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Measuring stochastic signals ("noise metrology") constitutes a central task in quantum sensing and the characterization of open quantum systems. Here we establish ultimate precision bounds for multiparameter estimation of stochastic signals…

Quantum Physics · Physics 2026-04-17 Anthony J. Brady , Yu-Xin Wang , Luis Pedro García-Pintos , Alexey V. Gorshkov

Noise and errors are unavoidable in any realistic quantum process, including processes designed to reduce noise and errors in the first place. In particular, quantum thermodynamical protocols for cooling can be significantly affected,…

Quantum Physics · Physics 2026-01-26 Jian Li , Xiaoyang Wang , Marcus Huber , Nicolai Friis , Pharnam Bakhshinezhad

We present an alternative form of master equation, applicable on the analysis of non-equilibrium dynamics of fermionic open quantum systems. The formalism considers a general scenario, composed by a multipartite quantum system in contact…

Quantum Physics · Physics 2017-11-15 Fabrício M. Souza , L. Sanz

Quantum computers have now surpassed classical simulation limits, yet noise continues to limit their practical utility. As the field shifts from proof-of-principle demonstrations to early deployments, there is no standard method for…

Quantum Physics · Physics 2025-05-29 J. A. Montanez-Barrera , Kristel Michielsen , David E. Bernal Neira

We present a two-step protocol for quantum measurement tomography that is light on classical co-processing cost and still achieves optimal sample complexity in the system dimension. Given measurement data from a known probe state ensemble,…

Quantum Physics · Physics 2025-12-01 Leonardo Zambrano , Sergi Ramos-Calderer , Richard Kueng

The technologies of quantum information and quantum control are rapidly improving, but full exploitation of their capabilities requires complete characterization and assessment of processes that occur within quantum devices. We present a…

Quantum computing has the potential to provide solutions to problems that are intractable on classical computers, but the accuracy of the current generation of quantum computers suffer from the impact of noise or errors such as leakage,…

Quantum Physics · Physics 2025-09-03 Benjamin Harper , Behnam Tonekaboni , Bahar Goldozian , Martin Sevior , Muhammad Usman

With the intense interest in small, noisy quantum computing devices comes the push for larger, more accurate -- and hence more useful -- quantum computers. While fully fault-tolerant quantum computers are, in principle, capable of achieving…

Quantum Physics · Physics 2022-04-22 Akshaya Jayashankar , My Duy Hoang Long , Hui Khoon Ng , Prabha Mandayam

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…

Quantum computing has significantly advanced in recent years, boasting devices with hundreds of quantum bits (qubits), hinting at its potential quantum advantage over classical computing. Yet, noise in quantum devices poses significant…

Quantum Physics · Physics 2025-07-24 Jinyang Li , Samudra Dasgupta , Yuhong Song , Lei Yang , Travis Humble , Weiwen Jiang

Hardware crosstalk in multi-tenant superconducting quantum computers constitutes a significant security threat, enabling adversaries to inject targeted errors across tenant boundaries. We present the first end-to-end framework for mapping…

Quantum Physics · Physics 2025-09-16 Syed Emad Uddin Shubha , Tasnuva Farheen

A protocol based on quantum error correction based characterization of quantum dynamics (QECCD) is developed for quantum process tomography on a two-qubit system interacting dissipatively with a vacuum bath. The method uses a 5-qubit…

Quantum Physics · Physics 2017-02-09 S. Omkar , R. Srikanth , Subhashish Banerjee , Anil Shaji

Contemporary methods for benchmarking noisy quantum processors typically measure average error rates or process infidelities. However, thresholds for fault-tolerant quantum error correction are given in terms of worst-case error rates --…

In this project we examine several different quantum key distribution protocols which we divide into ones utilizing qubits whose Hilbert spaces are two dimensional and ones whose Hilbert space dimension is greater than two, these units of…

Quantum Physics · Physics 2024-02-05 Yuval Idan , Avihai Didi

Accurate characterization of quantum systems is essential for the development of quantum technologies, particularly in the noisy intermediate-scale quantum (NISQ) era. While traditional methods for Hamiltonian learning and noise…

Quantum Physics · Physics 2025-07-18 Gubio G. de Lima , Iann Cunha , Leonardo Kleber Castelano

Characterizing strongly correlated matter is an increasingly central challenge in quantum science, where structure is often obscured by massive entanglement. From semiconductor heterostructures and 2D materials to synthetic atomic, photonic…

The efficiency of Quantum Characterisation, Verification, and Validation (QCVV) protocols highly hinges on the agreement between the assumed noise model and the underlying error mechanisms. As a matter of fact, errors in Quantum Processing…

Quantum Physics · Physics 2022-03-02 Ahmed Abid Moueddene , Nader Khammassi , Sebastian Feld , Said Hamdioui

Quantum Krylov subspace diagonalization (QKSD) is an emerging method used in place of quantum phase estimation in the early fault-tolerant era, where limited quantum circuit depth is available. In contrast to the classical Krylov subspace…

Quantum Physics · Physics 2024-09-20 Gwonhak Lee , Dongkeun Lee , Joonsuk Huh

Randomized Benchmarking allows to efficiently and scalably characterize the average error of an unitary 2-design such as the Clifford group $\mathcal{C}$ on a physical candidate for quantum computation, as long as there are no…

Quantum Physics · Physics 2015-11-04 T. Chasseur , F. K. Wilhelm

Quantum computation has been growing rapidly in both theory and experiments. In particular, quantum computing devices with a large number of qubits have been developed by IBM, Google, IonQ, and others. The current quantum computing devices…

Quantum Physics · Physics 2021-02-10 Rishabh Gupta , Rongxin Xia , Raphael D. Levine , Sabre Kais