Complexity theory Archives - IEEE Transactions on Quantum Engineering

Recursive Alternating Amplitude Embedding: A Hybrid Quantum Circuit Architecture for Balanced Depth and Width

October 6, 2026Agi Prasetiadi, Masahiro MamboEarly Access, Open AccessArchitecture, Circuits, Complexity theory, Computer architecture, Construction, Merging, Quantum state, Qubit, Trees (botanical), Vegetation

Abstract: Transforming classical data into quantum states is an important step in quantum information processing and quantum machine learning. Among various encoding methods, Amplitude Embedding is particularly attractive due to its exponential compression capability, allowing exponentially many classical values to be encoded using only a linear number of qubits. However, existing state preparation methods exhibit […]

Improved BP Decoding with Multiple Error-Path Detection for Topological Quantum Codes

October 2, 2026Jaemin Kim, Hyunwoo Jung, Jeongseok HaEarly Access, Open AccessChromium, Codes, Complexity theory, Copper, Decoding, Detectors, Error analysis, Poles and zeros, Table lookup, Vectors

Abstract: Topological quantum codes are promising candidates for realizing fault-tolerant quantum computing. In this context, belief propagation (BP) decoding is an efficient method for topological codes, offering high error-correction performance with low complexity. However, BP decoding suffers significant performance degradation due to quantum trapping sets (QTSs). Although various decoding schemes have been proposed to mitigate […]

Engineering minimal-complexity Clifford circuits controlled by microwaves via coherent phonon-mediated SiV− centers in diamond

May 26, 2026A. H. Homid, R. SalahEarly Access, Open AccessCircuits, Complexity theory, Diamond, Frequency, Joining processes, Phonons, Qubit, Silicon, Spinning, Timing

Abstract: Engineering quantum circuits that use minimal resource requirements is essential for suppressing noise-induced errors and enhancing the performance of quantum processors. Here, we propose minimal-complexity hardware constructions of Clifford circuits for implementing new two-qubit Clifford gates, effectively expanding the available Clifford circuit library. The circuits are realized through engineered coherent phonon-mediated interactions between two […]

Quantum-Assisted Optimization and Security for Trustworthy AI-Driven Healthcare

March 25, 2026Hafiz Muhammad Waseem, Gregory Epiphaniou, Carsten MapleOpen Access, Quantum InformationAccuracy, Artificial intelligence, Complexity theory, Decision making, Electronic healthcare, Genomics, Medical services, Optimization, Scalability, Security

Abstract: Digital health increasingly relies on artificial intelligence for clinical decision-making, patient management, and distributed learning, yet two persistent challenges remain: the computational complexity of optimization tasks, such as operating-room scheduling and genomic feature selection, and the need for robust security in federated and Internet-of-Medical-Things (IoMT) systems that are vulnerable to poisoning and spoofing attacks. […]

Beyond asymptotic scaling: Comparing functional quantum linear solvers

March 16, 2026Andreea-Iulia Lefterovici, Michael Perk, Debora Ramacciotti, Antonio F. Rotundo, S. E. Skelton, Martin SteinbachOpen Access, Quantum ComputingAccuracy, Approximation algorithms, Benchmark testing, Complexity theory, Costs, Hardware, Linear systems, Mathematical models, Quantum algorithm, Standards

Abstract: Solving systems of linear equations is a key subroutine in many quantum algorithms. In the last 15 years, many quantum linear solvers (QLS) have been developed, competing to achieve the best asymptotic worst-case complexity. Most QLS assume fault-tolerant quantum computers, so they cannot yet be benchmarked on real hardware. Because an algorithm with better […]

Improved Belief Propagation Decoding Algorithms for Surface Codes

June 6, 2025Jiahan Chen; Zhengzhong Yi; Zhipeng Liang; Xuan WangUncategorizedAccuracy, Belief propagation, Codes, Complexity theory, Error correction, Maximum likelihood decoding, Noise, Qubit, Silicon, Time complexity

Abstract: Quantum error correction is crucial for universal fault-tolerant quantum computing. Highly accurate and low-time-complexity decoding algorithms play an indispensable role in ensuring quantum error correction works effectively. Among existing decoding algorithms, belief propagation (BP) is notable for its nearly linear time complexity and general applicability to stabilizer codes. However, BP’s decoding accuracy without postprocessing […]

Q-Gen: A Parameterized Quantum Circuit Generator

May 20, 2025Yikai Mao; Shaswot Shresthamali; Masaaki KondoQuantum Software, UncategorizedComplexity theory, Computational modeling, Generators, Integrated circuit modeling, Logic gates, Quantum algorithm, Quantum circuit, Quantum computing, Quantum mechanics, Qubit

Abstract: Unlike most classical algorithms that take an input and give the solution directly as an output, quantum algorithms produce a quantum circuit that works as an indirect solution to computationally hard problems. In the full quantum computing workflow, most data processing remains in the classical domain except for running the quantum circuit in the […]

Mixed Grover: A Hybrid Version to Improve Grover’s Algorithm for Unstructured Database Search

March 28, 2025Romain Piron; Muhammad Idham Habibie; Claire GoursaudQuantum ComputingApproximation algorithms, Complexity theory, Costs, Databases, Flyback transformers, Optimization, Qubit, Registers, Search problems, Signal processing algorithms

Abstract: In this article, we propose a new strategy to exploit Grover’s algorithm for unstructured search problems. We first show that running Grover’s routine with a reduced number of iterations but allowing several trials presents a complexity advantage while keeping the same success probability. Then, by a theoretical analysis of the performance, we provide a […]

Two-Dimensional Beam Selection by Multiarmed Bandit Algorithm Based on a Quantum Walk

March 26, 2025Maki Arai, Tomoki Yamagami, Takatomo Mihana, Ryoichi Horisaki, Mikio HasegawaQuantum ComputingAntenna arrays, Antenna radiation patterns, Array signal processing, Channel capacity, Complexity theory, Location awareness, Massive MIMO, Probability distribution, Quantum computing, Training

Abstract: This article proposes a novel beam selection method using a multiarmed bandit (MAB) algorithm based on a quantum walk (QW) principle, aimed at improving system performance. A massive multiple-input multiple-output system, employing multiple high-gain beams within a high-frequency band, is indispensable for achieving large capacity in future wireless communications. However, as the number of […]

Two-Step Quantum Search Algorithm for Solving Traveling Salesman Problems

March 6, 2025Rei Sato, Cui Gordon, Kazuhiro Saito, Hideyuki Kawashima, Tetsuro Nikuni, Shohei WatabeQuantum ComputingComplexity theory, Costs, Encoding, Heuristic algorithms, Optimization, Quantum algorithm, Quantum circuit, Search problems, Traveling salesman problems, Urban areas

Quantum search algorithms, such as Grover’s algorithm, are anticipated to efficiently solve constrained combinatorial optimization problems. However, applying these algorithms to the traveling salesman problem (TSP) on a quantum circuit presents a significant challenge. Existing quantum search algorithms for the TSP typically assume that an initial state—an equal superposition of all feasible solutions satisfying the […]