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In traditional Hanbury Brown and Twiss (HBT) schemes, the thermal intensity-intensity correlations are phase insensitive. Here we propose a modified HBT scheme with phase conjugation to demonstrate the phase-sensitive and nonfactorizable features for thermal intensity-intensity correlation speckle. Our scheme leads to results that are similar to those of the two-photon speckle. We discuss the possibility of the experimental realization. The results provide us a deeper insight of the thermal correlations and may lead to more significant applications in imaging and speckle technologies.
208 - Li-Gang Wang , Shi-Yao Zhu , 2013
We investigate the Goos-H{a}nchen (GH) shifts of partially coherent fields (PCFs) by using the theory of coherence. We derive a formal expression for the GH shifts of PCFs in terms of Mercers expansion, and then clearly demonstrate the dependence of the GH shift of each mode of PCFs on spatial coherence and beam width. We discuss the effect of spatial coherence on the resultant GH shifts, especially for the cases near the critical angles, such as totally reflection angle.
149 - Li-Gang Wang , Shi-Yao Zhu , 2013
This comment is to show that our simulation data, based on our theory and method in Ref. [J. Phys. B 41, 055401 (2008)], are also in agreement with the experimental data presented for $D_{p}-D_{s}$ in Ref. [Phys. Rev. Lett. textbf{109}, 213901 (2012) ]. We also demonstrate how to show the effect of spatial coherence on the GH shifts in this comment, therefore we disagree with the claims in Ref. [Phys. Rev. Lett. textbf{109}, 213901 (2012)].
181 - Li-Gang Wang 2011
It is shown that the spatial Goos-Hanchen shift is greatly affected by spatial coherence. A typical example is given.
We study the quantum Zeno effect (QZE) in two many-body systems, namely the one-dimensional transverse-field Ising model and the Lipkin-Meshkov-Glick (LMG) model, coupled to a central qubit. Our result shows that in order to observe QZE in the Ising model, the frequency of the projective measurement should be of comparable order to that of the system sizes. The same criterion also holds in the symmetry broken phase of the LMG model while in the models polarized phase, the QZE can be easily observed.
116 - Li-Gang Wang , Yuen-Chi Tse , 2011
We have theoretically investigated the properties of electronic transport in graphene heterostructures, which are consisted of two different graphene superlattices with one-dimensional periodic potentials. It is found that such heterostructures posse ss an unusual tunneling state occurring inside the original forbidden gaps, and the electronic conductance is greatly enhanced and Fano factor is strongly suppressed near the energy of the tunneling state. Finally we present the matching condition of the impedance of the pseudospin wave for occuring the tunneling state by using the Bloch-wave expansion method.
133 - Li-Gang Wang , Xi Chen 2010
In this paper, the electronic band structures and its transport properties in the gapped graphene superlattices, with one-dimensional (1D) periodic potentials of square barriers, are systematically investigated. It is found that a zero averaged wave- number (zero-$overline{k}$ ) gap is formed inside the gapped graphene-based superlattices, and the condition for obtaining such a zero-$overline{k}$ gap is analytically presented. The properties of this zero-$overline{k}$ gap including its transmission, conductance and Fano factor are studied in detail. Finally it is revealed that the properties of the electronic transmission, conductance and Fano factor near the zero-$overline{k}$ gap are very insensitive to the structural disorder for the finite graphene-based periodic-barrier systems.
50 - Li-Gang Wang , Shi-Jian Gu , 2010
In this brief report, we present a proposal to observe the classical zeno effect via the frequent measurement in optics.
As a classical state, for instance a digitized image, is transferred through a classical channel, it decays inevitably with the distance due to the surroundings interferences. However, if there are enough number of repeaters, which can both check and recover the states information continuously, the states decay rate will be significantly suppressed, then a classical Zeno effect might occur. Such a physical process is purely classical and without any interferences of living beings, therefore, it manifests that the Zeno effect is no longer a patent of quantum mechanics, but does exist in classical stochastic processes.
85 - Li-Gang Wang , Zhi-Guo Wang , 2008
The Dirac point with a double-cone structure for optical fields, an optical analogy Dirac fermions in graphene, can be realized in optically homogenous metamaterials. The condition for the realization of Dirac point in optical systems is the varying of refractive index from negative to zero and then to positive. Our analytical and numerical analysis have verified that, similar to electrons in graphene, the light field near the Dirac point possesses of the pseudodiffusive property, obeying the 1/L scaling law, where L is the propagating distance of light inside the media.
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