Quantum bit processing method, quantum circuit, and quantum computer
By controlling the high excitation energy level of the qubit to resonate with the target resonant cavity and applying microwaves during the resonance process for adiabatic evolution, the problem of low initialization efficiency in the existing technology is solved, and fast and low-power qubit initialization is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-11-16
- Publication Date
- 2026-03-27
AI Technical Summary
In existing technologies, the initialization efficiency of qubits is low, and long-term and high-power microwave driving is required.
By controlling the high excitation energy level of the qubit to resonate with the target resonant cavity, and applying microwaves to the qubit during the continuous resonance process, the adiabatic evolution of the qubit is realized. The energy of the first excitation energy level is dissipated to the outside by the target resonant cavity, thus completing the initialization.
Fast, low-power qubit initialization was achieved, improving initialization efficiency and solving the problems of long initialization time and high power consumption.
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Figure CN115860129B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of quantum, in particular to a quantum bit processing method, a quantum circuit and a quantum computer. BACKGROUND
[0002] Unlike the low level and high level of traditional classical physical quantities representing 0 and 1, the quantum computing field uses physical quantities such as electron spin and light polarization as 0 state and 1 state of quantum bits. Without any operation, an ideal quantum bit should be 100% in the 0 state, but due to the temperature of tens of mK, a small amount of thermal excitation will still cause a part of the residual 1 state. And this part of the residual will bring an error to the initial state, causing more inaccuracy in subsequent calculations.
[0003] In the related art, when initializing a quantum bit, the method generally used is to use a direct microwave driving method, that is, directly applying a microwave to the quantum bit to initialize the quantum bit. However, the initialization time required by the above method is too long, and the required microwave power is also large, resulting in low initialization efficiency.
[0004] Therefore, in the related art, when initializing a quantum bit, there is a problem of low initialization efficiency.
[0005] In view of the above problems, no effective solution has been proposed so far. SUMMARY
[0006] The embodiments of the present application provide a quantum bit processing method, a quantum circuit and a quantum computer to at least solve the technical problem of low initialization efficiency in the related art when initializing a quantum bit.
[0007] According to an aspect of an embodiment of the present application, a quantum bit processing method is provided, comprising: controlling a high excitation energy level of a quantum bit to resonate with a target resonant cavity, wherein the high excitation energy level is an energy level greater than or equal to a second excitation energy level; during the process that the high excitation energy level of the quantum bit and the target resonant cavity are in continuous resonance, applying a microwave to the quantum bit, controlling the first excitation energy level of the quantum bit to perform adiabatic evolution to the dissipation energy level of the target resonant cavity, and initializing the quantum bit.
[0008] Optionally, the controlling the high excitation level of the quantum bit to resonate with the target resonant cavity comprises: obtaining a first relationship between a frequency of the high excitation level of the quantum bit and a magnetic flux applied on the quantum bit; obtaining a first target frequency of the target resonant cavity; based on the first relationship and the first target frequency, controlling the high excitation level of the quantum bit to resonate with the target resonant cavity by adjusting the magnetic flux applied on the quantum bit.
[0009] Optionally, the controlling the high excitation level of the quantum bit to resonate with the target resonant cavity comprises: obtaining a second relationship between a frequency of the target resonant cavity and a magnetic flux applied on the target resonant cavity; obtaining a second target frequency of the high excitation level of the quantum bit; based on the second relationship and the second target frequency, controlling the high excitation level of the quantum bit to resonate with the target resonant cavity by adjusting the magnetic flux applied on the target resonant cavity.
[0010] Optionally, the controlling the high excitation level of the quantum bit to resonate with the target resonant cavity comprises: controlling the high excitation level of the quantum bit to adiabatically reach a resonance point with the target resonant cavity by adjusting the magnetic flux applied on the quantum bit or the magnetic flux applied on the target resonant cavity.
[0011] Optionally, the controlling the first excitation level of the quantum bit to adiabatically evolve to the dissipative energy level of the target resonant cavity in the process that the high excitation level of the quantum bit and the target resonant cavity are in continuous resonance comprises: determining a target microwave, wherein a microwave intensity of the target microwave increases over time within a predetermined time period; and applying the target microwave to the quantum bit in the process that the high excitation level of the quantum bit and the target resonant cavity are in continuous resonance, and controlling the first excitation level of the quantum bit to adiabatically evolve to the dissipative energy level of the target resonant cavity.
[0012] Optionally, the determining the target microwave comprises: determining a microwave combination continuously comprising a first microwave segment, a second microwave segment, a third microwave segment and a fourth microwave segment as the target microwave, wherein an increasing rate of the microwave intensity of the first microwave segment increasing over time is a first increasing rate, an increasing rate of the microwave intensity of the second microwave segment increasing over time is a second increasing rate, and the first increasing rate is greater than the second increasing rate.
[0013] Optionally, the second increasing rate approaches zero, the microwave intensity of the third microwave segment decreases over time, and the fourth microwave segment is a microwave-free phase.
[0014] Optionally, the target resonant cavity is a read resonant cavity coupled with the quantum bit, and the read resonant cavity is used to read a quantum state of the quantum bit.
[0015] Optionally, the quantum bit is a Fluxonium quantum bit.
[0016] According to another aspect of the present application, a quantum circuit is provided, comprising: a target resonant cavity and a quantum bit, wherein the quantum bit is coupled with a read circuit through the target resonant cavity, and the target resonant cavity is coupled with the quantum bit, wherein the quantum bit is an initialized quantum bit, and the initialization of the quantum bit is achieved by: controlling a high excitation energy level of the quantum bit to resonate with the target resonant cavity, wherein the high excitation energy level is an energy level greater than or equal to a second excitation energy level, and during the process that the high excitation energy level of the quantum bit and the target resonant cavity are in continuous resonance, applying a microwave to the quantum bit, and controlling a first excitation energy level of the quantum bit to adiabatically evolve to a dissipation energy level of the target resonant cavity, thereby initializing the quantum bit.
[0017] According to still another aspect of the present application, a quantum chip is provided, comprising: the quantum circuit described above.
[0018] According to yet another aspect of the present application, a quantum memory is provided, comprising: the quantum circuit described above.
[0019] According to still another aspect of the present application, a quantum computer is provided, comprising: a quantum chip and a quantum memory, wherein the quantum chip and / or the quantum memory comprises the quantum circuit described above.
[0020] According to yet still another aspect of the present application, a computer readable storage medium is provided, comprising a stored program, wherein the computer readable storage medium controls a device where the computer readable storage medium is located to execute the quantum bit processing method described above when the program runs.
[0021] According to still yet another aspect of the present application, a computer device is provided, comprising: a memory and a processor, wherein the memory stores a computer program, and the processor is configured to execute the computer program stored in the memory, and the computer program controls the processor to execute the quantum bit processing method described above when the computer program runs.
[0022] In the embodiment of the present application, the initialization of the quantum bit is achieved by applying a microwave to the quantum bit in the process that the high excitation level of the quantum bit is in continuous resonance with the target resonant cavity, and controlling the first excitation level of the quantum bit to perform adiabatic evolution to the dissipation level of the target resonant cavity. In the above manner, the energy of the first excitation level is transferred to a higher level by applying a microwave to the quantum bit when the quantum bit and the target resonant cavity are resonated, and the higher level is resonated with the target resonant cavity, so that the energy of the first excitation level can be continuously transferred to the target resonant cavity, and then to the outside world, thereby achieving the initialization of the quantum bit. The whole process can be integrated as the adiabatic evolution of the first excitation level of the quantum bit to the dissipation level of the target resonant cavity. Compared with the related art, the quantum bit is directly excited to the dissipation level of the resonant cavity by modulating the microwave, which not only does not need long initialization time, but also does not need high-power microwave, and quickly achieves the initialization of the quantum bit. Moreover, the required microwave power is small, which effectively improves the efficiency of the initialization of the quantum bit, and further solves the technical problem of low initialization efficiency of the quantum bit in the related art. BRIEF DESCRIPTION OF DRAWINGS
[0023] The accompanying drawings, which are included to provide a further understanding of the present application and are incorporated in and constitute a part of this application, illustrate embodiments of the present application and together with the description serve to explain the present application. In the drawings:
[0024] Figure 1 Fig. 1 shows a hardware structure block diagram of a computer terminal for implementing a quantum bit processing method;
[0025] Figure 2 Fig. 2 is a flowchart of a quantum bit processing method according to Embodiment 1 of the present application;
[0026] Figure 3 Fig. 3 is a schematic diagram of a quantum circuit according to Embodiment 1 of the present application;
[0027] Figure 4 Fig. 4 is a schematic diagram of energy levels of a quantum bit and a read resonant cavity according to an optional embodiment of the present application;
[0028] Figure 5 Fig. 5 is a schematic diagram of the resonance of the second excitation level of a quantum bit and a read resonant cavity according to an optional embodiment of the present application;
[0029] Figure 6 Fig. 6 is a schematic diagram of energy level splitting appearing on the frequency spectrum of a quantum bit when the second excitation level of the quantum bit is resonated with a read resonant cavity according to an optional embodiment of the present application;
[0030] Figure 7 is a schematic diagram of a microwave applied to a quantum bit provided by an optional embodiment of the present application;
[0031] Figure 8 is a schematic diagram of a magnetic flux pulse applied to a quantum bit before the quantum bit reaches a resonance point provided by an optional embodiment of the present application;
[0032] Figure 9 is a structural block diagram of a quantum bit processing device according to an embodiment of the present application;
[0033] Figure 10 is a structural block diagram of a computer terminal according to an embodiment of the present application. DETAILED DESCRIPTION
[0034] In order to make the personnel in the technical field better understand the present application scheme, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the protection scope of the present application.
[0035] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily have to include only those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to the process, method, product or device.
[0036] First, some of the nouns or terms appearing in the description of the embodiments of the present application are applicable to the following explanations:
[0037] Stimulated Raman adiabatic path: a kind of adiabatic state transfer between two independent energy levels in a three-level system, which is realized by means of auxiliary energy level coupling between two independent energy levels
[0038] Bit initialization: resetting the bit state so that it is in the ground state or the first excited state before the calculation begins.
[0039] Energy level splitting: the splitting of two energy levels with the same energy in the presence of coupling.
[0040] Embodiment 1
[0041] According to the embodiments of the present application, a method embodiment of a quantum bit processing method is also provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from here.
[0042] The method embodiment provided by Embodiment 1 of the present application can be executed in a mobile terminal, a computer terminal or similar computing device. Figure 1 A hardware structure block diagram of a computer terminal (or mobile device) for implementing a quantum bit processing method is shown. As shown in Figure 1 , the computer terminal 10 (or mobile device) can include one or more processors (shown in the figure as 102a, 102b, …, 102n, the processor can include but not limited to a processing device such as a microprocessor MCU or a programmable logic device FPGA, etc.), a memory 104 for storing data, and a transmission device for communication function. In addition, it can also include a display, an input / output interface (I / O interface), a universal serial bus (USB) port (which can be included as one of the ports of the BUS bus), a network interface, a power supply and / or a camera. Those skilled in the art can understand that Figure 1 The structure shown is only schematic, which does not limit the structure of the above-mentioned electronic device. For example, the computer terminal 10 can also include more or less components than Figure 1 shown, or have a different configuration from Figure 1 shown.
[0043] It should be noted that the one or more processors and / or other data processing circuits described above can be referred to herein as "data processing circuits" in general. The data processing circuit can be embodied in whole or in part as software, hardware, firmware or any other combination. In addition, the data processing circuit can be a single independent processing module, or any one of the other elements combined into the computer terminal 10 (or mobile device) in whole or in part. As referred to in the embodiments of the present application, the data processing circuit as a kind of processor control (for example, the selection of the variable resistance terminal path connected with the interface).
[0044] The memory 104 can be used to store software programs of application software and modules, such as program instructions / data storage means corresponding to the quantum bit processing method in the embodiments of the present application, and the processor executes various functional applications and data processing by running the software programs and modules stored in the memory 104, that is, implements the vulnerability detection method of the application program as described above. The memory 104 can include a high-speed random access memory, and can also include a non-volatile memory, such as one or more magnetic storage devices, flash memories, or other non-volatile solid-state memories. In some examples, the memory 104 can further include a memory remotely arranged with respect to the processor, and these remote memories can be connected to the computer terminal 10 through a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.
[0045] The transmission device is used to receive or send data via a network. The specific examples of the above-mentioned network can include a wireless network provided by a communication provider of the computer terminal 10. In one example, the transmission device includes a network interface controller (NIC) which can be connected to other network devices through a base station so as to be able to communicate with the Internet. In one example, the transmission device can be a radio frequency (RF) module which is used to communicate with the Internet in a wireless manner.
[0046] The display can be, for example, a touch screen type liquid crystal display (LCD) which can enable a user to interact with the user interface of the computer terminal 10 (or mobile device).
[0047] It should be noted that in some optional embodiments, the above-mentioned Figure 1 The computer device (or mobile device) shown can include hardware elements (including circuitry), software elements (including computer code stored on a computer readable medium), or a combination of both hardware and software elements. It should be noted that in some embodiments, the functions of the above-mentioned Figure 1 is only one example of a particular specific embodiment, and is intended to show the types of components that can be present in the above-mentioned computer device (or mobile device).
[0048] Under the above-mentioned operating environment, the present application provides a quantum bit processing method as shown in Figure 2 . Figure 2 is a flowchart of the quantum bit processing method according to Embodiment 1 of the present application, as shown in Figure 2 , the flow includes the following steps:
[0049] Step S202, controlling the high excitation energy level of the quantum bit to resonate with the target resonant cavity, wherein the high excitation energy level is an energy level greater than or equal to the second excitation energy level;
[0050] As an optional embodiment, the execution subject of the quantum bit processing method can be a terminal or a server. The terminal can be various types of terminals, such as a computer terminal, a mobile terminal, a virtual terminal, and the like, but regardless of the type of terminal, the terminal needs to have a certain computing capability to meet the computing requirements. The server can also be in various forms, such as a single computer device, a computer cluster including multiple computers, a local computing unit, a remote cloud server, and the like.
[0051] As an optional embodiment, the type of the quantum bit can be various, such as a Fluxonium quantum bit, a Transmon quantum bit, a charge quantum bit, a phase quantum bit, and other types of frequency-adjustable quantum bits, which are not limited in the embodiments of the present application.
[0052] As an optional embodiment, when the quantum bit is a Fluxonium quantum bit, the Fluxonium has a large frequency adjustment range, and it is relatively easy to realize the coupling between the second excited state or a higher excited state of the quantum bit and the target resonant cavity. The large nonlinearity can ensure that the second excited state or a higher excited state of the quantum bit is coupled with the target resonant cavity without affecting the quantum bit.
[0053] As an optional embodiment, the type of the target resonant cavity can be various. For example, with respect to whether the target resonant cavity is related to the quantum bit, the target resonant cavity can be a read resonant cavity coupled with the quantum bit, and the read resonant cavity is used to read the quantum state of the quantum bit. Of course, the target resonant cavity can also be used to simply initialize the quantum bit, which is not exemplified here.
[0054] As an optional embodiment, when the target resonant cavity is a read resonant cavity used to read the quantum bit, the coupling between the quantum bit and the read resonant cavity is a weak coupling, that is, the read resonant cavity should as little as possible affect the quantum bit to avoid errors in the reading result of the quantum bit. In the manner provided in the embodiments of the present application, the initialization of the quantum bit is quickly realized through the energy level of the quantum bit itself, that is, the initialization of the quantum bit is realized in the case of weak coupling between the quantum bit and the read resonant cavity.
[0055] As an optional embodiment, the high excited energy level is an energy level greater than or equal to the second excited energy level. Alternatively, the high excited energy level is relative to the ground state and the first excited energy level of the quantum bit, such as the third excited energy level, the fourth excited energy level, and a higher excited energy level, and the like.
[0056] As an optional embodiment, when the high excitation energy level of the control quantum bit is resonant with the target resonant cavity, various ways can be adopted, for example, the control quantum bit can be controlled, or the target resonant cavity can be controlled, which will be described below.
[0057] As an optional embodiment, when the high excitation energy level of the control quantum bit is resonant with the target resonant cavity, the following way can be adopted: first, obtain the first relationship between the frequency of the high excitation energy level of the quantum bit and the magnetic flux applied to the quantum bit; obtain the first target frequency of the target resonant cavity; then, based on the first relationship and the first target frequency, control the high excitation energy level of the quantum bit to be resonant with the target resonant cavity by adjusting the magnetic flux applied to the quantum bit.
[0058] Wherein, when obtaining the first relationship between the frequency of the high excitation energy level of the quantum bit and the magnetic flux applied to the quantum bit, the frequency of the quantum bit can be measured after applying multiple different magnetic fluxes to the quantum bit, and the measurement result can be obtained, and then based on the multiple different magnetic fluxes and the different measurement frequencies corresponding to the magnetic fluxes, the relationship between the magnetic flux and the frequency of the quantum bit (i.e. the above-mentioned first relationship) can be simulated. The simulation method can be various, for example, the simulation can be obtained based on the predetermined mathematical modeling. For example, based on mathematical basis, a model including quantum bit parameter limit is established, and the above-mentioned first relationship between the frequency and the magnetic flux of the quantum bit is obtained by using model evolution based on the measurement data obtained by the above-mentioned measurement. When obtaining the first target frequency of the target resonant cavity, the frequency reader (for example, another resonant cavity reader) can be used to directly read, or other parameters of the target resonant cavity can be measured, and then the frequency of the target resonant cavity (i.e. the above-mentioned first target frequency) can be calculated based on the other parameters. Based on the first relationship and the first target frequency, by adjusting the magnetic flux applied to the quantum bit, the high excitation energy level of the quantum bit is resonant with the target resonant cavity, based on the first relationship, the target magnetic flux corresponding to the first target frequency is determined, and then the magnetic flux applied to the quantum bit is slowly adjusted, that is, the magnetic flux applied to the quantum bit is gradually increased, so that when the magnetic flux applied to the quantum bit reaches the above-mentioned target magnetic flux, the high excitation energy level of the quantum bit is resonant with the target resonant cavity.
[0059] As an optional embodiment, when the high excitation energy level of the quantum bit is controlled to resonate with the target resonant cavity, the following method can also be used: first, a second relationship between the frequency of the target resonant cavity and the magnetic flux applied to the target resonant cavity is obtained; a second target frequency of the high excitation energy level of the quantum bit is obtained; then, based on the second relationship and the second target frequency, the high excitation energy level of the quantum bit is controlled to resonate with the target resonant cavity by adjusting the magnetic flux applied to the target resonant cavity.
[0060] Similar to the above method of obtaining the first relationship between the frequency of the high excitation energy level of the quantum bit and the magnetic flux applied to the quantum bit, the second relationship between the frequency of the target resonant cavity and the magnetic flux applied to the target resonant cavity can also be obtained by the above method of measuring first and then simulating. The second target frequency of the high excitation energy level of the quantum bit can also be obtained by the method similar to the above method of obtaining the first target frequency of the target resonant cavity, that is, it can be obtained by direct measurement or by calculation based on other parameters of the target resonant cavity. When the high excitation energy level of the quantum bit is controlled to resonate with the target resonant cavity based on the second relationship and the second target frequency by adjusting the magnetic flux applied to the target resonant cavity, the magnetic flux of the target resonant cavity can be slowly increased to the corresponding magnetic flux after the corresponding magnetic flux is determined based on the second relationship and the second target frequency, so that the high excitation energy level of the quantum bit resonates with the target resonant cavity.
[0061] As an optional embodiment, controlling the high excitation energy level of the quantum bit to resonate with the target resonant cavity comprises: controlling the high excitation energy level of the quantum bit to adiabatically reach a resonance point with the target resonant cavity by adjusting the magnetic flux applied to the quantum bit or the magnetic flux applied to the target resonant cavity.
[0062] It should be noted that, whether the high excitation energy level of the quantum bit is controlled to reach the resonance point with the target resonant cavity by adjusting the magnetic flux applied to the quantum bit or by adjusting the magnetic flux applied to the target resonant cavity, it is achieved by an adiabatic method, which is a kind of evolution method that keeps the system in a transient eigenstate, and has strong robustness.
[0063] In step S204, during the process that the high excitation energy level of the quantum bit resonates with the target resonant cavity, a microwave is applied to the quantum bit to control the first excitation energy level of the quantum bit to adiabatically evolve to the dissipation energy level of the target resonant cavity, and the quantum bit is initialized.
[0064] As an optional embodiment, the microwave applied to the quantum bit is a microwave with small power, and is a microwave for making the quantum bit jump from the first excited state to the second excited state or a higher excited state. Compared with the microwave directly applied to the quantum bit to make the bit excited state jump to the coupled dissipative cavity, the microwave is not only small in power, but also easy to realize.
[0065] As an optional embodiment, the adiabatic evolution described above describes a process in which the instantaneous eigenstate of the system slowly evolves from the first excited state to the excited state of the resonant cavity under the control of the microwave.
[0066] As an optional embodiment, in the process of continuously resonating between the high excited state of the quantum bit and the target resonant cavity, the microwave applied to the quantum bit for controlling the quantum bit to perform adiabatic evolution from the first excited state to the dissipative energy level of the target resonant cavity can be determined as follows: determining a target microwave, wherein the microwave intensity of the target microwave increases over time within a predetermined time period; and applying the target microwave to the quantum bit to control the quantum bit to perform adiabatic evolution from the first excited state to the dissipative energy level of the target resonant cavity in the process of continuously resonating between the high excited state of the quantum bit and the target resonant cavity. By determining the target microwave that meets certain conditions, the accuracy of quantum bit initialization can be effectively improved.
[0067] As an optional embodiment, the target microwave described above can be a microwave of various forms as long as it can make the quantum bit perform adiabatic evolution from the first excited state to the dissipative energy level of the target resonant cavity. For example, the target microwave can be a microwave of the following form. That is, determining the target microwave can include: determining a microwave combination continuously including a first microwave segment, a second microwave segment, a third microwave segment, and a fourth microwave segment as the target microwave, wherein the microwave intensity of the first microwave segment increases over time at a first increasing rate, the microwave intensity of the second microwave segment increases over time at a second increasing rate, and the first increasing rate is greater than the second increasing rate. Among them, the second increasing rate tends to zero, the microwave intensity of the third microwave segment decreases over time, and the fourth microwave segment is a microwave-free phase. When the relationship between the microwave intensity and time is described by a curve, the first microwave segment can be a slowly rising curve, the second microwave segment can be a microwave segment corresponding to a period of time after the first microwave segment rises to a predetermined height, the third microwave segment can be a rapidly falling curve, and the fourth microwave segment can be a microwave-free phase, i.e., the microwave intensity is zero. It should be noted that the combination of the four microwave segments corresponds to only one example of the target microwave, and the present application is not limited thereto.
[0068] By the above steps, the initialization of the quantum bit is achieved by applying the microwave to the quantum bit in the process that the high excitation energy level of the quantum bit is in continuous resonance with the target resonant cavity, controlling the first excitation energy level of the quantum bit to perform adiabatic evolution to the dissipation energy level of the target resonant cavity. By the above method, when the quantum bit and the target resonant cavity are resonated, the microwave is applied to the quantum bit to make the first excitation energy level of the quantum bit jump to the high excitation energy level, that is, the energy of the first excitation energy level is transferred to a higher energy level, and the higher energy level is resonated with the target resonant cavity. Thus, the energy of the first excitation energy level can be continuously transferred to the target resonant cavity and then to the outside, thereby achieving the initialization of the quantum bit. Compared with the related art, the first excitation energy level of the quantum bit is directly excited to the resonant cavity by modulating the microwave, which not only does not need long initialization time and high-power microwave, but also quickly achieves the initialization of the quantum bit, and the required microwave power is small, thereby effectively improving the efficiency of the quantum bit initialization, and further solving the technical problem of low initialization efficiency of the quantum bit in the related art.
[0069] Figure 3 is a schematic diagram of a quantum circuit according to Embodiment 1 of the present application, as shown in Figure 3 the quantum circuit includes a target resonant cavity 32 and a quantum bit 34, wherein the quantum bit 34 is coupled with a readout line through the target resonant cavity 32, and the target resonant cavity is coupled with the quantum bit, wherein the quantum bit is an initialized quantum bit, and the initialization of the quantum bit is achieved by the following way: controlling the high excitation energy level of the quantum bit to be resonated with the target resonant cavity, wherein the high excitation energy level is an energy level greater than or equal to the second excitation energy level, and applying the microwave to the quantum bit in the process that the high excitation energy level of the quantum bit is in continuous resonance with the target resonant cavity, controlling the first excitation energy level of the quantum bit to perform adiabatic evolution to the dissipation energy level of the target resonant cavity, and initializing the quantum bit.
[0070] In the embodiments of the present application, a quantum chip is also provided, which includes the above quantum circuit.
[0071] In the embodiments of the present application, a quantum memory is also provided, which includes the above quantum circuit.
[0072] In the embodiments of the present application, a quantum computer is also provided, which includes a quantum chip and a quantum memory, wherein the quantum chip and / or the quantum memory includes the above quantum circuit.
[0073] Based on the above embodiments and optional embodiments, an optional implementation manner is provided.
[0074] The working frequency of the quantum bit is usually low, and a thermal steady state with a 1-state population not less than a certain value is maintained. Before the quantum bit works, the quantum bit needs to be initialized, and the system is cooled to the 0 state as much as possible. When the quantum bit is initialized, a scheme usually adopted is to use a microwave to excite the 1 state of the quantum bit into a dissipative system. In a superconducting quantum system, such a dissipative system is usually a readout resonant cavity of the quantum bit. For example, Fluxonium is a new type of quantum bit, which has the advantages of long decoherence time and large nonlinearity, and is one of the powerful competitors for realizing large-scale quantum computing in the future. However, the working frequency of Fluxonium is usually low, and a thermal steady state with a 1-state population not less than a certain value is maintained. For a large-scale Fluxonium chip, the chip needs to be initialized before subsequent parameter calibration processes are conveniently performed.
[0075] In the related art, a direct microwave drive is generally used to excite the bit into the readout resonant cavity. This scheme needs a long initialization time and a large microwave power, and is difficult to expand. In addition, in the related art, a frequency modulation scheme can also be used to realize the coupling between the resonant cavity and the bit. However, this scheme is limited by the frequency adjustable range of Fluxonium and the related parameter range and is difficult to realize. Therefore, in the related art, the direct microwave drive is generally selected. However, because the frequency of the quantum bit and the frequency of the readout resonant cavity are very different, the equivalent coupling between them is very weak, and therefore, a long-time and large-power microwave is needed to realize the state transfer process.
[0076] In order to realize fast and high-precision initialization, in the optional embodiment, a high-energy level of the quantum bit is resonated with the readout resonant cavity, and a microwave is used to transfer the energy of the quantum bit to the high-energy level, to complete the entire initialization process. In actual operation, the first excited state of the quantum bit, the high-energy level of the quantum bit and the readout resonant cavity constitute a three-energy-level subsystem. By using a stimulated Raman adiabatic path, a strong coupling between the quantum bit system and the readout cavity system can be realized without exciting the high-energy level of the quantum bit, and the initialization of the quantum bit is completed.
[0077] The optional embodiment provided by the present application will be described below.
[0078] Before the optional embodiment of the present application is described, the system formed by the coupling between the quantum bit and the readout resonant cavity will be described.
[0079] Figure 4 According to the optional embodiment of the present application, the energy level diagram of the coupling between the quantum bit and the readout resonant cavity is as shown in FIG. 1. Figure 4As shown, |g>, |e> and |0>, |1> represent the ground state and the first excited state of the quantum bit and the readout resonator respectively. According to this notation, the lower left, upper left and upper right balls represent the system of (quantum bit, readout resonator) in |g0>, |e0> and |g1> states respectively.
[0080] When the system is in |e0> and needs to reset the bit to |g>, parametric modulation can be performed on the frequency-adjustable quantum bit, and then the quantum bit and the fast-decaying readout resonator interact g_n, which effectively realizes the exchange of |e0> and |g1>. After this exchange, the quantum bit is initialized to the ground state. The excitation of the readout resonator can be quickly dissipated through strong coupling with the external environment, and finally the system stabilizes to |g0>.
[0081] Based on the above description, |g0>, |e0> and |g1> described above are the states of the system composed of the quantum bit and the readout resonator. Generally, when describing, the quantum bit and the readout resonator need to be involved. However, in order to simplify the description, when the state involved includes the ground state of the quantum state or the 1 state of the readout resonator, the state of the quantum state or the readout resonator will be ignored. For example, |g1> can be directly described as the first energy level state of the readout resonator, and the quantum bit is ignored because it is in the ground state. For example, |f0> can be directly described as the second excited energy level state of the quantum bit, and |e0> can be directly described as the first excited energy level state of the quantum bit.
[0082] In this optional embodiment, the high-energy level is the second excited energy level, and the target resonator is the readout resonator coupled with the quantum bit. This optional embodiment includes the following processing:
[0083] (1) That is, using magnetic flux regulation, the second excited energy level of the quantum bit is resonated with the readout resonator.
[0084] In this step, the magnetic flux regulation used above can be for the quantum bit or for the readout resonator. No matter which way is used, as long as the second excited state of the quantum bit is modulated to a state resonant with the readout resonator. In this optional embodiment, the magnetic flux modulation for the quantum bit is taken as an example for description.
[0085] Figure 5 is a schematic diagram of the resonance of the second excited energy level of the quantum bit and the readout resonator according to the optional embodiment of the present application, as shown in Figure 5As shown, by applying the magnetic flux regulation to the quantum bit, the second excited energy level of the quantum bit (corresponding to the second excited state |f0> in the figure) is resonant with the reading resonant cavity (specifically, the energy level |g1> of the reading resonant cavity). That is, the energy of the second excited state |f0> of the quantum bit is modulated to be resonant with the energy level |g1> of the reading resonant cavity by using the magnetic flux regulation. At this time, a level splitting coupled with the reading resonant cavity can be seen on the e f transition spectrum. Figure 6 is a schematic diagram of the level splitting on the spectrum of the quantum bit when the second excited energy level of the quantum bit is resonant with the reading resonant cavity according to an optional embodiment of the present application, as shown in Figure 6 As shown, the magnetic flux modulation required amplitude is defined at the intersection of the middle dashed line.
[0086] (2) At this time, the e0, f0 energy levels of the quantum bit and the g1 energy level of the reading resonant cavity form a three-level system.
[0087]
[0088] At this time, a microwave drive can be applied to the e f energy level, and the drive is marked as \Omega_{ef} (t). At the same time, the function of the magnetic flux modulation frequency is marked as \Delta (t). Generally, when resonant, \Delta (t) is set to 0, and the magnetic flux strength required at this time can be determined in the previous step.
[0089] (3) In the final implementation process, the magnetic flux regulation is applied to keep the f0 of the bit resonant with the g1 of the resonant cavity, and on this basis, the strength of \Omega_{ef} is slowly increased to realize the adiabatic evolution of e0 to g1. It should be noted that the form of the applied microwave waveform is not limited, as long as it meets the adiabatic evolution condition. Figure 7 is a schematic diagram of the microwave applied to the quantum bit according to an optional embodiment of the present application, as shown in Figure 7 As shown, the microwave range can be divided into four segments, the first segment is a ramp up phase, the second segment is a hold phase, the third is a ramp down phase, and the last is a phase of maintaining resonance without microwave drive for a period of time.
[0090] (4) For the magnetic flux modulation, it needs to be maintained at a stable value of resonance during the entire microwave drive process described above. However, before the microwave drive is applied, the quantum bit needs to be slowly changed from the working direct current bias point to the resonance point in advance. Figure 8 is a waveform schematic diagram of the magnetic flux pulse applied to the quantum bit before the quantum bit reaches the resonance point according to an optional embodiment of the present application, as shown in Figure 8As shown, a reference waveform that changes slowly is given, under the application of the magnetic flux pulse of the reference waveform, the quantum bit slowly reaches the resonance point. In this process of applying the magnetic flux pulse of the reference waveform, the quantum bit can reach the resonance point from the normal working point adiabatically, and the population on the higher energy level can be removed.
[0091] Through the above optional implementation, the initialization of the Fluxonium bit can be used, the auxiliary energy level is coupled with the bit system and the dissipation system respectively, high-efficiency bit initialization can be realized in a larger parameter space under smaller microwave driving, and high-precision initialization of the Fluxonium bit is realized.
[0092] It should be noted that in the present optional implementation, other bit energy levels such as the third excited state or higher excited states can be selected instead of the second excited state. Other dissipation channels can also be selected instead of the resonant cavity, and the microwave application port can be applied from the read line.
[0093] In the present optional implementation, since the driving can be applied through the energy level between the bit systems, the equivalent coupling is very strong, so the required microwave driving time and strength are shorter and weaker than those of the general initialization scheme. At the same time, the whole process is an adiabatic evolution, which has great robustness to parameter changes. In actual simulation, it can be seen that good initialization effect can be achieved in a larger microwave driving strength, driving frequency and magnetic flux range.
[0094] Therefore, by using the above optional implementation, the following effects can be achieved:
[0095] 1. The scheme uses the high energy level of the bit as an auxiliary, which can enhance the equivalent coupling between the bit calculation space and the read resonant cavity, and speed up the initialization speed.
[0096] 2. The whole process uses the adiabatic evolution process in the three energy levels, the initialization parameter range is large, and the robustness is good.
[0097] It should be noted that for the foregoing method embodiments, in order to simply describe, they are all expressed as a series of action combinations, but those skilled in the art should know that the present application is not limited by the action sequence described, because according to the present application, certain steps can be performed in other order or simultaneously. Secondly, those skilled in the art should know that the embodiments described in the specification all belong to preferred embodiments, and the actions and modules involved are not necessarily necessary for the present application.
[0098] Those skilled in the art can clearly understand that the method according to the above-mentioned embodiments can be realized by means of software and necessary general hardware platforms, and of course, can also be realized by hardware, but in many cases, the former is a better implementation. Based on such understanding, the technical solutions of the present application or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a computer readable storage medium (such as ROM / RAM, magnetic disk, or optical disc) and includes a plurality of instructions for causing a terminal device (which can be a mobile phone, a computer, a server, or a network device) to execute the method of each embodiment of the present application.
[0099] Embodiment 2
[0100] According to the embodiments of the present application, a device for implementing the above-mentioned quantum bit processing method is also provided, Figure 9 is a structural block diagram of the quantum bit processing device provided by the embodiments of the present application, as Figure 9 shown, the device comprises a first control module 92 and a second control module 98, which will be described below.
[0101] The first control module 92 is configured to control the high excitation level of the quantum bit to resonate with the target resonant cavity, wherein the high excitation level is an energy level greater than or equal to the second excitation level; the second control module 94 is connected to the first control module 92 and is configured to apply microwaves to the quantum bit during the process that the high excitation level of the quantum bit and the target resonant cavity are in continuous resonance, control the first excitation level of the quantum bit to adiabatically evolve to the dissipation energy level of the target resonant cavity, and initialize the quantum bit.
[0102] It should be noted that the first control module 92 and the second control module 98 correspond to steps S202 to S204 in Embodiment 1, and the above modules have the same instances and application scenarios as the corresponding steps, but are not limited to the content disclosed in Embodiment 1. It should be noted that the above modules can run in the computer terminal 10 provided in Embodiment 1 as part of the device.
[0103] Embodiment 3
[0104] The embodiments of the present application can provide a computer terminal, which can be any computer terminal device in a computer terminal group. Alternatively, in the present embodiment, the above-mentioned computer terminal can also be replaced by a terminal device such as a mobile terminal.
[0105] Alternatively, in the present embodiment, the above-mentioned computer terminal can be located in at least one network device of a plurality of network devices of a computer network.
[0106] In the embodiment, the computer terminal can execute program codes of the following steps in the qubit processing method of the application: controlling a high excitation energy level of a qubit to resonate with a target resonant cavity, wherein the high excitation energy level is an energy level greater than or equal to a second excitation energy level; applying a microwave to the qubit in a process in which the high excitation energy level of the qubit and the target resonant cavity are in continuous resonance, controlling an adiabatic evolution of a first excitation energy level of the qubit to a dissipation energy level of the target resonant cavity, and initializing the qubit.
[0107] Optionally, Figure 10 is a structural block diagram of a computer terminal according to an embodiment of the application. As shown in the figure, the computer terminal can include one or more (only one is shown in the figure) processors 102, a memory 104, and the like. Figure 10
[0108] The memory can be used to store software programs and modules, such as program instructions / modules corresponding to the qubit processing method and device in the embodiments of the application. The processor executes various functions and data processing by running the software programs and modules stored in the memory, that is, implements the above-mentioned qubit processing method. The memory can include a high-speed random access memory, and can also include a non-volatile memory, such as one or more magnetic storage devices, flash memories, or other non-volatile solid-state memories. In some examples, the memory can further include a memory remotely arranged with respect to the processor, which can be connected to the computer terminal through a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof.
[0109] The processor can call information and application programs stored in the memory through the transmission device to execute the following steps: controlling a high excitation energy level of a qubit to resonate with a target resonant cavity, wherein the high excitation energy level is an energy level greater than or equal to a second excitation energy level; applying a microwave to the qubit in a process in which the high excitation energy level of the qubit and the target resonant cavity are in continuous resonance, controlling an adiabatic evolution of a first excitation energy level of the qubit to a dissipation energy level of the target resonant cavity, and initializing the qubit.
[0110] Optionally, the processor can further execute program codes of the following steps: controlling a high excitation energy level of a qubit to resonate with a target resonant cavity, including: obtaining a first relationship between a frequency of the high excitation energy level of the qubit and a magnetic flux applied to the qubit; obtaining a first target frequency of the target resonant cavity; based on the first relationship and the first target frequency, controlling the high excitation energy level of the qubit to resonate with the target resonant cavity by adjusting the magnetic flux applied to the qubit.
[0111] Optionally, the processor can further execute program codes of the following steps: controlling the high excitation energy level of the quantum bit to resonate with the target resonant cavity, comprising: obtaining a second relationship between the frequency of the target resonant cavity and the magnetic flux applied to the target resonant cavity; obtaining a second target frequency of the high excitation energy level of the quantum bit; and based on the second relationship and the second target frequency, controlling the high excitation energy level of the quantum bit to resonate with the target resonant cavity by adjusting the magnetic flux applied to the target resonant cavity.
[0112] Optionally, the processor can further execute program codes of the following steps: controlling the high excitation energy level of the quantum bit to resonate with the target resonant cavity, comprising: controlling the high excitation energy level of the quantum bit to adiabatically reach a resonance point with the target resonant cavity by adjusting the magnetic flux applied to the quantum bit or the magnetic flux applied to the target resonant cavity.
[0113] Optionally, the processor can further execute program codes of the following steps: in the process that the high excitation energy level of the quantum bit and the target resonant cavity are in continuous resonance, applying a microwave to the quantum bit to control the first excitation energy level of the quantum bit to adiabatically evolve to the dissipation energy level of the target resonant cavity, comprising: determining a target microwave, wherein the microwave intensity of the target microwave increases over time within a predetermined time period; and in the process that the high excitation energy level of the quantum bit and the target resonant cavity are in continuous resonance, applying the target microwave to the quantum bit to control the first excitation energy level of the quantum bit to adiabatically evolve to the dissipation energy level of the target resonant cavity.
[0114] Optionally, the processor can further execute program codes of the following steps: determining the target microwave, comprising: determining a microwave combination continuously comprising a first microwave segment, a second microwave segment, a third microwave segment and a fourth microwave segment as the target microwave, wherein the microwave intensity of the first microwave segment increases at a first increasing rate over time, the microwave intensity of the second microwave segment increases at a second increasing rate over time, and the first increasing rate is greater than the second increasing rate.
[0115] Optionally, the processor can further execute program codes of the following steps: the second increasing rate approaches zero, the microwave intensity of the third microwave segment decreases over time, and the fourth microwave segment is a microwave-free phase.
[0116] Optionally, the processor can further execute program codes of the following steps: the target resonant cavity is a read resonant cavity coupled with the quantum bit, and the read resonant cavity is used to read the quantum state of the quantum bit.
[0117] Optionally, the processor can further execute program codes of the following steps: the quantum bit is a Fluxonium quantum bit.
[0118] Those skilled in the art can understand that, Figure 10The structure shown is only schematic, and the computer terminal can also be a smart phone (such as an Android phone, an iOS phone, etc.), a tablet computer, a palm computer, a Mobile Internet Device (MID), a PAD, or other terminal device. Figure 10 The above electronic device is not limited in structure. For example, the computer terminal 10 can further include more or fewer components (such as a network interface, a display device, etc.) than those shown in FIG. 1, or have a different configuration from that shown in FIG. 1. Figure 10 The above electronic device is not limited in structure. For example, the computer terminal 10 can further include more or fewer components (such as a network interface, a display device, etc.) than those shown in FIG. 1, or have a different configuration from that shown in FIG. 1. Figure 10 The above electronic device is not limited in structure. For example, the computer terminal 10 can further include more or fewer components (such as a network interface, a display device, etc.) than those shown in FIG. 1, or have a different configuration from that shown in FIG. 1.
[0119] Those skilled in the art can understand that all or part of the steps in the above-mentioned embodiments can be completed by instructing the hardware related to the terminal device by a program, and the program can be stored in a computer readable storage medium, which can include a flash disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, etc.
[0120] Embodiment 4
[0121] The embodiments of the present application also provide a computer readable storage medium. Optionally, in the present embodiment, the above computer readable storage medium can be used to save the program code executed by the quantum bit processing method provided in Embodiment 1.
[0122] Optionally, in the present embodiment, the above computer readable storage medium can be located in any one of the computer terminals in a computer terminal group in a computer network, or in any one of the mobile terminals in a mobile terminal group.
[0123] Optionally, in the present embodiment, the computer readable storage medium is configured to store program code for performing the following steps: controlling the high excitation energy level of the quantum bit to resonate with the target resonant cavity, wherein the high excitation energy level is an energy level greater than or equal to the second excitation energy level; applying microwaves to the quantum bit in the process that the high excitation energy level of the quantum bit and the target resonant cavity are in continuous resonance, controlling the first excitation energy level of the quantum bit to perform adiabatic evolution to the dissipation energy level of the target resonant cavity, and initializing the quantum bit.
[0124] Optionally, in the embodiment, the computer readable storage medium is further configured to store program code for performing the following step: controlling the high excitation energy level of the quantum bit to resonate with the target resonant cavity, comprising: obtaining a first relationship between the frequency of the high excitation energy level of the quantum bit and the magnetic flux applied to the quantum bit; obtaining a first target frequency of the target resonant cavity; and based on the first relationship and the first target frequency, controlling the high excitation energy level of the quantum bit to resonate with the target resonant cavity by adjusting the magnetic flux applied to the quantum bit.
[0125] Optionally, in the embodiment, the computer readable storage medium is further configured to store program code for performing the following step: controlling the high excitation energy level of the quantum bit to resonate with the target resonant cavity, comprising: obtaining a second relationship between the frequency of the target resonant cavity and the magnetic flux applied to the target resonant cavity; obtaining a second target frequency of the high excitation energy level of the quantum bit; and based on the second relationship and the second target frequency, controlling the high excitation energy level of the quantum bit to resonate with the target resonant cavity by adjusting the magnetic flux applied to the target resonant cavity.
[0126] Optionally, in the embodiment, the computer readable storage medium is further configured to store program code for performing the following step: controlling the high excitation energy level of the quantum bit to resonate with the target resonant cavity, comprising: controlling the high excitation energy level of the quantum bit to adiabatically reach a resonance point with the target resonant cavity by adjusting the magnetic flux applied to the quantum bit or the magnetic flux applied to the target resonant cavity.
[0127] Optionally, in the embodiment, the computer readable storage medium is further configured to store program code for performing the following step: in the process that the high excitation energy level of the quantum bit and the target resonant cavity are in continuous resonance, applying a microwave to the quantum bit to control the first excitation energy level of the quantum bit to adiabatically evolve to the dissipation energy level of the target resonant cavity, comprising: determining a target microwave, wherein the microwave intensity of the target microwave increases over time within a predetermined time period; and in the process that the high excitation energy level of the quantum bit and the target resonant cavity are in continuous resonance, applying the target microwave to the quantum bit to control the first excitation energy level of the quantum bit to adiabatically evolve to the dissipation energy level of the target resonant cavity.
[0128] Optionally, in the embodiment, the computer readable storage medium is further configured to store program code for performing the following step: determining the target microwave, comprising: determining that a microwave combination continuously comprising a first microwave segment, a second microwave segment, a third microwave segment and a fourth microwave segment is the target microwave, wherein the increasing rate of the microwave intensity of the first microwave segment increasing over time is a first increasing rate, the increasing rate of the microwave intensity of the second microwave segment increasing over time is a second increasing rate, and the first increasing rate is greater than the second increasing rate.
[0129] Optionally, in this embodiment, the computer readable storage medium is further configured to store program code for performing the following step: the second increasing rate approaches to zero, the microwave intensity of the third microwave segment decreases over time, and the fourth microwave segment is a microwave-free stage.
[0130] Optionally, in this embodiment, the computer readable storage medium is further configured to store program code for performing the following step: the target resonant cavity is a read resonant cavity coupled with the quantum bit, and the read resonant cavity is used to read the quantum state of the quantum bit.
[0131] Optionally, in this embodiment, the computer readable storage medium is further configured to store program code for performing the following step: the quantum bit is a Fluxonium quantum bit.
[0132] The above-mentioned serial numbers of embodiments of the application are only for description, and do not represent the advantages and disadvantages of the embodiments.
[0133] In the above-mentioned embodiments of the application, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.
[0134] In several embodiments provided in the present application, it should be understood that the disclosed technical contents can be implemented by other ways. Among them, the above-mentioned device embodiments are only schematic, for example, the division of the units is only a logical function division, and actual implementation can have another division way, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the displayed or discussed units can be indirect coupling or communication connection through some interfaces, units or modules, which can be electrical or other forms.
[0135] The units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, that is, they can be located in one place, or they can be distributed on a plurality of network units. According to actual needs, part or all of the units can be selected to achieve the purpose of the embodiment scheme.
[0136] In addition, each functional unit in each embodiment of the application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The above integrated unit can be realized in the form of hardware or in the form of software functional unit.
[0137] The integrated unit, if implemented in the form of a software function unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application, essentially or in other words, the part that contributes to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a computer readable storage medium, including a number of instructions to make a computer device (which can be a personal computer, a server or a network device, etc.) execute all or part of the steps of the methods described in various embodiments of the present application. The aforementioned computer readable storage medium includes: a U disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a mobile hard disk, a magnetic disk or an optical disk, and various media that can store program codes.
[0138] The above is only the preferred embodiment of the present application, it should be pointed out that, for those skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.
Claims
1. A method of processing a quantum bit, characterized by, The method comprises: controlling the high excitation energy level of the quantum bit to resonate with a target resonant cavity, wherein the high excitation energy level is an energy level greater than or equal to a second excitation energy level, and the target resonant cavity is coupled with the quantum bit; applying a microwave to the quantum bit to control the first excitation energy level of the quantum bit to adiabatically evolve to a dissipative energy level of the target resonant cavity during the process that the high excitation energy level of the quantum bit and the target resonant cavity are in continuous resonance, and initializing the quantum bit, wherein the adiabatic evolution is used to describe the process that the instantaneous eigenstate of the system evolves from the first excitation state to the excitation state of the resonant cavity under the regulation of the microwave. The method further comprises: controlling the high excitation energy level of the quantum bit to resonate with the target resonant cavity comprises:
2. The method of claim 1, wherein, controlling the high excitation energy level of the quantum bit to adiabatically reach a resonance point with the target resonant cavity by adjusting the magnetic flux applied to the quantum bit or the magnetic flux applied to the target resonant cavity. The method further comprises: obtaining a first relationship between the frequency of the high excitation energy level of the quantum bit and the magnetic flux applied to the quantum bit; obtaining a first target frequency of the target resonant cavity; 3. The method of claim 1, wherein, controlling the high excitation energy level of the quantum bit to resonate with the target resonant cavity by adjusting the magnetic flux applied to the quantum bit based on the first relationship and the first target frequency. The method further comprises: obtaining a second relationship between the frequency of the target resonant cavity and the magnetic flux applied to the target resonant cavity; obtaining a second target frequency of the high excitation energy level of the quantum bit; 4. The method of claim 1, wherein, controlling the high excitation energy level of the quantum bit to resonate with the target resonant cavity by adjusting the magnetic flux applied to the target resonant cavity based on the second relationship and the second target frequency. The method further comprises: determining a target microwave, wherein the microwave intensity of the target microwave increases over time within a predetermined time period; 5. The method of claim 4, wherein, applying the target microwave to the quantum bit to control the first excitation energy level of the quantum bit to adiabatically evolve to the dissipative energy level of the target resonant cavity during the process that the high excitation energy level of the quantum bit and the target resonant cavity are in continuous resonance. The method further comprises:
6. The method of claim 5, wherein, determining a microwave combination continuously comprising a first microwave segment, a second microwave segment, a third microwave segment and a fourth microwave segment as the target microwave, wherein the microwave intensity of the first microwave segment increases at a first increasing rate over time, the microwave intensity of the second microwave segment increases at a second increasing rate over time, and the first increasing rate is greater than the second increasing rate. The second increasing rate approaches zero, the microwave intensity of the third microwave segment decreases over time, and the fourth microwave segment is a microwave-free phase.
7. The method of claim 1, wherein, The target resonant cavity is a read resonant cavity coupled with the quantum bit, and the read resonant cavity is used for reading the quantum state of the quantum bit.
8. The method according to any one of claims 1 to 7, characterized in that, The quantum bit is a Fluxonium quantum bit.
9. A quantum circuit, comprising: Comprising: A target resonant cavity and a quantum bit, wherein the quantum bit is coupled with a read circuit through the target resonant cavity, and the target resonant cavity is coupled with the quantum bit, wherein the quantum bit is an initialized quantum bit, and the initialization of the quantum bit is obtained by controlling the high excitation level of the quantum bit to resonate with the target resonant cavity, wherein the high excitation level is an energy level greater than or equal to a second excitation level, and in the process that the high excitation level of the quantum bit and the target resonant cavity are in continuous resonance, microwaves are applied to the quantum bit, the first excitation level of the quantum bit is controlled to adiabatically evolve to the dissipation energy level of the target resonant cavity, and the quantum bit is initialized, wherein the controlling the high excitation level of the quantum bit to resonate with the target resonant cavity comprises: controlling the high excitation level of the quantum bit to adiabatically reach a resonance point with the target resonant cavity by adjusting the magnetic flux applied to the quantum bit or the magnetic flux applied to the target resonant cavity, the adiabatic evolution is used to describe the process that the instantaneous eigenstate of the system evolves from the first excitation state to the excitation state of the resonant cavity under the regulation of the microwaves, and the target resonant cavity is coupled with the quantum bit.
10. A quantum chip, characterized by, Comprising: The quantum circuit of claim 9.
11. A quantum memory, characterized in that, Comprising: The quantum circuit of claim 9.
12. A quantum computer, comprising: Comprising: The quantum chip and the quantum memory, wherein the quantum chip and / or the quantum memory comprises the quantum circuit of claim 9.
Citation Information
Patent Citations
Capacitively-shunted asymmetric DC-squid for qubit readout and reset
CN111108687A