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Innovation and Digital Transformation for a Sustainable World




           and the computational resources available to the analyst,     3.  QUANTUM COMPUTING
           although the newly developed improvements further refine
           the existing classification techniques and their effectiveness.  Quantum computing [17] represents a rapidly evolving
           The classification techniques of ML are depicted in Figure 3.  domain harnessing the principles of quantum mechanics
                                                              to execute computational tasks.  In contrast to classical
           2.1  Logistic Regression                           computers reliant on binary bits (0s and 1s), quantum
                                                              computers utilize quantum bits, or qubits. Qubits possess
           LR [14] as a tool for binary classification is a statistical  the unique ability to occupy multiple states simultaneously
           method. It approximates the probability that an input belongs  through superposition and entanglement phenomena, thereby
           to a categorical class using the logistic function, which is  empowering quantum computers to handle extensive data
           essentially a mapping between input features with the domain  volumes and execute specific calculations with remarkable
           (0, 1). The model learns the coefficients to yield the best  efficiency compared to classical counterparts. To define the
           fit, hence it can establish the relationship between input and  concept of quantum computing mathematically, Let H denote
           output given the data set. In terms of mathematics, the  the Hilbert space associated with the quantum computing
           probability of this prediction (  (x)) is given by  system.  A quantum computer operates by manipulating
                                     1                        qubits, which are represented as vectors in H. Each qubit can
                              (x) =                      (1)  be in a superposition of basis states, denoted by |0⟩ and |1⟩,
                                      −   x
                                          
                                  1 +   
                                                              where |0⟩ represents the state corresponding to the logical
           where    are coefficients, and x is the input vector. These
                                                              value 0, and |1⟩ represents the state corresponding to the
           coefficients are then optimized using methods such as
                                                              logical value 1.
           Maximum Likelihood Estimation, and the model is trained to
           accurately predict the output based on input variables.
                                                              3.1 Superpostion
           2.2 Support Vector Machine                         Quantum states can be represented as linear combinations
                                                              of basis states, allowing qubits to exist in a superposition of
           The SVM [15] is a supervised machine learning algorithm
                                                              states |  ⟩ =   |0⟩ +   |1⟩. Mathematically, for a single qubit
           designed to classify cases into two distinct classes.  In
                                                              |  ⟩, superposition is expressed as:
           binary classification, we have a dataset of    feature vectors x   
           and corresponding targets       together with labels, and SVM       |  ⟩ =   |0⟩ +   |1⟩         (4)
           aims to find the hyperplane represented by w and    which
           maximizes the margin between the classes. Here, let’s denote  where    and    are complex probability amplitudes satisfying
                                                                      2
                                                                2
           w as the weight vector,    for the bias, and x the input feature  |  | + |  | = 1, enabling the representation of both 0 and 1
           vector, formulated as -                            simultaneously.
                                  1    2
                              min ∥w∥                    (2)  3.2 Entanglement
                               w,   2
           that are to satisfy       (w · x    +   ) ≥ 1 for all   , and its decision  Entanglement  means  that  when  two  qubits  are
           function can be written as -                       correlated,regardless  of  their  physical  separation,one
                                                              qubit’s state depends on the other’s state. Mathematically,
                               (x) = |w · x +   |        (3)
                                                              for two qubits |  ⟩ an entangled state can be represented as:
           which, if    (x) ≥ 0, is the prediction of the class label for       1
           input x.                                                             √ (|00⟩ + |11⟩)             (5)
                                                                                 2
           2.3 Principal Component Analysis
                                                              3.3 Quantum Gates
           PCA [16] is a method for dimensionality reduction
                                                              Quantum gates are unitary operators that manipulate qubits
           and for visualising data, transforming original variables
                                                              to perform specific operations. Analogous to classical logic
           into orthogonal vectors called principal components, and
                                                              gates, quantum gates serve as the building blocks of quantum
           maximizing data variance.  Given an    ×    data matrix
                                                              algorithms. Mathematically, a quantum gate    operates on a
           X, PCA computes eigenvectors and eigenvalues of its
                                                                                ′
                                                              qubit |  ⟩ as   |  ⟩ = |   ⟩.
           covariance matrix. The first principal component, PC 1 , is
           the linear combination of variables maximizing variance,
                                                                    4.  QUANTUM MACHINE LEARNING
           with subsequent components PC 2 , PC 3 , . . . orthogonal to
           preceding ones, capturing remaining variance.  PCA’s
                                                              QML is a widening field of study where quantum computing
           essence lies in expressing data in terms of these components,
                                                              unites with machine learning.  In a nutshell, QML puts
           effectively reducing dimensionality while preserving the most
                                                              the properties/concepts of quantum mechanics into use to
           significant information.  Mathematically, PCA computes
                                                              design and invent new machine-learning algorithms with
           X pca = XV, where X pca contains principal component scores,
                                                              associated techniques. The classification techniques of QML
           V comprises eigenvectors, and X represents original data.
                                                              are depicted in Figure 4.
           .
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