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Logic Bell state concentration with parity check measurement
Jiu Liu, Lan Zhou, Wei Zhong, Yu-Bo Sheng
Frontiers of Physics. 2019, 14 (2 ): 21601-.
https://doi.org/10.1007/s11467-018-0866-z
Logic qubit plays an important role in current quantum communication. In this paper, we propose an efficient entanglement concentration protocol (ECP) for a new kind of logic Bell state, where the logic qubit is the concatenated Greenber–Horne–Zeilinger (C-GHZ) state. Our ECP relies on the nondemolition polarization parity check (PPC) gates constructed with cross-Kerr nonlinearity, and can distill one pair of maximally entangled logic Bell state from two same pairs of less-entangled logic Bell states. Benefit from the nondemolition PPC gates, the concentrated maximally entangled logic Bell state can be remained for further application. Moreover, our ECP can be repeated to further concentrate the less-entangled logic Bell state. By repeating the ECP, the total success probability can be effectively increased. Based on above features, this ECP may be useful in future long-distance quantum communication.
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Optomechanical properties of a degenerate nonperiodic cavity chain
Miao-Miao Zhao, Zhuo Qian, Bang-Pin Hou, Yong Liu, Yong-Hong Zhao
Frontiers of Physics. 2019, 14 (2 ): 22601-.
https://doi.org/10.1007/s11467-019-0898-z
The absorption of single-cavity and double-cavity optomechanical systems and periodic optomechanical lattices has previously been investigated extensively. In this paper, we present the absorption of a nonperiodic cavity chain, where the absorption value on the resonance point shows switchable dips or peaks, according to whether the optomechanical interaction is at an odd or even-numbered position in the chain. Meanwhile, the value of absorption due to the optomechanical interaction varies with the number of the bare cavities. The calculated results may have some novel applications, such as detecting the position of the movable mirror in a long cavity chain, which would be useful in quantum information processing based on optomechanical systems.
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Finite temperature physics of 1D topological Kondo insulator: Stable Haldane phase, emergent energy scale and beyond
Yin Zhong, Qin Wang, Yu Liu, Hai-Feng Song, Ke Liu, Hong-Gang Luo
Frontiers of Physics. 2019, 14 (2 ): 23602-.
https://doi.org/10.1007/s11467-018-0868-x
In recent years, interacting topological insulators have emerged as new frontiers in condensed matter physics, and the hotly studied topological Kondo insulator (TKI) is one of such prototypes. Although its zero-temperature ground-state has been widely investigated, the finite temperature physics on TKI is largely unknown. Here, we explore the finite temperature properties in a simplified model for TKI, namely the one-dimensional p -wave periodic Anderson model, with numerically exact determinant quantum Monte Carlo simulation. It is found that the topological Haldane phase established for groundstate is still stable against small thermal fluctuation and its characteristic edge magnetization develops at low temperature. Such facts emphasize the robustness of (symmetry-protected) topological order against temperature effect, which always exists at real physical world. Moreover, we use the saturated low-T spin structure factor and the 1 T -law of susceptibility to detect the free edge spin moment, interestingly the low-temperature upturn behavior of the latter one is similar to experimental finding in SmB6 at T <50 K. It implies that similar physical mechanism may work both for idealized models and realistic correlated electron materials. We have also identified an emergent energy scale T cr , which signals a crossover into interesting low-T regime and seems to be the expected Ruderman–Kittel–Kasuya–Yosida coupling. Finally, the collective Kondo screening effect has been examined and it is heavily reduced at boundary, which may give a fruitful playground for novel physics beyond the wellestablished Haldane phase and topological band insulators.
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A two-density approach to the general many-body problem and a proof of principle for small atoms and molecules
Thomas Pope, Werner Hofer
Frontiers of Physics. 2019, 14 (2 ): 23604-.
https://doi.org/10.1007/s11467-018-0872-1
An extended electron model fully recovers many of the experimental results of quantum mechanics while it avoids many of the pitfalls and remains generally free of paradoxes. The formulation of the manybody electronic problem here resembles the Kohn–Sham formulation of standard density functional theory. However, rather than referring electronic properties to a large set of single electron orbitals, the extended electron model uses only mass density and field components, leading to a substantial increase in computational efficiency. To date, the Hohenberg–Kohn theorems have not been proved for a model of this type, nor has a universal energy functional been presented. In this paper, we address these problems and show that the Hohenberg–Kohn theorems do also hold for a density model of this type. We then present a proof-of-concept practical implementation of this method and show that it reproduces the accuracy of more widely used methods on a test-set of small atomic systems, thus paving the way for the development of fast, efficient and accurate codes on this basis.
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Linear dipole behavior of single quantum dots encased in metal oxide semiconductor nanoparticles films
Guo-Feng Zhang, Yong-Gang Peng, Hai-Qing Xie, Bin Li, Zhi-Jie Li, Chang-Gang Yang, Wen-Li Guo, Cheng-Bing Qin, Rui-Yun Chen, Yan Gao, Yu-Jun Zheng, Lian-Tuan Xiao, Suo-Tang Jia
Frontiers of Physics. 2019, 14 (2 ): 23605-.
https://doi.org/10.1007/s11467-018-0874-z
Understanding of charge/energy exchange processes and interfacial interactions that occur between quantum dots (QDs) and the metal oxides is of critical importance to these QD-based optoelectronic devices. This work reports on linear dipole behavior of single near-infrared emitting CdSeTe/ZnS core/shell QDs which are encased in indium tin oxide (ITO) semiconductor nanoparticles films. A strong polarization anisotropy in photoluminescence emission is observed by defocused wide-field imaging and polarization measurement techniques, and the average polarization degree is up to 0.45. A possible mechanism for the observation is presented in which the electrons, locating at single QD surface from ITO by electron transfer due to the equilibration of the Fermi levels, result in a significant Stark distortion of the QD electron/hole wavefunctions. The Stark distortion results in the linear polarization property of the single QDs. The investigation of linear dipole behavior for single QDs encased in ITO films would be helpful for further improving QD-based device performance.
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On the existence of N *(890) resonance in S 11 channel of πN scatterings
Yu-Fei Wang, De-Liang Yao, Han-Qing Zheng
Frontiers of Physics. 2019, 14 (2 ): 24501-.
https://doi.org/10.1007/s11467-018-0877-9
Low-energy partial-wave πN scattering data is reexamined with the help of the production representation of partial-wave S matrix, where branch cuts and poles are thoroughly under consideration. The left-hand cut contribution to the phase shift is determined, with controlled systematic error estimates, by using the results of O (p 3 ) chiral perturbative amplitudes obtained in the extended-onmass- shell scheme. In S 11 and P 11 channels, severe discrepancies are observed between the phase shift data and the sum of all known contributions. Statistically satisfactory fits to the data can only be achieved by adding extra poles in the two channels. We find that a S 11 resonance pole locates at z r = (0.895±0.081)−(0.164±0.023)i GeV, on the complex s -plane. On the other hand, a P 11 virtual pole, as an accompanying partner of the nucleon bound-state pole, locates at z v = (0.966±0.018) GeV, slightly above the nucleon pole on the real axis below threshold. Physical origin of the two newly established poles is explored to the best of our knowledge. It is emphasized that the O (p 3 ) calculation greatly improves the fit quality comparing with the previous O (p 2 ) one.
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