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We present a scalable, robust approach to creating quantum programs of arbitrary size and complexity. The approach is based on the true abstraction of the problem. The quantum program is expressed in terms of a high-level model together…

While variational quantum algorithms (VQAs) have demonstrated considerable success in unconstrained optimization, their application to constrained combinatorial problems face a trade-off. Penalty-based methods, despite their circuit…

Quantum Physics · Physics 2026-03-09 Hui-Min Li , Yuan-Liang Han , Zhi-Xi Wang , Shao-Ming Fei

An algorithm is proposed to convert arbitrary unitary matrix to a sequence of $X$ gates and fully controlled $R_y, R_z$ and $R_1$ gates. This algorithm is used to generate Q# implementation for arbitrary unitary matrix. Some optimizations…

Quantum Physics · Physics 2025-01-15 Dmytro Fedoriaka

The characterization of a unitary gate is experimentally accomplished via Quantum Process Tomography, which combines the outcomes of different projective measurements to reconstruct the underlying operator. The process matrix is typically…

Quantum Physics · Physics 2025-09-17 Tareq Jaouni , Francesco Di Colandrea , Lorenzo Amato , Filippo Cardano , Ebrahim Karimi

We propose novel methods for the exact synthesis of single-qubit unitaries with high success probability and gate fidelity, considering both time-bin and frequency-bin encodings. The proposed schemes are experimentally implementable with a…

We prove a new lower bound for the unitary synthesis problem in the so-called 1.5-query setting. Our analysis establishes that any attempt to implement arbitrary n-qubit unitaries via limited oracle access requires resources that exceed the…

Quantum Physics · Physics 2025-08-22 Eric Huang

We present a method that outputs a sequence of simple unitary operations to prepare a given quantum state that is a generalized coherent state. Our method takes as inputs the expectation values of some relevant observables on the state to…

Quantum Physics · Physics 2020-01-08 Rolando D. Somma

In this paper, we demonstrate that optimal control algorithms can be used to speed up the implementation of modules of quantum algorithms or quantum simulations in networks of coupled qubits. The gain is most prominent in realistic cases,…

Quantum Physics · Physics 2008-12-20 T. Schulte-Herbrueggen , A. K. Spoerl , N. Khaneja , S. J. Glaser

We establish connections between state tomography, pseudorandomness, quantum state synthesis, and circuit lower bounds. In particular, let $\mathfrak{C}$ be a family of non-uniform quantum circuits of polynomial size and suppose that there…

Quantum Physics · Physics 2025-09-26 Nai-Hui Chia , Daniel Liang , Fang Song

High-fidelity and robust quantum manipulation is the key for scalable quantum computation. Therefore, due to the intrinsic operational robustness, quantum manipulation induced by geometric phases is one of the promising candidates. However,…

Quantum Physics · Physics 2020-09-23 Tao Chen , Pu Shen , Zheng-Yuan Xue

Quantum machine learning has shown promise for high-dimensional data analysis, yet many existing approaches rely on linear unitary operations and shared trainable parameters across outputs. These constraints limit expressivity and…

Quantum Physics · Physics 2026-02-17 Viktoria Patapovich , Maniraman Periyasamy , Mo Kordzanganeh , Alexey Melnikov

Quantum circuits are time dependent diagrams describing the process of quantum computation. Usually, a quantum algorithm must be mapped into a quantum circuit. Optimal synthesis of quantum circuits is intractable and heuristic methods must…

Quantum Physics · Physics 2008-02-27 D. Maslov , G. W. Dueck , D. M. Miller , C. Negrevergne

Construction of explicit quantum circuits follows the notion of the "standard circuit model" introduced in the solid and profound analysis of elementary gates providing quantum computation. Nevertheless the model is not always optimal (e.g.…

Quantum Physics · Physics 2007-05-23 K. Ch. Chatzisavvas , C. Daskaloyannis , C. P. Panos

The development of quantum control methods is an essential task for emerging quantum technologies. In general, the process of optimizing quantum controls scales very unfavorably in system size due to the exponential growth of the Hilbert…

Quantum Physics · Physics 2019-10-07 Jun Li

Quantum machine learning with quantum kernels for classification problems is a growing area of research. Recently, quantum kernel alignment techniques that parameterise the kernel have been developed, allowing the kernel to be trained and…

Unitary operations are the building blocks of quantum programs. Our task is to design effcient or optimal implementations of these unitary operations by employing the intrinsic physical resources of a given n-qubit system. The most common…

Quantum Physics · Physics 2007-05-23 Robert Zeier , Markus Grassl , Thomas Beth

As quantum computing technology advances, the complexity of quantum algorithms increases, necessitating a shift from low-level circuit descriptions to high-level programming paradigms. This paper addresses the challenges of developing a…

Quantum Physics · Physics 2025-03-04 Israel Reichental , Ravid Alon , Lior Preminger , Matan Vax , Amir Naveh

The creation of composite quantum gates that implement quantum response functions $\hat{U}(\theta)$ dependent on some parameter of interest $\theta$ is often more of an art than a science. Through inspired design, a sequence of $L$…

Quantum Physics · Physics 2018-02-02 Guang Hao Low , Theodore J. Yoder , Isaac L. Chuang

In this paper, we study time-optimal control problems related to system of two coupled qubits where the time scales involved in performing unitary transformations on each qubit are significantly different. In particular, we address the case…

Quantum Physics · Physics 2009-11-13 Robert Zeier , Haidong Yuan , Navin Khaneja

Simulating molecular systems on quantum processors has the potential to surpass classical methods in computational resource efficiency. The limited qubit connectivity, small processor size, and short coherence times of near-term quantum…

Quantum Physics · Physics 2025-04-08 Abhishek Sadhu , Aritra Sarkar , Akash Kundu