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We apply numerical optimization and linear algebra algorithms for classical computers to the problem of automatically synthesizing algorithms for quantum computers. Using our framework, we apply several common techniques from these…

Numerical Analysis · Mathematics 2025-09-16 Yuxin Huang , Benjamin E. Grossman-Ponemon , David A. B. Hyde

Heisenberg spin chains can act as quantum wires transferring quantum states either perfectly or with high fidelity. Gaussian packets of excitations passing through dual rails can encode the two states of a logical qubit, depending on which…

Quantum Physics · Physics 2016-07-06 Sahand Seifnashri , Farzad Keyanvash , Jahangir Nobakht , Vahid Karimipour

This work presents an optimization-based scalable quantum neural network framework for approximating $n$-qubit unitaries through generic parametric representation of unitaries, which are obtained as product of exponential of basis elements…

Quantum Physics · Physics 2024-01-17 Rohit Sarma Sarkar , Bibhas Adhikari

Recently, it is shown that quantum computers can be used for obtaining certain information about the solution of a linear system Ax=b exponentially faster than what is possible with classical computation. Here we first review some key…

Quantum Physics · Physics 2015-05-30 Yudong Cao , Anmer Daskin , Steven Frankel , Sabre Kais

We introduce Quantum Graph Neural Networks (QGNN), a new class of quantum neural network ansatze which are tailored to represent quantum processes which have a graph structure, and are particularly suitable to be executed on distributed…

This paper introduces quantum circuit $C^*$-algebra net, which provides a connection between $C^*$-algebra nets proposed in classical machine learning and quantum circuits. Using $C^*$-algebra, a generalization of the space of complex…

Machine Learning · Computer Science 2024-04-10 Yuka Hashimoto , Ryuichiro Hataya

Optimization of circuits is an essential task for both quantum and classical computers to improve their efficiency. In contrast, classical logic optimization is known to be difficult, and a lot of heuristic approaches have been developed so…

Quantum Physics · Physics 2025-05-14 Yusei Mori , Hideaki Hakoshima , Kyohei Sudo , Toshio Mori , Kosuke Mitarai , Keisuke Fujii

We show that $n$-bit integers can be factorized by independently running a quantum circuit with $\tilde{O}(n^{3/2})$ gates for $\sqrt{n}+4$ times, and then using polynomial-time classical post-processing. The correctness of the algorithm…

Quantum Physics · Physics 2024-01-09 Oded Regev

Quantum circuit design is a key bottleneck for practical quantum machine learning on complex, real-world data. We present an automated framework that discovers and refines variational quantum circuits (VQCs) using graph-based Bayesian…

Quantum Physics · Physics 2025-12-11 Prashant Kumar Choudhary , Nouhaila Innan , Muhammad Shafique , Rajeev Singh

Encoding classical data into quantum states is a central bottleneck in quantum machine learning: many widely used encodings are circuit-inefficient, requiring deep circuits and substantial quantum resources, which limits scalability on…

Quantum Physics · Physics 2026-02-19 Guang Lin , Toshihisa Tanaka , Qibin Zhao

One of the main challenges in the Variational Quantum Eigensolver (VQE) framework is construction of the unitary transformation. The dimensionality of the space for unitary rotations of $N$ qubits is $4^N-1$, which makes the choice of a…

Quantum Physics · Physics 2021-12-21 Artur F. Izmaylov , Manuel Díaz-Tinoco , Robert A. Lang

Algorithms with unitary oracles can be nested, which makes them extremely versatile. An example is the phase estimation algorithm used in many candidate algorithms for quantum speed-up. The search for new quantum algorithms benefits from…

Quantum Physics · Physics 2024-04-01 Zuzana Gavorová , Matan Seidel , Yonathan Touati

This paper examines the use of Quantized Neural Networks (QNNs) for two resource-constrained scientific applications: automated calibration of semi-conductor quantum bits (qubits) and scientific particle detectors. We evaluate the…

Algorithms based on non-unitary evolution have attracted much interest for ground state preparation on quantum computers. One recently proposed method makes use of ancilla qubits and controlled unitary operators to implement weak…

Quantum Physics · Physics 2025-12-25 Tobias Stollenwerk , Stuart Hadfield

Quantum machine learning is considered one of the flagship applications of quantum computers, where variational quantum circuits could be the leading paradigm both in the near-term quantum devices and the early fault-tolerant quantum…

Quantum Physics · Physics 2024-12-17 Yuqing Li , Jinglei Cheng , Xulong Tang , Youtao Zhang , Frederic T. Chong , Junyu Liu

We present a simple algorithm that implements an arbitrary $n$-qubit unitary operator using a Clifford+T circuit with T-count $O(2^{4n/3} n^{2/3})$. This improves upon the previous best known upper bound of $O(2^{3n/2} n)$, while the best…

Quantum Physics · Physics 2025-10-01 Xinyu Tan

Given a quantum gate implementing a $d$-dimensional unitary operation $U_d$, without any specific description but $d$, and permitted to use $k$ times, we present a universal probabilistic heralded quantum circuit that implements the exact…

Quantum Physics · Physics 2020-04-16 Marco Túlio Quintino , Qingxiuxiong Dong , Atsushi Shimbo , Akihito Soeda , Mio Murao

Let $U_d$ be a unitary operator representing an arbitrary $d$-dimensional unitary quantum operation. This work presents optimal quantum circuits for transforming a number $k$ of calls of $U_d$ into its complex conjugate $\bar{U_d}$. Our…

We attempt the use of a unitary operator to approximate the lattice Boltzmann collision operator. We use a modified amplitude encoding to bypass the renormalization that would have required classical processing at every step (thus eroding…

Quantum Physics · Physics 2026-01-08 Wael Itani , Katepalli R. Sreenivasan

Some fast algorithms for computing the eigenvalues of a block companion matrix $A = U + XY^H$, where $U\in \mathbb C^{n\times n}$ is unitary block circulant and $X, Y \in\mathbb{C}^{n \times k}$, have recently appeared in the literature.…

Numerical Analysis · Mathematics 2019-08-30 Roberto Bevilacqua , Gianna M. Del Corso , Luca Gemignani