This application claims priority from and the benefit of Korean Patent Applications No. 10-2016-0168244, filed on Dec. 12, 2016, which is hereby incorporated by reference for all purposes as if fully set forth herein.
Field of the Invention
The present invention relates to a quantum mechanical machine vision system and an arithmetic operation method, more specifically to a quantum mechanical machine vision system and an arithmetic operation method based on quantum dot.
Discussion of the Background
Human beings now have better analytical capabilities than machine analysis in many areas such as object recognition, knowledge representation, reasoning, learning and natural language processing. Accordingly, in order to imitate or surpass the human way of thinking mechanically, a complicated arithmetic operation method must be used.
An accurate solution to the problem of optimization of machine vision system is required to imitate or surpass human visual recognition ability as an example.
In order to solve the complex computation method of artificial view, there is a method of performing quantum mechanical calculation using quantum computing.
A quantum computer is a physical system that uses one or more quantum effects to perform calculations. A quantum computer capable of efficiently simulating other quantum computers is called a universal quantum computer (UQC).
1. Approach to Quantum Computation
There are several general approaches to the design and operation of quantum computers.
One approach corresponds to a ‘circuit model’ of quantum computation. In this approach, qubits operate in the order of a logical gate, which is a representation of a compiled algorithm. Circuit model quantum computers have some serious barriers in their actual implementation. In a circuit model, qubits are required to be coherent for a longer period of time than a single-gate time. This demand arises because circuit model quantum computers require operations, called quantum error correction, to operate. Quantum error correction cannot be performed without the qubit of a circuit model quantum computer that can maintain quantum coherence for a time interval of about 1000 times one gate time. There have been a number of studies focused on developing qubits with sufficient coherence to form basic information units of quantum computers. This is described in, for example, “Introduction to Quantum Algorithms”, by Shor, P. W. arXiv. org: quantph/0005003 (2001), pp. 1-27. This technical field is still stagnant due to the lack of the ability to enhance the coherence of the qubit to a level suitable for designing and operating real circuit model quantum computers.
2. Computational Complexity Theory
In computer science, computational complexity theory is a kind of computational theory required to solve a given computational problem and the theory of computation to study resources or costs. Costs are generally measured by abstract parameters called computational resources, such as time and space. The time means the number of steps necessary to solve the problem, and the space means the required amount of information storage or the amount of memory required.
Optimization problems correspond to problems where one or more objective functions are minimized and maximized under a set of constraints, sometimes with respect to a set of variables.
Simulation problems typically deal with the simulation of one system by another system during a typical time interval. For example, computer simulations consist of business processes, ecological habitats, protein folding, molecular ground states, and quantum systems. These problems often involve numerous diverse entities that are different from complex interrelationships and behavioral rules. Feynman suggests that a quantum system can be used to simulate several physical systems more efficiently than UTM.
Many optimization and simulation problems cannot be solved using UTM. Because of these limitations, computational elements are needed that can solve computational problems beyond the scope of the UTM. Other digital computer based systems and methods for solving optimization problems can be found.
An example of a technique for solving this optimization problem is described in Korean Patent No. 10-1309677 entitled ‘Method for Calculating Adoptive Quantum’.
The prior art discloses a quantum computing method using a quantum system that includes a plurality of qubits. In the prior art, quantum annealing is possible to obtain a desired minimum energy (or cost), which concurrently tracks a configuration of a superposition state, and especially, Adiabatic Quantum Computation (AQC) technique is used to perform quantum annealing. In addition, AQC uses a technique in which an adiabatic change of Hamiltonian from the initial state to the target state is obtained and a solution of the desired target state is finally obtained.
The above prior art describes the general operation of a quantum computing system to solve a complex problem, and in spite of the existence of this prior art, the selection of an optimized quantum system remains a very important problem to solve the complicated matter.
Accordingly, it is an object of the present invention to provide a quantum mechanical machine vision system and an arithmetic operation method based on quantum dot, which can facilitate calculation of complexity caused by an increase in the number of feature points for image identification.
A quantum mechanical arithmetic operation method based on quantum dots according to an exemplary embodiment of the present invention is performed by a quantum processing processor. The quantum mechanical arithmetic operation method comprises, obtaining a first labeled graph connecting between feature points of the first image and a second labeled graph connecting feature points of the second image, generating a point-to-point combination by matching the feature points of the first image with the feature points the second image, generating a conflict graph by adding the largest point-to-point combination by comparing the point-to-point combinations with the threshold, generating non-constrained binary optimization equation for finding a maximum independent set of conflict graphs, converting the non-constrained binary optimization equation into Ising model of the quantum system, and calculating the Hamiltonian of Ising model based on the quantum dots to obtain solution of the non-constrained binary optimization equation.
For example, calculating the Hamiltonian of Ising model based on the quantum dots to obtain solution of the non-constrained binary optimization equation may be performed by quantum dots arranged in a matrix shape.
In this case, neighboring quantum dots with the shortest distance in a column direction or a row direction may be connected to each other through the tunnel junction.
For example, the Hamiltonian of the Ising model may be calculated through adiabatic evolve, in calculating the Hamiltonian of Ising model based on the quantum dots to obtain solution of the non-constrained binary optimization equation.
On the other hand, the quantum mechanical arithmetic operation method may further comprise repeatedly learning the non-constrained binary optimization equation through machine learning.
A quantum mechanical machine vision system according to an exemplary embodiment of the present invention comprises an image acquisition module, a quantum processing processor and a memory unit. The image acquisition module acquires an image. The quantum processing processor processes the image obtained from the image acquisition module. The memory unit stores data necessary for computation of the quantum processing processor. The quantum processing processor obtains a first labeled graph connecting between feature points of the first image and a second labeled graph connecting feature points of the second image, generates a point-to-point combination by matching the feature points of the first image with the feature points the second image, generates a conflict graph by adding the largest point-to-point combination by comparing the point-to-point combinations with the threshold, generates non-constrained binary optimization equation for finding a maximum independent set of conflict graphs, converts the non-constrained binary optimization equation into Ising model of the quantum system, and calculates the Hamiltonian of Ising model based on quantum dots to obtain solution of the non-constrained binary optimization equation.
For example, the quantum processing processor may comprise quantum dots arranged in a matrix shape.
For example, neighboring quantum dots with the shortest distance in a column direction or a row direction are connected to each other through the tunnel junction.
For example, the quantum processing processor may further comprise a charge detection unit disposed adjacent to the quantum dots.
For example, the quantum processing processor may calculate the Hamiltonian of the Ising model through adiabatic evolve.
As described above, according to the quantum dot-based quantum mechanical machine vision system and an arithmetic operation method of the present invention, the NP problem generated as the number of feature points increases is replaced by Hamiltonian using Ising model, so that it can be easily calculated using quantum dots arranged in a matrix shape.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention.
The present invention is described more fully hereinafter with reference to the accompanying drawings, in which example embodiments of the present invention are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity.
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.
In the machine vision system, the computer or the robot compares the previously captured reference pattern with the photographed image to recognize the image, and this process is advanced through a training process. In general, an algorithm called a heuristic algorithm is applied to a particular type of image, and a heuristic algorithm can be applied in various ways depending on the image.
Generally, a brain recognizing human visual and visual information extracts feature points that can adequately describe a pattern represented by each image for pattern matching between different images, and the distance and direction between the feature points are synthetically recognized, so that the distance and direction are recognized as a pattern. The human brain then compares the pattern information extracted from the image to determine whether the two images match. This process is difficult by searching only by movement between a point and a point, but easy by obtaining patterns including surrounding points.
However, in machine vision with limited intelligence in general, it is extremely difficult to fully simulate the behavior of human brain or the interpretation of human sensory data. It is known as the NP-Hard Problem to simulate the behavior of the human brain.
In
In order to perform pattern recognition operations related to machine vision, a combination of feature vectors representing relative position information between respective points of interest (feature points) in each image is used, and a combination of these feature vectors is used as a reference for recognizing each image.
The process of extracting a reference pattern for each image can be performed by a process of extracting feature points and a process of determining relative position information between the feature points as a feature vector. This process is not a deterministic problem, but a non-deterministic problem in which it is necessary to find an optimized value by comparing the results.
Assuming that a reference pattern made up of a set of feature vectors between interest points (feature points) i, j, k in the image A in
In order to describe the mapping between the image A and the image B in
In the present invention, this optimization problem is solved by using quantum computing, and an arrow representing a connection between respective points of interest (feature points) is modeled as a dipole in an image. In this case, the arrow indicates the direction and length between the respective points of interest (feature points), and may be represented by a vector.
To this end, (i) a term indicating a mismatch between a feature point of the image A and a corresponding position of the feature point of the image B, and (ii) a term indicating spatial consistency between neighboring points can be defined by measuring divergence of matches of the neighboring points.
By utilizing the physical model of quantum computing, the most optimized pattern X in image A and the most optimized pattern Y image B can be found at the same time. By modeling together with a combination of feature vectors between interest points (feature points) i, j, k in the image A and a combination of feature vectors between interest points (feature points) α, β, γ in the image B as a physical model for quantum computing, and by observing the physical model, optimized reference patterns X and Y can be obtained. The optimized state can be obtained by taking the state of the physical model when the energy of the physical model is in the ground state. For example, when a physical model is implemented in a black box capable of quantum computing and physical properties of a physical model in a black box are observed when the target state (ground state) is obtained through an adiabatic evolution process using a physical model, the optimized reference patterns X and Y can be obtained.
At this time, the physical model including the dipole physical characteristics such that the combination of vectors between interest points (feature points) of each image is described by the dipole model can be selected as the physical model in the black box.
In the image A in
When the graph of the feature points i, j, k in image A of
d(i,α)=dfeature({right arrow over (f)}i,{right arrow over (f)}α), [Equation 1]
where d (i, α) is a scalar product between feature vectors {right arrow over (f)}i and {right arrow over (f)}α, and d (i, α) can be interpreted as a measure of the similarity of the correlated feature vectors and is a normalized value.
At this time, the combination between the point i obtained in image A and the point a obtained in image B can be defined as (i, α). If we define Tfeature as a point-wise threshold that indicates whether the combination (i, α) is a potential match suitable for describing the pattern, the combination (i, α) satisfying d (i, α)>Tfeature can be interpreted as a potential match suitable for describing the image pattern.
The conflict graph GC can be generated from the graphs GA and GB as a measure for measuring the similarity of the graphical representations of image A and image B in
Edges (i,α;j,β) in the conflict graph GC encode geometric consistency between {right arrow over (f)}i and {right arrow over (f)}j in the labelled graph GA corresponding to image A in
For all vertex pairs (Viα,Vjβ) in GC where i≠j and α≠β we calculate the geometric consistency of the two pairs of interest points d(i,α,j,β)=dgeometric({right arrow over (g)}i,j,{right arrow over (g)}αβ) which is normalized.
The geometric consistency measures the geometric compatibility of the match pairs (i,α) and (j,β) as the residual differences in local displacement, scale and rotation assignment of the associated interest points after the changes due to global translation, rotation and scaling have been normalized. A pair (i,α) and (j,β) are not allowed to match if they are in geometric conflict, i.e., the residual effects are two large.
If d(i,α,j,β)<Tgeometric, the pair (i,α) and (j,β) are considered in geometric conflict for a threshold Tgeometric. We draw an edge in GC between vertex pairs (Viα,Vjβ) if i≠j and α≠β and they in geometric conflict. By this prescription, we draw the conflict graph with at most L vertices. The maximum independent set of the conflict graph is equivalent to the maximum common subgraph of unlabeled graphs GA and GB.
Finding the maximum independent set for the conflicting graph GC can be translated as a quadratic unconstrained binary optimization problem defined by following Equation 2.
where Qiα,iα=−1 for all vertices and Qiα,jβ=L when there is an edge between the pair (i,α) and (j,β).
The minimum energy configuration enforces xiα=1 if and only if Viα belongs to the maximum independent set and xiα=0 otherwise. Equation 2 is a well know NP-hard problem which requires tremendous amount of computation time as L grows.
In the following, Equation 2 is modified to apply to adiabatic quantum computation for a quantum Ising Model.
Let X (where
be a column vector of N Boolean variables and Q is a N×N matrix such that, then Equation 2 can be rewritten as the following Equation 3.
Xopt=argmin X†QX wherein xiε(0,1}. [Equation 3]
On the other hand, quantum mechanical Ising problem is formulated as the following Equation 4 by applying the relation of S=2X−1 to the Equation 3.
Sopt=argmin{S†JS+h†S} where Siε{−1,1}. [Equation 4]
The S variables are called quantum-mechanical spin. This quantum Ising model can be solved by one particular model of quantum computation called adiabatic quantum computation (AQC).
In quantum mechanics, the spin states S=±1 are represented by orthogonal vectors in Hilbert space denoted as qubits. The two state of qubits are described by vectors as the following Equation 5.
The qubits can be extended to a vector by a linear combination called superposition, and this process is expressed as Equation 6.
|ϕ=α|0+β|1 with |α|2+|β|2=1. [Equation 6]
Larger quantum systems are constructed through tensor product of the individual qubit vector spaces, for example, as the following Equation 7.
Superpositions of N qubit states are also possible with the associated amplitudes representing the probability of observing the respective N spin state.
We also define single qubit operators can be defined as the following Equation 8.
If the operator of Equation (8) is applied to the qubit vector of Equation (5), the following Equation (9) can be obtained.
σ2|0=|0,σx|1=−|1. [Equation 9]
On 2-qubit state, an operator σz⊗I extracts the classical spin of the first qubit, I⊗σz extracts the classical spin of the second qubit and σz⊗σz extracts the product of the two classical spins.
The quantum-mechanical Ising model on N spins is represented as 2N×2N Hamiltonian represented as the following Equation 10.
where σiz is an operator σz acting on ith qubit.
To initialize the quantum system, another kind of spin operator σx can be defined as shown in Equation 11.
The spin operator of Equation 11 can flip the state of the qubit.
At this time, the ground state Hamiltonian can be expressed by following Equation 12 using a spin operator acting on the ith qubit.
The eigenstate of the ground state Hamiltonian of Equation 12 can be expressed as following Equation 13.
The time dependency of the quantum state of Equation 13 can be expressed by the Schrödinger equation of Equation 14.
To solve the quantum mechanical eigen modeling adiabatically, the convex form of the adiabatic Hamiltonian is obtained by using the initial condition given by |Ψ(0)>=|Φ>0 at t=0.
At t=0, the quantum system has the lowest energy state. At this time, the lowest energy state can give equal probability for all classical configurations. On the other hand, at t=T, it is designed to cope with the quantum mechanical Ising model problem to solve the artificial visual problem.
In this way, the NP-hard problem, which is difficult to classically handle, can be solved through quantum mechanical adiabatic evolution of a given quantum system.
The globally lowest classical configuration obtained by adiabatic quantum mechanics (AQC) can be a solution to the second-order, non-definite binary optimization problem, which is a complex computational problem related to artificial view. It has been mathematically proved that quantum computing can provide exponential speed-up in solving NP-hard problems compared to classical methods.
The process of training the adiabatic quantum computing system to solve the secondary unrestricted binary optimization problem defined by Equation 2 begins with hardware training using a classification algorithm. The classification algorithm is expressed by the following equation 16.
where xεRM are input patters to be classified, yε{−1,1} is the output of the classifier, hi:RM|→{−1,1} are feature detectors, and ωiε{0,1} is the weights to be optimized during training.
The training is achieved by solving the discrete optimization problem expressed as the following Equation 17.
Here, the above Equation 17 is described for S-number of training samples {(xs,ys)|=1, 2, . . . , S}.
Hereinafter, a hardware implementation for solving the machine vision problem and a mathematical expression for describing the hardware will be described.
connected via tunnel junction 122. Those quantum dots 121 can be fabricated via gate-defined quantum dot structure. The Hamiltonian for this system is given by the following Equation 18.
H=J12(t)σ1zσ2z+h1σ1z+h2σ2z [Equation 18]
In this equation, J12 (t) is controlled by an external bias. The individual spin detection of the electrons is performed by the charge detection unit 123.
On the other hand, Hamiltonian regarding to N quantum dots can be described by the following equation 19.
In Equation 19, Jij and hi are variables having a positive value, and are changed as the external power source is applied. The bias voltage applied to the gate can be appropriately adjusted to calculate the Hamiltonian of the quantum processing processor.
Hamiltonian at the initial (t=0) is Jij=0 for all i and j. In Equation 15, the T value is defined as T=ℏ/ΔE, and ΔE is the interval between the initial ground state and the global minimum energy.
Referring to
The image acquisition module 110 acquires an image. The image acquisition module 110 may include, for example, a CCD camera.
The quantum processing processor 120 processes the image obtained from the image acquisition module 110.
The memory unit 130 stores data necessary for the computation of the quantum processing processor 120.
The quantum processing processor 120 obtains a first labeled graph connecting between feature points of the first image and a second labeled graph connecting feature points of the second image, generates a point-to-point combination by matching the feature points of the first image with the feature points the second image, generates a conflict graph by adding the largest point-to-point combination by comparing the point-to-point combinations with the threshold, generates non-constrained binary optimization equation for finding a maximum independent set of conflict graphs, converts the non-constrained binary optimization equation into Ising model of the quantum system, and calculates the Hamiltonian of Ising model based on the quantum dots to obtain solution of the non-constrained binary optimization equation. The quantum processing processor 120 may learn repeatedly the non-constrained binary optimization equation through machine learning.
For example, the quantum processing processor 120 may include quantum dots 121 arranged in a matrix shape as shown in
At this time, neighboring quantum dots 121 with the shortest distance in a column direction or a row direction may be connected to each other through the tunnel junction 122.
The quantum processing processor 120 may further include a charge detection unit 123 disposed adjacent to the quantum dot 121 for detecting electrons of the quantum dot 121.
Meanwhile, in calculating the Hamiltonian of Ising model based on the quantum dots 121 to obtain solution of the non-constrained binary optimization equation, the Hamiltonian of Ising model can be calculated through adiabatic evolve. This process has been described in detail above, so redundant description is omitted.
As described above, according to the quantum dot-based quantum mechanical machine vision system and an arithmetic operation method of the present invention, the NP problem generated as the number of feature points increases is replaced by Hamiltonian using Ising model, so that it can be easily calculated using quantum dots arranged in a matrix shape.
It will be apparent to those skilled in the art that various modifications and variation may be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
Number | Date | Country | Kind |
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10-2016-0168244 | Dec 2016 | KR | national |
Number | Name | Date | Kind |
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8504497 | Amin | Aug 2013 | B2 |
20180165595 | Ahn | Jun 2018 | A1 |
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10-1309677 | Sep 2013 | KR |
Entry |
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Federico Spedalieri “Overcoming limitations of quantum annealers” International Workshop on Quantum Annealing and its Applications in Science and Industry (QuAASI'16—Jul. 2016) (Year: 2016). |
Chang-Yu Hsieh et al (hereinafter Hsieh)“Quantum circuits based on coded qubits encoded in chirality of electron spin complexes in triple quantum dots” Department of Physics, University of Ottawa Apr. 2010. (Year: 2010). |
Peter W. Shor, “Introduction to Quantum Algorithms”, arXiv:quant-ph/0005003v2; Jul. 6, 2001; pp. 1-17. |
Michael A. Nielsen et al., “Quantum Computation and Quantum Information”; 10th Anniversary Edition, 2010, Cambridge University Press, pp. 1-698. |
Hartmut Neven et al., “Image recognition with an adiabatic quantum computer I. Mapping to quadratic unconstrained binary optimization.” arXiv:0804.4457v1 [quant-ph]; Apr. 28, 2008; pp. 1-7. |
J. C. Wells, et al.; “Quantum-Dot Arrays: Simulation Results Toward Analog Computing”; Center for Engineering Science Advanced Research, Computer Science and Mathematics Division, Physics Division, 1996. |
Hartmut Neven et al., “QBoost: Large Scale Classifier Training with Adiabatic Quantum Optimization.”; JMLR: Workshop and Conference Proceedings 25; 2012; Asian Conference on Machine Learning; pp. 333-348. |
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20180165594 A1 | Jun 2018 | US |