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Variational Quantum Algorithms are among the most promising systems to implement quantum computing under the Noisy-Intermediate Scale Quantum (NISQ) technology. In variational quantum algorithm, wavefunction represented by a parametrized…

Quantum Physics · Physics 2023-01-02 H. Davoodi Yeganeh

Quantum error mitigation (QEM) is crucial for obtaining reliable results on quantum computers by suppressing quantum noise with moderate resources. It is a key factor for successful and practical quantum algorithm implementations in the…

Quantum Physics · Physics 2023-08-28 Shi-Xin Zhang , Zhou-Quan Wan , Chang-Yu Hsieh , Hong Yao , Shengyu Zhang

We outline a proposal to test quantum mechanics in the high-complexity regime using noisy intermediate-scale quantum (NISQ) devices. The procedure involves simulating a non-Clifford random circuit, followed by its inverse, and then checking…

Quantum Physics · Physics 2022-08-26 Kevin Slagle

Variational quantum circuits build the foundation for various classes of quantum algorithms. In a nutshell, the weights of a parametrized quantum circuit are varied until the empirical sampling distribution of the circuit is sufficiently…

Variational quantum algorithms (VQAs) are expected to become a practical application of near-term noisy quantum computers. Although the effect of the noise crucially determines whether a VQA works or not, the heuristic nature of VQAs makes…

Quantum Physics · Physics 2023-05-02 Kosuke Ito , Wataru Mizukami , Keisuke Fujii

Near-term quantum devices generally suffer from shallow circuit depth and hence limited expressivity due to noise and decoherence. To address this, we propose tensor-network-assisted parametrized quantum circuits, which concatenate a…

Quantum Physics · Physics 2023-12-01 Junxiang Huang , Wenhao He , Yukun Zhang , Yusen Wu , Bujiao Wu , Xiao Yuan

Quantum variational algorithms have garnered significant interest recently, due to their feasibility of being implemented and tested on noisy intermediate scale quantum (NISQ) devices. We examine the robustness of the quantum approximate…

Quantum Physics · Physics 2019-11-05 Yulong Dong , Xiang Meng , Lin Lin , Robert Kosut , K. Birgitta Whaley

Computational quantum technologies are entering a new phase in which noisy intermediate-scale quantum computers are available, but are still too small to benefit from active error correction. Even with a finite coherence budget to invest in…

Quantum Physics · Physics 2019-12-13 G. G. Guerreschi , A. Y. Matsuura

Noise on near-term quantum devices will inevitably limit the performance of Quantum Approximate Optimization Algorithm (QAOA). One significant consequence is that the performance of QAOA may fail to monotonically improve with depth. In…

Quantum Physics · Physics 2022-07-12 Yu Pan , Yifan Tong , Shibei Xue , Guofeng Zhang

Fighting against noise is crucial for NISQ devices to demonstrate practical quantum applications. In this work, we give a new paradigm of quantum error mitigation based on the vectorization of density matrices. Different from the ideas of…

Quantum Physics · Physics 2024-07-22 Zhong-Xia Shang , Zi-Han Chen , Cai-Sheng Cheng

Extracting useful information from noisy near-term quantum simulations requires error mitigation strategies. A broad class of these strategies rely on precise characterization of the noise source. We study the robustness of probabilistic…

Quantum Physics · Physics 2025-07-28 Pradeep Niroula , Sarang Gopalakrishnan , Michael J. Gullans

This study introduces a hybrid quantum-classical dispatching framework designed for power systems with high renewable penetration. The proposed method integrates a variational quantum algorithm with classical optimization to provide…

Quantum Physics · Physics 2026-01-27 Fu Zhang , Yuming Zhao

In the noisy intermediate-scale quantum era, emerging classical-quantum hybrid optimization algorithms, such as variational quantum algorithms (VQAs), can leverage the unique characteristics of quantum devices to accelerate computations…

There is increasing interest in the development of gate-based quantum circuits for the training of machine learning models. Yet, little is understood concerning the parameters of circuit design, and the effects of noise and other…

Quantum Physics · Physics 2021-12-14 Patrick Selig , Niall Murphy , Ashwin Sundareswaran R , David Redmond , Simon Caton

The present era of quantum processors with hundreds to thousands of noisy qubits has sparked interest in understanding the computational power of these devices and how to leverage it to solve practically relevant problems. For applications…

Quantum Physics · Physics 2026-04-15 Victor Martinez , Omar Fawzi , Daniel Stilck França

Variational hybrid quantum-classical algorithms (VHQCAs) are near-term algorithms that leverage classical optimization to minimize a cost function, which is efficiently evaluated on a quantum computer. Recently VHQCAs have been proposed for…

Quantum Physics · Physics 2020-04-07 Kunal Sharma , Sumeet Khatri , M. Cerezo , Patrick J. Coles

Variational Quantum Algorithms (VQAs), such as the Quantum Approximate Optimization Algorithm (QAOA) of [Farhi, Goldstone, Gutmann, 2014], have seen intense study towards near-term applications on quantum hardware. A crucial parameter for…

Quantum Physics · Physics 2023-07-12 Lennart Bittel , Sevag Gharibian , Martin Kliesch

The quantum approximate optimization algorithm (QAOA) is widely seen as a possible usage of noisy intermediate-scale quantum (NISQ) devices. We analyze the algorithm as a bang-bang protocol with fixed total time and a randomized greedy…

Quantum Physics · Physics 2020-09-16 Daniel Liang , Li Li , Stefan Leichenauer

Variational quantum algorithms, which consist of optimal parameterized quantum circuits, are promising for demonstrating quantum advantages in the noisy intermediate-scale quantum (NISQ) era. Apart from classical computational resources,…

Quantum Physics · Physics 2024-12-30 Chen Qian , Wei-Feng Zhuang , Rui-Cheng Guo , Meng-Jun Hu , Dong E. Liu

We study the properties of output distributions of noisy, random circuits. We obtain upper and lower bounds on the expected distance of the output distribution from the "useless" uniform distribution. These bounds are tight with respect to…