A suggested experiment to distinguish between the Bohmian Interpretation and the Standard Quantum Mechanics

Based on the double-slit experiment of electrons, we suggest a proposal of thought experiment to distinguish between the Bohmian Interpretation (BI) and the Standard Quantum Mechanics (SQM). We mainly focus on the discussion of the meaning of the wave function (Schr\"{o}dinger-$\psi$). The key technique is require to insert some slow-electrons or weak electron current into the space between the double-slit and the detector plane. We find that the two theories finally give out two totally different results about the affections which the externally inserted electrons cause to the original pattern of the interference fringes. Under the BI, the externally inserted electrons also can be influenced by the Quantum Potential (QP) in a totally same way with the electrons which come from the slits, so the positions they arrived at are preferred to certain bright zones, and the interference pattern will become more clearer. While under the SQM, the Schr\"{o}dinger-$\psi$ does not represent an objectively real field, but only a mathematical construction of the probability characteristics of the particle itself, so the externally inserted electrons and the electrons which come from the slits have no correlations with each other. No any priority positions at the detector plane the externally inserted electrons will arrive. And the affections are only the addition of a uniform bright background. In such a meaning, the dark zones of the fringes of the interference pattern have been filled.Comment: 9 pages, 3 figure

The role of the non-Gaussianity plays in the enhancement of the fidelity in continuous variable quantum teleportation

We investigated the role of non-Gaussianity (nG) plays in the enhancement of the fidelity in continuous-variable quantum teleportation of ideal Braunstein and Kimble (BK) protocol for coherent states, theoretically. The de-Gaussification procedure is realized through subtracting photons on the two-mode squeezed vacuum state (TMSVs). We find that the high fidelity always refers to a symmetrical arrangement of photon subtractions on the different modes of the TMSVs. The non-Gaussian resources demonstrate commendable superiorities compare with the Gaussian resources only for symmetrical arrangements of photon subtractions, however, the asymmetrical arrangements do not. When the total number of photon subtractions be a constant, we find that the optimal nG procedure prefers the most asymmetrical arrangement of subtractions. This characteristic is not consistent with the result that the highest fidelity refers to a symmetrical case. Under the same squeezing parameter, a higher nG might not always lead to a higher fidelity.Comment: updated to published version, some references are adde

Nonlinear bias dependence of spin-transfer torque from atomic first principles

We report first-principles analysis on the bias dependence of spin-transfer torque (STT) in Fe/MgO/Fe magnetic tunnel junctions. The in-plane STT changes from linear to nonlinear dependence as the bias voltage is increased from zero. The angle dependence of STT is symmetric at low bias but asymmetric at high bias. The nonlinear behavior is marked by a threshold point in the STT versus bias curve. The high-bias nonlinear STT is found to be controlled by a resonant transmission channel in the anti-parallel configuration of the magnetic moments. Disorder scattering due to oxygen vacancies in MgO significantly changes the STT threshold bias.Comment: 6page,4figure

Thermal induced monochromatic microwave generation in magnon-polariton

We propose thermal induced generation of monochromatic microwave radiation in magnon-polariton. Mechanism of thermal to microwave energy transformation is based on intrinsic energy loss compensation of coupled magnon and microwave cavity oscillators by thermal induced "negative damping". A singularity at an exceptional point is achieved when at the critical value of "negative damping" the damping of the system is fully compensated. At the exceptional point, the input energy is equally distributed between the magnon and photon subsystems of the magnon-polariton. The efficiency of transformation of thermal energy into useful microwave radiation is estimated to be as large as 17 percent due to magnon-photon coupling mediated direct conversation of spin current into microwave photons

Viscous boundary layer properties in turbulent thermal convection in a cylindrical cell: the effect of cell tilting

We report an experimental study of the properties of the velocity boundary layer in turbulent Rayleigh-B\'{e}nard convection in a cylindrical cell. The measurements were made at Rayleigh numbers $Ra$ in the range $2.8\times10^{8}<Ra<5.6\times10^{9}$ and were conducted with the convection cell tilted with an angle $\theta$ relative to gravity, at $\theta=0.5^{o}$, $1.0^{o}$, $2.0^{o}$, and $3.4^{o}$, respectively. The fluid was water with Prandtl number $Pr=5.3$. It is found that at small tilt angles ($\theta \le 1^{o}$), the measured viscous boundary layer thickness $\delta_{v}$ scales with the Reynolds number $Re$ with an exponent close to that for a Prandtl-Blasius laminar boundary layer, i.e. $\delta_{v} \sim Re^{-0.46\pm0.03}$. For larger tilt angles, the scaling exponent of $\delta_{v}$ with $Re$ decreases with $\theta$. The normalized mean horizontal velocity profiles measured at the same tilt angle but with different $Ra$ are found to have an invariant shape. But for different tilt angles, the shape of the normalized profiles is different. It is also found that the Reynolds number $Re$ based on the maximum mean horizontal velocity scales with $Ra$ as $Re \sim Ra^{0.43}$ and the Reynolds number $Re_{\sigma}$ based on the maximum rms velocity scales with $Ra$ as $Re_{\sigma} \sim Ra^{0.55}$, with both exponents do not seem to depend on the tilt angle $\theta$. We also examined the dynamical scaling method proposed bys Zhou and Xia [Phys. Rev. Lett. 104, 104301 (2010)] and found that in both the laboratory and the dynamical frames the mean velocity profiles show deviations from the theoretical Prandtl-Blasius profile, with the deviations increase with $Ra$. But profiles obtained from dynamical scaling in general have better agreement with the theoretical profile. It is also found that the effectiveness of this method appears to be independent of $Ra$.Comment: 28 pages,23 figure

On the Kolmogorov Constants for the Second-Order Structure Function and the Energy Spectrum

We examine the behavior of the Kolmogorov constants C_2, C_k, and C_{k1}, which are, respectively, the prefactors of the second order longitudinal structure function, the three dimensional and one-dimensional longitudinal energy spectrum in the inertial range. We show that their ratios, C_2/C_{k1} and C_k/C_{k1}, exhibit clear dependence on the micro-scale Reynolds number R_{\lambda}, implying that they cannot all be independent of R_{\lambda}. In particular, it is found that (C_{k1}/C_2-0.25) = 1.95R_{\lambda}^{-0.68}. The study further reveals that the widely-used relation C_2 = 4.02 C_{k1} holds only asymptotically when R_{\lambda} <= 10^5. It is also found that C_2 has much stronger R_{\lambda}-dependence than either C_k, or C_{k1} if the latter indeed has a systematic dependence on R_{\lambda}. We further show that the variable dependence on R_{\lambda} of these three numbers can be attributed to the difference of the inertial range in real- and wavenumber-space, with inertial range in real-space known to be much shorter than that in wavenumber space.Comment: 10 pages, 4 figures. Journal of Fluid Mechanics format (JFM.cls

Hawking Radiation as tunneling and the unified first law of thermodynamics for a class of dynamical black holes

An analysis of relations between the tunneling rate and the unified first law of thermodynamics at the trapping horizons of two kinds of spherically symmetric dynamical black holes is investigated. The first kind is the Vaidya-Bardeen black hole, the tunneling rate $\Gamma \sim e^{\triangle S}$ can be obtained naturally from the unified first law at the apparent horizon, which holds the form $dE_{H}=TdS+WdV$. Another is the McVittie solution, the action of the radial null geodesic of the outgoing particles does not always has a pole at the apparent horizon, while the ingoing mode always has one. The solution of the ingoing mode of the radiation can be mathematically reduced to the case in the FRW universe smoothly. However as a black hole, the physical meaning is unclear and even puzzling.Comment: 13 pages, no figure

Dynamics and flow-coupling in two-layer turbulent thermal convection

We present an experimental investigation of the dynamics and flow-coupling of convective turbulent flows in a cylindrical Rayleigh-Benard convection cell with two immiscible fluids, water and fluorinert FC-77 electronic liquid (FC77). It is found that one large-scale circulation (LSC) roll exists in each of the fluid layers, and that their circulation planes have two preferred azimuthal orientations separated by $\sim\pi$. A surprising finding of the study is that cessations/reversals of the LSC in FC77 of the two-layer system occur much more frequently than they do in single-layer turbulent RBC, and that a cessation is most likely to result in a flow reversal of the LSC, which is in sharp contrast with the uniform distribution of the orientational angular change of the LSC before and after cessations in single-layer turbulent RBC. This implies that the dynamics governing cessations and reversals in the two systems are very different. Two coupling modes, thermal coupling (flow directions of the two LSCs are opposite to each other at the fluid-fluid interface) and viscous coupling (flow directions of the two LSCs are the same at the fluid-fluid interface), are identified with the former one as the predominant mode. That most cessations (in the FC77 layer) end up as reversals can be understood as a symmetry breaking imposed by the orientation of the LSC in the water layer, which remained unchanged most of the time. Furthermore, the frequently occurring cessations and reversals are caused by the system switching between its two metastable states, i.e. thermal and viscous coupling modes. It is also observed that the strength of the LSC in water becomes weaker when the LSC in FC77 rotates faster azimuthally and that the flow strength in FC77 becomes stronger when the LSC in water rotates faster azimuthally, i.e. the influence of the LSC in one fluid layer on the other is not symmetric.Comment: 13 pages, 8 figure

Turbulent thermal convection over rough plates with varying roughness geometries

We present a systematic investigation of the effects of roughness geometry on turbulent Rayleigh-B\'enard convection (RBC) over rough plates with pyramid-shaped and periodically distributed roughness elements. Using a parameter $\lambda$ defined as the height of a roughness element over its base width, the heat transport, the flow dynamics and local temperatures are measured for the Rayleigh number range $7.50\times 10^{7} \leq Ra\leq 1.31\times 10^{11}$, and the Prandtl number $Pr$ from 3.57 to 23.34 at four values of $\lambda$. It is found that the heat transport scaling, i.e. $Nu\sim Ra^{\alpha}$ where $Nu$ is the Nusselt number, may be classified into three regimes. In Regime I, the system is in a dynamically smooth state. The heat transport scaling is the same as that in a smooth cell. In Regimes II and III, the heat transport enhances. When $\lambda$ is increased from 0.5 to 4.0, $\alpha$ increases from 0.36 to 0.59 in Regime II, and it increases from 0.30 to 0.50 in Regime III. The experiment demonstrates the heat transport scaling in turbulent RBC can be manipulated using $\lambda$. Previous studies suggest that the transition from Regime I to Regime II, occurs when the thermal boundary layer (BL) thickness becomes smaller than the roughness height $h$. Direct measurements of the viscous BL in the present study suggest that the transition from Regime II to Regime III is likely a result of the viscous BL thickness becoming smaller $h$. The scaling exponent of the Reynolds number $Re$ vs. $Ra$ changes from 0.471 to 0.551 when $\lambda$ is increased from 0.5 to 4.0. It is also found that increasing $\lambda$ increases the clustering of thermal plumes which effectively increases the plumes lifetime that are ultimately responsible for the enhanced heat transport.Comment: 27 pages, 19 figure

Suppressing correlated noise in signals transmitted over the Gaussian memory channels using 2N2N-port splitter and phase flips

A scheme for suppressing the correlated noise in signals transmitted over the bosonic Gaussian memory channels is proposed. This is a compromise solution rather than removing the noise completely. The scheme is based on linear optical elements, two $N$-port splitters and $N$ number of phase flips. The proposed scheme has the advantages that the correlated noise of the memory channels are greatly suppressed, and the input signal states can be protected excellently when transmitting over the noise channels. We examine the suppressing efficiency of the scheme for the correlated noise, both from quantum information of the states directly transmitted through the noise channel and also from the entanglement teleportation. The phase flips are very important aspects for the suppressions of the correlated noise, which transform the roles of the memory factor from completely negative to positive in quantum information communications. Increasing the number of beam splitters also can improve the suppressing efficiency of the scheme in communications.Comment: 10 pages, 23 figures. Accepted version, accepted for publication in Phys. Rev.