A refined structural analysis of the PTCDA monolayer on the reconstructed Au(1 1 1) surface—“Rigid or distorted carpet?”

The superstructures (H1 and H2) of perylenetetracarboxylicacid-dianhydride (PTCDA) monolayers on the reconstructed Au(1 1 1) surface reported by Mannsfeld et al. [S. Mannsfeld, M. Toerker, T. Schmitz-Hübsch, F. Sellam, T. Fritz, K. Leo, Org. Electron. 2 (2001) 121] are reinvestigated by high resolution low energy electron diffraction (SPALEED). The purpose of this investigation is to elucidate in detail the point-on-line (p-o-l) structural relation of the homogeneous adsorbate layer with respect to the three reconstruction domains of the Au(1 1 1) surface. For the H2 (non-equilibrium) structure, diffraction patterns without a spot splitting are found, indicating an almost perfect undisturbed overgrowth of the domain boundaries of the reconstruction. As a consequence, the superstructure does not follow strictly the p-o-l relation, but only in an averaged manner. Contrary for the H1 phase (equilibrium structure), a spot splitting is observed, which indicates that superstructure domains on different Au(1 1 1) reconstruction domains exhibit slightly different angular orientations, thus adopting p-o-l relations on all Au(1 1 1) reconstruction domains. The PTCDA layer on Au(1 1 1) may be thus considered as a rigid or distorted carpet, depending on the preparation conditions.     

Reply to: “Comment on: ‘Exposed-key weakness of αη’ [Phys. Lett. A 370 (2007) 131]” [Phys. Lett. A 372 (2008) 7091]

We present simulations countering the claims in [R. Nair, H.P. Yuen, Phys. Lett. A 372 (2008) 7091] that the approximation given in [C. Ahn, K. Birnbaum, Phys. Lett. A 370 (2007) 131, quant-ph/0612058] for the eavesdropper's entropy on the encrypted key cannot be valid, and additionally discuss ways in which our views on security requirements differ from those given in [R. Nair, H.P. Yuen, Phys. Lett. A 372 (2008) 7091].     

Erratum to “Effect of the time-dependent coupling on a superconducting qubit-field system under decoherence: Entanglement and Wehrl entropy” [Ann. Physics 361 (2015) 247–258]

The dynamics of a superconducting (SC) qubit interacting with a field under decoherence with and without time-dependent coupling effect is analyzed. Quantum features like the collapse–revivals for the dynamics of population inversion, sudden birth and sudden death of entanglement, and statistical properties are investigated under the phase damping effect. Analytic results for certain parametric conditions are obtained. We analyze the influence of decoherence on the negativity and Wehrl entropy for different values of the physical parameters. We also explore an interesting relation between the SC-field entanglement and Wehrl entropy behavior during the time evolution. We show that the amount of SC-field entanglement can be enhanced as the field tends to be more classical. The studied model of SC-field system with the time-dependent coupling has high practical importance due to their experimental accessibility which may open new perspectives in different tasks of quantum formation processing.