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To successfully perform quantum computations, it is often necessary to first accurately characterize the noise in the underlying hardware. However, it is well known that fundamental limitations prevent the unique identification of the…

Randomized benchmarking (RB) is the gold standard for experimentally evaluating the quality of quantum operations. The current framework for RB is centered on groups and their representations, but this can be problematic. For example,…

Quantum Physics · Physics 2022-12-22 Jianxin Chen , Dawei Ding , Cupjin Huang

We provide a purely quantum version of polar codes, achieving the symmetric coherent information of any qubit-input quantum channel. Our scheme relies on a recursive channel combining and splitting construction, where a two-qubit gate…

Quantum Physics · Physics 2021-05-04 Frédéric Dupuis , Ashutosh Goswami , Mehdi Mhalla , Valentin Savin

Fault-tolerant quantum error correction provides a strategy to protect information processed by a quantum computer against noise which would otherwise corrupt the data. A fault-tolerant universal quantum computer must implement a universal…

Accurate benchmarking of quantum gates is crucial for understanding and enhancing the performance of quantum hardware. A standard method for this is interleaved benchmarking, a technique which estimates the error on an interleaved target…

We study how much noise can be tolerated by a universal gate set before it loses its quantum-computational power. Specifically we look at circuits with perfect stabilizer operations in addition to imperfect non-stabilizer gates. We prove…

Quantum Physics · Physics 2009-12-24 Wim van Dam , Mark Howard

We describe a scalable experimental protocol for obtaining estimates of the error rate of individual quantum computational gates. This protocol, in which random Clifford gates are interleaved between a gate of interest, provides a bounded…

Coherent noise can be much more damaging than incoherent (probabilistic) noise in the context of quantum error correction. One solution is to use twirling to turn coherent noise into incoherent Pauli channels. In this Article, we show that…

Quantum Physics · Physics 2020-06-30 Zhenyu Cai , Xiaosi Xu , Simon C. Benjamin

We develop a family of quantum accreditation protocols for quantum circuits with non-Clifford two-qubit gates. The latter includes families of gates such as the fSim and XY families of gates, native to existing hardwares. We provide…

Quantum Physics · Physics 2026-05-20 Andrew Jackson , Theodoros Kapourniotis , Animesh Datta

Randomized benchmarking (RB) protocols are the most widely used methods for assessing the performance of quantum gates. However, the existing RB methods either do not scale to many qubits or cannot benchmark a universal gate set. Here, we…

Quantum error mitigation techniques mimic noiseless quantum circuits by running several related noisy circuits and combining their outputs in particular ways. How well such techniques work is thought to depend strongly on how noisy the…

Quantum Physics · Physics 2026-02-12 David Layden , Bradley Mitchell , Karthik Siva

Quantum computers have enabled solving problems beyond the current computers' capabilities. However, this requires handling noise arising from unwanted interactions in these systems. Several protocols have been proposed to address efficient…

Quantum Physics · Physics 2021-09-14 Ali Shaib , Mohamad H. Naim , Mohammed E. Fouda , Rouwaida Kanj , Fadi Kurdahi

The classical simulation of quantum circuits is of central importance for benchmarking near-term quantum devices. The fact that gates belonging to the Clifford group can be simulated efficiently on classical computers has motivated a range…

Quantum Physics · Physics 2023-07-12 Tomislav Begušić , Kasra Hejazi , Garnet Kin-Lic Chan

When visualised as an operation on the Bloch sphere, the qubit "pi-over-eight" gate corresponds to one-eighth of a complete rotation about the vertical axis. This simple gate often plays an important role in quantum information theory,…

Quantum Physics · Physics 2012-08-17 Mark Howard , Jiri Vala

For random quantum circuits on $n$ qubits of depth $\Theta(\log n)$ with depolarizing noise, the task of sampling from the output state can be efficiently performed classically using a Pauli path method [Aharonov et al. Proceedings of the…

Quantum Physics · Physics 2025-05-07 Guillermo González-García , J. Ignacio Cirac , Rahul Trivedi

We investigate the amount of noise required to turn a universal quantum gate set into one that can be efficiently modelled classically. This question is useful for providing upper bounds on fault tolerant thresholds, and for understanding…

Quantum Physics · Physics 2007-05-23 S. Virmani , Susana F. Huelga , Martin B. Plenio

Randomized benchmarking is a powerful technique to efficiently estimate the performance and reliability of quantum gates, circuits and devices. Here we propose to perform randomized benchmarking in a coherent way, where superpositions of…

Quantum Physics · Physics 2021-07-14 Jorge Miguel-Ramiro , Alexander Pirker , Wolfgang Dür

We investigate randomized benchmarking in a general setting with quantum gates that form a representation, not necessarily an irreducible one, of a finite group. We derive an estimate for the average fidelity, to which experimental data may…

Quantum Physics · Physics 2019-01-23 Daniel Stilck França , Anna-Lena Hashagen

Randomized benchmarking provides a tool for obtaining precise quantitative estimates of the average error rate of a physical quantum channel. Here we define real randomized benchmarking, which enables a separate determination of the average…

Quantum Physics · Physics 2018-08-23 A. K. Hashagen , S. T. Flammia , D. Gross , J. J. Wallman

Hamiltonian simulation is a key quantum algorithm for modeling complex systems. To implement a Hamiltonian simulation, it is typically decomposed into a list of Pauli strings, each corresponds to an RZ rotation gate with many Clifford…

Quantum Physics · Physics 2025-10-16 Yingheng Li , Xulong Tang , Paul Hovland , Ji Liu