Abstract In this work, we present quantum random forest prediction circuits for binary and multiclass classification problems and their gate complexities. Gate complexity is defined as the number of elementary one- and two-qubit gates. The presented prediction algorithm requires fewer elementary gates than the general upper bound.
In this work, we present a quantum circuit for a binary classification prediction algorithm using a random forest model. The quantum prediction algorithm is presented in our previous works. We construct a circuit and implement it using qiskit tools (python module for quantum programming). One of our goals is reducing the number of basic quantum gates (elementary gates). The set of basic quantum gates which we use in this work consists of single-qubit gates and a controlled NOT gate. The number of CNOT gates in our circuit is estimated by O(2n+2h+1) , when trivial circuit decomposition techniques give O(4∣X∣+n+h+2) CNOT gates, where n is the number of trees in a random forest model, h is a tree height and ∣X∣ is the length of attributes of an input object X . The prediction process returns an index of the corresponding class for the input X .
This study investigates the application of machine learning techniques for predicting gate depth in quantum computational systems, focusing on the relationship between quantum circuit parameters and computational performance. Using a dataset of 50 observations encompassing qubit count, gate depth, entanglement rate, and logical error rate, we developed and compared Linear Regression (LR) and Random Forest Regression (RFR) models for gate depth prediction. The research addresses critical challenges in quantum fault tolerance and circuit optimization, which are essential for achieving scalable quantum computation. Our analysis revealed strong negative correlation (-0.65) between qubit count and logical error rate, while gate depth showed moderate positive correlation (0.62) with error rates. The Random Forest model demonstrated superior performance with R² values of 0.96068 on training data and 0.87262 on testing data, significantly outperforming Linear Regression (R²: 0.87552 training, 0.60257 testing). Error metrics further confirmed RFR's superiority, achieving RMSE of 2.33 (training) and 2.97 (testing) compared to LR's 4.15 and 5.25 respectively. The study highlights the importance of quantum error correction mechanisms and the inherent trade-offs between circuit complexity and computational reliability. Both models showed expected performance degradation from training to testing, with RFR maintaining better generalization capabilities. These findings contribute to the development of typed models for quantum mechanics in computational applications, offering insights into quantum circuit optimization and fault-tolerant design. The research demonstrates that ensemble methods like Random Forest provide more robust predictions for quantum system parameters, supporting the advancement of practical quantum computing implementations and algorithm development. KeyWords: Quantum Computation, Gate Depth Prediction, Random Forest Regression, Quantum Error Correction, Machine Learning, Fault Tolerance.
In this work, we conducted an experiment on a quantum simulator for tasks of binary classification by the random forest method, estimated the time the complexity of the classical and quantum versions of the algorithms, as well as memory complexity of the algorithm for the quantum version. Previously we received temporal acceleration of the algorithm for prediction by using quantum amplitude amplification algorithm, and now tested the algorithm proposed by us on our quantum simulator and analyzed the predictive results.
For pure three-qubit states the classification of entanglement is both non-trivial and well understood. In this work, we study the quantum algorithmic complexity introduced in [1] of three-qubit pure states belonging to the most general class of entanglement. Contrary to expectations we find out that the degree of entanglement of states in this class quantified by the measure of 3-tangle, does not correlate with the quantum algorithmic complexity, defined as the length of the shortest circuit needed to prepare the state. For a given entangled state the evaluation of its quantum complexity is done via a pseudo random evolutionary algorithm. This algorithm allows us not only to determine the complexity of a quantum circuit in terms of the number of required quantum gates, but also to estimate another type of complexity related to the time required to obtain the correct answer.