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Bell's theorem shows that no hidden-variable model can explain the measurement statistics of a quantum system shared between two parties, thus ruling out a classical (local) understanding of nature. In this work we demonstrate that by…

Quantum Physics · Physics 2022-03-14 Benjamin Morris , Lukas J. Fiderer , Ben Lang , Daniel Goldwater

We introduce a method to dispersively detect alkali atoms in radio-frequency dressed states. In particular, we use dressed detection to measure populations and population differences of atoms prepared in their clock states. Linear…

Atomic Physics · Physics 2018-04-26 Sindhu Jammi , Tadas Pyragius , Mark G. Bason , Hans Marin Florez , Thomas Fernholz

For linear combinations of quantum product averages in an arbitrary bipartite state, we derive new quantum Bell-form and CHSH-form inequalities with the right-hand sides expressed in terms of a bipartite state. This allows us to specify in…

Quantum Physics · Physics 2011-01-04 Elena R. Loubenets

The existence of quantum correlations that allow one party to steer the quantum state of another party is a counterintuitive quantum effect that has been described already at the beginning of the past century. Steering occurs if…

Quantum Physics · Physics 2016-03-04 Tobias Moroder , Oleg Gittsovich , Marcus Huber , Roope Uola , Otfried Gühne

Quantum discord in a bipartite system can be dynamically revealed and quantified through purely local operations on one of the two subsystems. To achieve this, the local detection method harnesses the influence of initial correlations on…

Quantum Physics · Physics 2017-07-04 Manuel Gessner , Heinz-Peter Breuer , Andreas Buchleitner

We formulate an entanglement criterion using Peres-Horodecki positive partial transpose operations combined with the Schr\"odinger-Robertson uncertainty relation. We show that any pure entangled bipartite and tripartite state can be…

Quantum Physics · Physics 2009-11-13 J. Gillet , T. Bastin , G. S. Agarwal

We demonstrate that the unitary dynamics of a multi-qubit system can display hypersensitivity to initial state perturbation. This contradicts the common belief that the classical approach based on the exponential divergence of initially…

Quantum Physics · Physics 2023-07-28 Andrzej Grudka , Paweł Kurzyński , Adam S. Sajna , Jan Wójcik , Antoni Wójcik

Quantum steering has attracted increasing research attention because of its fundamental importance, as well as its applications in quantum information science. Here we leverage the power of the deep learning model to infer the steerability…

Quantum Physics · Physics 2024-03-05 Hong-Ming Wang , Huan-Yu Ku , Jie-Yien Lin , Hong-Bin Chen

Detecting entanglement in multipartite quantum states is an inherently probabilistic process, typically with a few measured samples. The level of confidence in entanglement detection quantifies the scheme's validity via the probability that…

The measurement of quantum states is one of the most important problems in quantum mechanics. We introduce a quantum state tomography technique in which the state of a qubit is reconstructed, while the qubit remains undetected. The key…

Quanta emitted by an open quantum system carry information about intrinsic parameters, enabling their estimation via continuous monitoring. In practice, however, only a fraction of the emitted quanta is detected, reducing the achievable…

Quantum Physics · Physics 2026-05-27 Robert Mattes , Igor Lesanovsky , Albert Cabot

The initialization of a quantum system into a certain state is a crucial aspect of quantum information science. While a variety of measurement strategies have been developed to characterize how well the system is initialized, for a given…

A superconducting qubit coupled to a microwave resonator provides a controllable system that enables fundamental studies of light-matter interactions. In the dispersive regime, photons in the resonator exhibit induced frequency and phase…

Separability problem is a long-standing tough issue in quantum information theory. In this paper, we propose a general method to detect entanglement via arbitrary measurement $\boldsymbol{X}$, by which several novel criteria are…

Quantum Physics · Physics 2022-08-18 Ma-Cheng Yang , Cong-Feng Qiao

Quantum entanglement is usually revealed via a well aligned, carefully chosen set of measurements. Yet, under a number of experimental conditions, for example in communication within multiparty quantum networks, noise along the channels or…

We consider a two-level quantum system (qubit) which is continuously measured by a detector. The information provided by the detector is taken into account to describe the evolution during a particular realization of measurement process. We…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Alexander N. Korotkov

A scheme for the detection of low-intensity optical coherent signals was studied which uses a probabilistic amplifier operated in the non-heralded version, as the underlying non-linear operation to improve the detection efficiency. This…

Quantum Physics · Physics 2016-06-15 Matteo Rosati , Andrea Mari , Vittorio Giovannetti

We focus on determining the separability of an unknown bipartite quantum state $\rho$ by invoking a sufficiently large subset of all possible entanglement witnesses given the expected value of each element of a set of mutually orthogonal…

Quantum Physics · Physics 2009-11-13 Lawrence M. Ioannou , Benjamin C. Travaglione

Highly quantum non-linear interactions between different bosonic modes lead to the generation of quantum non-Gaussian states, i.e. states that cannot be written as mixtures of Gaussian states. A paradigmatic example is given by…

We present a model to detect a classical state mixed with an idler photon from a polarization-entangled pair. A weak coherent light with a well-defined polarization, matched in wavelength to the idler photon, is injected into the idler…

Quantum Physics · Physics 2026-02-24 Kim Fook Lee , Prem Kumar