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We investigate the average steered coherence (ASC) of a central two-qubit system coupled to an XY spin-chain environment. It is shown that there exists subspace in which the initial states are immune to this environment. Outside of this subspace, the decay of the ASC can be significantly suppressed by tuning the interaction of the central qubits and its anisotropy in the z axis, as well as the anisotropy of the spin–spin interaction in the xy plane of the environment and the strength of the transverse magnetic field. For the initial Bell states and their unitary equivalent classes, one can also identify system and environmental parameters for which the ASC oscillates near its maximum even in the long-time interval.

We investigate the average steered coherence (ASC) and maximal steered coherence (MSC) of two qubits in a squeezed generalized amplitude damping channel modeled by a squeezed thermal bath with dissipation and memory. By considering the input Bell states, it is shown that while the dissipation and thermal effects induce decay of the ASC and MSC in the output states, the squeezing effect suppresses their decay in the strong (full) squeezing region for the input even-parity (odd-parity) Bell states. Besides, the memory effect due to correlated actions of the channel can also be exploited for suppressing decay of the ASC and MSC.

Coherence is intrinsically related to projective measurement. When the fixed projective measurement involves higher-rank projectors, the coherence resource is referred to as block coherence, which comes from the superposition of orthogonal subspaces. Here, we establish a set of quantitative relations for the interconversion between block coherence and multipartite entanglement under the framework of the block-incoherent operations. It is found that the converted multipartite entanglement is upper bounded by the initial block coherence of single-party system. Moreover, the generated multipartite entanglement can be transferred to its subsystems and restored to block coherence of the initial single-party system by means of local block-incoherent operations and classical communication. In addition, when only the coarse-grained quantum operations are accessible for the ancillary subsystems, we further demonstrate that a lossless resource interconversion is still realizable, and give a concrete example in three four-level systems. Our results provide a versatile approach to utilize different quantum resources in a cyclic fashion.

The uncertainty principle imposes a limitation on the measurement accuracy of two incompatible observables and has potential applications in quantum information science. We explore the bipartite entropic uncertainty relation and dense coding for two qubits coupled via dipole–dipole interaction and subject to a bosonic reservoir. It is shown that there exists a trade-off between the uncertainty bound and the dense coding capacity which results in their opposite dynamical behaviors. Moreover, the behaviors of the measurement uncertainty and the dense coding capacity rely crucially on the initial system–reservoir correlation, the strength of the dipole–dipole interaction, and the degree of non-Markovianity, and one can reduce the measurement uncertainty and enhance the dense coding capacity by tuning these parameters to appropriate values.

The effect of a reservoir on quantum communication depends on its spectral density. The efficiency of quantum teleportation and dense coding is explored when each one of the channel qubits is coupled simultaneously to multiple bosonic reservoirs. It is shown that the non-Markovianity triggered by increasing the reservoir number can induce revivals of quantum advantages of the two protocols after their disappearance. However, the backflow of information to the system that signifies non-Markovianity does not always induce immediate revivals of the quantum advantages. There may be a delayed effect for some initial states, and only as the backflow of information accumulates to a certain extent can the revivals of quantum advantages be triggered.

Abstract We examined decay dynamics of various geometric quantum discords (GQDs) for two interacting qubits described by the Heisenberg XY model and further coupled independently to their respective thermal reservoirs. Compared to the case of noninteracting qubits, our results showed that decay rates of the GQDs can be retarded apparently by properly choosing system parameters of the interaction term. In the long-time limit, the asymptotic values of the GQDs are enhanced evidently by tuning anisotropy of the model and strength of the transverse magnetic field. We further illuminated the relations between different GQDs on characterizing quantum correlations, and observed multiple sudden change behaviors of their dynamics.

Nonlocality is one unique property of quantum mechanics that differs from the classical world. One of its quantifications can be properly described as the maximum global effect caused by locally invariant measurements, known as measurement-induced nonlocality (MIN) (2011 Phys. Rev. Lett. 106 120401). Here, we propose quantifying the MIN by the trace norm. We show explicitly that this measure is monotonically decreasing under the action of a completely positive trace-preserving map, which is the general local quantum operation, on the unmeasured party for the bipartite state. This property avoids the undesirable characteristic appearing in the known measure of MIN defined by the Hilbert–Schmidt norm which may be increased or decreased by trivial local reversible operations on the unmeasured party. We obtain analytical formulas of the trace-norm MIN for any $(2\times n)$ -dimensional pure state, two-qubit state, and certain high-dimensional states. As with other quantum correlation measures, the newly defined MIN can be directly applied to various models for physical interpretations.

The article reports that Gene expression responses in zebrafish to short-term high-hydrostatic pressure . Topics include applied high-hydrostatic pressure treatment to wild-type AB line zebrafish (Danio rerio) and analyzed transcriptome data following treatment; and research provides basic data for predicting the migration of fish to the deep sea and for understanding the adaptive mechanisms of deep-sea fish.

By employing the tensor analysis technique, we propose three schemes of controlled teleportation: series controlled, circular controlled and network controlled teleportation. We discuss the necessary and sufficient condition for realizing these schemes, in which we use a general two-qubit entangled state instead of the GHZ state as the communication channel. This enables successful implementation of teleportation without using the Hadamard operation. [ABSTRACT FROM AUTHOR]

We report molecular dynamics studies of single-walled carbon nanotubes (SWCNT) as a bandage to connect separated SWCNTs for getting structures of random length. The mechanical properties of the connected SWCNT strands with different joint length under axial loads are investigated using the classical molecular dynamics simulations method. The interaction between atoms is modeled using the second-generation of reactive empirical bond-order (REBO) potential coupled with the Lennard–Jones (L–J) potential. The mechanical properties, such as Young's modulus, tensile strength, critical buckling strains and critical buckling loads are determined and presented for SWCNT and connected SWCNT strands. The results indicates that the joints made in this way have relatively high mechanical properties corresponding to that of the ideal SWCNTs. [ABSTRACT FROM AUTHOR]

We identify that quantum coherence is a valuable resource in the quantum heat engine, which is designed in a quantum thermodynamic cycle assisted by a quantum Maxwell’s demon. This demon is in a superposed state. The quantum work and heat are redefined as the sum of coherent and incoherent parts in the energy representation. The total quantum work and the corresponding efficiency of the heat engine can be enhanced due to the coherence consumption of the demon. In addition, we discuss an universal information heat engine driven by quantum coherence. The extractable work of this heat engine is limited by the quantum coherence, even if it has no classical thermodynamic cost. This resource-driven viewpoint provides a direct and effective way to clarify the thermodynamic processes where the coherent superposition of states cannot be ignored. [ABSTRACT FROM AUTHOR]