A quantum detection method based on quantum synchronization effect

Abstract

The invention belongs to the field of quantum technology and relates to a quantum detection method based on quantum synchronization effect, comprising the following steps: constructing a quantum system of a ring structure coupled in a nearest neighbor manner and satisfying the Heisenberg isotropic coupling condition; constructing an ideal initial state of the quantum system and performing unitary evolution to achieve quantum phase synchronization; integrating a detector using the quantum system after quantum phase synchronization and calibrating the detector; detecting a spatial region using the calibrated detector to obtain information about the quantum environment and determine the specific position of a target quantum bit; the invention can not only detect whether a target quantum bit exists in a spatial region, but also lock the specific position of the target quantum bit; the detection accuracy is adjusted by increasing the number of quantum bits in the quantum system; the reaction time after the detector is coupled with the target quantum bit can reach 5ns at the lowest; and the source of noise can be discovered, paving the way for the large-scale development of quantum systems.

Description

[0001] Technical Description

[0002] The invention belongs to the technical field of quantum detection and relates to a quantum detection method based on quantum synchronization effect. Background Art

[0003] The existing detection method of quantum synchronization technology is to use the spontaneous quantum synchronization effect between the non-equilibrium qubit and the detection qubit. The non-equilibrium qubit is coupled with the environment and the detection qubit acts as a probe. By adjusting the frequency of the probe, the non-equilibrium qubit and the probe will be converted into the same phase and the opposite phase. The rapid conversion between these two modes can be achieved by monitoring the dynamic process of the probe alone to reconstruct the spectral density of the environment. However, this detection method has higher requirements for the accuracy of parameters and poor scalability. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a quantum detection method based on the quantum synchronization effect.

[0005] In order to achieve the purpose of the present invention, the present invention is implemented by adopting the following technical solution.

[0006] A quantum detection method based on quantum synchronization effect, characterized in that it comprises the following steps:

[0007] S1. Construct a quantum system with a ring structure that is coupled in a nearest neighbor manner and satisfies the Heisenberg isotropic coupling condition;

[0008] S2. constructing an ideal initial state of the quantum system and performing unitary evolution to achieve quantum phase synchronization;

[0009] S3. Using the quantum system after quantum phase synchronization to integrate the detector, and calibrating the detector, wherein the calibration is to determine whether the distance between the target quantum bit and the detector meets the fitting condition when the position of the target quantum bit is known:

[0010] If the fitting condition is not met, step S2 is executed;

[0011] If the fitting conditions are met, the calibration is completed;

[0012] S4. Use the calibrated detector to detect the spatial area, obtain information about the quantum environment, and determine the specific location of the target quantum bit;

[0013] The Heisenberg isotropic coupling condition includes boundary conditions and isotropic Heisenberg interaction conditions, wherein:

[0014] The boundary conditions are A quantum system that can connect N quantum bits end to end to form a ring structure;

[0015] The isotropic Heisenberg interaction condition is J = J x,y =J z , which enables the quantum system to achieve quantum synchronization effect;

[0016] The ideal initial state is:

[0017]

[0018] In the formula, θ j (0) = θ N (0)(j-1) / (N-1) is used to represent the initial phase of the quantum bit;

[0019] The fitting condition is represented by a fitting function, and the expression of the fitting function is:

[0020]

[0021] In the formula, τ ji is the time for the jth quantum bit to jump out, s i represents the vertical distance between the target quantum bit and the plane where the synchronized quantum system is located, and α, β, η are coefficients obtained by fitting.

[0022] As a preferred solution of the present invention, the detector is integrated by a quantum system after quantum phase synchronization, a microwave source, an arbitrary waveform generator, an IQ mixer, a microwave line reader, a resonant cavity reader, a data acquisition card and a display.

[0023] As a preferred solution of the present invention, the quantum system is a Heisenberg spin chain model in which N quantum bits are coupled together in a nearest neighbor manner and, under the constraints of boundary conditions, form a ring-shaped structure connected end to end.

[0024] As a preferred embodiment of the present invention, the Hamiltonian corresponding to the Heisenberg spin chain model is expressed as follows:

[0025]

[0026] Where, N, ω j , J x,y and J z are the number of qubits, qubit frequency, Pauli operator, xy exchange type interaction and cross Kerr interaction of the quantum system.

[0027] As a preferred solution of the present invention, the ideal initial state |ψ(0)> undergoes unitary evolution under the drive of Hamiltonian (3): |ψ(t)>=e-iHt |ψ(0)>, during the unitary evolution, the phase θ of each quantum bit j (t) gradually converges to the synchronization phase θ s , thereby achieving quantum phase synchronization.

[0028] As a preferred solution of the present invention, the quantization degree of the quantum phase synchronization is achieved by the following steps:

[0029] S71. Define the variance of the quantum bit phase in the quantum system as:

[0030]

[0031] S72. In a two-dimensional plane, use N quantum bits to construct a ring-shaped quantum system in the form of nearest neighbor coupling, and set θ N =π, and the quantum system is driven by Hamiltonian (3) at time τ s Quantum phase synchronization is achieved at time τ s At this point, a target quantum bit in the same plane as the quantum system is coupled to every quantum bit in the quantum system with a coupling strength of J j , according to the coupling strength J j The size of the quantum bit in the quantum system and the time τ for the quantum bits in the quantum system to sequentially jump out of the quantum system j Inversely proportional relationship, define the relationship:

[0032]

[0033] In the formula, J c =J / 2,r j Yes and J j The distance between the qubit in the corresponding synchronization system and the target qubit;

[0034] S73, through the coupling strength J j The corresponding r is obtained by using formula (5) j Select at least three values ​​of r j value, and with the corresponding quantum bit as the center, the selected r j Draw a circle with the value as the radius to get a common intersection point, which is the location of the target quantum bit.

[0035] As a preferred embodiment of the present invention, the specific steps of the calibration are:

[0036] S81. Assume that the quantum system after quantum phase synchronization is initially in a two-dimensional plane, and determine the specific position of the target quantum bit in the two-dimensional plane;

[0037] S82, moving the quantum system in a direction perpendicular to the plane of the system to move it away from the target quantum bit, and calculating the quantum bit jump-out time {τ ji} and moving distance {s i} performs fitting operation and obtains the values ​​of fitting coefficients α, β, η, thereby determining {τ ji} and {s i}, and combined with formula (6) and equation (5) obtained according to the Pythagorean theorem

[0038]

[0039] The coupling strength J1 between the first quantum bit and the target bit in the quantum system is obtained as s i Change rule, here r 11 represents the distance between the first quantum bit in the quantum system and the target quantum bit in the plane where the quantum system is located, r 1i is the linear distance in space between the first quantum bit and the target quantum bit in the quantum system;

[0040] S83. Due to the change of J1, the time when the first quantum bit jumps out of synchronization changes, and the jump-out time of the first quantum bit {τ 1i} and {s i};

[0041] S84, respectively determine each {s i} corresponding to {τ 1i}, and according to the fitting function (2) {τ 1i} and {s i} Perform numerical fitting and obtain the values ​​of fitting coefficients α, β, η, thereby determining the relationship between the two sets of data and completing the calibration of the detector

[0042] Beneficial effects:

[0043] The present invention can not only detect whether there is a target quantum bit in the quantum environment, but also further lock the specific position of the quantum bit to facilitate the next step of operation;

[0044] Adjusting the detection accuracy by increasing the number of qubits in the quantum synchronization system;

[0045] The reaction time after the detector is coupled with the target quantum bit can be as low as 5ns;

[0046] The invention can also discover the source of noise, paving the way for the large-scale development of quantum systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1This is a flow chart of the quantum detection method of the present invention;

[0048] Figure 2 This is a schematic diagram of the initial state of the quantum system of the present invention;

[0049] Figure 3 A schematic diagram of the two-dimensional plane detection method of the present invention;

[0050] Figure 4 This is a schematic diagram of the calibration of the detector of the present invention;

[0051] Figure 5 The present invention is different in i Below, a schematic diagram of the first quantum bit jumping out of the quantum phase synchronization system;

[0052] Figure 6 It is a data fitting schematic diagram of the present invention;

[0053] Figure 7 It is a schematic diagram of three-dimensional space detection in the present invention. DETAILED DESCRIPTION

[0054] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0055] This invention provides a new quantum detection method. The principle of this method is to use the system after quantum phase synchronization as a probe to perform detection operations on the environment around the quantum system, thereby obtaining information about the quantum environment. First, we introduce the physical model of this technical solution, such as Figure 1 As shown, the quantum system is a quantum system with 12 quantum bits as a probe. The 12 quantum bits are coupled together in a nearest neighbor manner and connected end to end to form a ring. The physical model used is the Heisenberg spin chain model, and its corresponding Hamiltonian is as follows:

[0056]

[0057] Among them, N, ω j , J x,y and J z They are the number of bits of the probe quantum system, the quantum bit frequency, the Pauli operator, the interaction of the xy direction exchange type and the cross Kerr interaction. N=12 is selected. Unless otherwise specified, the following settings are the same.

[0058] In order to achieve quantum synchronization effects, two conditions must be met: (i) boundary conditions (ii) Isotropic Heisenberg interaction condition J = J x,y =J z The first condition connects the system into a closed loop, and the second condition enables the quantum system to achieve the desired quantum synchronization effect.

[0059] Set the qubit frequency to ω j / 2π=5.472GHz, the Heisenberg isotropic coupling strength is J / 2π=64MHz, and the ideal initial state of the quantum system is selected as

[0060]

[0061] The ideal initial phase of the quantum bit is θ j (0) = θ N (0)(j-1) / (N-1) represents the initial state ψ(0)>, driven by the Hamiltonian (1), undergoes unitary evolution |ψ(t)>=e -iHt |ψ(0)>, during the unitary evolution, the phase θ of each quantum bit j (t) gradually converges to the synchronization phase θ s , thereby achieving quantum phase synchronization.

[0062] In order to quantify the degree of quantum phase synchronization, the variance of the quantum bit phase in the quantum system is defined as:

[0063]

[0064] First, we consider the detection scheme in the two-dimensional plane, such as Figure 2 As shown, 12 quantum bits build a ring quantum system in the form of nearest neighbor coupling, setting θ N =π, and the quantum system is driven by Hamiltonian (1) at time τ s Quantum phase synchronization is achieved at this point. If a target quantum bit in the same plane as the synchronized quantum system is coupled with every quantum bit in the system and the coupling strength is J j The strength of the coupling determines the time it takes for the quantum bits in the synchronization system to jump out of the synchronization system one by one. The one with the largest coupling strength will jump out first, and the jump-out time is τ j With J j There is an inverse proportional relationship between them. The relationship is defined as:

[0065]

[0066] In the formula, J c =J / 2,r j Yes and J jThe distance between the qubit in the corresponding synchronization system and the target qubit is calculated by j We can use the relationship to obtain the corresponding r j Then select at least three r j And take the corresponding quantum bit as the center and select r j Draw a circle with the radius , so that we can get a common intersection point, which is the location of the target quantum bit.

[0067] In order to facilitate use, the quantum system after quantum phase synchronization needs to be integrated into a fully automatic detector. However, before use, the detector needs to be calibrated in a series of steps, such as Figure 3 As shown, assuming that the synchronized quantum system is initially in a two-dimensional plane, refer to Figure 2 , and initially we can determine the specific position of the target quantum bit in the two-dimensional plane, and then move it away from the target quantum bit in the direction perpendicular to the plane of the quantum phase synchronization system. The moving distances are {s1=0,s2=0.5,s3=1,s4=1.5,s5=2,s6=2.5}. Each movement will cause the coupling strength between the quantum bit in the quantum phase synchronization system and the target quantum bit to change, which will further cause the time {τ} for the quantum bit in the quantum phase synchronization system to jump out of the synchronization state. ji} changes, here we only need to determine the time {τ ji} and {s i}, we use the jump-out time {τ 1i} as an example. Combining the following relationship and equation (4)

[0068]

[0069] The coupling strength J1 between the first quantum bit and the target bit in the synchronization system can be obtained as s i Change, here r 11 is a known quantity representing the distance between the first quantum bit and the target bit in the synchronization system in the two-dimensional plane, r 1i is the distance between the first quantum bit and the target bit in space. Since the change of J1 causes the time when the first quantum bit jumps out of synchronization to change, the jump-out time of the first quantum bit {τ 1i} and {s i}. Figure 5 As shown, we determine each {s i} corresponding to {τ 1i}, and through the fitting function {τ1i} and {s i} to perform numerical fitting to obtain the relationship between the two sets of data and complete the calibration of the detector, such as Figure 6 As shown, the fitting function is expressed as:

[0070]

[0071] Quantum bits in a quantum environment can be easily detected using a calibrated detector.

[0072] As an embodiment of the present invention, the detector is integrated by a quantum system after quantum phase synchronization, a microwave source, an arbitrary waveform generator, an IQ mixer, a microwave line reader, a resonant cavity reader, a data acquisition card and a display.

[0073] As an embodiment of the present invention, a method for detecting quantum bits in three-dimensional space is as follows: first, a calibrated detector is scanned over a large range in three-dimensional space to determine whether there are any quantum bits nearby. This process only requires observing the detector dashboard. When the dashboard shows that the quantum bit we use to detect in the quantum phase synchronization system (which we call the detection bit) has jumped out of the synchronization state, it indicates that there are quantum bits nearby. Then, the detector is reset to synchronize all quantum bits again and fine-tune the position of the detector in space based on the original position (note that the detector must be reset each time the position is adjusted) until a position appears where the vertical distance s between the target quantum bit and the plane of the two-dimensional quantum phase synchronization system satisfies the time {τ ji} and {s i}, in this case, s is the distance between the target quantum bit and the plane of the two-dimensional quantum phase synchronization system. x Assuming that is the coordinate of the target quantum bit on the x-axis of the three-dimensional space, then the plane where the two-dimensional quantum synchronization system is located is the yz plane in the three-dimensional space. The same method can be used to obtain the coordinates of the target quantum bit on the y-axis and z-axis in the space. Based on this, we can determine the position of the target quantum bit in the three-dimensional space (s x ,s y ,s z ),like Figure 7 shown.

[0074] The technical solution of the present invention is described in detail above in conjunction with the embodiments / drawings, but the present invention is not limited to the above technical solution. For ordinary technicians in this technical field, after knowing the contents recorded in the present invention, they can make several equivalent changes and substitutions without departing from the principle of the present invention. These equivalent changes and substitutions should also be regarded as belonging to the protection scope of the present invention.

Claims

1. A quantum detection method based on quantum synchronization effect, characterized in that: The steps include: S1. Construct a quantum system with a ring structure that is coupled in a nearest neighbor manner and satisfies the Heisenberg isotropic coupling condition; S2. constructing an ideal initial state of the quantum system and performing unitary evolution to achieve quantum phase synchronization; S3. Using the quantum system integrated detector after quantum phase synchronization, and calibrating the detector, wherein the calibration is to determine whether the distance between the target quantum bit and the detector meets the fitting condition when the position of the target quantum bit is known: If the fitting condition is not met, step S2 is executed; If the fitting conditions are met, the calibration is completed; S4. Use the calibrated detector to detect the spatial area, obtain information about the quantum environment, and determine the specific location of the target quantum bit; The Heisenberg isotropic coupling condition includes boundary conditions and isotropic Heisenberg interaction conditions, wherein: The boundary conditions are A quantum system that can connect N quantum bits end to end to form a ring structure; The isotropic Heisenberg interaction condition is J = J x,y =J z , which enables the quantum system to achieve quantum synchronization effect; The ideal initial state is: In the formula, θ j (0) = θ N (0)(j-1) / (N-1) is used to represent the initial phase of the quantum bit; The fitting condition is represented by a fitting function, and the expression of the fitting function is: In the formula, τ ji is the time for the jth quantum bit to jump out, s i represents the vertical distance between the target quantum bit and the plane where the synchronized quantum system is located, and α, β, η are coefficients obtained by fitting.

2. A quantum detection method based on quantum synchronization effect according to claim 1, characterized in that: The detector is integrated with a quantum system after quantum phase synchronization, a microwave source, an arbitrary waveform generator, an IQ mixer, a microwave line reading, a resonant cavity reading, a data acquisition card and a display.

3. A quantum detection method based on quantum synchronization effect according to claim 1, characterized in that: The quantum system is a Heisenberg spin chain model in which N quantum bits are coupled together in a nearest neighbor manner and, under the constraints of boundary conditions, form a ring-shaped structure connected end to end.

4. A quantum detection method based on quantum synchronization effect according to claim 3, characterized in that: The Hamiltonian corresponding to the Heisenberg spin chain model is expressed as follows: Where, N, ω j , J x,y and J z are the number of qubits, qubit frequency, Pauli operator, xy exchange type interaction and cross Kerr interaction of the quantum system.

5. The quantum detection method based on quantum synchronization effect according to claim 1, characterized in that: The ideal initial state |ψ(0)> undergoes unitary evolution driven by Hamiltonian (3) |ψ(t)>=e -iHt |ψ(0)>, during the unitary evolution, the phase θ of each quantum bit j (t) gradually converges to the synchronization phase θ s , thereby achieving quantum phase synchronization.

6. A quantum detection method based on quantum synchronization effect according to claim 5, characterized in that: The quantization degree of the quantum phase synchronization is achieved by the following steps: S71. Define the variance of the quantum bit phase in the quantum system as: S72. In a two-dimensional plane, use N quantum bits to construct a ring-shaped quantum system in the form of nearest neighbor coupling, and set θ N =π, and the quantum system is driven by Hamiltonian (3) at time τ s Quantum phase synchronization is achieved at time τ s At this point, a target quantum bit in the same plane as the quantum system is coupled to every quantum bit in the quantum system with a coupling strength of J j , according to the coupling strength J j The size of the quantum bit in the quantum system and the time τ for the quantum bits in the quantum system to sequentially jump out of the quantum system j Inversely proportional relationship, define the relationship: In the formula, J c =J / 2,r j Yes and J j The distance between the qubit in the corresponding synchronization system and the target qubit; S73, through the coupling strength J j The corresponding r is obtained by using formula (5) j Select at least three values ​​of r j value, and with the corresponding quantum bit as the center, the selected r j Draw a circle with the value as the radius to get a common intersection point, which is the location of the target quantum bit.

7. The quantum detection method based on quantum synchronization effect according to claim 1, characterized in that: The specific steps of the calibration are: S81. Assume that the quantum system after quantum phase synchronization is initially in a two-dimensional plane, and determine the specific position of the target quantum bit in the two-dimensional plane; S82, moving the quantum system in a direction perpendicular to the plane of the system to move it away from the target quantum bit, and calculating the quantum bit jump-out time {τ ji } and moving distance {s i } performs fitting operation and obtains the values ​​of fitting coefficients α, β, η, thereby determining {τ ji } and {s i }, and combined with formula (6) and equation (5) obtained according to the Pythagorean theorem Obtain the coupling strength J1 between the first quantum bit and the target bit in the quantum system as s i Change rule, here r 11 represents the distance between the first quantum bit in the quantum system and the target quantum bit in the plane where the quantum system is located, r 1i is the linear distance in space between the first quantum bit and the target quantum bit in the quantum system; S83. Due to the change of J1, the time when the first quantum bit jumps out of synchronization changes, and the jump-out time of the first quantum bit {τ 1i } and {s i }; S84, respectively determine each {s i } corresponding to {τ 1i }, and according to the fitting function (2) {τ 1i and {s i }Perform numerical fitting and obtain the values ​​of fitting coefficients α, β, η, so as to determine the relationship between the two sets of data and complete the calibration of the detector.

Images