Entanglement and discord assisted entropic uncertainty relations under decoherence

The uncertainty principle is a crucial aspect of quantum mechanics.It has been shown that quantum entanglement as well as more general notions of correlations,such as quantum discord,can relax or tighten the entropic uncertainty relation in the presence of an ancillary system.We explored the behaviour of entropic uncertainty relations for system of two qubits—one of which subjects to several forms of independent quantum noise,in both Markovian and non-Markovian regimes.The uncertainties and their lower bounds,identified by the entropic uncertainty relations,increase under independent local unital Markovian noisy channels,but they may decrease under non-unital channels.The behaviour of the uncertainties(and lower bounds)exhibit periodical oscillations due to correlation dynamics under independent non-Markovian reservoirs.In addition,we compare different entropic uncertainty relations in several special cases and find that discord-tightened entropic uncertainty relations offer in general a better estimate of the uncertainties in play.

Reduction of entropic uncertainty in entangled qubits system by local PT-symmetric operation

We investigate the quantum-memory-assisted entropic uncertainty for an entangled two-qubit system in a local quantum noise channel with PT-symmetric operation performing on one of the two particles. Our results show that the quantum-memory-assisted entropic uncertainty in the qubits system can be reduced effectively by the local PT-symmetric operation. Physical explanations for the behavior of the quantum-memory-assisted entropic uncertainty are given based on the property of entanglement of the qubits system and the non-locality induced by the re-normalization procedure for the non-Hermitian PT-symmetric operation.

Quantum correlation and entropic uncertainty in a quantum-dot system

We explore the dynamical behaviors of the measurement uncertainty and quantum correlation for a vertical quantumdot system in the presence of magnetic field, including electron-electron interaction and Coulomb-blocked systems. Stemming from the quantum-memory-assisted entropic uncertainty relation, the uncertainty of interest is associated with temperature and parameters related to the magnetic field. Interestingly, the temperature has two kinds of influences on the variation of measurement uncertainty with respect to the magnetic-field-related parameters. We also discuss the relation between the lower bound of Berta et al. and the quantum discord. It is found that there is a natural competition between the quantum discord and the entropy min_(Π~B_(i)) SΠ~B_(i)(ρ_(A|B)). Finally, we bring in two improved bounds to offer a more precise limit to the entropic uncertainty.

Quantum correlation enhanced bound of the information exclusion principle

We investigate the information exclusion principle for multiple measurements with assistance of multiple quantum memories that are well bounded by the upper and lower bounds.The lower bound depends on the observables'complementarity and the complementarity of uncertainty whilst the upper bound includes the complementarity of the observables,quantum discord,and quantum condition entropy.In quantum measurement processing,there exists a relationship between the complementarity of uncertainty and the complementarity of information.In addition,based on the information exclusion principle the complementarity of uncertainty and the shareability of quantum discord can exist as an essential factor to enhance the bounds of each other in the presence of quantum memory.

Entropic uncertainty relation of a qubit–qutrit Heisenberg spin model and its steering

We investigate the quantum-memory-assisted entropic uncertainty relation(QMA-EUR)in a Heisenberg XYZ mixed-spin(1/2,1)model.Coupling strength,Dzyaloshinskii–Moriya(DM)interaction and inhomogeneous magnetic field,respectively,contributing to QMA-EUR by a thermal entanglement in the hybrid-spin model are studied in detail.Furthermore,we compare the uncertainty of the bipartite hybrid model with those of qubit–qubit and qutrit–qutrit systems.Meanwhile,the effects of local PT-symmetric operation and weak measurement on the steering of entropic uncertainty are analyzed.We find that the local PT-symmetric operation can reduce the entropic uncertainty,and the entropic uncertainty can also be decreased by weak measurement reversal.

Manipulating the measured uncertainty under Lee-Yang dephasing channels through local PT-symmetric operations

Uncertainty relation lies at the heart of quantum physics,which is one of the fundamental characteristics of quantum mechanics.With the advent of quantum information theory,entropic uncertainty relation was proposed,which plays an important and irreplaceable role in quantum information science.In this work,we attempt to observe dynamics of entropic uncertainty in the presence of quantum memory under two different types of Lee-Yang dephasing channels.It is interesting to find that the dephasing channels have a negative effect on decreasing the uncertainty and the analogous partition function is anti-correlated with the uncertainty.In addition,we here propose an effective strategy to manipulate the uncertainty of interest of the subsystem by performing a parity-time symmetric(PT-symmetric)operation.It is worth noting that the uncertainty of measurement will be reduced to a certain extent by properly modulating the PT-symmetric operations under the considered channels.In this sense,we argue that our explorations offer insight into dynamics of entropic uncertainty in typical Lee-Yang dephasing channels,and might be beneficial to quantum measurement estimation in practical quantum systems.