Frequency division multiplexing module for quantum bits and quantum chip
Through the frequency division multiplexing module in superconducting quantum chips, frequency selection is used by bandpass filters and quantum couplers, which solves the problem of control line limitation and achieves an increase in the number of quantum bits.
Patent Information
- Application Number
- CN202410032702.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-09
- Publication Date
- 2025-07-11
AI Technical Summary
In large-scale superconducting quantum chips, signal fan-out of control lines becomes a bottleneck that limits the growth of the number of qubits, and how to achieve precise regulation of qubits is the key.
The frequency division multiplexing module is designed, and multiple microwave pulses of different frequencies are input through the control line, and frequency selection is performed using a bandpass filter and a quantum coupler to realize CZ gate or CNOT gate operation, reducing the number of control lines.
On the basis of ensuring the fidelity of the quantum gate, the number of control lines is reduced and the number scale of quantum bits of the quantum chip is increased.
Smart Images
Figure CN120297432A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of quantum communication technology, and more particularly, to a frequency division multiplexing module for qubits and a quantum chip. Background Art
[0002] With the rapid development of quantum computer technology, how to achieve precise control of quantum systems is the focus of the development of quantum computing. Superconducting quantum chips implemented by superconducting qubits are one of the most effective physical platforms for current quantum computing. How to achieve precise control of large-scale superconducting quantum chips is the core technology and challenge for improving the precision of quantum manipulation.
[0003] In the face of a large number of superconducting qubit processors, the signal fan-out of the control lines will become a bottleneck restricting the growth of the scale of the number of qubits. Designing a suitable quantum chip control scheme and the corresponding chip structure is an important way to reduce the number of control lines and ensure the control precision of each qubit. Summary of the Invention
[0004] In view of this, embodiments of the present disclosure provide a frequency division multiplexing module for qubits and a quantum chip.
[0005] One aspect of the embodiments of the present disclosure provides a frequency division multiplexing module for qubits, including:
[0006] At least one control line for inputting microwave pulses, wherein the microwave pulses are simultaneously superimposed with a plurality of sub-pulses of different frequencies;
[0007] A plurality of band-pass filters, each of the band-pass filters is connected to the control line, wherein the device parameters of different band-pass filters are different, and the band-pass filter only allows a sub-pulse of one frequency to pass through;
[0008] A plurality of quantum couplers, one of the quantum couplers is connected to one of the band-pass filters, and the bandwidth parameters of different quantum couplers are different;
[0009] Wherein, the quantum coupler performs a logical operation on two qubits based on the sub-pulse output by the band-pass filter corresponding to the quantum coupler.
[0010] According to an embodiment of the present disclosure, under the action of the sub-pulse output by the band-pass filter corresponding to the quantum coupler, the quantum coupler activates the interaction between two qubits related to the quantum coupler to implement a CZ gate or a CNOT gate.
[0011] According to an embodiment of the present disclosure, the number of the quantum couplers is determined according to the amplitude suppression ratio of the band-pass filter.
[0012] According to an embodiment of the present disclosure, the bandpass filter includes a superconducting bandpass filter, where the superconducting bandpass filter includes any one of a filter formed by a superconducting resonator formed by a coplanar waveguide, a filter of a slot-line mode resonator, and a filter of a lumped superconducting circuit resonator.
[0013] According to an embodiment of the present disclosure, the filter formed by the superconducting resonator formed by the coplanar waveguide is generated by coupling a plurality of superconducting resonators of the same frequency through the coplanar waveguide, where the device parameters include the passband bandwidth, the passband attenuation, and the rectangularity coefficient.
[0014] According to an embodiment of the present disclosure, when the length of the superconducting resonator is changed, the center frequency of the superconducting bandpass filter changes;
[0015] When the distance between different superconducting resonators is changed, the coupling strength between different superconducting resonators changes.
[0016] According to an embodiment of the present disclosure, a plurality of the quantum couplers are connected to the control line through the bandpass filter in an array form.
[0017] Another aspect of the embodiment of the present disclosure provides a quantum chip, including the frequency division multiplexing module as described above.
[0018] According to an embodiment of the present disclosure, by setting a plurality of bandpass filters on each control line, so that the bandpass filter outputs only a sub-pulse of one frequency to the quantum coupler, so that the quantum coupler realizes the quantum gate operation on two qubits under the action of the sub-pulse of this frequency. Thus, on the basis of ensuring the fidelity of the quantum gate, the number of control lines is reduced, and further the scale of the number of qubits of the quantum chip is increased. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Through the following description of the embodiments of the present disclosure with reference to the drawings, the above and other objects, features, and advantages of the present disclosure will become clearer. In the drawings:
[0020] Figure 1 Schematically shows a circuit diagram of the frequency division multiplexing module according to an embodiment of the present disclosure; and
[0021] Figure 2 Schematically shows a usage diagram of the frequency division multiplexing module according to an embodiment of the present disclosure. DETAILED DESCRIPTION
[0022] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the following detailed description, for the sake of explanation, numerous specific details are set forth in order to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is obvious that one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concepts of the present disclosure.
[0023] The terms used herein are merely for describing specific embodiments and are not intended to limit the present disclosure. The terms "including", "comprising", etc. used herein indicate the presence of the described features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.
[0024] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.
[0025] In the case of using expressions such as "at least one of A, B, and C, etc.", generally, it should be interpreted according to the meaning commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but not be limited to a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).
[0026] Figure 1 A circuit schematic diagram of a frequency division multiplexing module according to an embodiment of the present disclosure is schematically shown.
[0027] As Figure 1 shown, the frequency division multiplexing module for qubits includes:
[0028] At least one control line for inputting microwave pulses, and the microwave pulses are simultaneously superimposed with multiple sub-pulses of different frequencies;
[0029] Multiple band-pass filters, each band-pass filter is connected to the control line, wherein the device parameters of different band-pass filters are different, and the band-pass filter only allows a sub-pulse of one frequency to pass through;
[0030] Multiple quantum couplers, one quantum coupler is connected to one band-pass filter, and the bandwidth parameters of different quantum couplers are different;
[0031] Wherein, the quantum coupler processes two qubits based on the sub-pulse output by the band-pass filter corresponding to the quantum coupler.
[0032] According to an embodiment of the present disclosure, the frequency of the microwave pulse can be specifically set according to actual requirements. For example, it can be set to be selected within the frequency range of 50 MHz to 8 GHz, and specifically, the target frequency can be selected within the optional frequency range of approximately 500 MHz. Different sub-pulses are arranged at a frequency interval of 30 MHz.
[0033] According to an embodiment of the present disclosure, after the microwave pulse is input on the control line, each band-pass filter only allows sub-pulses of one frequency to pass through. For example, the first band-pass filter allows sub-pulses of 100 MHz to pass through, the second band-pass filter allows sub-pulses of 200 MHz to pass through... the nth band-pass filter allows sub-pulses of 100n MHz to pass through.
[0034] According to an embodiment of the present disclosure, the quantum coupler connected to the first band-pass filter processes two qubits corresponding to the quantum coupler based on its own bandwidth parameter when receiving sub-pulses of 100 MHz, thereby realizing a quantum gate operation.
[0035] According to an embodiment of the present disclosure, by setting multiple band-pass filters on each control line, the band-pass filter only outputs sub-pulses of one frequency to the quantum coupler, so that the quantum coupler realizes the quantum gate operation on two qubits under the action of the sub-pulses of this frequency. Thus, on the basis of ensuring the fidelity of the quantum gate, the number of control lines is reduced, and further, the number scale of qubits of the quantum chip is increased.
[0036] According to an embodiment of the present disclosure, under the action of the sub-pulses output by the band-pass filter corresponding to the quantum coupler, the quantum coupler activates the interaction between two qubits related to the quantum coupler to realize a CZ gate or a CNOT gate.
[0037] According to an embodiment of the present disclosure, the CZ gate means that when the control bit (i.e., the sub-pulse) is 1, a Z operation is performed on the qubit.
[0038] According to an embodiment of the present disclosure, the CNOT gate means that when the control bit (i.e., the sub-pulse) is 1, an X operation is performed on the qubit.
[0039] According to an embodiment of the present disclosure, the frequency for each quantum coupler to achieve AC needs to be designed according to the bit frequency method, and the band-pass frequency of the band-pass filter is specifically designed according to the driving frequency required by each quantum coupler. Among them, the input frequency bandwidth of each quantum coupler can be set to 5 MHz.
[0040] According to an embodiment of the present disclosure, the number of quantum couplers is determined according to the amplitude suppression ratio of the band-pass filter.
[0041] According to an embodiment of the present disclosure, the bandpass filter includes a superconducting bandpass filter, wherein the superconducting bandpass filter includes any one of a filter made of a superconducting resonator formed by a coplanar waveguide, a filter of a slotline mode resonator, and a filter of a lumped superconducting circuit resonator.
[0042] According to an embodiment of the present disclosure, the filter made of a superconducting resonator formed by a coplanar waveguide is generated by coupling a plurality of superconducting resonators of the same frequency through a coplanar waveguide, wherein the device parameters include passband bandwidth, passband attenuation, and rectangularity coefficient.
[0043] According to an embodiment of the present disclosure, when the length of the superconducting resonator is changed, the center frequency of the superconducting bandpass filter changes;
[0044] When the distance between different superconducting resonators is changed, the coupling strength between different superconducting resonators changes.
[0045] According to an embodiment of the present disclosure, when the center frequency and the coupling strength change, the passband bandwidth, passband attenuation, and rectangularity coefficient can be changed.
[0046] According to an embodiment of the present disclosure, a plurality of quantum couplers are connected to a control line through a bandpass filter in an array form.
[0047] In one embodiment, the superconducting AC CZ gate can be realized by microwave pulses in the frequency range of 50 MHz to 8 GHz. Considering some potential frequency conflicts in the AC CZ gate, the available frequencies for a given chip are divided into optional frequency intervals of approximately 500 MHz to select the target frequency. By arranging the frequency intervals of different AC CZ gates at a frequency interval of 30 MHz and achieving an amplitude suppression ratio of 30 dB at 15 dB for each filter, the error caused by the mutual interference of signals of different AC CZ gates can be negligible in the experiment. Under this control scheme, the goal of controlling m quantum couplers with one control line and independently realizing the CZ gate can be achieved, so that the number of required quantum coupler control lines is reduced to 1 / m of the original.
[0048] In a specific embodiment, each control line can independently control 15 quantum couplers to realize the AC CZ gate, and has almost no influence on the fidelity of the AC CZ gate, which can greatly reduce the number of control lines required for the superconducting quantum chip and reduce the scale of the control lines of the quantum coupler to 1 / 15 of the original.
[0049] Figure 2 A schematic diagram of the use of a frequency division multiplexing module according to an embodiment of the present disclosure is schematically shown.
[0050] According to an embodiment of the present disclosure, as Figure 2As shown, the digital numbers represent qubits, and the horizontal bars are couplers connecting two qubits. A specific frequency needs to be applied to each quantum coupler to activate the interaction between the two connected qubits, thereby implementing the CZ gate. In the traditional control scheme, each quantum coupler requires a dedicated control line to input the microwave signal of the target frequency. In the present disclosure, N quantum couplers can be connected to a single control line through band-pass filters. In actual control, the corresponding frequency microwave pulses for performing the CZ gate can be input through the control line. Due to the isolation of the band-pass filter corresponding to the quantum coupler, the quantum coupler will only respond to the microwave sub-pulses of the target frequency.
[0051] Another aspect of the embodiments of the present disclosure provides a quantum chip, including multiple frequency-division multiplexing modules and other necessary functional modules to implement the complete functions of the quantum chip.
[0052] According to the embodiments of the present disclosure, by setting multiple band-pass filters on each control line, the band-pass filter outputs only one frequency of sub-pulses to the quantum coupler, so that the quantum coupler realizes the quantum gate operation on two qubits under the action of the sub-pulses of this frequency. Thus, on the basis of ensuring the fidelity of the quantum gate, the number of control lines is reduced, and further the scale of the number of qubits of the quantum chip is increased.
[0053] The above describes the embodiments of the present disclosure. However, these embodiments are only for illustrative purposes and not for limiting the scope of the present disclosure. Although the embodiments are separately described above, this does not mean that the measures in each embodiment cannot be used advantageously in combination. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art can make various substitutions and modifications, and these substitutions and modifications should all fall within the scope of the present disclosure.
Claims
1. A frequency division multiplexing module for qubits, comprising: At least one control line for inputting microwave pulses, wherein the microwave pulses are simultaneously superimposed with multiple sub-pulses of different frequencies; Multiple band-pass filters, each of the band-pass filters being connected to the control line, wherein the device parameters of different band-pass filters are different, and the band-pass filter only allows a sub-pulse of one frequency to pass through; Multiple quantum couplers, one quantum coupler being connected to one of the band-pass filters, and the bandwidth parameters of different quantum couplers are different; Wherein, the quantum coupler performs a logical operation on two qubits based on the sub-pulse output by the band-pass filter corresponding to the quantum coupler.
2. The frequency division multiplexing module according to claim 1, wherein, Under the action of the sub-pulse output by the band-pass filter corresponding to the quantum coupler, the quantum coupler activates the interaction between two qubits associated with the quantum coupler to implement a CZ gate or a CNOT gate.
3. The frequency division multiplexing module according to claim 1, wherein, The number of the quantum couplers is determined according to the amplitude suppression ratio of the band-pass filter.
4. The frequency division multiplexing module according to claim 1, wherein, The band-pass filter includes a superconducting band-pass filter, wherein the superconducting band-pass filter includes any one of a filter made of a superconducting resonator formed by a coplanar waveguide, a filter of a slot-line mode resonator, and a filter of a lumped superconducting circuit resonator.
5. The frequency division multiplexing module according to claim 4, wherein The filter made of a superconducting resonator formed by a coplanar waveguide is generated by coupling multiple superconducting resonators of the same frequency through a coplanar waveguide, wherein the device parameters include passband bandwidth, passband attenuation, and rectangularity coefficient.
6. The frequency division multiplexing module according to claim 4, wherein, When the length of the superconducting resonator is changed, the center frequency of the superconducting band-pass filter is changed; When the distance between different superconducting resonators is changed, the coupling strength between different superconducting resonators is changed.
7. The frequency division multiplexing module according to claim 1, wherein, Multiple of the quantum couplers are connected to the control line through the band-pass filter in an array form.
8. A quantum chip, comprising: The frequency division multiplexing module according to any one of claims 1 to 7.