Modern Physics Letters B

Carbon nanotubes, nanometer-diameter tubes made of carbon atoms, have garnered significant attention from researchers over the past 15 years due to their outstanding properties such as excellent electronic transport characteristics and mechanical strength. Because of their ability to carry extremely high current densities, their high aspect ratio, and small tip radius that enhances an external electric field greatly, one particularly promising area of interest has been the usage of nanotubes as electron sources. In this article we will try to provide an overview of the subject from various experimental and theoretical angles.

Through the Radon transformation of the normally ordered Wigner operator we introduce two mutually conjugate intermediate coordinate-momentum representations. Based on them we construct the appropriate quantum phase space theory which includes the new Wigner operator adapting to this space. We find that the new Wigner function's marginal distribution for a state |Ψ〉 is just the quantum tomogram of the state |Ψ〉.

Based on the density matrix approach and iterative treatment, the third-harmonic generation (THG) susceptibility of a wurtzite nitride coupling quantum well (CQW) with strong built-in electric fields have been theoretically investigated. The band non-parabolicity effect of nitride heterostructures has been taken into account. A typical wurtzite AlGaN/GaN CQW are chosen to perform numerical calculations. The result shows that, the THG coefficients sensitively depend on the structural parameters of the CQW system. Moreover, a strong THG process can be realized in the nitride CQW by choosing a group of appropriate structural parameters and doped fraction.

In this paper, we proposed a protocol which can produce a perfect copy of an unknown bipartite three-dimension equatorial entangled state with assistance from a state preparer. In this protocol, the maximally entangled and non-maximally entangled two-qutrit states are used as the quantum channels, respectively. The first stage of the protocol requires the usual teleportation. In the second stage of the protocol, with the assistance of the preparer, the perfect copy of an original unknown state can be produced.

The intense ultrashort laser interacting with the thermonuclear fuel may produce a relativistic plasma and MeV electron beam, how to fix the Lorentz factors of the particles in the plasma and model the energy deposition of MeV electron beams are important subjects. In this letter, we demonstrate the exact relation between the average Lorentz factor and the temperature of the system; and then obtained the relativistic modified formula for the energy loss of the relativistic electron-beam due to binary electron-electron collisions. Another important energy loss mechanism, the excitation of Langmuir collective plasma oscillation, is also treated within the relativistic framework. Hence, we re-examine theoretically the possibility of igniting hot spots in the super-compressed DT target and the answer is that the fast ignitor scenario is able to yield thermonuclear ignition in the target.

The evolution of the current-voltage characteristic in K_0.3MoO₃ was observed intuitively with the presence of current cycling. No variation of the ohmic conductivity was distinguished, while the threshold field for the charge density waves depinning exhibited distinct enhancement with the current cycling. These results were attributed to the electric field-assisted metastable states' relaxation of the charge density waves.

Investigation of nonlinear absorption coefficient of eosin blue dye based side chain poly(methacrylate) films is presented using diode pumped Nd:YAG laser radiation (λ=532 nm) and the Z-scan technique. The effect of the concentration in polymer film and the increase in the number of methylene spacers, hooked to the eosin blue dye, on the nonlinear absorption coefficient is also discussed. It is shown that the nonlinear absorption coefficient in samples is due to the two-photon absorption effect. Moreover, the optical limiting characteristics of polymers film are explored.