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Many hybrid quantum-classical algorithms for the application of ground state energy estimation in quantum chemistry involve estimating the expectation value of a molecular Hamiltonian with respect to a quantum state through measurements on…

Determining the quantum-classical boundary between quantum circuits which can be efficiently simulated classically and those which cannot remains a fundamental question. One approach to classical simulation is to represent the output of a…

Quantum Physics · Physics 2026-05-06 Zejun Liu , Bryan K. Clark

The rapid development of quantum technology demands efficient characterization of complex quantum many-body states. However, full quantum state tomography requires an exponential number of measurements in system size, preventing its…

Quantum Physics · Physics 2024-12-04 Yadong Wu , Ce Wang , Juan Yao , Hui Zhai , Yi-Zhuang You , Pengfei Zhang

We provide and experimentally demonstrate an accreditation protocol that upper-bounds the variation distance between noisy and noiseless probability distributions of the outputs of arbitrary quantum computations. We accredit the outputs of…

Quantum Physics · Physics 2021-10-13 Samuele Ferracin , Seth T. Merkel , David McKay , Animesh Datta

Near term quantum computers with a high quantity (around 50) and quality (around 0.995 fidelity for two-qubit gates) of qubits will approximately sample from certain probability distributions beyond the capabilities of known classical…

Quantum Physics · Physics 2018-01-23 Sergio Boixo , Sergei V. Isakov , Vadim N. Smelyanskiy , Hartmut Neven

Scalable characterization of quantum processors is crucial for mitigating noise and imperfections. While randomized measurement protocols enable efficient access to local observables, inferring a globally consistent description of…

Quantum Physics · Physics 2026-03-10 Zidu Liu , Dominik S. Wild

Achieving chemical accuracy with shallow quantum circuits is a significant challenge in quantum computational chemistry, particularly for near-term quantum devices. In this work, we present a Clifford-based Hamiltonian engineering…

Quantum Physics · Physics 2024-01-09 Jiace Sun , Lixue Cheng , Weitang Li

We present the generalization of the CNC formalism, based on closed and noncontextual sets of Pauli observables, to the setting of odd-prime-dimensional qudits. By introducing new CNC-type phase space point operators, we construct a…

Quantum Physics · Physics 2024-07-16 Michael Zurel , Arne Heimendahl

Quantum computers can efficiently simulate Lindbladian dynamics, enabling powerful applications in open system simulation, thermal and ground-state preparation, autonomous quantum error correction, dissipative engineering, and more. Despite…

Quantum Physics · Physics 2025-10-20 Wenjun Yu , Xiaogang Li , Qi Zhao , Xiao Yuan

The Gottesman-Knill theorem asserts that a quantum circuit composed of Clifford gates can be efficiently simulated on a classical computer. Here we revisit this theorem and extend it to quantum circuits composed of Clifford and T gates,…

Quantum Physics · Physics 2019-04-11 Sergey Bravyi , David Gosset

A defining feature in the field of quantum computing is the potential of a quantum device to outperform its classical counterpart for a specific computational task. By now, several proposals exist showing that certain sampling problems can…

Quantum Physics · Physics 2020-09-23 Rawad Mezher , Joe Ghalbouni , Joseph Dgheim , Damian Markham

A major challenge in developing quantum computing technologies is to accomplish high precision tasks by utilizing multiplex optimization approaches, on both the physical system and algorithm levels. Loss functions assessing the overall…

Quantum Physics · Physics 2021-03-03 Zhen Wang , Yanzhu Chen , Zixuan Song , Dayue Qin , Hekang Li , Qiujiang Guo , H. Wang , Chao Song , Ying Li

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

In a recent work a quantum error mitigation protocol was applied to the expectation values obtained from circuits on the IBM Eagle quantum processor with up $127$ - qubits with up to $60 \; - \; \mbox{CNOT}$ layers. To benchmark the…

Quantum Physics · Physics 2023-07-03 Sajant Anand , Kristan Temme , Abhinav Kandala , Michael Zaletel

We construct a pairwise measurement-based code on eight qubits that is error correcting for circuit noise, with fault distance 3. The code can be implemented on a subset of a rectangular array of qubits with nearest neighbor connectivity of…

Quantum Physics · Physics 2024-09-23 Linnea Grans-Samuelsson , David Aasen , Parsa Bonderson

Measuring the expectation value of Pauli operators on prepared quantum states is a fundamental task in a multitude of quantum algorithms. Simultaneously measuring sets of operators allows for fewer measurements and an overall speedup of the…

Quantum Physics · Physics 2019-07-19 Andrew Jena , Scott Genin , Michele Mosca

We construct a polynomial-time classical algorithm that samples from the output distribution of noisy geometrically local Clifford circuits with any product-state input and single-qubit measurements in any basis. Our results apply to…

Quantum Physics · Physics 2026-01-09 Jon Nelson , Joel Rajakumar , Dominik Hangleiter , Michael J. Gullans

Scrambling of quantum information is an important feature at the root of randomization and benchmarking protocols, the onset of quantum chaos, and black-hole physics. Unscrambling this information is possible given perfect knowledge of the…

Quantum Physics · Physics 2024-03-06 Lorenzo Leone , Salvatore F. E. Oliviero , Seth Lloyd , Alioscia Hamma

To address the challenge posed by noise in real quantum devices, quantum error mitigation techniques play a crucial role. These techniques are resource-efficient, making them suitable for implementation in noisy intermediate-scale quantum…

Quantum Physics · Physics 2024-11-26 Jordi Pérez-Guijarro , Alba Pagès-Zamora , Javier R. Fonollosa

We consider the problem of jointly estimating expectation values of many Pauli observables, a crucial subroutine in variational quantum algorithms. Starting with randomized measurements, we propose an efficient derandomization procedure…

Quantum Physics · Physics 2021-07-21 Hsin-Yuan Huang , Richard Kueng , John Preskill
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