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Background: With evidence of a rapidly aging population globally, there is need to continuously address the wellbeing of this vulnerable age group. The concern of the subjective wellbeing of the elderly is essential for constructing a healthy and positive aging society. To promote the elderly’s subjective wellbeing, the role of character strengths and depression on subjective wellbeing for older adults needs to be explored. Methods: A large sample of 8839 elders from the 2017-2018 survey of the Chinese Longitudinal Healthy Longevity Survey (CLHLS) were included. The Chinese version of the character strengths scale, the 10-item CES-D scale (Center for Epidemiologic Studies Short Depression Scale) were applied to assess the elderly‘s character strengths and depression respectively. Self-reported quality of life (SelfQoL) and health (Selfhealth) were used to evaluate the subjective wellbeing in participants. IBM SPSS Statistics 25.0 and AMOS version 23.0 were adopted to analyze the data.Results: The average age of participants was 81.27 years. Among these elderly participants, a greater character strengths levels were more evidenced and pronounced among those with a younger age, longer years of education, higher household income, greater social security and social insurance, less depression, higher SelfQoL and Selfhealth levels. Depression had a partial mediation effect of character strengths on self-reported subjective wellbeing, which explained a 36% in total variance (R2=0.36). In addition, character strengths had a statistically significant positive and direct effect on subjective wellbeing (β= 0.290, PConclusion: Depression is an unignored mediator that regulates the effect of character strengths on subjective wellbeing in the elderly. Character strengths and depression may be the new intervention targets to promote and enhance the elderly's subjective wellbeing. Future tailored intervention should focus on relieving the elderly's depression and promoting the development of their character strengths.

Low dissipation, tunable coupling to other quantum systems, and unique features of phonons in the aspects of propagation, detection and others suggest the applications of quantized mechanical resonators in phonon-based quantum information processing (QIP) in a way different from their photonic counterpart. In this paper, we propose the first protocol of entanglement concentration for nonlocal phonons from quantized mechanical vibration. We combine the optomechanical cross-Kerr interaction with the Mach-Zehnder interferometer and, by means of twice optomechanical interactions and the photon analysis with respect to the output of the interferometer, achieve ideal entanglement concentration about less-entangled nonlocal phonon Bell and Greenberger-Horne-Zeilinger states. Our protocol is useful for preserving the entangled phonons for the use of high quality phonon-based QIP in future., 7 pages, 5 figures

Quantum logic gates are essential in quantum information processing. Here, we propose three heralded schemes for universal quantum gates, including the controlled-NOT, Toffoli, and Fredkin gates on atomic systems, assisted by the scattering of photons off single emitters in one-dimensional waveguides. Interestingly, our schemes can turn faulty scattering processes of photons off atoms into the detection of the photon polarization. Furthermore, auxiliary atomic qubits are not needed and only one photon medium is adopted. With current technology, we discuss the feasibility of these universal quantum gates, concluding that they are feasible and scalable in solid-state quantum systems. We provide a different method for realizing universal quantum gates, and it may be useful in quantum information processing in the future.

The multiphoton near-infrared, quantum cutting luminescence in Er3+/Tm3+ co-doped telluride glass was studied. We found that the near-infrared 1800-nm luminescence intensity of (A) Er3+(8%)Tm3+(0.5%):telluride glass was approximately 4.4 to 19.5 times larger than that of (B) Tm3+(0.5%):telluride glass, and approximately 5.0 times larger than that of (C) Er3+(0.5%):telluride glass. Additionally, the infrared excitation spectra of the 1800 nm luminescence, as well as the visible excitation spectra of the 522 nm and 652 nm luminescence, of (A) Er3+(8%)Tm3+(0.5%):telluride glass are very similar to those of Er3+ ions in (C) Er3+(0.5%):telluride glass, with respect to the shapes of their excitation spectral waveforms and peak wavelengths. Moreover, we found that there is a strong spectral overlap and energy transfer between the infrared luminescence of Er3+ donor ions and the infrared absorption of Tm3+ acceptor ions. The efficiency of this energy transfer {4I13/2(Er3+) → 4I15/2(Er3+), 3H6(Tm3+) → 3F4(Tm3+)} between the Er3+ and Tm3+ ions is approximately 69.8%. Therefore, we can conclude that the observed behaviour is an interesting multiphoton, near-infrared, quantum cutting luminescence phenomenon that occurs in novel Er3+-Tm3+ ion pairs. These findings are significant for the development of next-generation environmentally friendly germanium solar cells, and near-to-mid infrared (1.8–2.0 μm) lasers pumped by GaN light emitting diodes.

We propose a heralded quantum repeater based on the scattering of photons off single emitters in one-dimensional waveguides. We show the details by implementing nonlocal entanglement generation, entanglement swapping, and entanglement purification modules with atoms in waveguides, and discuss the feasibility of the repeater with currently achievable technology. In our scheme, the faulty events can be discarded by detecting the polarization of the photons. That is, our protocols are accomplished with a fidelity of 100% in principle, which is advantageous for implementing realistic long-distance quantum communication. Moreover, additional atomic qubits are not required, but only a single-photon medium. Our scheme is scalable and attractive since it can be realized in solid-state quantum systems. With the great progress on controlling atom-waveguide systems, the repeater may be very useful in quantum information processing in the future.

Adiabatic quantum control is a very important approach for quantum physics and quantum information processing. It holds the advantage with robustness to experimental imperfections but accumulates more decoherence due to the long evolution time. Here, we propose a universal protocol for fast and robust quantum control in multimode interactions of a quantum system by using shortcuts to adiabaticity. The results show this protocol can speed up the evolution of a multimode quantum system effectively, and it can also keep the robustness very good while adiabatic quantum control processes cannot. We apply this protocol for the quantum state transfer in quantum information processing in the photon-phonon interactions in an optomechanical system, showing a perfect result. These good features make this protocol have the capability of improving effectively the feasibility of the practical applications of multimode interactions in quantum information processing in experiment., 7 pages, 6 figures. The text overlaps partially with arXiv: 1610.09938. A general way is given for the fast and robust quantum control on multimode interactions by using shortcuts to adiabaticity, not just the transitionless intra-cavity quantum state transfer in optomechanical systems in arXiv: 1610.09938 (an application of this way). That is, the goal and the method are changed largely

We investigate the entanglement dynamics of two local two-state quantum systems coupling to a bosonic mode and a common structured bath. Here the bosonic mode is damped by a broadband reservoir and acts as a probe mode for the use of continuous quantum measurement feedback, and the bath has a structure characterized by the Ohmic spectral density. We first present the non-Markovian master equation for the two-state quantum systems and then the corresponding hierarchical equations of motion (HEOM). We illustrate the equivalence between the HEOM approach and the perturbation theory. HEOM-calculations show that the quantum measurement feedback plays a positive role in the entanglement generation, and the non-Markovian effect of the Ohmic bath could greatly enhance this action. We reveal in detail the dependence of the scheme on the spectral density parameters, the temperature of the bath, and the measurement feedback strength. The numerical results are obtained with the HEOM truncated at the third order, which are equal to those obtained with sixth-order perturbation theory.

We present two schemes of Lau effect for an object, an electromagnetically induced grating generated based on the electromagnetically induced effect. The Lau interference pattern is detected either directly in the way of the traditional Lau effect measurement with a classical thermal light being the imaging light, or indirectly and nonlocally in the way of two-photon coincidence measurement with a pair of entangled photons being the imaging light.

We discuss the reversible storage of an entangled two-mode wavepacket in separated two atomic ensembles based on electromagnetically induced transparency. By introducing wavepacket dark-states, we show the dynamic transfer of quantum information of the wavepacket between the optical field and the atomic ensembles. We examine in detail the performance of the scheme focusing on the reversible storage of an entangled two-photon wavepacket in the case where the effects of the environment and the thermal motions of atoms are taken into consideration.

We discuss the generation and stabilization of entanglement between two distant atoms in a driven cascaded two-cavity system with homodyne-based feedback control. As the scheme works freely, the two atoms can fall into a steady state close to the Bell state $$\left| \varPhi _{+}\right\rangle $$?+ with an amount of entanglement inverse to its decay rate in a narrow parameter region. The homodyne feedback enlarges this region and makes the system robust against the unexpected imperfections.

This study proposes the first high-capacity quantum secure direct communication (QSDC) with two-photon six-qubit hyper-entangled Bell states in two longitudinal momentum and polarization degrees of freedom (DOFs) of photon pairs, which can be generated using two 0.5 mm-thick type-I β barium borate crystal slabs aligned one behind the other and an eight-hole screen. The secret message can be independently encoded on the photon pairs with 64 unitary operations in all three DOFs. This protocol has a higher capacity than previous QSDC protocols because each photon pair can carry 6 bits of information, not just 2 or 4 bits. Our QSDC protocol decreases the influence of decoherence from environment noise by exploiting the decoy photons to check the security of the transmission of the first photon sequence. Compared with two-way QSDC protocols, our QSDC protocol is immune to an attack by an eavesdropper using Trojan horse attack strategies because it is a one-way quantum communication. The QSDC protocol has good applications in the future quantum communication because of all these features.

We theoretically investigate the quantum scattering of a single-photon pulse interacting with an ensemble of $\Lambda$-type three-level atoms coupled to a one-dimensional waveguide. With an effective non-Hermitian Hamiltonian, we study the collective interaction between the atoms mediated by the waveguide mode. In our scheme, the atoms are randomly placed in the lattice along the axis of the one-dimensional waveguide, which closely corresponds to the practical condition that the atomic positions can not be controlled precisely in experiment. Many interesting optical properties occur in our waveguide-atom system, such as electromagnetically induced transparency (EIT) and optical depth. Moreover, we observe that strong photon-photon correlation with quantum beats can be generated in the off-resonant case, which provides an effective candidate for producing non-classical light in experiment. With remarkable progress in waveguide-emitter system, our scheme may be feasible in the near future., Comment: 10 pages,7 figures

In this paper, the author introduced resonance mechanism into the stability analysis of power system, established comprehensive mathematical model including units and power grids by considering the effects from generation side and line side. On this basis, the author simulated several typical disturbances to analysis by MATLAB SIMULINK. The result showed that the power oscillation will be caused when the natural frequency of the grid and the frequency of disturbances are same or similar, especially in multi-area interconnected power system. The disturbances from different units can produce a significant impact transient or sustained oscillation by superposition, endanger the stability of power system.