We discuss the problem of separation total correlations in a given quantum state into entanglement, dissonance, and classical using concept relative entropy as distance measure correlations. This allows us to put all on an equal footing. Entanglement whose definition is introduced here, jointly belong what known discord. Our methods are completely applicable for multipartite systems arbitrary dimensions. investigate additivity relations between different show that dissonance may be present...

A beam splitter is a simple, readily available device which can act to entangle the output optical fields. We show that necessary condition for fields at of be entangled pure input states exhibit nonclassical behavior. generalize this proof arbitrary (pure or impure) Gaussian states. Specifically, nonclassicality entanglement field modes with help splitter. conjecture general property splitter: Nonclassicality inputs entangling in

There have been theoretical and experimental studies on quantum nonlocality for continuous variables, based dichotomic observables. In particular, we are interested in two cases of observables the light field variables: One case is even odd numbers photons other no photon presence photons. We analyze various to give maximum violation Bell's inequalities continuous-variable states. discuss an observable which gives inequality any entangled pure state. However, it does not be a maximally state...

We investigate the conditions to entangle two qubits interacting with local environments driven by a continuous-variable correlated field. find transfer entanglement from driving field both in dynamical and steady-state cases. see how quantum correlations initially present play critical role entanglement-transfer process. The system we treat is general enough be adapted different physical setups.

We present generic Bell inequalities for multipartite arbitrary dimensional systems. The that any local realistic theory must obey are violated by quantum mechanics even A large set of variants shown to naturally emerge from the inequalities. discuss particular all systems including odd

A key element in the architecture of a quantum information processing network is reliable physical interface between fields and qubits. We study process entanglement transfer engineering, where two remote qubits respectively interact with entangled two-mode continuous variable (CV) field. quantify induced qubit state at expenses loss CV system. discuss range mixed states which can be obtained this set-up. Furthermore, we suggest protocol to determine residual entangling power light fields,...

We study a Hamiltonian system describing three–spin-1/2 cluster-like interaction competing with an Ising-like exchange. show that the ground state in cluster phase possesses symmetry protected topological order. A continuous quantum transition occurs as result of competition between and Ising terms. At critical point is self-dual. The geometric entanglement also studied used to investigate transition. Our findings one dimension corroborate analysis two-dimensional generalization system,...

Ultranarrow bandwidth single-photon sources operating at room-temperature are of vital importance for viable optical quantum technologies scale, including key distribution, cloud-based information processing networks, and metrology. Here we show a ultranarrow source generating single-mode photons rate 5 MHz based on an inorganic CsPbI3 perovskite dot embedded in tunable open-access microcavity. When coupled to cavity mode, the emission becomes single-mode, spectrum narrows down just ∼1 nm....

We formulate a conclusive teleportation protocol for system in d-dimensional Hilbert space utilizing the positive operator valued measurement at sending station. The ensures some perfect events when channel is only partially entangled, expense of lowering overall average fidelity. find change fidelity as optimizing and discuss how much information remains inconclusive parts teleportation.

We show that two qubits can be entangled by local interactions with an two-mode continuous variable state. This is illustrated the evolution of two-level atoms interacting a squeezed Two modes field are injected respectively into spatially separate cavities and then sent to interact resonantly cavity field. find may even state which has been decohered while penetrating cavity.

We focus here on the uncertainty of an observable $Y$ caused by a precise measurement $X$. illustrate effect analyzing general scenario two successive measurements spin components $X$ and $Y$. derive optimized entropic limit that quantifies necessary amount observed in subsequent compare this bound to recently derived error-disturbance relations discuss how information quantum measurements.

We investigate the buildup of quasi-long-range order in $XX$ chain with a transverse magnetic field at finite size. As is varied, ground state system displays multiple level crossings producing sequence entanglement jumps. Using partial fidelity and susceptibility, we study transition to thermodynamic limit argue that topological can be described terms kink-antikink pairs marked by edge spin entanglement.

It is known that measurement-device-independent quantum key distribution (MDI-QKD) provides ultimate security from all types of side-channel attack on detectors at the expense low rate. In present study, we propose MDI-QKD using three-dimensional states and show protocol improves secret rate under analysis mismatched-basis statistics. Specifically, analyze $3d$-MDI-QKD with askew aligned sources, meaning original sources contain unwanted instead expected one. We evaluate identify regime in...

Abstract Under the scenario of generalized measurements, it can be questioned how much quantum uncertainty attributed to measuring device, independent in measured system. On course answer question, we suggest a new class entropic relation that differentiates from device imperfection due unsharpness measurement. In order quantify unsharpness, and analyze quantity characterizes based on Shannon entropy. Using quantity, obtain lower bound with has been shown also obtained under sharp...

In this paper, we prove, extend and review possible mappings between the two-dimensional (2D) cluster state, Wen's model, 2D Ising chain Kitaev's toric code model. We introduce a duality transformation to map lattice state into topologically ordered Wen Then, investigate how mapping could be achieved physically, which allows us discuss rate at system can achieved. Next, using fermionization method, model is mapped series of 1D interactions. Considering boundary terms with then reveals chains...

Physical systems have some degree of disorder present in them. We discuss how to treat natural, thermal entanglement any random macroscopic system from which a thermodynamic witness bounded by constant can be found. propose that functional many-body perturbation theory applied allow either quenched or an annealed average over the taken. find, when considering example $XX$ Heisenberg spin chain with coupling strength, region natural detected both witnesses enhanced disorder.

Joint quantum measurements of noncommuting observables are possible, if one accepts an increase in the measured variances. A necessary condition for a joint measurement to be possible is that probability distribution exists measurement. This fact suggests there may link with Bell inequalities, as these will satisfied and only all involved exists. We investigate connections between inequalities conditions possible. Mermin's inequality three-particle Greenberger-Horne-Zeilinger state turns out...

A Gaussian distribution of a quantum state with continuous spectra is known to maximize the Shannon entropy at fixed variance. Applying it pair canonically conjugate observables $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{x}$ and \^{}\fi{}}{p}$, entropic uncertainty relation can take suggestive form, where standard deviations ${\ensuremath{\sigma}}_{x}$ ${\ensuremath{\sigma}}_{p}$ are featured explicitly. From construction relation, follows in transparent manner that (i) implies...

For the purpose of nonlocality test, we propose a general correlation observable two parties by utilizing local $d$-outcome measurements with SU($d$) transformations and classical communications. Generic symmetries observables are found for test nonlocality. It is shown that these dramatically reduce number numerical variables, which important analysis A linear combination observables, reduced to Clauser-Horne-Shimony-Holt (CHSH) Bell's inequality outcome measurements, led...

We investigate macroscopic entanglement in an infinite XX spin-$\frac{1}{2}$ chain with staggered magnetic field, ${B}_{l}=B+{e}^{\ensuremath{-}i\ensuremath{\pi}l}b$. Using single-site entropy and by constructing witness, we search for the existence of when system is at absolute zero, as well thermal equilibrium. Although role alternating field $b$ is, general, to suppress do $B$ $T$, find that $T=0$, introducing allows even uniform arbitrarily large. region amount spin can be enhanced a field.

We propose a schematic setup of quantum key distribution (QKD) with an improved secret rate based on high-dimensional states. Two degrees-of-freedom single photon, orbital angular momentum modes, and multi-path are used to encode information. Its practical implementation consists optical elements that within the reach current technologies such as multiport interferometer. show proposed feasible protocol has much sophistication compared previous 2-dimensional known detector-device-independent QKD.

We propose a scheme to test Bell's inequalities for an arbitrary number of measurement outcomes on entangled continuous-variable (CV) states. The Bell correlation functions are expressible in terms phase-space quasiprobability with complex ordering parameters, which can experimentally be determined via local CV-qubit interaction. demonstrate that CV systems give higher violations these than the ones developed two-outcome observables.

The most general class of non-locality criteria for N-partite d-chotomic systems with k number measurement settings is derived under the constraint symmetries. It complete characterisation multi-partite when correlation assumed to be symmetric choice settings. generalized condition obtained using functions, which are from Fourier analysis probability spectrums. found that local hidden variable (LHV) model violated by multipartite quantum states and constraints violation maximally entangled...

We derive entropic uncertainty relations for successive generalized measurements by using general descriptions of quantum measurement within two {distinctive operational} scenarios. In the first scenario, merging {two measurements} into one we consider scheme as a method to perform an overall {composite} measurement. second on other hand, it measure pair jointly measurable observables marginalizing over distribution obtained in this scheme. course work, identify that limits one's ability...