CN113255922A - Quantum entanglement quantization method and device, electronic device and computer readable medium - Google Patents
Quantum entanglement quantization method and device, electronic device and computer readable medium Download PDFInfo
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Abstract
The disclosure provides a quantum entanglement quantization method and device, and relates to the technical field of artificial intelligence such as quantum neural networks. The specific implementation scheme is as follows: obtaining a parameterized quantum circuit and a loss function circuit corresponding to the parameterized quantum circuit, wherein the parameterized quantum circuit comprises adjustable parameters; acting the parameterized quantum circuit on the two quantum states to obtain an intermediate quantum state; applying the loss function circuit on the intermediate quantum state to obtain a loss function, wherein the loss function corresponds to the similarity between the output quantum state of the loss function circuit and the initial state, and any two quantum bits of the initial state are not entangled; adjusting the adjustable parameters to obtain a loss value of the maximum loss function; based on the loss values, the log negativity of the two-sided quantum states is determined. This embodiment reduces resource consumption in the quantum entanglement quantization process.
Description
Technical Field
The present disclosure relates to the field of quantum computing technologies, and in particular, to the field of artificial intelligence technologies such as quantum neural networks, and in particular, to a quantum entanglement quantization method and apparatus, an electronic device, a computer-readable medium, and a computer program product.
Background
Quantum entanglement (quantum entanglement) is a phenomenon peculiar to quantum mechanics. When several particles interact with each other, since the properties possessed by each particle are combined into bulk properties, the properties cannot be described separately, and only the properties of the bulk system can be described, which is called quantum entanglement.
How to quantify the entanglement degree of a quantum system is an extremely important problem in the quantum field. At present, Logarithmic negativity (Logarithmic connectivity) is a common method for measuring entanglement degree, and a calculation formula of the Logarithmic negativity shows that the calculation of the Logarithmic negativity by adopting quantum equipment is a great problem.
Disclosure of Invention
A quantum entanglement quantization method and apparatus, an electronic device, a computer-readable medium, and a computer program product are provided.
According to a first aspect, there is provided a quantum entanglement quantization method, the method comprising: obtaining a parameterized quantum circuit and a loss function circuit corresponding to the parameterized quantum circuit, wherein the parameterized quantum circuit comprises adjustable parameters; acting the parameterized quantum circuit on two quantum states to be measured to obtain an intermediate quantum state; applying the loss function circuit on the intermediate quantum state to obtain a loss function, wherein the loss function corresponds to the similarity between the output quantum state of the loss function circuit and the initial state, and any two quantum bits of the initial state are not entangled; adjusting the adjustable parameters to obtain a loss value of the maximum loss function; based on the loss values, the log negativity of the two-sided quantum states is determined.
According to a second aspect, there is provided a quantum entanglement quantization apparatus, the apparatus comprising: an obtaining unit configured to obtain a parameterized quantum circuit and a loss function circuit corresponding to the parameterized quantum circuit, the parameterized quantum circuit including adjustable parameters; an intermediate acting unit configured to act the parameterized quantum circuit on two square quantum states to be measured, resulting in an intermediate quantum state; a loss action unit configured to act the loss function circuit on the intermediate quantum state to obtain a loss function, the loss function corresponding to a similarity between an output quantum state of the loss function circuit and an initial state, no entanglement being present between any two qubits of the initial state; an adjusting unit configured to adjust the adjustable parameter to obtain a loss value of the loss function maximization; a determination unit configured to determine a log negativity of the two-sided quantum states based on the loss value.
According to a third aspect, there is provided an electronic device comprising: at least one processor; and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, the instructions being executable by the at least one processor to enable the at least one processor to perform the method as described in any one of the implementations of the first aspect.
According to a fourth aspect, there is provided a non-transitory computer readable storage medium having stored thereon computer instructions for causing a computer to perform a method as described in any one of the implementations of the first aspect.
According to a fifth aspect, there is provided a computer program product comprising a computer program which, when executed by a processor, implements a method as described in any of the implementations of the first aspect.
The quantum entanglement quantization method and device provided by the embodiment of the disclosure comprise the steps of firstly, obtaining a parameterized quantum circuit and a loss function circuit corresponding to the quantum circuit; secondly, acting the parameterized quantum circuit on two quantum states to be detected to obtain an intermediate quantum state; thirdly, acting the loss function circuit on the intermediate quantum state to obtain a loss function; adjusting the adjustable parameters to obtain a loss value with a maximized loss function; finally, determining the logarithm negativity of two quantum states based on the loss value, wherein the embodiment of the disclosure is suitable for different quantum computing platforms and has high practicability; the logarithm negativity can be calculated for two quantum states of any given state, so that the universality of quantum entanglement quantization is improved; by adjusting the adjustable parameters, only one measurement is adopted in each round of quantum state optimization process, and compared with a traditional quantum entanglement metering mode such as quantum chromatography, the resource consumption in the quantum entanglement quantification process is reduced.
It should be understood that the statements in this section do not necessarily identify key or critical features of the embodiments of the present disclosure, nor do they limit the scope of the present disclosure. Other features of the present disclosure will become apparent from the following description.
Drawings
The drawings are included to provide a better understanding of the present solution and are not to be construed as limiting the present disclosure. Wherein:
fig. 1 is a flow diagram of one embodiment of a quantum entanglement quantization method according to the present disclosure;
FIG. 2 is a schematic diagram of the structure of a parameterized quantum circuit and a loss function circuit in an embodiment of the disclosure;
FIG. 3 is a schematic diagram of another structure of a loss function circuit in an embodiment of the present disclosure;
FIG. 4 is a schematic diagram of a third structure of a loss function circuit according to an embodiment of the disclosure;
fig. 5 is a schematic structural diagram of an embodiment of a quantum entanglement quantization apparatus according to the present disclosure;
fig. 6 is a block diagram of an electronic device for implementing a quantum entanglement quantization method of an embodiment of the present disclosure.
Detailed Description
Exemplary embodiments of the present disclosure are described below with reference to the accompanying drawings, in which various details of the embodiments of the disclosure are included to assist understanding, and which are to be considered as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the present disclosure. Also, descriptions of well-known functions and constructions are omitted in the following description for clarity and conciseness.
In order to better understand the methods provided by the embodiments of the present disclosure, the following explains the related concepts related to the embodiments of the present disclosure.
A quantum state is a state of motion of a microscopic particle described by a plurality of quantum numbers.
Classic computer or traditional computer, computer with classic physics as the theoretical basis of information processing. Classic computers store data or programs using the most easily implemented binary data bits in classic physics, each represented by a 0 or 1, called a bit or bit, as the smallest unit of information. The classic computer itself has inevitable weaknesses: one is the most fundamental limitation of computing process energy consumption. The minimum energy required for a logic element or memory cell should be more than a few times kT; information moisture and heating energy consumption; thirdly, when the wiring density of the computer chip is high, the uncertainty of the electronic position is small and the uncertainty of the momentum is large according to the heisenberg uncertainty relation. The electrons are no longer bound and there are quantum interference effects that can even destroy the performance of the chip.
Quantum computers (quantum computers) are physical devices that perform high-speed mathematical and logical operations, store and process quantum information in compliance with quantum mechanical properties and laws. When a device processes and calculates quantum information and runs quantum algorithms, the device is a quantum computer. Quantum computers implement a new mode of information processing following the unique quantum dynamics law. For parallel processing of computational problems, quantum computers have an absolute advantage in speed over classical computers. The transformation of each superposed component by the quantum computer is equivalent to a classical calculation, all the classical calculations are completed simultaneously and superposed according to a certain probability amplitude to give an output result of the quantum computer, and the calculation is called quantum parallel calculation. Quantum parallel processing greatly improves the efficiency of quantum computers, allowing them to accomplish tasks that classic computers cannot accomplish, such as factorization of a large natural number. Quantum correlation is essentially exploited in all quantum ultrafast algorithms. Therefore, quantum parallel computation of a classical state is replaced by a quantum state, so that the computation speed and the information processing function which are incomparable with a classical computer can be achieved, and meanwhile, a large amount of computation resources are saved.
Quantum entanglement, as a resource, is a key resource for realizing various Quantum information technologies such as Quantum secure communication, Quantum computation, Quantum network, and the like, for example, a key for realizing Quantum key distribution (Quantum key distribution), Quantum super-dense coding (Quantum super-dense coding), Quantum invisible state (Quantum termination), and the like, and the quality of the resource directly determines the quality of the Quantum information scheme effect, so how to quantitatively analyze the Quantum system entanglement resource is very important for the application and development of recent Quantum technologies.
Log-negativity, a method for measuring the degree of entanglement of two-sided quantum states (e.g., two-sided A, B, with both sides A or B having N quantum bits), specifically, assuming composite quantum system AB at two-sided quantum states ρABIf the number of quantum bits of the system a is not more than that of the system B, the logarithm negativity of the composite system AB is defined as:
wherein the upper scale gamma isAPartial transpose (Partial transpose) representing the system A, | | |1Trace norm (trace norm) is expressed with the logarithm being the base 2 logarithm. Since partial transpose is a mathematical definition, it is not possible to use quantum devices to perform log-negative computations directly from the definition. For readable to-be-detected two-square quantum state rhoABBy adopting the quantum entanglement quantization method provided by the embodiment of the disclosure, the logarithm negativity of the quantum entanglement quantization method can be estimated, and further quantum entanglement resources are quantitatively estimated.
Quantum state chromatography (Quantum state tomogry) is a traditional method for calculating logarithm negativity, and the method firstly obtains a matrix form of a whole Quantum system, and then calculates partial transposition and logarithm by means of post-processing. Because the operation of partial transposition only exists in a mathematical level and no corresponding quantum operation exists in a physical level, the operation of partial transposition is split into a Pally gate which can be executed on quantum equipment, and then the Pally gate can be obtained in a post-processing mode
And then calculating the logarithm to obtain the logarithm negativity. This approach is simple thoughAnd intuitive, but require the consumption of a large number of quantum states.
Fig. 1 shows a flow 100 of one embodiment of a quantum entanglement quantization method according to the present disclosure, the quantum entanglement quantization method comprising the steps of:
In this embodiment, an application scenario of the quantum entanglement quantization method may be entanglement resource quantization of two quantum states of an N (N >2) quantum bit. Alternatively, the quantum entanglement quantization method may be applied to electronic devices such as recent quantum devices, such as quantum computers and the like. In order to better describe the scheme provided by the embodiments of the present disclosure, in the following description, a quantum entanglement quantization method is applied to an electronic device for specific explanation.
In this embodiment, the electronic device obtains the parameterized quantum circuit, where the parameterized quantum circuit is a parameterized quantum circuit with adjustable parameters, for example, the parameterized quantum circuit includes a plurality of single-quantum-bit revolving gates and a controlled back gate, where parameters of the plurality of single-quantum-bit revolving gates form a vector, and the vector is an adjustable parameter of the parameterized quantum circuit. In some implementation scenarios, the parameterized quantum circuit may also be referred to as a quantum neural network.
In this embodiment, the loss function circuit is a circuit for implementing a loss function, and based on requirements of the loss function, the loss function circuit is obtained after a plurality of tests, and the circuit can maximize all quantum states acting on the loss function circuit, and the obtained quantum states can be close to the initial state. Any two quantum bits in the initial state are not entangled, all the quantum states acting on the loss function circuit can be enabled to be close to the initial state in the maximum output quantum state output by the loss function circuit by adjusting the adjustable parameters of the parameterized quantum circuit, namely the similarity between the output quantum state and the initial state is the maximum.
In this embodiment, the function of the loss function circuit is to convert the maximum entangled state of the intermediate quantum state into the |0> state, thereby discovering entangled resources embedded in the intermediate quantum state.
In this embodiment, the parameterized quantum circuit corresponds to a loss function circuit, for example, if two square quantum states of 10 qubits are input, the loss function outputs a single quantum state of 10 qubits, and each qubit of the output quantum state corresponds to a qubit of the two square quantum states.
In this embodiment, the two-sided quantum state to be measured may be a matrix formed by two-sided quantum states, where each side may have M (M)>1) Qubits. For example for two square quantum states p to be measuredABMay include a first quantum state ρAAnd a second quantum state ρBWherein A is an n-dimensional quantum system, B is an m-dimensional quantum system, m is less than or equal to n, and m and n are positive integers.
In this embodiment, after the electronic device obtains the parameterized quantum circuit, the two quantum states to be measured are applied to the parameterized quantum circuit, so as to obtain an intermediate quantum state, which is a brand new quantum state relative to the two quantum states.
The loss function corresponds to the similarity between the output quantum state of the loss function circuit and the initial state, and any two quantum bits in the initial state are not entangled.
In this embodiment, after the electronic device obtains the loss function circuit and the intermediate quantum state, the intermediate quantum state is applied to the loss function circuit, so that the output quantum state output by the loss function circuit can be obtained, and the output quantum state is a brand new quantum state relative to the intermediate quantum state.
In this embodiment, the loss function is a function representing a degree of similarity between the output quantum state and the initial state, when the degree of similarity between the output quantum state and the initial state is the highest, the maximized loss function is obtained, since there is no entanglement between any two qubits in the initial state, the obtained maximized loss function is also a measurement method for converting the intermediate quantum state from the maximum entangled state to the non-entangled state, and the process of maximizing the loss function by adjusting the adjustable parameter is also a process for finding the degree of entanglement between two quantum states.
And 104, adjusting the adjustable parameters to obtain a loss value with the maximized loss function.
In this embodiment, the loss function is obtained based on the intermediate quantum state and the loss function circuit, the intermediate quantum state is obtained by the parameterized quantum circuit acting on the two quantum states to be measured, the parameterized quantum circuit includes an adjustable parameter, if the adjustable parameter of the parameterized quantum circuit to be measured is adjusted, the obtained intermediate quantum state acting on the two quantum states to be measured based on the parameterized quantum circuit is correspondingly adjusted, and further the value obtained by the loss function is correspondingly adjusted,
in this embodiment, the loss function can be maximized by adjusting the adjustable parameter, that is, the maximized loss function is obtained by adjusting the adjustable parameter of the parameter quantization circuit for multiple times, and the maximized loss value of the output quantum state close to the initial state is obtained.
Optionally, the adjusting the adjustable parameter to obtain the loss value maximized by the loss function includes: and adjusting the adjustable parameters, and performing iterative processing on the loss function to maximize the loss function and obtain the loss value of the maximized loss function.
In some optional implementations of this embodiment, the parameterized quantum circuit is a quantum neural network, and the adjusting the adjustable parameter to obtain the loss value with the maximized loss function includes: adjusting adjustable parameters by adopting a gradient descent method, and performing iterative processing on the loss function to maximize the loss function; and taking the value of the maximized loss function as the loss value of the maximized loss function.
In the optional implementation mode, the adjustable parameters are adjusted by adopting a gradient descent method, so that the loss value of the loss function can be gradually maximized, the operation is simpler, the reliability of adjusting the adjustable parameters is ensured, and the workload of quantum entanglement quantization can be effectively reduced.
Alternatively, other optimization methods besides the gradient descent method may be used to adjust the adjustable parameters, and the loss function is iteratively processed, that is, the above-mentioned processes from step 101 to step 103 are repeated to maximize the loss function, so as to obtain a loss value maximized by the loss function.
In this embodiment, the logarithmic negativity is a reliable measurement mode of quantum entangled resources, and the logarithmic negativity of two quantum states can be obtained by a maximized loss value of the loss function.
Specifically, by providing the function circuit, the loss function can be expressed by the following equation:
in the formula (1), 0ABIs a representation of an initial state, 0ABAll qubits representing an initial state have a quantum state of |0>And Tr () represents a trace function of the matrix,
representing the output quantum state of the loss function circuit.
When obtaining the maximum loss value L of the loss functionmaxThen, the logarithmic negativity of the two-sided quantum states can be estimated as follows:
wherein in formula (2), d is 2nAnd n is the number of quantum bits of the A system.
In some optional implementations of this embodiment, the determining the log negativity of the target quantum state based on the loss value includes: calculating to obtain the sum of all Schmidt coefficients of the two-side quantum state based on the loss value; and calculating to obtain the logarithm negativity of the two-side quantum state based on the sum of all Schmidt coefficients.
In this optional implementation, the maximum loss value can be determined to have a physical relationship with the schmitt coefficient of the two quantum states through the arranged loss function circuit, and the logarithm negativity EN(ρ) satisfies the following formula:
EN(ρ)＝2log2∑cj (2)
in formula (2), Σ cjRepresenting two-dimensional quantum states rhoABThe sum of all Schmidt coefficients (Schmidt coefficients).
The maximum loss value of the loss function is
Quantum state rho estimation based on quantum neural networkABThe logarithm negativity of the quantum state can be obtained from the sum of all the schmitt coefficients in the equation (2).
In the optional implementation mode, the sum of the maximized loss value and the Schmitt coefficient is determined through the set loss function, the logarithm negativity of two quantum states can be quickly and conveniently obtained, and a reliable calculation way is provided for quantifying entangled resources between the quantum states.
The quantum entanglement quantization method provided by the embodiment of the disclosure includes the steps of firstly, obtaining a parameterized quantum circuit and a loss function circuit corresponding to the quantum circuit; secondly, acting the parameterized quantum circuit on two quantum states to be detected to obtain an intermediate quantum state; thirdly, acting the loss function circuit on the intermediate quantum state to obtain a loss function; adjusting the adjustable parameters to obtain a loss value with a maximized loss function; finally, determining the logarithm negativity of two quantum states based on the loss value, wherein the embodiment of the disclosure is suitable for different quantum computing platforms and has high practicability; the logarithm negativity can be calculated for two quantum states of any given state, so that the universality of quantum entanglement quantization is improved; by adjusting the adjustable parameters, only one measurement is adopted in each round of quantum state optimization process, and compared with a traditional quantum entanglement metering mode such as quantum chromatography, the resource consumption in the quantum entanglement quantification process is reduced.
In some optional implementations of this embodiment, the two-sided quantum state includes at least two qubits, the two qubits including: a first qubit and a second qubit, the parameterized quantum circuit comprising at least two parametric sub-circuits, the parametric sub-circuits comprising: a first parametric sub-circuit corresponding to the first qubit and a second parametric sub-circuit corresponding to the second qubit.
Specifically, the steps performed by the quantum entanglement quantization method of the present embodiment are described in detail in conjunction with the parameterized quantum circuit and the loss function circuit shown in fig. 2:
1. preparing two parametrically adjustable parametric quantum circuits, e.g. the first parametric sub-circuit in FIG. 2
And a second parametric sub-circuit
And initializing a first parametric sub-circuit
Adjustable parameter of
Initializing a second parameter sub-circuit
Adjustable parameter of
2. Applying a parameterized quantum circuit to two quantum states rho to be measuredABObtaining intermediate quantum states of the parameterized quantum circuit output
3. Action loss function circuit W in intermediate quantum state
Get the loss function
4. Adjusting adjustable parameters in parameterized quantum circuits by gradient descent or other optimization methods
Steps 2-3 are repeated to maximize the loss function L.
5. The maximum loss value of the loss function is LmaxThereby calculating the logarithm negativity of
In this optional implementation, the two-sided quantum state includes a first quantum bit and a second quantum bit, the first parameter sub-circuit acts on the first quantum bit, the second parameter sub-circuit acts on the second quantum bit, the intermediate quantum state acts together through the loss function circuit to obtain a loss function for the two-sided quantum state, and the adjustable parameters in the first parameter sub-circuit and the second parameter sub-circuit are further adjusted to obtain a loss value with the maximized loss function.
In the optional implementation mode, the two first parameter sub-circuits and the two second parameter sub-circuits are arranged, so that the quantum states of all the two quantum states can be adjusted, and the reliability of the obtained logarithm negativity is ensured.
In this embodiment, the classic bit in the classic computer can only be in one of two states, i.e. 0 and 1 (which may correspond to the high and low voltage of the transistor in the physical view). In contrast, a qubit in a quantum device can be in not only two states |0> but also |1> but also in a superposition of the two.
To ensure that there is no entanglement between any two qubits in the initial state, in some alternative implementations of the present embodiment, each qubit in the initial state may be set to the |0> state. In this alternative implementation, the loss function circuit may include: a controlled back-gating gate and a hadamard gate.
Taking two-sided quantum states as an example of two qubit systems, as shown in fig. 3, each of the a and B systems has one qubit, i.e., n ═ m ═ 1. Randomly generating a two-square quantum state rho on an AB composite systemABFirst parameter sub-circuit
And a second parametric sub-circuit
The two ends of the controlled back-gates which are respectively connected into the loss function circuit also comprise a Hadamard gate (as H in figure 3) and a measurement, and the loss function circuit in figure 3 can obtain the loss function as follows:
for example,
the method of the embodiment can obtain the maximized loss function Lmax0.84228, logarithmic negativity can be directly calculated using equation (2), which is the process of logarithmic negativity calculation:
in the optional implementation mode, each quantum bit in the initial state is set to be in a state of |0>, when the loss function circuit comprises a controlled back gate and a Hadamard gate, the setting of the loss function can be simply and conveniently realized, and the metering step of quantum entanglement quantization is simplified.
To ensure that there is no entanglement between any two qubits in the initial state, in some alternative implementations of the present embodiment, each qubit in the initial state may be set to a |1> state. In this alternative implementation, the loss function circuit may include: controlled back gates, hadamard gates, and pauli X gates.
Taking two-sided quantum states as an example of two qubit systems, as shown in fig. 4, each of the systems a and B has one qubit, i.e., n ═ m ═ 1. Randomly generating a two-square quantum state rho on an AB composite systemABFirst parameter sub-circuit
And a second parametric sub-circuit
The two ends of the controlled back gate respectively connected to the loss function circuit further include a hadamard gate (as H in fig. 4), a pauli X gate and a measurement, and the loss function circuit in fig. 4 can obtain a loss function as follows:
in the loss function, 1ABIs a form of representation in an initial state, 1ABAll qubits representing an initial state have a quantum state of |1>And Tr () represents a trace function of the matrix,
representing the output quantum state of the loss function circuit.
In the optional implementation mode, each quantum bit in the initial state is set to be in the state |1>, when the loss function circuit comprises a controlled back gate, a Hadamard gate and a Paglie X gate, the setting of the loss function can be simply and conveniently realized, and an optimized implementation mode is provided for measuring the logarithm negativity.
In order to ensure that there is no entanglement between any two qubits in the initial state, in some alternative implementations of this embodiment, the qubit in the initial state may be set to a |0> state and a |1> state, that is, the qubit in the initial state has quantum states including |0> and |1>, and in this alternative implementation, the loss function circuit may include: controlled back gates, hadamard gates, and pauli X gates.
In this alternative implementation, the initial state is a quantum state without entanglement between qubits, and when the quantum state of the qubits in the initial state includes |0> and |1>, |0> state and |1> state, there is no order requirement, for example, if the initial state is a two-qubit system, then the two qubits in the initial state may be |0>, |1>, or |1>, |0 >; for another example, the initial state is a five-qubit system, and the five qubits in the initial state can be |1>, |0>, |1 >. When the quantum state of the qubit includes |0> and |1>, in the loss function circuit, a pauli X gate may be placed in the loss function branch corresponding to the qubit of the |1> state, so as to achieve that all the quantum states of the qubit of the initial state are |0 >.
It should be noted that the controlled back gate, the hadamard gate, and the pauli X gate are all unit gates having different functions in the quantum device, and are not described herein again.
In the optional implementation mode, the qubits in the initial state are set to be in the state |1> and the state |0>, when the loss function circuit comprises the controlled back gate, the hadamard gate and the pauli X gate, the setting of the loss function can be simply and conveniently realized, and an optimized implementation mode is provided for measuring the logarithm negativity.
With further reference to fig. 5, as an implementation of the methods illustrated in the above figures, the present disclosure provides an embodiment of a quantum entanglement quantization apparatus, which corresponds to the method embodiment illustrated in fig. 1, and which is particularly applicable in various electronic devices.
As shown in fig. 5, the quantum entanglement quantization apparatus 500 provided by the present embodiment includes: an acquisition unit 501, an intermediate action unit 502, a loss action unit 503, an adjustment unit 504, and a determination unit 505. The obtaining unit 501 may be configured to obtain a parameterized quantum circuit and a loss function circuit corresponding to the parameterized quantum circuit, where the parameterized quantum circuit includes adjustable parameters. The intermediate acting unit 502 may be configured to act the parameterized quantum circuit on the two square quantum states to be measured, resulting in an intermediate quantum state. The loss action unit 503 may be configured to act the loss function circuit on the intermediate quantum state to obtain a loss function, where the loss function corresponds to a similarity between an output quantum state of the loss function circuit and an initial state, and there is no entanglement between any two qubits in the initial state. The adjusting unit 504 may be configured to adjust the adjustable parameter to obtain a loss value with a maximized loss function. The determining unit 505 may be configured to determine the logarithm negativity of the two-sided quantum states based on the loss value.
In the present embodiment, in the quantum entanglement quantization apparatus 500: the specific processing of the obtaining unit 501, the middle action unit 502, the loss action unit 503, the adjusting unit 504, and the determining unit 505 and the technical effects thereof can refer to the related descriptions of step 101, step 102, step 103, step 104, and step 105 in the corresponding embodiment of fig. 1, which are not described herein again.
In some optional implementations of this embodiment, the quantum state of each qubit in the initial state is |0>, and the loss function circuit includes: a controlled back-gating gate and a hadamard gate.
In some optional implementations of this embodiment, the quantum state of each qubit in the initial state is |1>, and the loss function circuit includes: controlled back gates, hadamard gates, and pauli X gates.
In some optional implementations of this embodiment, the quantum state of the qubit in the initial state includes |0> and |1>, and the loss function circuit includes: controlled back gates, hadamard gates, and pauli X gates.
In some optional implementations of this embodiment, the two-sided quantum state includes at least two qubits, and the two qubits include: a first qubit and a second qubit, the parameterized quantum circuit comprising at least two parametric sub-circuits, the parametric sub-circuits comprising: a first parametric sub-circuit corresponding to the first qubit and a second parametric sub-circuit corresponding to the second qubit.
In some optional implementations of this embodiment, the adjusting unit 504 includes: an adjusting module (not shown in the figure) and a value taking module (not shown in the figure). The adjusting module may be configured to adjust the adjustable parameter by using a gradient descent method, and perform iterative processing on the loss function to maximize the loss function. The value module may be configured to take the value of the maximized loss function as the loss value maximized by the loss function.
In some optional implementations of this embodiment, the determining unit includes: coefficient calculation module (not shown), entanglement calculation module (not shown). Wherein the coefficient calculation module may be configured to calculate a sum of all schmitt coefficients of the two-sided quantum states based on the loss value. The entanglement computation module may be configured to compute a log negativity of the two-sided quantum states based on a sum of all schmitt coefficients.
In the quantum entanglement quantization apparatus provided in the embodiment of the present disclosure, first, the obtaining unit 501 obtains a parameterized quantum circuit and a loss function circuit corresponding to the quantum circuit; secondly, the intermediate action unit 502 acts the parameterized quantum circuit on the two quantum states to be measured to obtain an intermediate quantum state; thirdly, the loss function circuit is acted on the intermediate quantum state by the loss action unit 503 to obtain a loss function; then, the adjusting unit 504 adjusts the adjustable parameter to obtain the loss value of the maximum loss function; finally, the determining unit 505 determines the logarithm negativity of two quantum states based on the loss value, and the embodiment of the disclosure is suitable for different quantum computing platforms and has high practicability; the logarithm negativity can be calculated for two quantum states of any given state, so that the universality of quantum entanglement quantization is improved; by adjusting the adjustable parameters, only one measurement is adopted in each round of quantum state optimization process, and compared with a traditional quantum entanglement metering mode such as quantum chromatography, the resource consumption in the quantum entanglement quantification process is reduced.
The present disclosure also provides an electronic device, a readable storage medium, and a computer program product according to embodiments of the present disclosure.
FIG. 6 illustrates a schematic block diagram of an example electronic device 600 that can be used to implement embodiments of the present disclosure. Electronic devices are intended to represent various forms of digital computers, such as laptops, desktops, workstations, personal digital assistants, servers, blade servers, mainframes, and other appropriate computers. The electronic device may also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions, are meant to be examples only, and are not meant to limit implementations of the disclosure described and/or claimed herein.
As shown in fig. 6, the apparatus 600 includes a computing unit 601, which can perform various appropriate actions and processes according to a computer program stored in a Read Only Memory (ROM)602 or a computer program loaded from a storage unit 608 into a Random Access Memory (RAM) 603. In the RAM603, various programs and data required for the operation of the device 600 can also be stored. The calculation unit 601, the ROM 602, and the RAM603 are connected to each other via a bus 604. An input/output (I/O) interface 605 is also connected to bus 604.
A number of components in the device 600 are connected to the I/O interface 605, including: an input unit 606 such as a keyboard, a mouse, or the like; an output unit 607 such as various types of displays, speakers, and the like; a storage unit 608, such as a magnetic disk, optical disk, or the like; and a communication unit 609 such as a network card, modem, wireless communication transceiver, etc. The communication unit 609 allows the device 600 to exchange information/data with other devices via a computer network such as the internet and/or various telecommunication networks.
The computing unit 601 may be a variety of general and/or special purpose processing components having processing and computing capabilities. Some examples of the computing unit 601 include, but are not limited to, a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), various dedicated Artificial Intelligence (AI) computing chips, various computing units running machine learning model algorithms, a Digital Signal Processor (DSP), and any suitable processor, controller, microcontroller, and so forth. The calculation unit 601 performs the respective methods and processes described above, such as the quantum entanglement quantization method. For example, in some embodiments, the quantum entanglement quantization method may be implemented as a computer software program tangibly embodied in a machine-readable medium, such as storage unit 608. In some embodiments, part or all of the computer program may be loaded and/or installed onto the device 600 via the ROM 602 and/or the communication unit 609. When the computer program is loaded into the RAM603 and executed by the computing unit 601, one or more steps of the quantum entanglement quantization method described above may be performed. Alternatively, in other embodiments, the computation unit 601 may be configured to perform the quantum entanglement quantization method by any other suitable means (e.g., by means of firmware).
Various implementations of the systems and techniques described here above may be implemented in digital electronic circuitry, integrated circuitry, Field Programmable Gate Arrays (FPGAs), Application Specific Integrated Circuits (ASICs), Application Specific Standard Products (ASSPs), system on a chip (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and/or combinations thereof. These various embodiments may include: implemented in one or more computer programs that are executable and/or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, receiving data and instructions from, and transmitting data and instructions to, a storage system, at least one input device, and at least one output device.
Program code for implementing the methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable quantum entanglement quantization device, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowchart and/or block diagram to be performed. The program code may execute entirely on the machine, partly on the machine, as a stand-alone software package partly on the machine and partly on a remote machine or entirely on the remote machine or server.
In the context of this disclosure, a machine-readable medium may be a tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.
To provide for interaction with a user, the systems and techniques described here can be implemented on a computer having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to a user; and a keyboard and a pointing device (e.g., a mouse or a trackball) by which a user can provide input to the computer. Other kinds of devices may also be used to provide for interaction with a user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user may be received in any form, including acoustic, speech, or tactile input.
The systems and techniques described here can be implemented in a computing system that includes a back-end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front-end component (e.g., a user computer having a graphical user interface or a web browser through which a user can interact with an implementation of the systems and techniques described here), or any combination of such back-end, middleware, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: local Area Networks (LANs), Wide Area Networks (WANs), and the Internet.
The computer system may include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other.
In the technical scheme of the disclosure, the acquisition, storage, application and the like of the personal information of the related user all accord with the regulations of related laws and regulations, and do not violate the good customs of the public order.
It should be understood that various forms of the flows shown above may be used, with steps reordered, added, or deleted. For example, the steps described in the present disclosure may be executed in parallel or sequentially or in different orders, and are not limited herein as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved.
The above detailed description should not be construed as limiting the scope of the disclosure. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made in accordance with design requirements and other factors. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present disclosure should be included in the scope of protection of the present disclosure.
Claims (16)
1. A method of quantum entanglement quantification, the method comprising:
obtaining a parameterized quantum circuit and a loss function circuit corresponding to the parameterized quantum circuit, wherein the parameterized quantum circuit comprises adjustable parameters;
the parameterized quantum circuit acts on two quantum states to be measured to obtain an intermediate quantum state;
applying the loss function circuit to the intermediate quantum state to obtain a loss function, where the loss function corresponds to a similarity between an output quantum state of the loss function circuit and an initial state, and any two qubits in the initial state are not entangled;
adjusting the adjustable parameters to obtain a loss value of the maximized loss function;
determining the log negativity of the two-sided quantum states based on the loss value.
2. The method of claim 1, wherein the quantum state of each qubit of the initial state is |0>, and the loss function circuit comprises: a controlled back-gating gate and a hadamard gate.
3. The method of claim 1, wherein the quantum state of each qubit of the initial state is |1>, and the loss function circuit comprises: controlled back gates, hadamard gates, and pauli X gates.
4. The method of claim 1, wherein the quantum state of the qubit of the initial state comprises |0> and |1>, and the loss function circuit comprises: controlled back gates, hadamard gates, and pauli X gates.
5. The method of claim 1, wherein the two-sided quantum state comprises at least two qubits, the two qubits comprising: a first qubit and a second qubit, the parameterized quantum circuit comprising at least two parametric sub-circuits, the parametric sub-circuits comprising: a first parametric sub-circuit and a second parametric sub-circuit, the first parametric sub-circuit corresponding to the first qubit and the second parametric sub-circuit corresponding to the second qubit.
6. The method of claim 1, wherein said adjusting said adjustable parameter to obtain a loss value at which said loss function is maximized comprises:
adjusting the adjustable parameters by adopting a gradient descent method, and performing iterative processing on the loss function to maximize the loss function;
and taking the value of the maximized loss function as the loss value maximized by the loss function.
7. The method of one of claims 1 to 6, wherein said determining log negativity of said target quantum state based on said loss value comprises:
calculating the sum of all Schmitt coefficients of the two-side quantum states based on the loss value;
and calculating to obtain the logarithm negativity of the two-side quantum state based on the sum of all the Schmidt coefficients.
8. A quantum entanglement quantization apparatus, the apparatus comprising:
an obtaining unit configured to obtain a parameterized quantum circuit and a loss function circuit corresponding to the parameterized quantum circuit, the parameterized quantum circuit including adjustable parameters;
an intermediate acting unit configured to act the parameterized quantum circuit on two square quantum states to be measured, resulting in an intermediate quantum state;
a loss action unit configured to act the loss function circuit on the intermediate quantum state to obtain a loss function, the loss function corresponding to a similarity of an output quantum state of the loss function circuit and an initial state, any two qubits of the initial state being free of entanglement;
an adjusting unit configured to adjust the adjustable parameter to obtain a loss value of the loss function maximization;
a determination unit configured to determine a log negativity of the two-sided quantum states based on the loss value.
9. The apparatus of claim 8, wherein the quantum state of each qubit of the initial state is |0>, and the loss function circuit comprises: a controlled back-gating gate and a hadamard gate.
10. The apparatus of claim 8, wherein the quantum state of each qubit of the initial state is |1>, and the loss function circuit comprises: controlled back gates, hadamard gates, and pauli X gates.
11. The apparatus of claim 8, wherein the quantum state of the qubit of the initial state comprises |0> and |1>, and the loss function circuit comprises: controlled back gates, hadamard gates, and pauli X gates.
12. The apparatus of claim 8, wherein the adjustment unit comprises:
an adjustment module configured to adjust the adjustable parameter using a gradient descent method and to iteratively process the loss function to maximize the loss function;
a dereferencing module configured to dereference the maximized loss function as a loss value maximized by the loss function.
13. The apparatus according to one of claims 8-12, wherein the determining unit comprises:
a coefficient calculation module configured to calculate a sum of all Schmitt coefficients of the two-sided quantum states based on the loss value;
and the entanglement calculation module is configured to calculate the logarithm negativity of the two-side quantum states based on the sum of all the Schmidt coefficients.
14. An electronic device, comprising:
at least one processor; and
a memory communicatively coupled to the at least one processor; wherein the content of the first and second substances,
the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of any one of claims 1-7.
15. A non-transitory computer readable storage medium having stored thereon computer instructions for causing the computer to perform the method of any one of claims 1-7.
16. A computer program product comprising a computer program which, when executed by a processor, implements the method of any one of claims 1-7.
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