共查询到20条相似文献,搜索用时 15 毫秒
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We study the formation of dark states and the Aharonov-Bohm effect in symmetrically/asymmetrically coupled three-and four-quantum-dot systems.It is found that without a transverse magnetic field,destructive interference can trap an electron in a dark state.However,the introduction of a transverse magnetic field can disrupt the dark state,giving rise to oscillation in current.For symmetrically structured quantum-dot systems,the oscillation has a period of one flux quanta.But for asymmetrically structured dot systems,the period of oscillation is halved.In addition,the dephasing due to charge noise also blocks the formation of dark states,while it does not change the period of oscillation. 相似文献
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CHEN Ai-xi DENG Li 《原子与分子物理学报》2006,23(B04):111-115
The theoretical investigation of quantum coherent atomic oscillations between two coupled Bose-Eimtein condensates(BECs) is studied. We apply the inseparable wave function of time-space to describe twotrapped BECs in a double-well magnetic trap. According to Thomas-Fermi approximation, dynamical equations ofthe interwell phase difference and population imbalance are obtained. Using numerical method, coherent atomictunneling and macroscopic quantum self-trapping(MQST) effect are investigated. 相似文献
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The theoretical investigation of quantum coherent atomic oscillations between two coupled Bose-Einstein condensates(BECs) is studied. We apply the inseparable wave function of time-space to describe two trapped BECs in a double-well magnetic trap. According to Thomas-Fermi approximation, dynamical equations of the interwell phase difference and population imbalance are obtained. Using numerical method, coherent atomic tunneling and macroscopic quantum self-trapping(MQST) effect are investigated. 相似文献
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L.S. Vaidhyanathan M.P. Janawadkar 《Physica C: Superconductivity and its Applications》2010,470(17-18):693-695
Resistance oscillations as a function of magnetic field were observed in superconductor–magnetic tunnel junctions of Nb–Fe–FeOx–SiO2–Au–Nb. Junctions involving superconductor–magnetic layer superconductor system are exciting because for certain regime of ferromagnetic layer thickness, a Josephson coupling with an intrinsic phase difference of π might be stabilized. For fabrication of the tunnel junctions the thin films were deposited by RF/DC magnetron sputtering. Using photolithography and reactive ion etching, square junctions of size varying from 50 μm to 250 μm were defined. I–V characteristics and R vs. H characteristics were studied at 4.2 K. When the magnetic field is applied parallel to the junction plane, measurements of the junction resistance as a function of magnetic field at a fixed temperature show resistance peaks whenever the total magnetic flux through the junction equals an integral multiple of flux quantum. The penetration depth of the superconducting electrodes was estimated from the positions of the resistance peaks. 相似文献
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We discuss the phenomenological implications of the neutron (n) oscillation into the mirror neutron (n'), a hypothetical particle exactly degenerate in mass with the neutron but sterile to normal matter. We show that the present experimental data allow a maximal n-n' oscillation in vacuum with a characteristic time tau much shorter than the neutron lifetime, in fact as small as 1 sec. This phenomenon may manifest in neutron disappearance and regeneration experiments perfectly accessible to present experimental capabilities and may also have interesting astrophysical consequences, in particular, for the propagation of ultra high energy cosmic rays. 相似文献
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Debashis Gangopadhyay Animesh Sinha Roy 《The European Physical Journal C - Particles and Fields》2017,77(4):260
Three-flavoured neutrino oscillations are investigated in the light of the Leggett–Garg inequality (LGI). The results obtained are: (a) The maximum violation of the LGI is 2.17036 for neutrino path length \(L_{1}=140.15 \) km and \(\Delta L=1255.7 \) km. (b) The presence of the mixing angle \(\theta _{13}\) enhances the maximum violation of LGI by \(4.6\%\). (c) The currently known mass hierarchy parameter \(\alpha = 0.0305\) increases the maximum violation of LGI by \(3.7\%\). (d) The presence of a CP-violating phase parameter enhances the maximum violation of LGI by \(0.24\%\), thus providing an alternative indicator of CP violation in three-flavoured neutrino oscillations. The outline of an experimental proposal is suggested whereby the findings of this investigation may be verified. 相似文献
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We report temperature cross correlation and velocity profile measurements in the aspect-ratio-one convection cell filled with water. A sharp transition from a random chaotic state to a correlated turbulent state of finite coherence time is found when the Rayleigh number becomes larger than a critical value Ra(c) approximately equal to 5 x 10(7). The experiment reveals a unique mechanism for the onset of coherent oscillations in turbulent Rayleigh-Bénard convection. 相似文献
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Along the geodesic we calculate the interference phase of the mass neutrinos propagating in the radial direction in the Reissner-Nordstrom field. From the calculation we find that, though there exists electric charge in the gravitational source, the phase increases very little compared with that in the Schwarzschild field. 相似文献
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《Physics letters. [Part B]》2006,642(4):372-376
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Shao-Long Chen Xiao-Gang He Xue-Qian Li Ho-Chin Tsai Zheng-Tao Wei 《The European Physical Journal C - Particles and Fields》2009,59(4):899-906
Unparticles have dramatic effects on particle and antiparticle oscillations in meson–antimeson and muonium–antimuonium systems.
Unlike the usual tree-level contributions to meson oscillations from heavy-particle exchange, which results in a small Γ
12, the unparticle may have sizeable contributions to both M
12 and Γ
12 due to the fractional dimension
of the unparticle. If the unparticle effect dominates the contributions (which may happen in D
0–
mixing) to the meson mixing parameters x and y, we find that
. The mass difference Δm in meson mixing can provide interesting constraints on the unparticle interactions. The unparticle interaction can significantly
enhance the CP asymmetry in meson mixing, which can be tested in more accurate experiments in the future. Interesting constraints
on unparticle and particle interactions can also be obtained using muonion and antimuonion oscillation data. 相似文献
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We study the collective dynamics in a degenerate Bose–Fermi mixture of 174Yb and 173Yb atoms. We excite collective oscillations by a sudden reduction of the trapping confinement and observe low m=0 quadrupole oscillations of condensates in 174Yb. First the oscillations in 174Yb atoms alone are investigated, and they are well described by the time-dependent Gross–Pitaevskii equation in the Thomas–Fermi approximation. Using the same procedure the quadrupole oscillations are excited for a 174Yb–173Yb Bose–Fermi mixture. In comparing data taken with and without fermionic 173Yb atoms, the oscillation frequency of the quadrupole mode in the condensate decreases with the presence of 173Yb atoms. 相似文献
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We report on experiments investigating quantum transport and band interferometry of an atomic Bose-Einstein condensate in an optical lattice with a two-band miniband structure, realized with a Fourier-synthesized optical lattice potential. Bloch-Zener oscillations, the coherent superposition of Bloch oscillations and Landau-Zener tunneling between the two bands, are observed. When the relative phase between paths in different bands is varied, an interference signal is observed, demonstrating the coherence of the dynamics in the miniband system. Measured fringe patterns of this Stückelberg interferometer allow us to interferometrically map out the band structure of the optical lattice over the full Brillouin zone. 相似文献
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A. Smerzi S. Raghavan S. Fantoni S.R. Shenoy 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,24(4):431-435
Oscillations in quantum phase about a mean value of π, observed across micropores connecting two
3
He
-
B
baths, are explained in a Ginzburg-Landau phenomenology. The dynamics arises from the Josephson phase relation,the interbath
continuity equation, and helium boundary conditions. The pores are shown to act as Josephson tunnel junctions, and the dynamic
variables are the inter bath phase difference and fractional difference in superfluid density at micropores. The system maps
onto a non-rigid, momentum-shortened pendulum, with inverted-orientation oscillations about a vertical tilt angle φ = π, and other modes are predicted.
Received 19 March 2001 相似文献
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A class of recharge–discharge oscillator model for the El Ni?o/Southern Oscillation (ENSO) is considered. A stable limit cycle is obtained by transforming the ENSO model into the van der Pol-Duffing equation. We proved that there exists periodic oscillations in the ENSO recharge–discharge oscillator model. 相似文献
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《Nuclear Physics B》1998,524(3):505-523
We consider the “standard” spectrum of the active neutrinos (characterized by strong mass hierarchy and small mixing) with additional sterile neutrino, vs. The sterile neutrino mixes strongly with the muon neutrino, so that vμ ↔ vs oscillations solve the atmospheric neutrino problem. We show that the parametric enhancement of the vμ ↔ vs oscillations occurs for the high energy atmospheric neutrinos which cross the core of the Earth. This can be relevant for the anomaly observed by the MACRO experiment. Solar neutrinos are converted both to vμand vs. The heaviest neutrino (≈ vτ) may compose the hot dark matter of the Universe. The phenomenology of this scenario is elaborated and crucial experimental signatures are identified. We also discuss properties of the underlying neutrino mass matrix. 1998 Published by Elsevier Science B.V. 相似文献