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Quantum metrology overcomes standard precision limits and plays a central role in science and technology. Practically it is vulnerable to imperfections such as decoherence. Here, we demonstrate quantum metrology for noisy channels such that…

Quantum Physics · Physics 2018-04-25 Kunkun Wang , Xiaoping Wang , Xiang Zhan , Zhihao Bian , Jian Li , Barry C. Sanders , Peng Xue

Measurement of entanglement remains an important problem for quantum information. We present the design and simulation of an experimental method for entanglement estimation for a general multiqubit state. The system can be in a pure or a…

Quantum Physics · Physics 2012-11-09 E. C. Behrman , J. E. Steck

Quantum technologies available currently contain noise in general, often dubbed noisy intermediate-scale quantum (NISQ) systems. We here present the verification of noise in measurement readout errors in cloud-based quantum computing…

Quantum Physics · Physics 2022-02-10 Seungchan Seo , Joonwoo Bae

Measurement-based entanglement is a method for entangling quantum systems through the state projection that accompanies a parity measurement. We derive a stochastic master equation describing measurement-based entanglement of a pair of…

Quantum Physics · Physics 2024-07-17 Remy L. Delva , Jonas Mielke , Guido Burkard , Jason R. Petta

We study the symmetry properties in the dynamics of quantum correlations for two-qubit systems in one-sided noisy channels, with respect to a switch in the location of noise from one qubit to the other. We consider four different channel…

Quantum Physics · Physics 2017-08-25 Henri Lyyra , Göktuğ Karpat , Chuan-Feng Li , Guang-Can Guo , Jyrki Piilo , Sabrina Maniscalco

We examine the complementarity among coherence (visibility), predictability, and entanglement for qubit and qutrit systems subjected to noisy quantum channels. Using the system-path entanglement framework, analytical expressions for all…

Quantum Physics · Physics 2025-12-01 Pratidhwani Swain , Ramita Sarkar , Sukanta K. Tripathy , Prasanta K. Panigrahi

Signal to noise ratio is key to any measurement. Recent progress in semi/super-conductor technology have pushed the signal detection sensitivity to the ultimate quantum level, but the noise issue remains largely untouched and, in many…

Quantum Physics · Physics 2025-02-13 Yu-Ping Huang , Yongxiang Hu

Quantum information protocols are inevitably affected by decoherence which is associated with the leakage of quantum information into an environment. In this paper we address the possibility of recovering the quantum information from an…

Quantum Physics · Physics 2015-05-14 Metin Sabuncu , Radim Filip , Gerd Leuchs , Ulrik L. Andersen

Quantum metrology stands as a leading application of quantum science and technology, yet noise often constrains its precision and sensitivity. In near-term quantum metrology, existing protocols largely depend on virtual state purification,…

Quantum Physics · Physics 2025-12-03 Xiaodie Lin , Haidong Yuan

The efficient generation of high-fidelity entangled states is the key element for long-distance quantum communication, quantum computation and other quantum technologies, and at the same time the most resource-consuming part in many…

Quantum Physics · Physics 2021-07-28 Ferran Riera Sàbat , Pavel Sekatski , Alexander Pirker , Wolfgang Dür

A method is proposed for obtaining the spectrum for noise that causes the phase decoherence of a qubit directly from experimentally available data. The method is based on a simple relationship between the spectrum and the coherence time of…

Quantum Physics · Physics 2015-05-28 Tatsuro Yuge , Susumu Sasaki , Yoshiro Hirayama

Noise in entangled quantum systems is difficult to characterize due to many-body effects involving multiple degrees of freedom. This noise poses a challenge to quantum computing, where two-qubit gate performance is critical. Here, we…

Quantum error mitigation (QEM) is vital for noisy intermediate-scale quantum (NISQ) devices. While most conventional QEM schemes assume discrete gate-based circuits with noise appearing either before or after each gate, the assumptions are…

Quantum Physics · Physics 2021-03-12 Jinzhao Sun , Xiao Yuan , Takahiro Tsunoda , Vlatko Vedral , Simon C. Bejamin , Suguru Endo

Quantum impurities exhibit fascinating many-body phenomena when the small interacting impurity changes the physics of a large noninteracting environment. The characterisation of such strongly correlated non-perturbative effects is…

Mesoscale and Nanoscale Physics · Physics 2023-01-16 Lidia Stocker , Stefan H. Sack , Michael S. Ferguson , Oded Zilberberg

We introduce new measures of decoherence appropriate for evaluation of quantum computing designs. Environment-induced deviation of a quantum system's evolution from controlled dynamics is quantified by a single numerical measure. This…

Mesoscale and Nanoscale Physics · Physics 2010-10-12 Leonid Fedichkin , Arkady Fedorov , Vladimir Privman

Conventional computers have evolved to device components that demonstrate failure rates of 1e-17 or less, while current quantum computing devices typically exhibit error rates of 1e-2 or greater. This raises concerns about the reliability…

Quantum Physics · Physics 2022-11-02 Samudra Dasgupta , Travis S. Humble

Entangled qubits transported through space is a key element in many prospective quantum information systems, from long-distance quantum communication to large modular quantum processors. The moving qubits are decohered by time- and…

Mesoscale and Nanoscale Physics · Physics 2024-09-09 Aleksandr S. Mokeev , Yu-Ning Zhang , Viatcheslav V. Dobrovitski

Noisy intermediate-scale quantum (NISQ) computers have gate errors and decoherence, limiting the depth of circuits that can be implemented on them. A strategy for NISQ algorithms is to reduce the circuit depth at the expense of increasing…

Quantum Physics · Physics 2019-01-09 Yigit Subasi , Lukasz Cincio , Patrick J. Coles

We present a two-state practical quantum bit commitment protocol, the security of which is based on the current technological limitations, namely the nonexistence of either stable long-term quantum memories or nondemolition measurements.…

We describe an entanglement purification protocol to generate maximally entangled states with high efficiencies from two-mode squeezed states or from mixed Gaussian continuous entangled states. The protocol relies on a local quantum…

Quantum Physics · Physics 2009-10-31 Lu-Ming Duan , G. Giedke , J. I. Cirac , P. Zoller