Digital baseband for low-temperature quantum bit control and quantum bit controller

Abstract

The invention discloses a digital baseband for low-temperature quantum bit control and a quantum bit controller, the digital baseband combines a DDS (Direct Digital Synthesizer) and an AWG (Arrayed Waveguide Grating) mode, realizes efficient frequency, phase and amplitude adjustment by utilizing the DDS mode, provides the generation capability of any waveform through the AWG mode, meets the requirement of quantum bits for executing complex operation, and improves the quantum bit control efficiency. Meanwhile, the X-channel DDS module and the Y-channel DDS module of the XY driver are respectively provided with a numerical control oscillator, so that independent digital intermediate-frequency pulses can be generated at the same time, frequency division multiplexing is realized, simple sin waves can be directly output, waveform pulse data can be read from an XY-channel memory, and correspondingly modulated pulse waveform data can be output according to different requirements; therefore, quantum bit control can be efficiently and flexibly realized, a plurality of signals can share the same communication channel, the channel utilization rate is optimized, and the overall transmission efficiency of the digital baseband is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of digital baseband, and particularly to a digital baseband for low-temperature qubit manipulation and a qubit manipulator. Background Art

[0002] In the process of developing quantum computing technology, one of the most core requirements is to significantly increase the scale of the quantum computing system. However, there are still some challenges in the expansion and improvement of the current quantum control system. For example, since room-temperature devices need to be connected to low-temperature qubits through hundreds of coaxial cables, which greatly limits the scalability of the devices. Although low-temperature CMOS integrated circuits operating in the temperature range of 1 - 4K can reduce the requirements for interconnecting room-temperature measurement and control signals, improve the measurement and control fidelity of qubits, and realize the measurement and control of large-scale physical qubit arrays, and become one of the integrated solutions for the measurement and control system of quantum chips. However, due to different control requirements for different qubits and obvious performance differences and drifts in the manufactured quantum arrays, it is required that the qubit manipulator has high flexibility.

[0003] In a low-temperature quantum control system, the digital baseband plays a crucial role in the qubit manipulator. It can not only generate and control the complex signals required by qubits, but also improve the manipulation speed and fidelity, and contribute to the construction of a scalable quantum computing system. However, currently, the digital basebands of all qubit manipulators have only one control mode and cannot achieve high-flexibility qubit manipulation. Summary of the Invention

[0004] In view of the above deficiencies of the prior art, the object of the present invention is to provide a digital baseband for low-temperature qubit manipulation. By designing and combining the DDS and AWG modes in the digital baseband architecture, using the DDS mode to achieve efficient frequency, phase, and amplitude adjustment, and providing the ability to generate arbitrary waveforms through the AWG mode, it can meet the requirements of qubits when performing complex operations and can achieve high-flexibility qubit manipulation.

[0005] The digital baseband for low-temperature qubit manipulation provided by the present invention includes: a plurality of driver units; moreover, each of the driver units includes: an XY driver and a Z driver; wherein,

[0006] The XY driver includes:

[0007] An XY channel memory for storing waveform pulse data of the X channel and the Y channel;

[0008] An XY channel sequencer configured with an instruction set for coordinating the sequence playback of the X channel and the Y channel;

[0009] and an X-channel DDS module, a Y-channel DDS module, an X-channel multiplexer, and a Y-channel multiplexer;

[0010] Wherein, the X-channel is composed of a DDS sub-channel and an AWG sub-channel that respectively serve as one input of the X-channel multiplexer; the Y-channel is composed of a DDS sub-channel and an AWG sub-channel that respectively serve as one input of the Y-channel multiplexer; moreover, the DDS sub-channel of the X-channel provides waveform pulse data output independently by the X-channel DDS module or provides waveform pulse data output jointly by the X-channel DDS module and the XY-channel memory; the DDS sub-channel of the Y-channel provides waveform pulse data output independently by the Y-channel DDS module or provides waveform pulse data output jointly by the Y-channel DDS module and the XY-channel memory; the AWG sub-channels of the X-channel and the Y-channel both directly provide waveform pulse data output by the XY-channel memory;

[0011] The Z driver includes:

[0012] a Z-channel memory for storing waveform pulse data of the Z-channel;

[0013] a Z-channel sequencer configured with an instruction set for coordinating the sequence playback of the Z-channel;

[0014] Wherein, the Z-channel directly provides waveform pulse data output by the Z-channel memory.

[0015] According to a specific embodiment, in the digital baseband for low-temperature qubit manipulation provided by the present invention, the X-channels, Y-channels, and Z-channels of several of the driver units respectively output waveform data streams in parallel through corresponding parallel-to-serial interfaces.

[0016] According to a specific embodiment, in the digital baseband for low-temperature qubit manipulation provided by the present invention, both the X-channel DDS module and the Y-channel DDS module have a numerically controlled oscillator for simultaneously generating independent digital intermediate-frequency pulses;

[0017] Both the X-channel DDS module and the Y-channel DDS module have four adders and four multipliers; among them, the first adder is used to modulate the configured phase parameter on the digital intermediate frequency pulse generated by the numerically controlled oscillator; the second adder is used to modulate the configured phase calibration parameter on the waveform pulse data output by the first adder; the waveform pulse data output by the second adder is input to the first multiplier after being converted by the cosine function look-up table; the waveform pulse data output by the first adder is input to the second multiplier after being converted by the sine function look-up table; the third multiplier is used to multiply the configured envelope parameter, I-wave amplitude parameter, and Q-wave amplitude parameter and then input them to the first multiplier to modulate the waveform pulse data converted by the cosine function look-up table; the fourth multiplier is used to multiply the configured envelope parameter, I-wave amplitude parameter, and Q-wave amplitude parameter and then input them to the second multiplier to modulate the waveform pulse data converted by the sine function look-up table; the third adder is used to modulate the configured DC calibration parameter on the waveform pulse data output by the first multiplier;

[0018] Moreover, the fourth adder of the X-channel DDS module is used to modulate the waveform pulse data output by the second multiplier of the Y-channel DDS module on the waveform pulse data output by the third adder of the X-channel DDS module; the fourth adder of the Y-channel DDS module is used to modulate the waveform pulse data output by the second multiplier of the X-channel DDS module on the waveform pulse data output by the third adder of the Y-channel DDS module; the waveform pulse data output by the fourth adders of the X-channel DDS module and the Y-channel DDS module are respectively output as the waveform pulse data of their DDS sub-channels.

[0019] According to a specific embodiment, in the digital baseband for low-temperature qubit manipulation provided by the present invention, the instruction set configured by the XY-channel sequencer defines the duration, envelope parameter, I-wave amplitude parameter, Q-wave amplitude parameter, phase parameter, phase calibration parameter, and DC calibration parameter of each sequence; the XY-channel memory stores the envelope parameters respectively used for modulating the waveform pulse data of the X-channel DDS module and the Y-channel DDS module.

[0020] According to a specific embodiment, in the digital baseband for low-temperature qubit manipulation provided by the present invention, when the numerically controlled oscillators of the X-channel DDS module and the Y-channel DDS module are configured to generate the same digital intermediate frequency pulse, and the envelope parameter stored in the XY-channel memory for modulating the waveform pulse data of the X-channel DDS module is a Gaussian envelope, and the envelope parameter for modulating the waveform pulse data of the Y-channel DDS module is a Gaussian derivative envelope, the X-channel and the Y-channel output DRAG pulse data.

[0021] According to a specific embodiment, in the digital baseband for low-temperature qubit manipulation provided by the present invention, the Z driver further includes: an adder; wherein, the adder is used to modulate the configured bias parameter onto the waveform pulse data output by the Z-channel memory.

[0022] Based on the same inventive concept, the present invention further provides a qubit manipulator, which is characterized by including the digital baseband for low-temperature qubit manipulation provided by the invention, an X-channel DAC, a Y-channel DAC, and a Z-channel DAC; wherein, the digital baseband for low-temperature qubit manipulation is connected to the input ends of the X-channel DAC, the Y-channel DAC, and the Z-channel DAC respectively through its corresponding parallel-to-serial interface.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. The digital baseband for low-temperature qubit manipulation provided by the present invention improves the flexibility of qubit manipulation by designing and combining the DDS and AWG modes in the digital baseband architecture. The DDS mode is used to achieve efficient frequency, phase, and amplitude adjustment, and the AWG mode is used to provide the ability to generate arbitrary waveforms, meeting the requirements of qubits when performing complex operations and improving the fidelity of qubit control.

[0025] 2. In the digital baseband for low-temperature qubit manipulation provided by the present invention, both the X-channel DDS module and the Y-channel DDS module of the XY driver have a numerically controlled oscillator, which can simultaneously generate independent digital intermediate-frequency pulses; thus, not only can a simple sin wave be directly output, but also waveform data can be read from the XY-channel memory and then different modulated pulse waveform data can be output to achieve frequency-division multiplexing; therefore, the present invention can enable multiple signals to share the same communication channel, optimize the channel utilization rate, and thus improve the overall transmission efficiency of the digital baseband; in addition, by generating the same digital intermediate-frequency pulses, DRAG pulse data or chirp pulse data for qubit frequency search can be output, and leakage of adjacent quantum energy levels can be suppressed.

[0026] 3. The digital baseband for low-temperature qubit manipulation provided by the present invention adopts 512 XY-channel sequencers and Z-channel sequencers, which can sequentially output 512 different waveform sequences. The duration, envelope parameter, I-wave amplitude parameter, Q-wave amplitude parameter, phase parameter, phase calibration parameter, and DC calibration parameter of each sequence can be configured in the sequencer, which can not only ensure the accuracy and flexibility of qubit operations, but also efficiently process a large number of quantum gate operations.

[0027] 4. The digital baseband for low-temperature qubit manipulation provided by the present invention uses the AWG mode for the Z channel. It can not only shape the rising and falling edges of the Z pulse (the fastest is 0.5 ns), but also compensate for the reflection between the Qubit and the 50 Ω coaxial cable, improving the fidelity of qubit control.

[0028] 5. The digital baseband for low-temperature qubit manipulation provided by the present invention simultaneously uses multiple driver units, and all driver units achieve parallel operation through a parallel-to-serial interface. For example, 4 driver units with digital blocks having a clock frequency of 500 MHz operate in parallel, which can support the output of a 2 GHz, 12-bit data stream for the DAC, and greatly improve the DC efficiency. Description of the Drawings

[0029] Figure 1 Schematic diagram of the digital baseband architecture for low-temperature qubit manipulation provided by the present invention;

[0030] Figure 2 Schematic diagram of the architecture of the qubit manipulator provided by the present invention;

[0031] Figure 3 Digital pulse timing diagram of qubit control of the digital baseband provided by the present invention;

[0032] Figure 4 Schematic diagram of the FPGA verification architecture for verifying the digital baseband provided by the present invention;

[0033] Figure 5 Test results of the digital baseband AWG mode single-pulse continuous playback mode deduced from the FPGA verification architecture of the present invention;

[0034] Figure 6 Test results of the digital baseband DDS mode single-pulse continuous playback mode deduced from the FPGA verification architecture of the present invention;

[0035] Figure 7 Test results of the physical XY channel and Z channel fabricated based on the digital baseband of the present invention;

[0036] Figure 8 (a) Test results of the physical DRAG waveform fabricated based on the digital baseband of the present invention;

[0037] Figure 8 (b) Test results of the spectrum of the physical DRAG waveform fabricated based on the digital baseband of the present invention;

[0038] Figure 9 (a) Test results of the physical Z channel AWG mode fabricated based on the digital baseband of the present invention;

[0039] Figure 9 (b) shows the test results of the physical Z-channel cable reflection compensation made based on the digital baseband of the present invention. Detailed implementation manners

[0040] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments. Any technology implemented based on the content of the present invention belongs to the scope of the present invention.

[0041] As Figure 1 shown, in an embodiment of the present invention, the digital baseband provided for low-temperature qubit manipulation by the present invention uses four driver units with a clock frequency of 5000 MHz to achieve an output of 2 GHz and 12-bit data stream in support of the DAC; wherein, each of the driver units includes: an XY driver and a Z driver; wherein,

[0042] The XY driver includes:

[0043] An XY-channel memory for storing waveform pulse data of the X-channel and the Y-channel;

[0044] An XY-channel sequencer configured with an instruction set for coordinating the sequence playback of the X-channel and the Y-channel;

[0045] And, an X-channel DDS module and a Y-channel DDS module, an X-channel multiplexer MUX1 and a Y-channel multiplexer MUX2;

[0046] Wherein, the X-channel is composed of a DDS sub-channel and an AWG sub-channel respectively serving as one input of the X-channel multiplexer MUX1; the Y-channel is composed of a DDS sub-channel and an AWG sub-channel respectively serving as one input of the Y-channel multiplexer MUX2; moreover, the DDS sub-channel of the X-channel is provided with waveform pulse data output independently by the X-channel DDS module or jointly by the X-channel DDS module and the XY-channel memory; the DDS sub-channel of the Y-channel is provided with waveform pulse data output independently by the Y-channel DDS module or jointly by the Y-channel DDS module and the XY-channel memory; the AWG sub-channels of the X-channel and the Y-channel are both directly provided with waveform pulse data output by the XY-channel memory;

[0047] The Z driver includes:

[0048] A Z-channel memory for storing waveform pulse data of the Z-channel;

[0049] A Z-channel sequencer configured with an instruction set for coordinating the sequence playback of the Z-channel;

[0050] Among them, the Z-channel directly provides waveform pulse data output by the Z-channel memory.

[0051] Specifically, in this embodiment, the X-channels, Y-channels, and Z-channels of the four driver units respectively output waveform data streams in parallel through corresponding parallel-to-serial interfaces. That is, the X-channels of the four driver units are output in parallel through the parallel-to-serial interface PSI1, the Y-channels of the four driver units are output in parallel through the parallel-to-serial interface PSI2, and the Z-channels of the four driver units are output in parallel through the parallel-to-serial interface PSI3.

[0052] Therefore, the digital baseband for low-temperature qubit manipulation provided by the present invention improves the flexibility of qubit manipulation by designing a combined DDS and AWG mode dual-mode in the digital baseband architecture. The DDS mode is used to achieve efficient frequency, phase, and amplitude adjustment, and the AWG mode is used to provide the ability to generate arbitrary waveforms, meeting the requirements of qubits when performing complex operations and improving the fidelity of qubit control. Moreover, multiple driver units are adopted at the same time, and all driver units work in parallel through parallel-to-serial interfaces. For example, 4 driver units with digital blocks having a clock frequency of 500 MHz work in parallel, which can support the output of a 2 GHz, 12-bit data stream for the DAC, and greatly improve the DC efficiency.

[0053] At the same time, both the X-channel DDS module and the Y-channel DDS module have a numerically controlled oscillator for simultaneously generating independent digital intermediate frequency pulses, that is, the X-channel DDS module generates digital intermediate frequency pulses through the numerically controlled oscillator NCO 0 to generate digital intermediate frequency pulses, and the Y-channel DDS module generates digital intermediate frequency pulses through the numerically controlled oscillator NCO 1 to generate digital intermediate frequency pulses.

[0054] Both the X-channel DDS module and the Y-channel DDS module have four adders and four multipliers; among them, the first adder is used to modulate the configured phase parameter onto the digital intermediate frequency pulses generated by the numerically controlled oscillator; the second adder is used to modulate the configured phase calibration parameter (β 0 / 1 ) onto the output waveform pulse data of the first adder; the waveform pulse data output by the second adder is input to the first multiplier after being converted by the cosine function look-up table; the waveform pulse data output by the first adder is input to the second multiplier after being converted by the sine function look-up table; the third multiplier is used to configure the envelope parameter (V env,0 / 1 ), the I-wave amplitude parameter (α i0 / 1 ), and the Q-wave amplitude parameter (α q0 / 1) After multiplication, input to the first multiplier to modulate the waveform pulse data converted by the cosine function look-up table; the fourth multiplier is used to multiply the configured envelope parameter (V env,0 / 1 ), the I-wave amplitude parameter (α i0 / 1 ), and the Q-wave amplitude parameter (α q0 / 1 ) and then input to the second multiplier to modulate the waveform pulse data converted by the sine function look-up table; the third adder is used to modulate the configured DC calibration parameter (γ 0 / 1 ) onto the waveform pulse data output by the first multiplier;

[0055] Moreover, the fourth adder of the X-channel DDS module is used to modulate the waveform pulse data Q 1 output by the second multiplier of the Y-channel DDS module onto the waveform pulse data I 0 output by the third adder of the X-channel DDS module; the fourth adder of the Y-channel DDS module is used to modulate the waveform pulse data Q 0 output by the second multiplier of the X-channel DDS module onto the waveform pulse data I 1 output by the seventh multiplier of the Y-channel DDS module; the waveform pulse data I 0 and I 1 output by the fourth adders of the X-channel DDS module and the Y-channel DDS module are respectively used as the waveform data outputs of their DDS sub-channels.

[0056] In implementation, in the digital baseband for low-temperature qubit manipulation provided by the present invention, the instruction set configured by the XY-channel sequencer defines the duration t of each sequence, the envelope parameter (V env,0 / 1 ), the I-wave amplitude parameter (α i0 / 1 ), the Q-wave amplitude parameter (α q0 / 1 ), the phase parameter the phase calibration parameter (β 0 / 1 ), and the DC calibration parameter (γ 0 / 1 ); the XY-channel memory stores the envelope parameter (V env,0 / 1 ) respectively for modulating the waveform pulse data of the X-channel DDS module and the Y-channel DDS module.

[0057] When the digital baseband for low-temperature qubit manipulation provided by the present invention operates in the DDS mode, since each XY driver includes two numerically controlled oscillators NCO 0 , NCO 1 can simultaneously generate independent digital intermediate frequency pulses (which can be pulses of different frequencies), that is, frequency division multiplexing (FDM) is achieved. Therefore, in each parallel channel, the 12-bit phase output by the numerically controlled oscillator is passed through the phase parameter Phase calibration parameter (β 0 / 1 ) is converted into 12-bit sine wave (Q wave) and cosine wave (I wave) respectively through the function look-up table LUT. When a simple continuous sin wave signal needs to be output, the I wave and Q wave pass through the I wave amplitude parameter (α i0 / 1 ), Q wave amplitude parameter (α q0 / 1 ) and DC calibration parameter (γ 0 / 1 ) and then are directly output; when different waveform pulses need to be output, the I wave and Q wave are multiplied by the envelope parameter (V env,0 / 1 )(stored in the XY channel memory, that is, XY SRAM) to obtain the required modulated waveform pulse data.

[0058] In addition, the two numerically controlled oscillators NCO 0 and NCO 1 of the XY driver can also be used as the IQ channels to generate the same digital intermediate frequency signal, so as to realize the generation of DRAG pulse data. According to the DRAG generation formula:

[0059]

[0060] where, Gaussian(t,A,σ,Tpulse)=Aexp{-t 2 / (2σ 2 )}, A is the amplitude of the waveform, σ is the pulse width of the waveform, t is the time of the waveform, and β is the scaling parameter of the waveform. When the envelope parameter V env,0 (I wave) output by the XY SRAM has a Gaussian envelope and the envelope parameter V env,1 (Q wave) output has a Gaussian derivative envelope, DRAG pulse data can be generated. By correcting the imaginary component of DRAG through the scaling parameter β, a notch can be introduced to suppress the leakage of adjacent quantum energy levels.

[0061] Therefore, the digital baseband for low-temperature qubit manipulation provided by the present invention is designed such that both the X-channel DDS module and the Y-channel DDS module of the XY driver have a numerically controlled oscillator, which can simultaneously generate independent digital intermediate frequency pulses; thus, not only can a simple sin wave be directly output, but also waveform data can be read from the XY channel memory and then different modulated pulse waveform data can be output to realize frequency division multiplexing; therefore, the present invention enables multiple signals to share the same communication channel, optimizes the channel utilization rate, and thus improves the overall transmission efficiency of the digital baseband; in addition, by generating the same digital intermediate frequency pulses, DRAG pulse data or chirp pulse data for qubit frequency search can be output, and the leakage of adjacent quantum energy levels can be suppressed.

[0062] When the digital baseband for low-temperature qubit manipulation provided by the present invention operates in the AWG mode, in the XY channel, the XY SRAM of the XY driver has a size of 24 kByte, which can support a maximum waveform length of 16 k points, or a waveform length of 8 μs for a 2 Gsps 12-bit DAC. In the Z channel, the waveform pulse data of the Z driver directly flows from the Z SRAM to the DAC connected to the digital baseband output, enriching the possibilities of qubit control. In addition, most Z drivers can only provide rectangular pulses, while the Z driver in the present invention adopts the AWG mode. At the same time, the Z driver further includes: an adder; the adder is used to modulate the configured bias parameter onto the waveform pulse data output from the Z channel memory. Therefore, in addition to a fast rising edge of 0.5 ns, it can not only shape the rising and falling edges of the Z pulse, but also compensate for the reflection between the qubit and the 50 Ω coaxial cable. Two Z drivers share an independent 24 kByte Z SRAM. Inside the Z channel sequencer, each Z channel waveform pulse data has a predefined edge transition waveform data, followed by a DC code for long-term bias.

[0063] Therefore, for the digital baseband for low-temperature qubit manipulation provided by the present invention, the Z channel adopts the AWG mode, which can not only shape the rising and falling edges of the Z pulse (the fastest 0.5 ns), but also compensate for the reflection between the Qubit and the 50 Ω coaxial cable, improving the fidelity of qubit control.

[0064] During implementation, both the XY driver and the Z driver have instruction sets that can coordinate the sequence playback of up to 512 steps, and can sequentially output 512 different waveform sequences. The duration t, envelope parameter (V env,0 / 1 ), I-wave amplitude parameter (α i0 / 1 ), Q-wave amplitude parameter (α q0 / 1 ), phase parameter phase calibration parameter (β 0 / 1 ), and DC calibration parameter (γ 0 / 1 ) of each sequence are predefined in the sequence generator. Among them, the envelope parameter (V env,0 / 1 ) can be configured and defined by the XY SRAM.

[0065] As Figure 3 shown, it is a digital pulse timing diagram for qubit control in which the XY drivers XY1 and XY2 in two driver units operate in the DDS mode, and the Z drivers Z1 and Z2 operate in the AWG mode. After the hardware trigger (in) is started, under the control of the sequencer with a maximum depth of 512, the XY driver generates a radio frequency pulse sequence of 4 - 8 GHz for quantum logic gate control. The duration t (t 1 , t 2, t 3 , t 4 ), envelope parameter (V env,0 / 1 ), I-wave amplitude parameter (α i0 / 1 ), Q-wave amplitude parameter (α q0 / 1 ), phase parameter phase calibration parameter (β 0 / 1 ), and DC calibration parameter (γ 0 / 1 ) are all predefined in the XY channel sequencer. Therefore, the Z driver, together with the XY drivers, performs qubit initialization. After the sequence ends, another trigger (out) is issued as an identifier for qubit readout. Therefore, the digital baseband for cryogenic qubit manipulation provided by the present invention can not only ensure the accuracy and flexibility of qubit operations, but also efficiently process a large number of quantum gate operations.

[0066] As Figure 2 shown, in an embodiment of the present invention, a qubit manipulator is further provided, which includes the digital baseband for cryogenic qubit manipulation provided by the invention, an X-channel DAC (IDAC), a Y-channel DAC (QDAC), and a Z-channel DAC (ZDAC); wherein, the digital baseband for cryogenic qubit manipulation is respectively connected to the input ends of the X-channel DAC, the Y-channel DAC, and the Z-channel DAC through its corresponding parallel-to-serial interfaces (i.e., PSI1, PSI2, and PSI3).

[0067] Furthermore, the digital baseband provided by the present invention is verified with the FPGA verification architecture as Figure 4 shown. After writing the verilog language of the digital baseband on the test carrier board, the FPGA is responsible for the initialization and configuration processes, and interacts with the external waveform file through the VIO (Virtual Input Output) module to generate the required control signals. The FPGA also communicates with the digital baseband part of the chip through the digital SPI interface, generates the core clock signal through the MMCM (Multi-Mode Clock Manager), and works in cooperation with the DAC (Digital-to-Analog Converter) to generate accurate analog signals. These signals are transmitted through the FMC (FPGA Mezzanine Card) daughter card, which contains a CLK_PLL (Clock Phase Locked Loop) for clock synchronization, and are output to the oscilloscope through the SMA connector for observing and analyzing the signal waveforms. The entire system is triggered (Trig) and reset (RST) through LVCMOS (Low-Voltage CMOS) signals to ensure signal synchronization and system stability. The waveform multiplexer allows selecting and switching waveforms under different test conditions for comprehensive verification.

[0068] As Figure 5As shown, the test results of continuous playback of digital single pulses of the digital baseband provided by the present invention operating in the AWG mode show that the XY channels can output continuous sine waves (blue lines), and the Z channel can output a fixed level (green line).

[0069] As Figure 6 shown, the test results of continuous playback of digital single pulses of the XY channels of the digital baseband provided by the present invention operating in the DDS mode can output continuous sine waves.

[0070] After the FPGA verification architecture is completed, further test verification is carried out on the physical digital baseband fabricated according to the digital baseband concept provided by the present invention.

[0071] First, the XY and Z pulses measured by using a 4K hardware trigger are used. The carrier frequency of the XY pulses is 6.4~GHz, and their timing, amplitude, and envelope are controlled by a sequencer. The test results as Figure 7 shown are obtained, that is, the envelope lines of the XY pulses include various waveform types such as cosine waves, square waves, triangular waves, and Gaussian waves, and the pulse duration, time interval, and amplitude can be flexibly controlled. In addition, the time-domain waveform of the Z driver is also shown in the figure, where each Z pulse in the Z channel sequencer has a predefined edge transition waveform, followed by DC coding for long-term biasing, with high flexibility and controllability.

[0072] Next, the DRAG pulse data at 4.2~K with a radio frequency of 6.4~GHz is tested. As Figure 8 shown, 26~dB suppression is achieved at the designed non-harmonic frequency of 1.72~MHz, confirming the effective non-linear suppression of the physical digital baseband.

[0073] Finally, the performance of the Z driver is tested, where Figure 9 (a) shows the use of cable reflection compensation in the AWG mode, which plays a role in optimizing signal transmission. Figure 9 (b) shows the fast rise time and edge shaping of 0.5 ns of the Z pulse, indicating that the digital baseband has excellent time-domain response characteristics.

[0074] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A digital baseband for low-temperature quantum bit manipulation, characterized in that: include: a number of drive units; Moreover, each of the drive units includes: an XY drive and a Z drive; wherein the XY drive includes: XY channel memory, used to store waveform pulse data of X channel and Y channel; An XY channel sequencer configured with an instruction set for coordinating sequence playback of the X channel and the Y channel; and, an X-channel DDS module and a Y-channel DDS module, an X-channel multiplexer and a Y-channel multiplexer; Wherein, the X channel is composed of a DDS sub-channel and an AWG sub-channel which are respectively used as one input of the X channel multiplexer; the Y channel is composed of a DDS sub-channel and an AWG sub-channel which are respectively used as one input of the Y channel multiplexer; and the DDS sub-channel of the X channel is provided with waveform pulse data output by the X channel DDS module alone or by the X channel DDS module in combination with the XY channel memory; the DDS sub-channel of the Y channel is provided with waveform pulse data output by the Y channel DDS module alone or by the Y channel DDS module in combination with the XY channel memory; the AWG sub-channels of the X channel and the Y channel are both provided with waveform pulse data output directly by the XY channel memory; The Z-driver comprises: Z channel memory, used for storing waveform pulse data of Z channel; A Z channel sequencer configured with an instruction set for coordinating sequence playback of the Z channel; Wherein, the Z channel directly provides waveform pulse data output by the Z channel memory.

2. The digital baseband for cryogenic quantum bit manipulation according to claim 1, characterized in that: The X channels, the Y channels and the Z channels of the plurality of driver units respectively output waveform data streams in parallel through corresponding parallel-to-serial interfaces.

3. The digital baseband for cryogenic quantum bit manipulation according to claim 1, characterized in that: The X-channel DDS module and the Y-channel DDS module each have a digitally controlled oscillator for simultaneously generating independent digital intermediate frequency pulses; The X-channel DDS module and the Y-channel DDS module each have four adders and four multipliers; wherein the first adder is used to modulate the configured phase parameter on the digital intermediate frequency pulse generated by the digitally controlled oscillator; the second adder is used to modulate the configured phase calibration parameter on the waveform pulse data output by the first adder; the waveform pulse data output by the second adder is input to the first multiplier after being converted by a cos function lookup table; the waveform pulse data output by the first adder is input to the second multiplier after being converted by a sin function lookup table; the third multiplier is used to multiply the configured envelope parameter, I wave amplitude parameter and Q wave amplitude parameter and input them to the first multiplier to modulate the waveform pulse data converted by the cos function lookup table; the fourth multiplier is used to multiply the configured envelope parameter, I wave amplitude parameter and Q wave amplitude parameter and input them to the second multiplier to modulate the waveform pulse data converted by the sin function lookup table; the third adder is used to modulate the configured DC calibration parameter on the waveform pulse data output by the first multiplier; Moreover, the fourth adder of the X-channel DDS module is used to modulate the waveform pulse data output by the second multiplier of the Y-channel DDS module on the waveform pulse data output by the third adder of the X-channel DDS module; the fourth adder of the Y-channel DDS module is used to modulate the waveform pulse data output by the second multiplier of the X-channel DDS module on the waveform pulse data output by the third adder of the Y-channel DDS module; the waveform pulse data output by the fourth adders of the X-channel DDS module and the Y-channel DDS module are respectively output as the waveform pulse data of their DDS sub-channels.

4. The digital baseband for cryogenic quantum bit manipulation according to claim 3, characterized in that: The instruction set configured by the XY channel sequencer defines the duration, envelope parameters, I wave amplitude parameters, Q wave amplitude parameters, phase parameters, phase calibration parameters and DC calibration parameters of each sequence; the XY channel memory stores envelope parameters for waveform pulse data modulation of the X channel DDS module and the Y channel DDS module respectively.

5. The digital baseband for cryogenic quantum bit manipulation according to claim 4, characterized in that: When the digitally controlled oscillators of the X-channel DDS module and the Y-channel DDS module generate the same digital intermediate frequency pulse, and the envelope parameters for the waveform pulse data modulation of the X-channel DDS module stored in the XY channel memory are Gaussian envelopes, and the envelope parameters for the waveform pulse data modulation of the Y-channel DDS module are Gaussian derivative envelopes, the X-channel and the Y-channel output DRAG pulse data.

6. The digital baseband for cryogenic quantum bit manipulation according to claim 1, characterized in that: The Z driver further includes: an adder; wherein the adder is used to modulate the configured bias parameters on the waveform pulse data output by the Z channel memory.

7. A quantum bit manipulator, characterized in that: The invention comprises a digital baseband for low-temperature quantum bit manipulation, an X-channel DAC, a Y-channel DAC and a Z-channel DAC as claimed in claims 1 to 6; wherein the digital baseband for low-temperature quantum bit manipulation is respectively connected to the input ends of the X-channel DAC, the Y-channel DAC and the Z-channel DAC through their corresponding parallel-to-serial interfaces.

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