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A complete, non-demolition procedure is established for measuring multi-qubit entangled states, such as the Bell-states and the GHZ-states, which is essential in certain processes of quantum communication, computation, and teleportation. No…

Quantum Physics · Physics 2016-09-08 Ulf Larsen

Quantum metrology aims to enhance measurement precision beyond the standard quantum limit (SQL), the benchmark set by classical resources, enabling advances in sensing, imaging, and fundamental physics. A critical milestone beyond the SQL…

Quantum Physics · Physics 2025-08-19 Kimin Park , Tanjung Krisnanda , Yvonne Gao , Radim Filip

Quantum metrology protocols using entangled states of large spin ensembles attempt to achieve measurement sensitivities surpassing the standard quantum limit (SQL), but in many cases they are severely limited by even small amounts of…

Quantum Physics · Physics 2023-11-06 Martin Koppenhöfer , Peter Groszkowski , A. A. Clerk

Quantum coherence of superposed states, especially of entangled states, is indispensable for many quantum technologies. However, it is vulnerable to environmental noises, posing a fundamental challenge in solid-state systems including spin…

Entanglement-enhanced quantum metrology explores the utilization of quantum entanglement to enhance measurement precision. When particles in a probe are prepared into a quantum entangled state, they collectively accumulate information about…

Quantum Physics · Physics 2024-08-20 Jiahao Huang , Min Zhuang , Chaohong Lee

Entanglement is a resource to improve the sensitivity of quantum sensors. In an ideal case, using an entangled state as a probe to detect target fields, we can beat the standard quantum limit by which all classical sensors are bounded.…

Quantum-enhanced sensors, which surpass the standard quantum limit (SQL) and approach the fundamental precision limits dictated by quantum mechanics, are finding applications across a wide range of scientific fields. This quantum advantage…

Quantum Physics · Physics 2025-09-23 Yinan Chen , Andreas Elben , Angel Rubio , Gil Refael

Optomechanical systems have been exploited in ultrasensitive measurements of force, acceleration, and magnetic fields. The fundamental limits for optomechanical sensing have been extensively studied and now well understood -- the intrinsic…

Entanglement is generally considered necessary for achieving the Heisenberg limit in quantum metrology. We construct analogues of Dicke and GHZ states on a single $N+1$ dimensional qudit that achieve precision equivalent to symmetrically…

Quantum Physics · Physics 2023-09-26 Pragati Gupta

We microscopically model the decoherence dynamics of entangled coherent states under the influence of vacuum fluctuation. We derive an exact master equation with time-dependent coefficients reflecting the memory effect of the environment,…

Quantum Physics · Physics 2009-06-02 Jun-Hong An , Mang Feng , Wei-Min Zhang

The relations between the resource theoretic measures of quantum coherence are rigorously investigated for various Markovian and non-Markovian channels for the two-qubit $X$ states with specific attention to the maximum and minimum…

Quantum Physics · Physics 2022-06-07 Sandeep Mishra , Kishore Thapliyal , Anirban Pathak

We show that in presence of a local and uncorrelated dephasing noise, quantum advantage can be obtained in the Fisher information-based lower bound of the minimum uncertainty in estimating parameters of the system Hamiltonian. The quantum…

Quantum Physics · Physics 2024-05-27 Aparajita Bhattacharyya , Ahana Ghoshal , Ujjwal Sen

Quantum mechanics allows entanglement enhanced measurements to be performed, but loss remains an obstacle in constructing realistic quantum metrology schemes. However, recent work has revealed that entangled coherent states (ECSs) have the…

Quantum Physics · Physics 2015-06-18 P. A. Knott , W. J. Munro , J. A. Dunningham

We study dynamics of the measurement process in quantum dot systems, where a particular state out of coherent superposition is observed. The ballistic point-contact placed near one of the dots is taken as a noninvasive detector. We…

Mesoscale and Nanoscale Physics · Physics 2009-10-30 S. A. Gurvitz

Quantum metrology protocols allow to surpass precision limits typical to classical statistics. However, in recent years, no-go theorems have been formulated, which state that typical forms of uncorrelated noise can constrain the quantum…

Quantum Physics · Physics 2016-03-30 Andrea Smirne , Jan Kolodynski , Susana F. Huelga , Rafal Demkowicz-Dobrzanski

We experimentally demonstrate the achievement of the entanglement assisted capacity for classical information transmission over a depolarizing channel. The implementation is based on the generation and local manipulation of 2-qubit Bell…

Quantum Physics · Physics 2015-06-05 Andrea Chiuri , Sandro Giacomini , Chiara Macchiavello , Paolo Mataloni

Quantum metrology with entangled states in realistic noisy environments always suffers from decoherence. Therefore, the measurement precision is greatly reduced. Here we applied the dynamical decoupling method to protect the $N$-qubit…

Quantum Physics · Physics 2016-12-21 Yang Dong , Xiang-Dong Chen , Guang-Can Guo , Fang-Wen Sun

Entanglement and entanglement-assisted are useful resources to enhance the mutual information of the Pauli channels, when the noise on consecutive uses of the channel has some partial correlations. In this Paper, we study…

Quantum Physics · Physics 2015-06-26 A. Fahmi , M. Golshani

We introduce a general model for a network of quantum sensors, and we use this model to consider the question: When can entanglement between the sensors, and/or global measurements, enhance the precision with which the network can measure a…

Quantum Physics · Physics 2018-02-28 Timothy J. Proctor , Paul A. Knott , Jacob A. Dunningham

In the realm of quantum information processing, the efficient characterization of entangled states poses an overwhelming challenge, rendering the traditional methods including quantum tomography unfeasible and impractical. To tackle this…

Quantum Physics · Physics 2025-12-09 Ye-Chao Liu , Jiangwei Shang