Quantum system error detection method, quantum system error detection device, and quantum computer system including same

Abstract

The present invention provides a quantum system error detection device, the device comprising: a control register for receiving information representing a quantum state of a control qubit and outputting an operation result; an auxiliary register for receiving, on a one-to-one basis, information representing a quantum state of a target qubit; a CNOT gate connected to the control register and the auxiliary register; a first detector connected to the control register and configured to measure a quantum state of the control qubit to which the CNOT gate is applied; a second detector connected to the auxiliary register and configured to measure a quantum state of the auxiliary qubit to which the CNOT gate is applied; a probability calculation unit for calculating probabilities of quantum states of the control qubit and the target qubit from measurement results of the first detector and the second detector; and an error rate calculation unit for calculating error rates of quantum state initialization, the CNOT gate, and quantum measurement from the probabilities calculated by the probability calculation unit.

Description

Quantum system error detection method, quantum system error detection device, and quantum computer system including the same

[0001] The present invention relates to a quantum system error detection device method, a quantum system error detection device, and a quantum computer system including the same, and in particular to a quantum system error detection method, a quantum system error detection device, and a quantum computer system including the same for calculating the error rate of quantum state initialization, quantum state conversion, and quantum state measurement.

[0002] The process of preparing to start the quantum information processing process is called system initialization, and the purpose of system initialization is to prepare a specific quantum state.

[0003] Quantum state initialization is the process of initializing a quantum computer system into a specific quantum state; noise occurs during quantum state preparation due to various factors, such as interactions with the system's surroundings or defects in the equipment generating the quantum state.

[0004] Even when an initialized quantum state is input into a quantum circuit of a quantum computer to transform the quantum state and generate quantum entanglement, noise may exist due to the quantum circuit, for example, a CNOT gate.

[0005] In addition, noise can also occur during the process of measuring the quantum state transformed by the quantum circuit.

[0006] Therefore, the results of measuring the quantum state represent a combination of quantum state initialization errors, quantum state transition errors, and quantum measurement errors; however, it is not possible to accurately identify the main causes of the errors and the error rates by source of noise.

[0007] The present invention aims to provide a protocol for calculating the error rate of a quantum state initialization, a quantum circuit that converts the quantum state, such as a CNOT gate, and a quantum measurement, respectively.

[0008] A quantum system error detection device according to one embodiment of the present invention includes: a control register that receives the quantum state of a control qubit and outputs a calculation result; an auxiliary register that receives the quantum state of a target qubit in a one-to-one manner; a CNOT gate connected to the control register and the auxiliary register; a first detector connected to the control register and measuring the quantum state of the control qubit to which the CNOT gate is applied; a second detector connected to the auxiliary register and measuring the quantum state of the target qubit to which the CNOT gate is applied; a probability calculation unit that calculates the probability of the quantum states of the control qubit and the target qubit from the measurement results of the first detector and the second detector; and an error rate calculation unit that calculates the error rate of quantum state initialization, CNOT gate, and quantum detection from the probability calculated by the probability calculation unit.

[0009] A quantum system error detection device according to one embodiment of the present invention may further include an error occurrence determination unit that determines the cause of an error by comparing the magnitudes of the error rates of quantum state initialization, CNOT gate, and quantum measurement.

[0010] The initialization quantum states of the control qubit and the target qubit are all It could be.

[0011] The probability calculation unit is the quantum state (i,j∈{ of the control qubit (S) and the target qubit (A) , Calculate the probability by dividing the number of measurement results by the total number of measurements.

[0012] A quantum system error detection method according to an embodiment of the present invention comprises: a step of preparing an initialization quantum state of a control qubit and a target qubit; a step of performing a CNOT gate operation on the initialization quantum state of the control qubit and the target qubit; a step of measuring the quantum state of the control qubit and the target qubit after the CNOT gate operation; a step of calculating a probability that a measurement result value of the quantum state of the control qubit and the target qubit will be obtained; and a step of calculating the error rates of the quantum state initialization, the CNOT gate, and the quantum measurement, respectively, from the probability calculated based on the measurement result of the quantum state of the control qubit and the target qubit.

[0013] A quantum system error detection method according to one embodiment of the present invention may further include a step of determining the cause of an error by comparing the magnitudes of the error rates of quantum state initialization, CNOT gates, and quantum measurements.

[0014] The probability calculation step calculates the probability by dividing the number of measurement results for each quantum state of the control qubit and the target qubit by the total number of measurements.

[0015] According to an embodiment of the present invention, by measuring the error of quantum state initialization, the error of quantum measurement, and the CNOT gate error rate, the cause of the error generating noise that is combined with each other in a quantum computer system for quantum information processing can be accurately detected.

[0016] In addition, according to an embodiment of the present invention, the initialization of a specific quantum state of a quantum system can be prepared with high accuracy based on the cause of the detected error, and the diagnosis of the quantum circuit and the abnormality of the detector can be easily determined.

[0017] FIG. 1 is a block diagram schematically illustrating the configuration of a computer device according to an embodiment of the present invention.

[0018] FIG. 2 is a drawing illustrating a quantum system error detection device according to an embodiment of the present invention.

[0019] FIG. 3 is a flowchart illustrating a quantum system error detection method according to an embodiment of the present invention.

[0020] Exemplary embodiments of the present invention are described below with reference to the accompanying drawings, which include various details of the embodiments of the present invention, for ease of understanding; this should be considered merely illustrative. Accordingly, those skilled in the art should realize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this disclosure. Likewise, for clarity and brevity, descriptions of well-known functions and structures are omitted from the following description.

[0021] According to various embodiments, each of the described components may include a singular or multiple entities. According to various embodiments, one or more of the components or steps may be omitted, or one or more other components or steps may be added. Generally or additionally, multiple components may be integrated into a single component. In this case, the integrated component may perform one or more functions of each of the multiple components in the same or similar manner as those performed by the corresponding component among the multiple components prior to integration. According to various embodiments, steps performed by a module, program, or other component may be executed sequentially, in parallel, iteratively, or heuristically, or one or more of the steps may be executed in a different order, omitted, or one or more other steps may be added.

[0022] Hereinafter, a quantum system error detection method, a quantum system error detection device, and a quantum computer system including the same according to an embodiment of the present invention will be described with reference to the drawings.

[0023] FIG. 1 is a block diagram schematically illustrating the configuration of a computer device according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a quantum state initialization device according to an embodiment of the present invention. FIG. 3 is a flowchart illustrating a quantum initialization method according to an embodiment of the present invention.

[0024] Referring to FIG. 1, the computer device (100) may include at least one of a communication module (110), an input module (120), an output module (130), a memory (140), and a processor (150). In some embodiments, at least one of the components of the computer device (100) may be omitted, and at least one other component may be added. In some embodiments, at least two of the components of the computer device (100) may be implemented as a single integrated circuit.

[0025] A communication module (110) can perform communication with an external device from a computer device (100). The communication module (110) can establish a communication channel between the computer device (100) and the external device and perform communication with the external device through the communication channel. Here, the external device may include at least one of a group consisting of another computer device, a base station, and a wireless communication module. A wired communication module may be connected to the external device via a wire and communicate via a wire. A wireless communication module may include at least one of a short-range communication module or a long-range communication module. A short-range communication module may communicate with the external device using a short-range communication method. For example, a short-range communication method may include at least one of a group consisting of Bluetooth, WiFi Direct, and Infrared Data Association (IrDA). A long-range communication module may communicate with the external device using a long-range communication method. Here, the long-range communication module may communicate with the external device through a network. For example, the network may include at least one computer network among the group consisting of a cellular network, the Internet, a LAN (Local Area Network), and a WAN (Wide Area Network).

[0026] The input module (120) can input a signal to be used in at least one component of the computer device (100). The input module (120) may be configured to detect a signal directly input by a user or to generate a signal by detecting changes in the surroundings. For example, the input module (120) may include at least one of a group consisting of a mouse, a keypad, a microphone, and a sensor module having at least one sensor.

[0027] The output module (130) can output information to the outside of the computer device (100). The output module (130) may include at least one of a display module configured to output information visually or an audio output module capable of outputting information as an audio signal. For example, the audio output module may include at least one of a speaker or a receiver.

[0028] Memory (140) can store various data used by at least one component of the computer device (100). For example, memory (140) may include at least one of volatile memory or non-volatile memory. Data may include at least one program and associated input data or output data. The program may be stored in memory (140) as software containing at least one instruction and may include at least one of a group consisting of an operating system, middleware, or application.

[0029] The processor (150) can control at least one component of the computer device (100) by executing a program in memory (140). Through this, the processor (150) can perform data processing or operations. At this time, the processor (150) can execute instructions stored in memory (140).

[0030] A computer device (100) according to one embodiment of the present invention may be a quantum system that performs quantum computing or quantum communication. Such a quantum system can reduce possible computational errors by performing computations with a noise-free quantum state.

[0031] A computing device (100) according to one embodiment of the present invention may include a quantum system error detection device (200) that initializes a noise-free quantum state to perform quantum operations in at least one of a quantum communication module (110), an input module (120), an output module (130), a memory (140), and a processor (150).

[0032] Referring to FIG. 2, a quantum system error detection device (200) according to an embodiment of the present invention comprises: a control register (210) that receives the quantum state of a control qubit (S) and outputs a calculation result; an auxiliary register (220) that receives the quantum state of a target qubit in a one-to-one manner; a CNOT gate (230) connected to the control register (210) and the auxiliary register (220); a first detector (240) connected to the control register (210) and measuring the quantum state of the control qubit to which the CNOT gate (230) is applied; a second detector (250) connected to the auxiliary register and measuring the quantum state of the target qubit to which the CNOT gate is applied; a probability calculation unit (260) that calculates the probability of the quantum states of the control qubit and the target qubit from the measurement results of the first detector (240) and the second detector (250); and quantum state initialization, CNOT gate, and quantum measurement from the probability calculated by the probability calculation unit (260). It includes an error rate calculation unit (270) that calculates the error rate.

[0033] Referring to FIG. 2, the control register (210) receives the initialization quantum state of the control qubit (S) and outputs the quantum state of the control qubit (S) to which the CNOT gate (230) has been applied to the first detector (240).

[0034] The auxiliary register (220) receives the initialization quantum state of the target qubit (A) and outputs the quantum state of the target qubit (A) to which the CNOT gate (230) has been applied to the second detector (250).

[0035] The CNOT gate (230) is connected to the control register (210) and the auxiliary register (220) and performs a CNOT gate operation on the initialization quantum state of the control qubit (S) input to the control register (210) and the target qubit (A) input to the auxiliary register (220).

[0036] The first detector (240) is connected to the control register (210) to measure the quantum state of the control qubit (S) to which the CNOT gate (230) is applied.

[0037] The second detector (250) is connected to the auxiliary register (220) to measure the quantum state of the target qubit (A) to which the CNOT gate (230) is applied.

[0038] In some embodiments, the first detector (240) and the second detector (250) may include an operator using quantum detector tomography (QDT). In some embodiments, the first detector (240) and the second detector (250) may include a quantum circuit for measuring a quantum state.

[0039] The first detector (240) and the second detector (250) are possible quantum states mixed with noise (i,j∈{ , For example, 1,000 measurement results are taken.

[0040] The first detector (240) and the second detector (250) according to an embodiment of the present invention are in the initialization quantum state of the control qubit (S) and the target qubit (A). Each of these is repeated, for example, 1000 are input into the CNOT gate (230), and the quantum state of the control qubit (S) and target qubit (A) is repeated multiple times, for example, 1000 times, to perform the operation of the CNOT gate (230).

[0041] Meanwhile, unlike in Fig. 2, a single detector is connected to both the control register (210) and the auxiliary register (220) to measure the results of the quantum states of the control qubit (S) and the auxiliary qubit (A) after the operation of the CNOT gate (230).

[0042] The probability calculation unit (260) calculates the quantum state (i,j∈{ of the control qubit (S) and the target qubit (A) , The probability (p(ij)(where i,j∈{0,1})) can be calculated by dividing the number of measurement results by the total number of measurements.

[0043] In addition, the probability calculation unit (260) calculates the initialization quantum state of the input control qubit (S) and the target qubit (A), for example You can calculate the probability (p(01), p(10), p(11)) for other measurement results and determine the remaining probability (p(00)).

[0044] The error rate calculation unit (270) calculates the error rates of the quantum state initialization, CNOT gate, and quantum measurement, which are the causes of noise, from the calculated probability distribution.

[0045] Meanwhile, although not illustrated, a quantum system error detection device according to one embodiment of the present invention may further include an error occurrence determination unit that determines the cause of the error by comparing the magnitude of the error rates of quantum state initialization, CNOT gate, and quantum measurement.

[0046] The quantum system error detection device (200) includes a protocol for calculating the error rate of quantum state initialization, CNOT gate, and quantum measurement.

[0047] The quantum information processing process generally consists of (1) quantum state initialization, (2) quantum state transformation, and (3) quantum state measurement. Current quantum systems have noise in all three stages.

[0048] Accordingly, in order to implement a reliable quantum system, it is necessary to calculate the error in quantum state initialization, the error during quantum state transition, and the error rate during quantum state measurement.

[0049] (1) Noise generated during quantum state initialization

[0050] Quantum state initialization is the process of initializing a quantum system into a specific quantum state, and noise occurs during this initialization due to various factors, such as interactions with the system's surroundings or defects in the device that generates the quantum state.

[0051] In a quantum computer system, the initialized quantum state is A quantum state that can be represented as and includes noise is It can be represented as.

[0052] The fidelity (f) for the accuracy of quantum state initialization is defined as follows.

[0053]

[0054] The initial quantum fidelity of a noisy quantum state can be set to 1 / 2 < f < 1. Additionally, the error rate of quantum state initialization can be expressed as 1 - f.

[0055] (2) Noise generated in the CNOT gate

[0056] Noise exists in the CNOT gate, which is an entanglement generation gate, and the error in the CNOT gate can be characterized as a depolarization channel.

[0057] The operation of the CNOT gate can be expressed as follows.

[0058] V2 =

[0059] The operation of a CNOT gate with an error rate ε can be expressed as follows.

[0060] V2(ㆍ)V2 †→ (1 - ε)V2(ㆍ)V2 † + εtr[ㆍ]

[0061] (3) Noise generated in quantum measurement

[0062] Quantum measurement described as a POVM (Positive Operator-Valued Measure) is a process of reading a quantum state to determine the measurement probability, in which detectors, such as a first detector (240) and a second detector (250) according to an embodiment of the present invention, measure the result of a quantum state containing noise due to various factors.

[0063] The purpose of noise-free quantum measurement POVM is M0= (1-q) + q , M1= (1-q) + q It is described as. When performing quantum measurements with the next noise-free POVM for the state, M0= The probability that a measurement is detected is 1.

[0064] In addition, the POVM of a noisy quantum measurement is M0= (1-q) + q , M1= (1-q) + q It is described as.

[0065] When performing quantum measurements with the following noisy POVM for the state, The probability that a measurement is detected is (1-q), and The probability of this being detected is q.

[0066] Here, q is the error rate of quantum measurement and can be expressed by the following equation:

[0067] q = =

[0068] The quantum states of the control qubit (S) and the target qubit (A) After initializing and applying the CNOT gate, the quantum states of the control qubit (S) and the target qubit (A) are measured by the first detector (240) and the second detector (250).

[0069] When the measured results of the quantum states of the control qubit (S) and the target qubit (A) are denoted as i,j ∈ {0, 1}, respectively, the probability p(ij) of each result (where i,j ∈ {0, 1}) can be expressed as one of p(00), p(01), p(10), and p(11).

[0070] p(00) is the initialization quantum state of the control qubit (S) and the target qubit (A). It refers to the probability that when a CNOT gate is applied by inputting as such, the measured result values ​​of the quantum states of the control qubit (S) and the target qubit (A) are both 0.

[0071] p(01) is the initialization quantum state of the control qubit (S) and the target qubit (A). When a CNOT gate is applied by inputting as, the quantum state measurement result of the control qubit (S) is The measurement result of the quantum state of the target qubit (A) is It refers to the probability of the case.

[0072] p(10) is the initialization quantum state of the control qubit (S) and the target qubit (A). When a CNOT gate is applied by inputting as, the quantum state measurement result is The measurement result of the quantum state of the target qubit (A) is It refers to the probability of the case.

[0073] p(11) is the initialization quantum state of the control qubit (S) and the target qubit (A). When the CNOT gate is applied by inputting as such, the quantum state measurement results of the control qubit (S) and the target qubit (A) are all It refers to the probability of the case.

[0074] The error rate calculation unit (270) can determine the error rates (1-f, q, ε) of the quantum state initialization, quantum measurement, and CNOT gate based on the probability p(ij) (where i, j∈{0, 1}) of the measurement result of the quantum state, by finding the numerical solutions of the four equations that are the protocols for calculating the error rate.

[0075] p(00) = (1-ε)[f 2 (1-q) 2 + (1-f) 2 q 2 + f(1-f)(1-q)q + (1-f) 2 q(1-q) + (1-f)fq 2 ] + ε / 4,

[0076] p(01) = (1-ε)[f 2 (1-q)q + (1-f) 2 q 2 + f(1-f)(1-q) 2 + (1-f) 2 q 2 + (1-f)fq(1-q)] + ε / 4,

[0077] p(10) = (1-ε)[f 2 q(1-q) + (1-f) 2 (1-q)q + f(1-f)q 2 + (1-f) 2 (1-q) 2 + (1-f)f(1-q)q] + ε / 4,

[0078] p(11) = (1-ε)[f 2 q 2 + (1-f) 2 (1-q) 2 + f(1-f)q(1-q) + (1-f) 2 (1-q)q + (1-f)f(1-q) 2 ] + ε / 4.

[0079] Example (p(00), p(01), p(10), p(11)) (1-f, q, ε) Example 1 (0.666, 0,154, 0.09, 0.09) (0.1, 0.1, 0) Example 2 (0.7312, 0.1252, 0.0540, 0.0896) (0.1, 0.05, 0.01) Example 3 (0.8327, 0.0777, 0.0530, 0.0366) (0.03, 0.05, 0.03) Example 4 (0.7887, 0.0961, 0.0576, 0.0576) (0.05 0.05, 0.05) Example 5(0.8215, 0.0754, 0.0674, 0.0357)(0.01, 0.05, 0.1)

[0080] Table 1 shows the initialization quantum states of the control qubit (S) and the auxiliary qubit (A), all The number of cases of the measured result values ​​was counted and each was expressed as a probability after applying 5 types of CNOT gates by repeating the input 1000 times.

[0081] Referring to Table 1, the probabilities for Example 1 were found to be p(00) = 0.666, p(01) = 0.154, p(10) = 0.09, and p(11) = 0.09. The measured values ​​of the quantum states of the control qubit (S) and the auxiliary qubit (A) were all In the case of 666, the measurement result of the quantum state of the control qubit (S) is and the measurement result of the quantum state of the auxiliary qubit (A) is In this case, the measurement result of the quantum state of the control qubit (S) at 154 is and the measurement result of the quantum state of the auxiliary qubit (A) is In this case, the measurement results of the quantum states of 90 and the control qubit (S) and the auxiliary qubit (A) are all In this case, it was counted 90 times.

[0082] The error rate calculation unit (270) calculates the error rate using a protocol for calculating the error rate of quantum state initialization, CNOT gate, and quantum measurement, and the error rate is as shown in the right column of Table 1.

[0083] In the case of Example 1, the error rate ε of the CNOT gate is 0, the quantum state initialization error rate 1-f is 0.1, and the quantum state measurement error rate q is calculated to be 0.1, indicating that the cause of the error occurs during the quantum state initialization preparation process and the quantum state measurement process.

[0084] In the case of Example 2, the error rate ε of the CNOT gate is 0.01, the quantum state initialization error rate 1-f is 0.1, and the error rate q of the quantum state measurement is calculated to be 0.05, indicating that the cause of the error mainly occurs during the quantum state initialization preparation process, occurs partially during the quantum state measurement process, and occurs at a low frequency during the CNOT gate application process.

[0085] In the case of Example 3, the error rate ε of the CNOT gate is 0.03, the quantum state initialization error rate 1-f is 0.03, and the error rate q of the quantum state measurement is calculated to be 0.05, indicating that the cause of the error mainly occurs during the quantum state measurement process and partially occurs during the quantum state initialization preparation and the application of the CNOT gate.

[0086] In the case of Example 4, the error rate ε of the CNOT gate is 0.05, the quantum state initialization error rate 1-f is 0.05, and the error rate q of the quantum state measurement is calculated to be 0.05, indicating that the cause of the error occurs at the same rate during the quantum state initialization preparation, quantum state measurement, and CNOT gate application processes.

[0087] In the case of Example 5, the error rate ε of the CNOT gate is 0.1, the quantum state initialization error rate 1-f is 0.01, and the error rate q of the quantum state measurement is calculated to be 0.05, indicating that the cause of the error mainly occurs during the CNOT gate application process, partially during the quantum state measurement process, and at a low frequency during the quantum state initialization preparation process.

[0088] FIG. 3 is a flowchart illustrating a quantum system error detection method according to an embodiment of the present invention.

[0089] Referring to FIG. 3, the initialization quantum state of the control qubit (S) and the target qubit (A) in the quantum computer system is prepared (S310).

[0090] The quantum state that a quantum computer system must be initialized to is, for example, A quantum state that can be represented as and includes noise is It can be represented as follows. The fidelity (f) for the accuracy of quantum state initialization is defined as follows.

[0091]

[0092] Next, a CNOT gate operation is performed on the initialization quantum state of the control qubit (S) and the target qubit (A) (S320).

[0093] The operation of the CNOT gate can be expressed as follows.

[0094] V2 =

[0095] The operation of a CNOT gate with an error rate ε can be expressed as follows.

[0096] V2(ㆍ)V2 † → (1 - ε)V2(ㆍ)V2 † + εtr[ㆍ]

[0097] Next, the quantum states of the control qubit (S) and the target qubit (A) after the operation of the CNOT gate are measured using the first detector (240) and the second detector (250) (S330).

[0098] The purpose of noise-free quantum measurement POVM is M0= (1-q) + q , M1= (1-q) + q It is described as. When performing quantum measurements with the next noise-free POVM for the state, M0= The probability that a measurement is detected is 1.

[0099] In addition, the POVM of a noisy quantum measurement is M0= (1-q) + q , M1= (1-q) + q It is described as.

[0100] When performing quantum measurements with the following noisy POVM for the state, The probability that a measurement is detected is (1-q), and The probability of this being detected is q.

[0101] Here, q is the error rate of quantum measurement and can be expressed by the following equation:

[0102] q = =

[0103] Next, the probability p(ij) (where i,j∈{0, 1}) of the measurement result of the quantum state of the control qubit (S) and the target qubit (A) is calculated (S340).

[0104] The probability calculation unit (260) calculates the quantum state (i,j∈{ of the control qubit (S) and the target qubit (A) , The probability can be calculated by dividing the number of measurement results by the total number of measurements.

[0105] Next, the error rates for quantum state initialization, CNOT gate, and quantum detection are each calculated from the probabilities calculated based on the measurement results of the quantum states of the control qubit (S) and the target qubit (A) (S350).

[0106] The error rate calculation unit (270) can determine the error rates (1-f, q,ε) of the quantum state initialization, quantum measurement, and CNOT gate based on the probability p(ij) of the measurement result of the quantum state (where i,j∈{0, 1}) by finding the numerical solutions to the following four equations.

[0107] p(00) = (1-ε)[f 2 (1-q) 2 + (1-f) 2 q 2 + f(1-f)(1-q)q + (1-f) 2 q(1-q) + (1-f)fq 2 ] + ε / 4,

[0108] p(01) = (1-ε)[f 2 (1-q)q + (1-f) 2 q 2 + f(1-f)(1-q) 2 + (1-f) 2 q 2 + (1-f)fq(1-q)] + ε / 4,

[0109] p(10) = (1-ε)[f 2 q(1-q) + (1-f) 2 (1-q)q + f(1-f)q 2 + (1-f) 2 (1-q) 2 + (1-f)f(1-q)q] + ε / 4,

[0110] p(11) = (1-ε)[f 2 q 2 + (1-f) 2 (1-q) 2 + f(1-f)q(1-q) + (1-f) 2 (1-q)q + (1-f)f(1-q) 2 ] + ε / 4.

[0111] Meanwhile, although not illustrated, a quantum system error detection method according to one embodiment of the present invention may further include a step of determining the cause of an error by comparing the magnitudes of the error rates of quantum state initialization, CNOT gate, and quantum measurement.

[0112] Referring again to Table 1, in the case of Example 3, the error rate ε of the CNOT gate is 0.03, the quantum state initialization error rate 1-f is 0.03, and the quantum state measurement error rate q is calculated to be 0.05, so it can be determined that the cause of the error mainly occurs during the quantum state measurement process.

[0113] The device and method described above may be implemented as a hardware component, a software component, and / or a combination of a hardware component and a software component.

[0114] For example, the devices and components described in the embodiments may be implemented using one or more general-purpose or special-purpose computers, such as a processor, controller, Arithmetic Logic Unit (ALU), digital signal processor, microcomputer, Field Programmable Gate Array (FPGA), Programmable Logic Unit (PLU), microprocessor, or any other device capable of executing and responding to instructions. The processing unit may execute an operating system and one or more software applications executed on said operating system. Additionally, the processing unit may access, store, manipulate, process, and generate data in response to the execution of software. For ease of understanding, the processing unit may be described as being used as a single unit, but those skilled in the art will understand that the processing unit may include multiple processing elements and / or multiple types of processing elements. For example, the processing unit may include multiple processors or one processor and one controller. Additionally, other processing configurations, such as parallel processors, are also possible.

[0115] Software may include computer programs, code, instructions, or a combination of one or more of these, and may configure a processing unit to operate as desired or instruct the processing unit independently or collectively. Software and / or data may be embodied in any type of machine, component, physical device, computer storage medium, or device to be interpreted by the processing unit or to provide instructions or data to the processing unit. Software may be distributed over networked computer systems and stored or executed in a distributed manner. Software and data may be stored on one or more computer-readable recording media.

[0116] The method according to various embodiments may be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer-readable medium. In this case, the medium may continuously store a program executable by a computer, or temporarily store it for execution or download. Furthermore, the medium may be various recording or storage means in the form of a single or several combined hardware, and may not be limited to a medium directly connected to a computer system but may exist distributed over a network. Examples of media include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs and DVDs; magneto-optical media such as floptical disks; and media configured to store program instructions, including ROM, RAM, and flash memory. Additionally, other examples of media may include recording or storage media managed by app stores that distribute applications or sites and servers that supply or distribute various other software.

Claims

A control register that receives the quantum state of a control qubit as input and outputs the operation result; An auxiliary register that receives the quantum state of a target qubit one-to-one; A CNOT gate connected to the control register and the auxiliary register; A first detector connected to the control register and measuring the quantum state of the control qubit to which a CNOT gate is applied; A second detector connected to the above auxiliary register to measure the quantum state of the target qubit to which the CNOT gate is applied; A probability calculation unit that calculates the probability of the quantum state of the control qubit and the target qubit from the measurement results of the first detector and the second detector; and A quantum system error detection device comprising an error rate calculation unit that calculates the error rate of quantum state initialization, CNOT gate, and quantum detection from the probability calculated by the probability calculation unit above. In Article 1, A quantum system error detection device further comprising an error occurrence determination unit that determines the cause of an error by comparing the magnitudes of the error rates of quantum state initialization, CNOT gate, and quantum measurement. In Article 1, The initialization quantum states of the control qubit and the target qubit are all Quantum system error detection device. In Article 1, The above probability calculation unit is the quantum state (i,j∈{ of the control qubit (S) and the target qubit (A) , A quantum system error detection device that calculates a probability by dividing the number of measurement results by the total number of measurements. A step of preparing the initialization quantum state of the control qubit and the target qubit; A step of performing a CNOT gate operation on the initialization quantum state of the control qubit and the target qubit; A step of measuring the quantum states of the control qubit and the target qubit after the operation of the CNOT gate; A step of calculating the probability that the measurement result value of the quantum state of the control qubit and the target qubit will be obtained; and A quantum system error detection method comprising the step of calculating the error rates of quantum state initialization, CNOT gate, and quantum measurement, respectively, from probabilities calculated based on the measurement results of the quantum states of the control qubit and the target qubit. In Article 5, A quantum system error detection method further comprising the step of determining the cause of an error by comparing the magnitudes of the error rates of quantum state initialization, CNOT gates, and quantum measurements. In Article 5, The above probability calculation step is a quantum system error detection method that calculates a probability by dividing the number of measurement results by the total number of measurements for each quantum state of the control qubit and the target qubit.

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