gate of the bit quantum dot, and a first DC voltage signal having a voltage value of the first target voltage, a second DC voltage signal having a voltage value of the second target voltage, and the first RF reading signal are respectively applied to the gate of the sensing quantum dot to read the information of the sensing quantum dot.

[0011] In the above method, preferably, the impedance matching circuit includes an inductor, and a first adjustable capacitor and a second adjustable capacitor electrically connected to both ends of the inductor, and the step of adjusting the impedance matching circuit in the measurement link so that the impedance of the sensing quantum dot matches the characteristic impedance of the measurement link includes:

[0012] Respectively adjusting voltage values ​​of a third DC voltage signal applied to the first adjustable capacitor and the second adjustable capacitor to adjust the characteristic impedance of the measurement link;

[0013] Applying a fourth DC voltage signal and a second radio frequency reading signal to the gate of the sensing quantum dot and obtaining an S21 curve showing that the attenuation value of the reflected signal varies with the voltage value of the third DC voltage signal;

[0014] Determine that the voltage value corresponding to the trough position of the S21 curve is a third target voltage;

[0015] A third DC voltage signal of the third target voltage is applied to the first adjustable capacitor and the second adjustable capacitor to match the characteristic impedance of the measurement link with the impedance of the sensing quantum dot.

[0016] The method as described above, preferably, after the step of adjusting the impedance matching circuit in the measurement link so that the impedance of the sensing quantum dot matches the characteristic impedance of the measurement link, further comprises:

[0017] Applying a fourth DC voltage signal with a voltage value within a first preset range to the gate of the sensing quantum dot;

[0018] Applying the second radio frequency reading signal to the gate of the sensing quantum dot and obtaining an S21 curve of the reflection signal;

[0019] Determine a target voltage range within the first preset range in which the attenuation change value of the S21 curve is greater than a preset value;

[0020] A fourth DC voltage signal applied to the gate of the sensing quantum dot is updated according to the target voltage range.

[0021] In the above method, preferably, the gate includes a barrier gate, a pump gate and an accumulation gate, and the applying of the first DC voltage signal, the first RF read signal and the second DC voltage signal to the gate of the sensing quantum dot to obtain the Coulomb peak phase diagram of the sensing quantum dot includes:

[0022] Applying the first DC voltage signal to the barrier gate of the sensing quantum dot;

[0023] Applying the second DC voltage signal to the pump gate of the sensing quantum dot;

[0024] Applying the first radio frequency read signal to the accumulation gate of the sensing quantum dot;

[0025] The corresponding relationship between the voltage of the signal output by the accumulation gate reflection and the voltage of the first DC voltage signal and the voltage of the second DC voltage signal is determined to be the Coulomb peak phase diagram.

[0026] In the above method, preferably, the determining of the corresponding relationship between the voltage of the signal output by the induction quantum dot reflection and the voltage of the first DC voltage signal and the voltage of the second DC voltage signal as the Coulomb peak phase diagram includes:

[0027] Applying a first DC voltage signal of a first preset voltage value to the barrier gate, sequentially applying a second DC voltage signal of a voltage value in a second preset range to the pump gate, and applying the first radio frequency read signal to the accumulation gate of the sensing quantum dot, to obtain a first corresponding relationship between the voltage of the signal reflected and output by the accumulation gate and the voltage value in the second preset range;

[0028] Traversing the voltage values ​​of the first DC voltage signal in a third preset range, applying a second DC voltage signal with a voltage value in a second preset range to the pump gate, and applying the first radio frequency read signal to the accumulation gate of the sensing quantum dot, to obtain a second corresponding relationship between the voltage of the signal reflected and output by the accumulation gate and the voltage value in the third preset range;

[0029] The Coulomb peak phase diagram is determined according to the first corresponding relationship and the second corresponding relationship.

[0030] In the method described above, preferably, the second DC voltage signal includes a fixed amplitude DC signal and a triangular wave signal, the first DC voltage signal of the first preset voltage value is applied to the barrier gate, the second DC voltage signal of the voltage value of the second preset range is applied to the pump gate in sequence, and the first RF read signal is applied to the accumulation gate of the induction quantum dot, and the first corresponding relationship between the voltage of the signal reflected and output by the accumulation gate and the voltage value of the second preset range is obtained, including:

[0031] Applying a first DC voltage signal of a first preset voltage value to the barrier gate;

[0032] Sequentially applying a second DC voltage signal having a voltage value in a second preset range to the pumping gate;

[0033] applying the first radio frequency read signal to the accumulation gate;

[0034] Collecting the voltage value of the signal reflected and output by the accumulation gate when the voltage value of the second DC voltage signal changes linearly with the amplitude of the rising section or the falling section of the triangular wave signal;

[0035] The first corresponding relationship is obtained by changing the voltage value of the reflected output signal with the amplitude of the rising section or the falling section of the triangular wave signal.

[0036] In the above method, preferably, applying the second DC voltage signal to the gate of the bit quantum dot, and respectively applying the first DC voltage signal and the second DC voltage signal corresponding to the first target voltage and the second target voltage, and the first RF reading signal to the gate of the sensing quantum dot to read the information of the sensing quantum dot, comprises:

[0037] Applying a first DC voltage signal corresponding to the first target voltage to the barrier gate of the sensing quantum dot;

[0038] Applying the second DC voltage signal to the pump gate of the bit quantum dot;

[0039] Applying a second DC voltage signal corresponding to the second target voltage to a pump gate of the sensing quantum dot;

[0040] The first radio frequency reading signal is applied to the accumulation gate of the sensing quantum dot to read the information of the sensing quantum dot.

[0041] On the other hand, the present application provides a semiconductor quantum dot measurement and control system, wherein a bit quantum dot and a sensing quantum dot having a mutually coupled effect are formed on a semiconductor quantum chip, and the state of the sensing quantum dot is read through a measurement link to obtain information of the bit quantum dot; the system comprises:

[0042] A first adjustment module, adjusting an impedance matching circuit in the measurement link so that the impedance of the sensing quantum dot matches the characteristic impedance of the measurement link;

[0043] A first measuring module, used for applying a first DC voltage signal, a first radio frequency reading signal and a second DC voltage signal to the gate of the sensing quantum dot to obtain a Coulomb peak phase diagram of the sensing quantum dot;

[0044] A first determination module, configured to determine a first target voltage of the first DC voltage signal and a second target voltage of the second DC voltage signal according to a change value of the reflected voltage in the Coulomb peak phase diagram;

[0045] The second measuring module is used to apply the second DC voltage signal to the gate of the bit quantum dot, and respectively apply the first DC voltage signal and the second DC voltage signal corresponding to the first target voltage and the second target voltage, and the first RF reading signal to the gate of the sensing quantum dot to read the information of the sensing quantum dot.

[0046] In the above system, preferably, the first measurement module comprises:

[0047] A DC voltage source, used for outputting the first DC voltage signal and a fixed amplitude DC signal;

[0048] An arbitrary waveform generator, used for outputting the triangular wave signal;

[0049] A radio frequency source, configured to output the first radio frequency reading signal;

[0050] A signal acquisition card, used to collect the reflected signal output by the gate of the sensing quantum dot;

[0051] The triangular wave signal and the fixed amplitude DC signal are processed into the second DC voltage signal by a signal superimposer.

[0052] On the other hand, the present application provides a quantum computer, which uses any of the above methods to test quantum dots on a semiconductor quantum chip, or uses the above system to test quantum dots on a semiconductor quantum chip.

[0053] Compared with the prior art, this application proposes a method for measuring semiconductor quantum dots, which can be applied to the radio frequency reflection fast readout technology for testing and characterizing silicon-based quantum chips. By introducing an impedance matching network between the quantum chip and the measurement link, the impedance matching network is used to provide real-time feedback on the impedance changes of adjacent charge detectors caused by the spin state changes of the spin quantum bits in the quantum chip. Since this new technology does not use traditional low-frequency DC transmission, but uses a radio frequency signal source as the input signal, performs signal modulation and demodulation with the quantum dots respectively, and reads the signal through a high-frequency signal link, while optimizing the gate input signal of the semiconductor quantum chip, it can achieve higher measurement bandwidth and measurement efficiency.

[0054] The present application provides a semiconductor quantum dot measurement and control system and a quantum computer including the above-mentioned semiconductor quantum dot measurement method, and therefore has the same beneficial effects, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 A schematic diagram of the structure of a gate of a semiconductor quantum chip provided in an embodiment of the present application;

[0056] Figure 2 A schematic diagram of a process for measuring semiconductor quantum dots provided in an embodiment of the present application;

[0057] Figure 3 A schematic diagram of a DC voltage signal and a triangular wave signal provided in an embodiment of the present application;

[0058] Figure 4 A schematic diagram of a synthesis of a DC voltage signal and a triangular wave signal provided in an embodiment of the present application;

[0059] Figure 5 A specific schematic diagram of a Coulomb peak phase diagram provided in an embodiment of the present application;

[0060] Figure 6 A schematic diagram of the connection between an impedance matching circuit and a gate provided in an embodiment of the present application;

[0061] Figure 7 A schematic diagram of a flow chart of adjusting the impedance of an impedance matching circuit provided in an embodiment of the present application;

[0062] Figure 8 A schematic diagram of a process for updating a voltage signal applied to a sensing quantum dot gate provided in an embodiment of the present application;

[0063] Fig. 9 A schematic diagram of a process for obtaining a Coulomb peak phase diagram provided in an embodiment of the present application Figure 1 ;

[0064] Fig.10A schematic diagram of a process for obtaining a Coulomb peak phase diagram provided in an embodiment of the present application Figure 2 ;

[0065] Fig.11 A schematic diagram of a process for obtaining a first corresponding relationship provided in an embodiment of the present application;

[0066] Fig.12 A schematic diagram of a process for reading a sensing quantum dot provided in an embodiment of the present application;

[0067] Fig.13 A schematic diagram of the composition of a semiconductor quantum dot measurement and control system provided in an embodiment of the present application.

[0068] In the reference numerals:

[0069] 1-substrate, 3-impedance matching circuit;

[0070] 11-drain, 12-source, 22-pumping gate, 23-accumulation gate, 10-first regulating module, 20-first measuring module, 30-first determining module, 40-second measuring module;

[0071] 211 - a first barrier gate, 212 - a second barrier gate. DETAILED DESCRIPTION

[0072] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application, and cannot be interpreted as limitations on the present application.

[0073] In the description of the present application, it should be understood that the terms "center", "up", "down", "left", "right", etc., indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0074] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0075] As attached Figure 1 The gate schematic diagram of the semiconductor quantum chip shown is a gate schematic diagram of a semiconductor chip designed by the applicant for radio frequency reflection reading technology, 1 is a substrate of the semiconductor quantum chip, and electrodes 11 and 12 are respectively a drain and a source formed on opposite sides of the substrate for applying a DC voltage signal for excitation. Electrode 211, electrode 212, electrode 22, and electrode 23 are all gates, and the signals applied and the signal effects are different. Specifically, electrode 211 is a first barrier gate, electrode 212 is a second barrier gate, and electrode 22 is a pump gate; the pump gate 22 is used to apply a DC voltage signal to adjust the potential of the two-dimensional electron gas below the electrode to form a quantum dot in the channel, wherein the quantum dot can be a bit quantum dot or an induction quantum dot for reading the bit quantum dot; the first barrier gate 211 and the second barrier gate 212 are also used to apply a DC voltage signal to adjust the potential of the two-dimensional electron gas, and the DC voltage signal applied to the first barrier gate 211 and the second barrier gate 212 will also have a regulating effect on the potential of the quantum dot, and it works together with the DC voltage signal applied to the pump gate 22 to regulate the quantum dot; electrode 23 is an accumulation gate, which is used to apply a radio frequency signal to read the induction quantum dot to obtain information of the bit quantum dot.

[0076] In addition, Figure 1 Only one quantum dot is exemplified in the figure, which is a sensing quantum dot in this embodiment, including at least 4 gate structures; the gate of the bit quantum dot is similar to the gate structure of the sensing quantum dot, both including a first barrier gate 211, a second barrier gate 212 and a pump gate 22, which are used to apply a DC voltage signal to form a bit quantum dot, but the difference is that the gate of the bit quantum dot does not include an accumulation gate 23 for reading, and the measurement of the bit quantum dot is to apply a measurement signal to the accumulation gate 23 of the sensing quantum dot for reading. In the semiconductor quantum chip, the sensing quantum dot and the bit quantum dot are adjacent, and the sensing quantum dot is used as a measuring device for the bit quantum dot, and the information of the bit quantum dot is obtained by measuring the charge change of the sensing quantum dot.

[0077] In addition, when applying a radio frequency signal to the accumulation gate 23 of the sensing quantum dot to read the charge change of the sensing quantum dot, the gate corresponding to the sensing quantum dot and the gate corresponding to the bit quantum dot both need to apply a DC voltage signal to form the sensing quantum dot and the bit quantum dot.

[0078] As attached Figure 2 As shown, in an embodiment of the present application, a measurement method for measuring semiconductor quantum dots using radio frequency signals is provided, wherein bit quantum dots and sensing quantum dots that are coupled to each other are formed on a semiconductor quantum chip, and the state of the sensing quantum dots is read through a measurement link to obtain information of the bit quantum dots; the method comprises:

[0079] Step S10: adjusting the impedance matching circuit in the measurement link to match the impedance of the sensing quantum dot with the characteristic impedance of the measurement link.

[0080] In this embodiment, a DC voltage source is used to output a DC voltage signal to the gate of the semiconductor quantum chip to form a sensing quantum dot or a bit quantum dot; and a radio frequency source is used to output a radio frequency reading signal to the gate of the sensing quantum dot for reading. A measurement link is provided between the radio frequency source and the semiconductor quantum chip, and an impedance matching circuit is integrated in the measurement link. The impedance of the sensing quantum dot is matched with the characteristic impedance of the measurement link by adjusting the impedance matching circuit, and then the charge change of the sensing quantum dot is sensitively measured by the impedance matching circuit. Among them, when the impedance of the sensing quantum dot is equal to the characteristic impedance of the measurement link, the impedance matching degree is high. The characteristic impedance of the measurement link is generally 50 ohms. By adjusting the impedance matching circuit, the impedance of the sensing quantum dot can be adjusted to 50 ohms to match the characteristic impedance of the measurement link.

[0081] The impedance of the sensing quantum dot can be adjusted by the impedance of the impedance matching circuit. When the impedance of the sensing quantum dot is equal to the characteristic impedance of the measurement link, the reading of the sensing quantum dot is optimal. At this time, the impedance matching circuit is most sensitive to the reading of the sensing quantum dot. When the charge of the sensing quantum dot changes slightly, it can also be measured by the impedance matching circuit to improve the measurement sensitivity of the sensing quantum dot.

[0082] Step S20: applying a first DC voltage signal, a first RF read signal and a second DC voltage signal to the gate of the sensing quantum dot to obtain a Coulomb peak phase diagram of the sensing quantum dot.

[0083] Combined with Figure 1As shown, a voltage signal is applied to the gate of the corresponding sensing quantum dot on the semiconductor quantum chip to form a sensing quantum dot. In this embodiment, the voltage signal applied to the gate of the sensing quantum dot includes a first DC voltage signal and a second DC voltage signal, wherein the voltage values ​​of the first DC voltage signal and the second DC voltage signal are variable. When testing the semiconductor chip, a first radio frequency read signal is applied to the gate of the sensing quantum dot, and the corresponding relationship between the reflected voltage obtained after the signal reflected and output by the sensing quantum dot is measured by a measuring device and the voltage value of the first DC voltage signal and the voltage value of the second DC voltage signal applied to the gate of the sensing quantum dot is represented by a three-dimensional graph, i.e., a Coulomb peak phase diagram. The Coulomb peak phase diagram is used to characterize the change in the reflected voltage of the signal reflected and output by the gate of the sensing quantum dot with the voltage value of the first DC voltage signal and the voltage value of the second DC voltage signal. Information on the state change of the sensing quantum dot can be obtained through the reflected voltage in the Coulomb peak phase diagram.

[0084] As described above, when the first RF signal is applied to test the sensing quantum dot to obtain the Coulomb peak phase diagram, the voltage value of the second DC voltage signal applied to the intermediate gate of the sensing quantum dot and the bit quantum dot is variable, and changes linearly within a preset amplitude range, such as 1V-5V. In the prior art, the voltage signal is generally provided by a DC voltage source, and the voltage value of the DC voltage signal output by the DC voltage source is generally a fixed value. When the DC voltage source is manipulated to output a DC voltage signal with a variable voltage value, the response is very slow, which directly affects the measurement efficiency of the sensing quantum dot. An arbitrary waveform generator can also be used to output a voltage signal with a variable voltage value. The voltage value of the voltage signal output by the arbitrary waveform generator is generally low and cannot meet the requirements for testing the sensing quantum dots.

[0085] Combined with Figure 3 and attached Figure 4 As shown, in this embodiment, a fixed amplitude DC signal and a triangular wave signal are synthesized to obtain a second DC voltage signal whose voltage value changes linearly within a preset amplitude range; Figure 3 The fixed amplitude DC signal and the triangular wave signal are respectively exemplified, wherein the voltage value of the fixed amplitude DC signal is fixed, and the voltage amplitude of the triangular wave signal is variable. The voltage variation curve of the synthesized second DC voltage signal is shown in the attached figure. Figure 4 As shown, it can be found that the change in the voltage value of the second DC voltage signal corresponds to the change in the voltage amplitude of the triangular wave signal. For example, the voltage value of the fixed amplitude DC signal is 3V, the voltage amplitude of the triangular wave signal is {-1.5V, 1.5V}, and the waveform of the synthesized second DC voltage signal is also a triangular wave signal, and its voltage amplitude is {1.5V, 4.5V}. The voltage amplitude changes linearly in both the rising and falling sections, which is used to meet the requirements of the voltage signal for controlling the sensing quantum dots or bit quantum dots.

[0086] In addition, Figure 3 and attached Figure 4 The curve diagrams of the fixed amplitude DC signal, the triangular wave signal, and the second DC voltage signal in the example are only examples. In specific measurements, the output time of the signal, the voltage value, the waveform parameters of the triangular wave, etc. need to be determined according to requirements and will not be repeated in this embodiment.

[0087] In this embodiment, a fixed amplitude DC signal is provided by a DC voltage source, and a triangular wave signal is provided by an arbitrary waveform generator. The fixed amplitude DC signal output by the DC voltage source and the triangular wave signal output by the arbitrary waveform generator are synthesized into a second DC voltage signal and output, so that the voltage value of the second DC voltage signal applied to the gate of the sensing quantum dot changes linearly within a preset amplitude range, and the voltage amplitude is relatively high, which meets the requirements for testing the sensing quantum dot. In addition, the DC voltage source outputs a fixed amplitude DC signal, and the arbitrary waveform generator can directly output a triangular wave signal, which has a fast response, and thus generates a fast response of the second DC voltage signal, which can improve the measurement efficiency of the sensing quantum dot.

[0088] Step S30: determining a first target voltage of the first DC voltage signal and a second target voltage of the second DC voltage signal according to a change value of the reflected voltage in the Coulomb peak phase diagram.

[0089] As described in step S20, the Coulomb peak phase diagram is used to characterize the change of the reflected voltage of the signal output by the gate reflection of the sensing quantum dot with the voltage value of the first DC voltage signal and the voltage value of the second DC voltage signal. The information of the state change of the sensing quantum dot can be obtained through the reflected voltage in the Coulomb peak phase diagram. The maximum change value of the reflected voltage in the Coulomb peak phase diagram corresponds to the state in which the state change of the sensing quantum dot is most sensitive. The voltage values ​​of the first DC voltage signal and the second DC voltage signal when the change value of the reflected voltage in the Coulomb peak phase diagram is the largest are determined as the first target voltage and the second target voltage, and the voltages of the first DC voltage signal and the second DC voltage signal applied to the gate of the sensing quantum dot are updated.

[0090] As attached Figure 5 In the illustrated Coulomb peak phase diagram, the horizontal axis U3 represents the voltage value of the second DC voltage signal, and 2.5V-4.5V corresponds to the changing voltage value; the vertical axis U4 on the left represents the voltage value of the first DC voltage signal, and 0V-3V corresponds to the changing voltage value; the vertical axis on the right represents the voltage value of the reflected signal, and the brighter the white area in the three-dimensional diagram, the larger the corresponding voltage value of the reflected signal. Through the Coulomb peak phase diagram, the voltage values ​​of the first DC voltage signal and the second DC voltage signal can be obtained when the voltage change of the reflected signal is obvious.

[0091] The measurement of the bit quantum dot is achieved by measuring the charge change of the sensing quantum dot on the quantum chip, so the sensitivity of the state change of the sensing quantum dot directly affects the measurement accuracy of the bit quantum dot; the first target voltage of the first DC voltage signal and the second target voltage of the second DC voltage signal when the state change of the sensing quantum dot is most sensitive are determined by the Coulomb peak phase diagram. When the bit quantum dot is measured subsequently, the first DC voltage signal of the first target voltage and the second DC voltage signal of the second target voltage are applied to the gate of the sensing quantum dot to ensure that the sensing quantum dot is in the most sensitive state, thereby improving the measurement accuracy of the bit quantum dot.

[0092] Step S40: Apply the second DC voltage signal to the gate of the bit quantum dot, and respectively apply a first DC voltage signal with a voltage value of the first target voltage, a second DC voltage signal with a voltage value of the second target voltage, and the first RF reading signal to the gate of the sensing quantum dot to read the information of the sensing quantum dot.

[0093] A second DC voltage signal is applied to the gate of the corresponding bit quantum dot to form a bit quantum dot under the gate, and the second DC voltage signal applied to the gate of the bit quantum dot is the same voltage signal as the second DC voltage signal applied to the gate of the sensing quantum dot, and the parameters of the voltage signals are the same.

[0094] As described above, applying a second DC voltage signal whose voltage value varies linearly within a preset range to the gate of the sensing quantum dot can increase the response speed of the voltage signal, thereby improving the measurement efficiency of the sensing quantum dot. Similarly, the voltage signal applied to the gate of the bit quantum dot also uses a second DC voltage signal whose voltage value varies linearly, which can increase the response speed of the voltage signal applied to the bit quantum dot. When measuring the bit quantum dot through the sensing quantum dot, the measurement efficiency can also be improved.

[0095] First, the target voltage values ​​of the first DC voltage signal and the second DC voltage signal applied to the gate of the sensing quantum dot are determined through step S30, and the first DC voltage signal with a voltage value of the first target voltage and the second DC voltage signal with a voltage value of the second target voltage are applied to the gate of the sensing quantum dot to ensure that the sensing quantum dot is in the most sensitive state; then the second DC voltage signal is applied to the gate of the bit quantum dot on the semiconductor quantum chip to form the bit quantum dot; and then the first radio frequency reading signal is applied to the gate of the sensing quantum dot to read the information of the sensing quantum dot to obtain the information of the bit quantum dot.

[0096] In this embodiment, the sensing quantum dots are measured by transmitting a radio frequency read signal through an impedance matching circuit. The radio frequency read signal is used as an input signal to perform signal modulation and demodulation with the sensing quantum dots on the quantum chip. The signal is read through a high-frequency signal link. Compared with the traditional low-frequency DC transmission measurement method, the measurement bandwidth and efficiency are greatly improved.

[0097] In addition, when reading the sensing quantum dots, the DC voltages applied to the gates of the sensing quantum dots and the bit quantum dots for forming quantum dots all use a second DC voltage signal, which improves the response speed of the output voltage signal and thereby improves the measurement efficiency of the sensing quantum dots.

[0098] Furthermore, the measurement of the bit quantum dot is achieved by measuring the sensing quantum dot, and when the sensing quantum dot is tested, the change of the sensing quantum dot is obtained through the impedance matching circuit; therefore, the impedance matching circuit and the measurement sensitivity of the sensing quantum dot directly affect the measurement of the bit quantum dot. In this embodiment, the impedance of the impedance matching circuit in the measurement link is first adjusted to match the impedance of the sensing quantum dot with the characteristic impedance of the measurement link to ensure the measurement sensitivity of the sensing quantum dot; and the voltage values ​​of the first DC voltage signal and the second DC voltage signal applied when the sensing quantum dot is most sensitive are obtained through the Coulomb peak phase diagram, and the applied first DC voltage signal and the second DC voltage signal are updated to ensure that the change of the sensing quantum dot is most sensitive, which greatly improves the measurement accuracy of the bit quantum dot.

[0099] As attached Figure 6 As shown, in this embodiment, the impedance matching circuit 3 includes an inductor, and a first adjustable capacitor and a second adjustable capacitor electrically connected to both ends of the inductor. Specifically, the impedance matching circuit 3 adopts an LC impedance matching network of an inductor and a capacitor, and selects a first adjustable capacitor and a second adjustable capacitor with adjustable capacitance values.

[0100] As attached Figure 7 As shown, in this embodiment, adjusting the impedance matching circuit in the measurement link so that the impedance of the sensing quantum dot matches the characteristic impedance of the measurement link includes:

[0101] Step S101: respectively adjusting the voltage values ​​of the third DC voltage signal applied to the first adjustable capacitor and the second adjustable capacitor to adjust the characteristic impedance of the measurement link.

[0102] Combined with Figure 6 As shown, the capacitance values ​​of the first adjustable capacitor and the second adjustable capacitor are adjusted by the third DC voltage signal to adjust the impedance of the impedance matching circuit, thereby ensuring that the impedance of the sensing quantum dot is the same as the impedance of the transmission link, thereby ensuring the measurement accuracy of the sensing quantum dot.

[0103] Step S102: applying a fourth DC voltage signal and a second radio frequency reading signal to the gate of the sensing quantum dot and obtaining an S21 curve showing how the attenuation value of the reflected signal changes with the voltage value of the third DC voltage signal.

[0104] The fourth DC voltage signal is used to form the sensing quantum dot, and the second RF reading signal is used to read the information of the sensing quantum dot. When the voltage value of the third DC voltage signal is adjusted, the impedance of the impedance matching circuit will change, and the reflected signal output by the gate reflection of the sensing quantum dot read by the impedance matching circuit will also change. Specifically, the attenuation value of the reflected signal will change with the voltage value of the third DC voltage signal, and the reflected signal can be collected by the measuring device to obtain the S21 curve of the attenuation value change. In this embodiment, the measuring device can be a vector network analyzer.

[0105] Step S103: Determine the voltage value corresponding to the trough position of the S21 curve as the third target voltage. The S21 curve is used to characterize the attenuation value of the reflected signal. At the trough position of the S21 curve, the impedance matching circuit has the highest response sensitivity to the sensing quantum dot pair. The corresponding voltage value at this time is determined as the third target voltage, which is the voltage value of the third DC voltage signal.

[0106] Step S104: Apply a third DC voltage signal of the third target voltage to the first adjustable capacitor and the second adjustable capacitor to match the impedance of the sensing quantum dot with the characteristic impedance of the measurement link. Obtain the S21 curve of the reflection signal output by the gate reflection of the sensing quantum dot through steps S101-S103 to determine the third target voltage when the impedance matching circuit has the best response sensitivity, apply a third DC voltage signal with a voltage value of the third target voltage to the first adjustable capacitor and the second adjustable capacitor, and adjust the impedance of the sensing quantum dot through the impedance matching circuit to match the characteristic impedance of the measurement link, ensuring that the reading of the sensing quantum dot is at the best sensitivity.

[0107] Continue to attach Figure 6 The schematic diagram of the impedance matching circuit shown includes a first adjustable capacitor and a second adjustable capacitor. When adjusting the third DC voltage signal applied to the first adjustable capacitor and the second adjustable capacitor, the same third DC voltage signal can be used for synchronous adjustment, or two third DC voltage signals with different voltage values ​​can be used to adjust the first adjustable capacitor and the second adjustable capacitor respectively.

[0108] Two third DC voltage signals with different voltage values ​​are used to respectively adjust the first adjustable capacitor and the second adjustable capacitor. It is necessary to respectively execute steps S101 to S104 for the two third DC voltage signals to determine the third target voltages of the third DC voltage signals respectively applied to the first adjustable capacitor and the second adjustable capacitor, which will not be described in detail in this embodiment.

[0109] In addition, if attached Figure 8 As shown, as an implementation of an embodiment of the present application, after the step of adjusting the impedance matching circuit in the measurement link to make the impedance of the sensing quantum dot match the characteristic impedance of the measurement link, it also includes:

[0110] Step 111: Apply a fourth DC voltage signal with a voltage value within a first preset range to the gate of the sensing quantum dot.

[0111] Step 112: Apply the second radio frequency reading signal to the gate of the sensing quantum dot and obtain the S21 curve of the reflection signal.

[0112] Combined with Figure 1 As shown, when reading the sensing quantum dot, it is necessary to apply a DC voltage to the pumping gate 22 and apply a radio frequency reading signal to the accumulation gate 23. In this embodiment, the fourth DC voltage signal applied to the gate of the semiconductor quantum chip includes multiple voltage values ​​within the first preset range, for example, the first preset range is {2.5V, 4.5V}. Among them, the first preset range includes several voltage values. When the fourth DC voltage signal corresponding to each voltage value is applied to the gate of the sensing quantum dot, a second radio frequency reading signal is applied to the same gate and the S21 parameter of the reflected signal is obtained through the measuring device. The voltage values ​​within the first preset range are traversed to obtain an S21 curve including multiple S21 parameters; the attenuation value of the S21 curve changes with the voltage value within the first preset range.

[0113] Step 113: Determine the target voltage range within the first preset range in which the attenuation change value in the S21 curve is greater than the preset value. The change information of the sensing quantum dot can be obtained by measuring the S21 parameter of the reflection signal through the measuring device, and the attenuation change value can be determined by the attenuation value of the S21 curve. For example, if the maximum attenuation value in the S21 curve is 30dB and the minimum attenuation value is 10dB, then the attenuation change value is 20dB. The attenuation change value can characterize the response sensitivity of the sensing quantum dot to the change of the fourth DC voltage signal. It can be understood that the larger the attenuation change value, the more sensitive the measurement of the sensing quantum dot is to the fourth DC voltage signal applied to the sensing quantum dot gate at this time. When the attenuation change value is very small, the measurement of the sensing quantum dot is insensitive.

[0114] Specifically, a preset value can be set for the attenuation change value, and then the voltage value of the fourth DC voltage signal is determined based on the measured S21 curve to determine whether it meets the requirement of the attenuation change value; when the requirement of the attenuation change value is not met, the voltage value of the first preset range needs to be adjusted, and the process returns to step S11. When the requirement of the attenuation change value is met, the voltage range within the first preset range corresponding to when the attenuation change value in the S21 curve is greater than the preset value is determined as the target voltage range.

[0115] Step 114: Update the fourth DC voltage signal applied to the gate of the sensing quantum dot according to the target voltage range. After the target voltage range is determined in step S113, the first preset range of the fourth DC voltage signal applied to the gate of the sensing quantum dot is updated to ensure that the sensing quantum dot is sensitive to the response when the RF read signal is applied to the gate of the sensing quantum dot.

[0116] As attached Fig. 9 As shown, applying a first DC voltage signal, a first RF reading signal and a second DC voltage signal to the gate of the sensing quantum dot to obtain the Coulomb peak phase diagram of the sensing quantum dot includes:

[0117] Step S201: applying the first DC voltage signal to the barrier gate of the sensing quantum dot.

[0118] Step S202: applying the second DC voltage signal to the pump gate of the sensing quantum dot.

[0119] Step S203: applying the first radio frequency reading signal to the accumulation gate of the sensing quantum dot.

[0120] When reading the sensing quantum dot, it is necessary to apply the first DC voltage signal and the second DC voltage signal to the barrier gate and the pump gate respectively to form the sensing quantum dot, and then apply the first RF reading signal to the accumulation gate of the sensing quantum dot for reading.

[0121] Step S204: determining a corresponding relationship between a voltage of a signal outputted by the induction quantum dot reflection and a voltage change of the first DC voltage signal and a voltage change of the second DC voltage signal as the Coulomb peak phase diagram.

[0122] After applying the first DC voltage signal, the second DC voltage signal and the first RF read signal to the barrier gate, the pump gate and the accumulation gate of the sensing quantum dot in steps S201 and S203, the accumulation gate will reflect and output the reflection signal, and the reflection signal is collected by the measuring device, and the voltage of the reflection signal can be obtained by processing the reflection signal. As described above, the voltage values ​​of the applied first DC voltage signal and the second DC voltage signal will affect the reflected signal output, so the voltage of the reflection signal has a corresponding relationship with the voltage values ​​of the first DC voltage signal and the second DC voltage signal. When the voltage values ​​of the first DC voltage signal and the second DC voltage signal change, the voltage of the reflection signal obtained by the measuring device will also change accordingly, and the corresponding relationship between the voltage of the reflection signal and the change of the voltage values ​​of the first DC voltage signal and the second DC voltage signal is determined as a Coulomb peak phase diagram. It should be supplemented that the Coulomb peak phase diagram is a three-dimensional data diagram, which is obtained by repeatedly changing the voltage values ​​of the first DC voltage signal and the second DC voltage signal and measuring the voltage of the reflection signal.

[0123] In combination with the description of step S111 to step S114, the target voltage range of the fourth DC voltage signal applied to the gate of the sensing quantum dot can be determined by the range of the attenuation change value of the S21 curve; wherein the fourth DC voltage signal is applied to the pump gate of the sensing quantum dot to form the sensing quantum dot, that is, the attached Figure 1 Electrode 22. In step S202, the second DC voltage signal applied to the barrier gate of the sensing quantum dot is also used to form the sensing quantum dot. Therefore, the voltage of the second DC voltage signal can be preset according to the target voltage range of the fourth DC voltage signal to ensure that after the second DC voltage signal is applied to the pump gate of the sensing quantum dot, the voltage change of the reflected output signal obtained when the first RF read signal is applied to the accumulation gate for testing is more obvious, thereby improving the resolution of the Coulomb peak phase diagram.

[0124] Combined with Fig.10 As shown, as an implementation of an embodiment of the present application, the corresponding relationship between the voltage of the signal reflected and output by the induction quantum dot and the voltage of the first DC voltage signal and the voltage change of the second DC voltage signal is the Coulomb peak phase diagram, including:

[0125] Step S2031: Apply a first DC voltage signal of a first preset voltage value to the barrier gate, sequentially traverse and apply a second DC voltage signal of a voltage value in a second preset range to the pump gate, and apply the first RF read signal to the accumulation gate of the sensing quantum dot to obtain a first corresponding relationship between the voltage of the signal reflected and output by the accumulation gate and the voltage value in the second preset range.

[0126] Step S2032: traverse the voltage value of the first DC voltage signal in a third preset range, apply a second DC voltage signal with a voltage value in a second preset range to the pump gate, and apply the first RF read signal to the accumulation gate of the sensing quantum dot, to obtain a second corresponding relationship between the voltage of the signal reflected and output by the accumulation gate and the voltage value in the third preset range.

[0127] As described in the above steps S201-S203, the Coulomb peak phase diagram is data of the voltage of the reflected signal output by the gate reflection of the sensing quantum dot as the voltage of the first DC voltage signal and the voltage of the second DC voltage signal change. Specifically, the voltage value of the first DC voltage signal is first set to the first preset voltage value, and a number of voltage values ​​within the second preset range are traversed in sequence. When traversing each voltage value, the first RF reading signal is applied to the accumulation gate of the sensing quantum dot, and the first corresponding relationship between the voltage value of the reflected signal output and the voltage value within the second preset range is measured. For example, the voltage value of the first DC voltage signal is set to 3V, and the second preset range is determined to be {2.5V, 4.5V}, that is, a second DC voltage signal that changes linearly within {2.5V, 4.5V} is applied to the pump gate of the sensing quantum dot, and the corresponding relationship between the voltage value of the reflected signal and the voltage value within the second preset range is obtained.

[0128] In addition, the voltage value of the first DC voltage signal is traversed within the third preset range, and the steps of applying the second DC voltage signal with a voltage value in the second preset range to the pump gate and applying the first RF read signal to the accumulation gate are repeated to obtain a second corresponding relationship between the voltage of the signal output by the induction quantum dot reflection and the voltage value in the third preset range.

[0129] For example, the third preset range is {0V, 5V}, and its voltage step is 0.5V. At the beginning of the traversal, the voltage value of the first DC voltage signal is set to 0.5V, and the second DC voltage signal is traversed within the second preset range to obtain the current voltage value of the reflected signal; then the voltage value of the first DC voltage signal is set to 1V, and the second DC voltage signal is traversed within the second preset range to obtain the current voltage value of the reflected signal, until the voltage values ​​within the third preset range are traversed, and a second corresponding relationship between the voltage value of the reflected signal and the voltage value within the third preset range is obtained.

[0130] It should be added that when obtaining the first corresponding relationship and the second corresponding relationship, the second DC voltage is traversed within the second preset range. The step values ​​of the second preset range and the third preset range are adjusted according to specific test accuracy requirements, and this embodiment is only an example.

[0131] Step S2033: determining the Coulomb peak phase diagram according to the first corresponding relationship and the second corresponding relationship.

[0132] The first corresponding relationship and the second corresponding relationship obtained in step S2031 and step S2032 are both one-to-one corresponding data. The first corresponding relationship and the second corresponding relationship can be displayed in a three-dimensional graph in the form of a three-dimensional coordinate graph, which is a Coulomb peak phase diagram. Figure 5 shown.

[0133] Combined with Figure 1 As shown, the gates of the sensing quantum dots include a barrier gate 211 and a barrier gate 212. When a first DC voltage signal is applied to the gates for traversal in step S2032, the first DC voltage signals applied to the barrier gates 211 and 212 can be applied and traversed separately.

[0134] Specifically, the first DC voltage signal applied to the barrier gate 211 is first set to a voltage signal of a preset value, the first DC voltage signal applied to the barrier gate 212 is traversed within a third preset range, steps S2032 and S2033 are repeated, and a Coulomb peak phase diagram is obtained. Then, the preset value of the first DC voltage signal applied to the barrier gate 211 is adjusted, the first DC voltage signal applied to the barrier gate 212 is traversed within the third preset range, steps S2032 and S2033 are repeated, and a Coulomb peak phase diagram is obtained again.

[0135] The preset value of the first DC voltage signal applied to the barrier gate 211 can be traversed within the fourth preset range, and then combined with the first DC voltage signal applied to the barrier gate 212 to traverse within the third preset range to obtain a plurality of Coulomb peak phase diagrams. According to the plurality of Coulomb peak phase diagrams, the target voltage values ​​of the first DC voltage signals respectively applied to the barrier gates 211 and 212 can be determined to ensure a higher sensitivity of the sensing quantum dots.

[0136] Combined with Fig.11 As shown, as an implementation of an embodiment of the present application, the step of applying a first DC voltage signal of a first preset voltage value to the barrier gate, sequentially traversing the step of applying a second DC voltage signal of a voltage value in a second preset range to the pump gate, and obtaining a first corresponding relationship between the voltage of the signal reflected and output by the induction quantum dot and the voltage value in the second preset range, includes:

[0137] Step S20311: applying a first DC voltage signal of a first preset voltage value to the barrier gate.

[0138] Step S20312: sequentially applying a second DC voltage signal having a voltage value within a second preset range to the pump gate.

[0139] Step S20313: applying the first RF read signal to the accumulation gate.

[0140] Step S20314: collecting the voltage value of the signal reflected and output by the accumulation gate when the voltage value of the second DC voltage signal changes linearly with the amplitude of the rising section or the falling section of the triangular wave signal.

[0141] Step S20315: obtaining the first corresponding relationship between the voltage value of the reflected output signal and the amplitude of the rising segment or the falling segment of the triangular wave signal.

[0142] In the above step S2031, the voltage value of the second DC voltage signal varies within the second preset range; in combination with the above description, the second DC voltage signal is synthesized by the second DC voltage signal and the triangular wave signal, and the voltage value of the second DC voltage signal varies with the amplitude of the triangular wave signal. Figure 5 It can be found that the change of the voltage value within the second preset range is not monotonically increasing or monotonically decreasing, but changes synchronously with the rising and falling segments of the triangular wave signal. Therefore, within the second preset range, the voltage value of the second DC voltage signal includes several continuous rising and falling segments.

[0143] In an embodiment of the present application, when the voltage value of the second DC voltage signal is a rising segment waveform of a triangular wave signal, the voltage signal applied to the pump gate steps from a small voltage to a large voltage; when the voltage value of the second DC voltage signal is a falling segment waveform of a triangular wave signal, the voltage signal applied to the pump gate steps from a large voltage to a small voltage; when a measuring device is used to measure the reflected signal output by the pump gate of the inductive quantum dot, multiple measurements are performed and the average value is taken; when multiple measurements all select the second DC voltage signal applied to the pump gate as a complete rising segment or multiple measurements all select the falling segment, the voltage value of the reflected signal during the rising segment or the falling segment is collected, which can improve the measurement accuracy of the voltage of the reflected signal.

[0144] For example, when measuring 10 times, the second DC voltage signal applied to the pump gate is selected as a complete rising segment, and the voltage value of the reflected signal during the rising segment is collected; or the second DC voltage signal applied to the pump gate is selected as a complete falling segment, and the voltage value of the reflected signal during the falling segment is collected.

[0145] As attached Fig.12As shown, in this embodiment, after determining the first target voltage of the first DC voltage signal and the second target voltage of the second DC voltage signal, when testing the sensing quantum dot, the second DC voltage signal is applied to the gate of the bit quantum dot, and the first DC voltage signal and the second DC voltage signal corresponding to the first target voltage and the second target voltage, and the first radio frequency reading signal are respectively applied to the gate of the sensing quantum dot to read the information of the sensing quantum dot, including:

[0146] Step S401: applying a first DC voltage signal corresponding to the first target voltage to the barrier gate of the sensing quantum dot.

[0147] Step S402: applying the second DC voltage signal to the pump gate of the bit quantum dot.

[0148] Step S403: applying a second DC voltage signal corresponding to the second target voltage to the pump gate of the sensing quantum dot.

[0149] Step S404: applying the first radio frequency reading signal to the accumulation gate of the sensing quantum dot to read the information of the sensing quantum dot.

[0150] As attached Fig.13 As shown, based on the same application concept, the embodiment of the present application also provides a semiconductor quantum dot measurement and control system, wherein a bit quantum dot and a sensing quantum dot that are mutually coupled are formed on a semiconductor quantum chip, and the state of the sensing quantum dot is read through a measurement link to obtain information of the bit quantum dot; the measurement and control system comprises: a first adjustment module 10, which is used to adjust the impedance matching circuit in the measurement link so that the impedance of the sensing quantum dot matches the characteristic impedance of the measurement link; a first measurement module 20, which is used to apply a first DC voltage signal, a first RF reading signal and a second DC voltage signal to the gate of the sensing quantum dot to obtain the Coulomb peak phase diagram of the sensing quantum dot; wherein the second The DC voltage signal includes a second DC voltage signal and a triangular wave signal; the voltage value of the second DC voltage signal changes with the amplitude of the triangular wave signal; a first determination module 30 is used to determine the first target voltage of the first DC voltage signal and the second target voltage of the second DC voltage signal according to the change value of the reflection voltage in the Coulomb peak phase diagram; a second measurement module 40 is used to apply the second DC voltage signal to the gate of the bit quantum dot, and respectively apply the first DC voltage signal and the second DC voltage signal corresponding to the first target voltage and the second target voltage, and the first RF reading signal to the gate of the sensing quantum dot to read the information of the sensing quantum dot.

[0151] Combined with Figure 1As shown, forming sensing quantum dots and bit quantum dots on a semiconductor quantum chip requires applying multiple DC voltage signals and a second DC voltage signal, and also requires applying a radio frequency reading signal to read the sensing quantum dots to obtain the information of the bit quantum dots, and measuring the reflected signal collected after applying the radio frequency reading signal.

[0152] Specifically, the first adjustment module 10 for adjusting the impedance of the impedance matching circuit can use a DC voltage source, and adjust the impedance of the impedance matching by adjusting the voltage signal output by the DC voltage source. Figure 6 Schematic diagram of the circuit structure of the first inductor, the first adjustable capacitor and the second adjustable capacitor.

[0153] In addition, the first measurement module 20 may include signal analysis instruments such as a DC voltage source, a radio frequency source, a vector network analyzer, and a spectrum analyzer to provide the required first DC voltage signal, a first radio frequency reading signal, and a second DC voltage signal; the first measurement module may also include data analysis software or data processing software installed in a computer to process the data of the reflected signal output by the gate of the sensing quantum dot to obtain a Coulomb peak phase diagram.

[0154] The first determination module 30 may include image analysis software installed in a computer, and determine the first target voltage of the first DC voltage signal and the second target voltage of the second DC voltage signal according to the change value of the reflection voltage in the Coulomb peak phase diagram. The second measurement module 40 may include a signal source device such as a DC voltage source and a radio frequency source to provide the required first DC voltage signal, second radio frequency reading signal and second DC voltage signal. The second measurement module may also include a signal analysis instrument such as a vector network analyzer and a spectrum analyzer to process the data of the reflection signal output by the gate of the sensing quantum dot to obtain the information of the sensing quantum dot.

[0155] In the embodiment of the present application, the first measurement module 20 includes: a DC voltage source 201, used to output the first DC voltage signal and the second DC voltage signal; an arbitrary waveform generator 202, used to output the triangular wave signal; a radio frequency source 203, used to output the first radio frequency reading signal; a signal acquisition card 204, used to collect the reflection signal output by the gate of the sensing quantum dot; wherein the triangular wave signal and the second DC voltage signal are processed into the second DC voltage signal by a signal superimposer.

[0156] Combined with Figure 1As shown, it should be supplemented that the first RF signal and the second RF signal are applied to the accumulation gate 23, the reflected signal is also output through the accumulation gate 23, and the signal acquisition card is also collected through the accumulation gate 23. In specific applications, a directional coupler is arranged outside the accumulation gate 23 of the semiconductor quantum chip, and the input end of the directional coupler receives the first RF signal and the second RF signal and transmits them to the accumulation gate 23 through the output end; the output end of the directional coupler is also used to receive the reflected signal output by the accumulation gate 23 and output it to the signal acquisition card through the coupling end of the directional coupler.

[0157] When the reflected signal output by the accumulation gate 23 is collected by the signal acquisition card 2, the reflected signal output by the gate of the induction quantum dot is collected when the arbitrary waveform generator outputs the rising section or the falling section of the triangular wave signal.

[0158] Based on the same application concept, an embodiment of the present application also provides a quantum computer, which uses any of the above-mentioned semiconductor quantum dot measurement methods to test the quantum dots on the semiconductor quantum chip, or uses the above-mentioned semiconductor quantum dot measurement and control system to test the quantum dots on the semiconductor quantum chip.

[0159] In the description of this specification, the description with reference to the terms "some embodiments" or "examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0160] The above are only preferred embodiments of the present application and do not have any limiting effect on the present application. Any technical personnel in the relevant technical field, without departing from the scope of the technical solution of the present application, may make any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present application, which shall be deemed as the content of the technical solution of the present application and still fall within the protection scope of the present application.

Claims

1. A method for measuring semiconductor quantum dots, characterized in that: A semiconductor quantum chip is provided with mutually coupled bit quantum dots and sensing quantum dots, and the state of the sensing quantum dots is read through a measurement link to obtain information of the bit quantum dots; the method comprises: Adjusting an impedance matching circuit in the measurement link so that the impedance of the sensing quantum dot matches the characteristic impedance of the measurement link; Applying a first DC voltage signal, a first radio frequency reading signal and a second DC voltage signal to the gate of the sensing quantum dot to obtain a Coulomb peak phase diagram of the sensing quantum dot; Determine a first target voltage of the first DC voltage signal and a second target voltage of the second DC voltage signal according to a change value of the reflected voltage in the Coulomb peak phase diagram; The second DC voltage signal is applied to the gate of the bit quantum dot, and a first DC voltage signal having a voltage value of the first target voltage, a second DC voltage signal having a voltage value of the second target voltage, and the first RF reading signal are respectively applied to the gate of the sensing quantum dot to read the information of the sensing quantum dot.

2. The method according to claim 1, characterized in that The impedance matching circuit includes an inductor, and a first adjustable capacitor and a second adjustable capacitor electrically connected to both ends of the inductor, and the step of adjusting the impedance matching circuit in the measurement link so that the impedance of the sensing quantum dot matches the characteristic impedance of the measurement link includes: Respectively adjusting voltage values ​​of a third DC voltage signal applied to the first adjustable capacitor and the second adjustable capacitor to adjust the characteristic impedance of the measurement link; Applying a fourth DC voltage signal and a second radio frequency reading signal to the gate of the sensing quantum dot and obtaining an S21 curve showing that the attenuation value of the reflected signal varies with the voltage value of the third DC voltage signal; Determine that the voltage value corresponding to the trough position of the S21 curve is a third target voltage; A third DC voltage signal of the third target voltage is applied to the first adjustable capacitor and the second adjustable capacitor to match the characteristic impedance of the measurement link with the impedance of the sensing quantum dot.

3. The method according to claim 2, characterized in that After the step of adjusting the impedance matching circuit in the measurement link so that the impedance of the sensing quantum dot matches the characteristic impedance of the measurement link, the method further includes: Applying a fourth DC voltage signal with a voltage value within a first preset range to the gate of the sensing quantum dot; Applying the second radio frequency reading signal to the gate of the sensing quantum dot and obtaining an S21 curve of the reflection signal; Determine a target voltage range within the first preset range in which the attenuation change value of the S21 curve is greater than a preset value; A fourth DC voltage signal applied to the gate of the sensing quantum dot is updated according to the target voltage range.

4. The method according to claim 1, characterized in that The gate includes a barrier gate, a pump gate and an accumulation gate, and the first DC voltage signal, the first RF read signal and the second DC voltage signal are applied to the gate of the sensing quantum dot to obtain the Coulomb peak phase diagram of the sensing quantum dot, including: Applying the first DC voltage signal to the barrier gate of the sensing quantum dot; Applying the second DC voltage signal to the pump gate of the sensing quantum dot; Applying the first radio frequency read signal to the accumulation gate of the sensing quantum dot; The corresponding relationship between the voltage of the signal output by the accumulation gate reflection and the voltage of the first DC voltage signal and the voltage of the second DC voltage signal is determined to be the Coulomb peak phase diagram.

5. The method according to claim 4, characterized in that The determination of the corresponding relationship between the voltage of the signal output by the induction quantum dot reflection and the voltage of the first DC voltage signal and the voltage of the second DC voltage signal is the Coulomb peak phase diagram, including: Applying a first DC voltage signal of a first preset voltage value to the barrier gate, sequentially applying a second DC voltage signal of a voltage value in a second preset range to the pump gate, and applying the first radio frequency read signal to the accumulation gate of the sensing quantum dot, to obtain a first corresponding relationship between the voltage of the signal reflected and output by the accumulation gate and the voltage value in the second preset range; Traversing the voltage values ​​of the first DC voltage signal in a third preset range, applying a second DC voltage signal with a voltage value in a second preset range to the pump gate, and applying the first radio frequency read signal to the accumulation gate of the sensing quantum dot, to obtain a second corresponding relationship between the voltage of the signal reflected and output by the accumulation gate and the voltage value in the third preset range; The Coulomb peak phase diagram is determined according to the first corresponding relationship and the second corresponding relationship.

6. The method according to claim 5, characterized in that The second DC voltage signal includes a fixed amplitude DC signal and a triangular wave signal, the first DC voltage signal of the first preset voltage value is applied to the barrier gate, the second DC voltage signal of the voltage value of the second preset range is applied to the pump gate in sequence, and the first RF read signal is applied to the accumulation gate of the induction quantum dot, and the first corresponding relationship between the voltage of the signal reflected and output by the accumulation gate and the voltage value of the second preset range is obtained, including: Applying a first DC voltage signal of a first preset voltage value to the barrier gate; Sequentially applying a second DC voltage signal having a voltage value in a second preset range to the pumping gate; applying the first radio frequency read signal to the accumulation gate; Collecting the voltage value of the signal reflected and output by the accumulation gate when the voltage value of the second DC voltage signal changes linearly with the amplitude of the rising section or the falling section of the triangular wave signal; The first corresponding relationship is obtained by changing the voltage value of the reflected output signal with the amplitude of the rising section or the falling section of the triangular wave signal.

7. The method according to claim 4, characterized in that The step of applying the second DC voltage signal to the gate of the bit quantum dot, and applying the first DC voltage signal and the second DC voltage signal corresponding to the first target voltage and the second target voltage, and the first radio frequency reading signal to the gate of the sensing quantum dot to read the information of the sensing quantum dot, comprises: Applying a first DC voltage signal corresponding to the first target voltage to the barrier gate of the sensing quantum dot; Applying the second DC voltage signal to the pump gate of the bit quantum dot; Applying a second DC voltage signal corresponding to the second target voltage to a pump gate of the sensing quantum dot; The first radio frequency reading signal is applied to the accumulation gate of the sensing quantum dot to read the information of the sensing quantum dot.

8. A semiconductor quantum dot measurement and control system, characterized in that: A semiconductor quantum chip is provided with mutually coupled bit quantum dots and sensing quantum dots, and the state of the sensing quantum dots is read through a measurement link to obtain information of the bit quantum dots; the system comprises: A first adjustment module, adjusting an impedance matching circuit in the measurement link so that the impedance of the sensing quantum dot matches the characteristic impedance of the measurement link; A first measuring module, used for applying a first DC voltage signal, a first radio frequency reading signal and a second DC voltage signal to the gate of the sensing quantum dot to obtain a Coulomb peak phase diagram of the sensing quantum dot; A first determination module, configured to determine a first target voltage of the first DC voltage signal and a second target voltage of the second DC voltage signal according to a change value of the reflected voltage in the Coulomb peak phase diagram; The second measuring module is used to apply the second DC voltage signal to the gate of the bit quantum dot, and respectively apply the first DC voltage signal and the second DC voltage signal corresponding to the first target voltage and the second target voltage, and the first RF reading signal to the gate of the sensing quantum dot to read the information of the sensing quantum dot.

9. The system according to claim 8, characterized in that The first measurement module comprises: A DC voltage source, used for outputting the first DC voltage signal and a fixed amplitude DC signal; An arbitrary waveform generator, used for outputting the triangular wave signal; A radio frequency source, configured to output the first radio frequency reading signal; A signal acquisition card, used to collect the reflected signal output by the gate of the sensing quantum dot; The triangular wave signal and the fixed amplitude DC signal are processed into the second DC voltage signal by a signal superimposer.

10. A quantum computer, characterized in that: The quantum dots on a semiconductor quantum chip are tested using the method described in any one of claims 1 to 7, or the quantum dots on a semiconductor quantum chip are tested using the system described in claim 8 or 9.

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