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In the fields of quantum mechanics and quantum information science, the traces of reduced density matrix powers play a crucial role in the study of quantum systems and have numerous important applications. In this paper, we propose a…

Quantum Physics · Physics 2025-07-24 Rui-Qi Zhang , Xiao-Qi Liu , Jing Wang , Ming Li , Shu-Qian Shen , Shao-Ming Fei

Although quantum circuit depth is commonly used to approximate circuit runtimes, it overlooks a prevailing trait of current hardware implementation: different gates have different execution times. Recognizing the potential for…

Quantum Physics · Physics 2025-09-17 Matthew Tremba , Paul Hovland , Ji Liu

Efficient and high-performance quantum error correction is essential for achieving fault-tolerant quantum computing. Low-depth random circuits offer a promising approach to identifying effective and practical encoding strategies. In this…

Quantum Physics · Physics 2026-03-02 Guoding Liu , Zhenyu Du , Zi-Wen Liu , Xiongfeng Ma

The hope of the quantum computing field is that quantum architectures are able to scale up and realize fault-tolerant quantum computing. Due to engineering challenges, such ''cheap'' error correction may be decades away. In the meantime, we…

Quantum Physics · Physics 2025-02-17 Rutuja Kshirsagar , Amara Katabarwa , Peter D. Johnson

We study a classical model for the accumulation of errors in multi-qubit quantum computations. By modeling the error process in a quantum computation using two coupled Markov chains, we are able to capture a weak form of time-dependency…

Quantum Physics · Physics 2021-04-26 Long Ma , Jaron Sanders

Improving over an earlier construction by Kaye and Zalka, Maslov et al. describe an implementation of Shor's algorithm which can solve the discrete logarithm problem on binary elliptic curves in quadratic depth O(n^2). In this paper we show…

Quantum Physics · Physics 2013-11-15 Martin Roetteler , Rainer Steinwandt

Quantum phase estimation plays a central role in quantum simulation as it enables the study of spectral properties of many-body quantum systems. Most variants of the phase estimation algorithm require the application of the global unitary…

Reversible circuits for modular multiplication $Cx$%$M$ with $x<M$ arise as components of modular exponentiation in Shor's quantum number-factoring algorithm. However, existing generic constructions focus on asymptotic gate count and…

Emerging Technologies · Computer Science 2015-04-06 Igor L. Markov , Mehdi Saeedi

Accurate and robust quantum process tomography (QPT) is crucial for verifying quantum gates and diagnosing implementation faults in experiments aimed at building universal quantum computers. However, the reliability of QPT protocols is…

Accurate and precise control of large quantum systems is paramount to achieve practical advantages on quantum devices. Therefore, benchmarking the hardware errors in quantum computers has drawn significant attention lately. Existing…

Quantum Physics · Physics 2023-01-18 Bharath Hebbe Madhusudhana

We introduce a single-number metric, quantum volume, that can be measured using a concrete protocol on near-term quantum computers of modest size ($n\lesssim 50$), and measure it on several state-of-the-art transmon devices, finding values…

Quantum Physics · Physics 2019-10-14 Andrew W. Cross , Lev S. Bishop , Sarah Sheldon , Paul D. Nation , Jay M. Gambetta

Accurate methods of assessing the performance of quantum gates are extremely important. Quantum process tomography and randomized benchmarking are the current favored methods. Quantum process tomography gives detailed information, but…

Quantum Physics · Physics 2014-05-08 Austin G. Fowler , D. Sank , J. Kelly , R. Barends , John M. Martinis

Quantum circuit simulation provides the foundation for the development of quantum algorithms and the verification of quantum supremacy. Among the various methods for quantum circuit simulation, tensor network contraction has been increasing…

Quantum Physics · Physics 2023-07-11 Hiroyuki Ootomo , Hidetaka Manabe , Kenji Harada , Rio Yokota

Predicting properties of large-scale quantum systems is crucial for the development of quantum science and technology. Shadow estimation is an efficient method for this task based on randomized measurements, where many-qubit random Clifford…

Quantum Physics · Physics 2024-04-24 Qingyue Zhang , Qing Liu , You Zhou

Quantum process tomography is an experimental technique to fully characterize an unknown quantum process. Standard quantum process tomography suffers from exponentially scaling of the number of measurements with the increasing system size.…

Quantum Physics · Physics 2022-08-02 Shichuan Xue , Yong Liu , Yang Wang , Pingyu Zhu , Chu Guo , Junjie Wu

Current approaches to fault-tolerant quantum computation will not enable useful quantum computation on near-term devices of 50 to 100 qubits. Leading proposals, such as the color code and surface code schemes, must devote a large fraction…

Quantum Physics · Physics 2017-11-08 Peter D. Johnson , Jonathan Romero , Jonathan Olson , Yudong Cao , Alán Aspuru-Guzik

We give new bounds on the circuit complexity of the quantum Fourier transform (QFT). We give an upper bound of O(log n + log log (1/epsilon)) on the circuit depth for computing an approximation of the QFT with respect to the modulus 2^n…

Quantum Physics · Physics 2007-05-23 Richard Cleve , John Watrous

Quantum process tomography is a procedure by which the unknown dynamical evolution of an open quantum system can be fully experimentally characterized. We demonstrate explicitly how this procedure can be implemented with a nuclear magnetic…

Quantum Physics · Physics 2007-05-23 Andrew M. Childs , Isaac L. Chuang , Debbie W. Leung

A milestone in the field of quantum computing will be solving problems in quantum chemistry and materials faster than state-of-the-art classical methods. The current understanding is that achieving quantum advantage in this area will…

Quantum Physics · Physics 2023-11-08 Guoming Wang , Daniel Stilck França , Ruizhe Zhang , Shuchen Zhu , Peter D. Johnson

Dynamic simulation of materials is a promising application for near-term quantum computers. Current algorithms for Hamiltonian simulation, however, produce circuits that grow in depth with increasing simulation time, limiting feasible…

Quantum Physics · Physics 2022-03-10 Lindsay Bassman , Roel Van Beeumen , Ed Younis , Ethan Smith , Costin Iancu , Wibe A. de Jong