Exact Entanglement dynamics in Three Interacting Qubits

Motivated by recent experimental study on coherent dynamics transfer in three interacting atoms or electron spins \cite{Barredo:2015,Rosenfeld:2018}, here we study entanglement entropy transfer in three interacting qubits. We analytically calculate time evolutions of wave function, density matrix and entanglement of the system. We find that initially entangled two qubits may alternatively transfer their entanglement entropy to other two qubit pairs. So that dynamical evolution of three interacting qubits may produce a genuine three-partite entangled state through entanglement entropy transfers. In particular, different pairwise interactions of the three qubits endow symmetric and asymmetric evolutions of the entanglement transfer, characterized by the quantum mutual information and concurence. Finally, we discuss an experimental proposal of three Rydberg atoms for testing the entanglement dynamics transfer of this kind.Comment: 6 pages + 5 figure

Laboratory Evaluation of Unbound RAP as a Pavement Base Material

More than 50 million tons of asphalt pavements are milled every year in the United States (Taha 1999). The economical benefit attracts the recycling practice of utilizing RAP as paving materials. In unbound RAP material, aged asphalt wraps aggregates. It is believed that unbound RAP performs differently from usual unbound material due to the existence of asphalt wrap. In the present study, triaxial tests were conducted for the unbound RAP under different temperatures. In addition, limestone and gravel were tested in order to compare with RAP. The resilient modulus, triaxial static creep behavior and hysteresis loops were obtained to compare the differences between the unbound RAP, limestone and gravel. The specimens were prepared at optimum moisture content and equivalent compaction work. The laboratory results indicated the RAP characteristics change with different temperature. It was found that RAP requires more compaction work than limestone and gravel. According to AASHTO 307-99, higher resilient moduli were obtained in RAP than limestone and gravel. However, larger permanent deformation was observed in RAP. Specific design consideration should be added for utilizing RAP as base material. As part of my graduate research, finite element analysis was conducted for pile foundation over cavernous bedrock and for an Accelerated Loading Facility (ALF) in Louisiana Transportation Research Center (LTRC). The FE simulations were attached in Appendices

Harmonisch modengekoppelter Faserlaser mit GHz Wiederholungsrate unter Verwendung optoakustischer Effekte in photonischen Kristallfasern

This work is concerned with the use of enhanced optoacoustic interactions in the solid-core photonic crystal fibre (PCF) for achieving stable passive high-harmonic mode-locked (HHML) fibre lasers that can generate GHz-rate pulse trains and other types of long-range bound-states of solitons. This specially-designed solid-core PCF, with hollow-channels that surround the µm-sized core, is able to confine both the acoustic mode and the optical mode tightly within the fibre core, leading to a GHz-rate optoacoustic interaction that is about two orders-of-magnitude stronger than in the conventional all-solid fibres. By inserting a short piece of such PCF into a conventional passive mode-locked ring-fibre laser, the pulse repetition rate can be locked to the acoustic resonance, while being largely decoupled from the meters-long cavity length, resulting in hundreds of evenly-spaced pulses in the cavity. Such a pulse sequence can coherently drive an acoustic wave in the PCF, while the acoustic wave can act back on the pulse sequence through the opto-elastic effect. The acoustic wave then effectively forms an optoacoustic lattice which divides the cavity round-trip time into hundreds of time-slots. In each time-slot, a single-soliton can be trapped. The temporal trapping potentials, which are formed by the cooperation between the acoustic wave and the cavity group velocity dispersion, ensured the self-stabilized pulse spacings and highly suppressed the relative timing-jitter. Based on this optoacoustic mode-locking mechanism, a stable soliton fibre laser at GHz-rate has been achieved with a wideband tunability and low noise level. In addition, by combining the optoacoustic mode-locking scheme with a newly discovered stretched-soliton effect, a fibre laser with simultaneous GHz-repetition-rate and sub-100-fs pulse duration was realized at a moderate pump power. The multi-pulses that are locked through the optoacoustic interactions in the PCF are uncorrelated in phase relations due to the non-interferometric nature of optoacoustic mode-locking. Each pulse can be regarded as an independent sub-lase pulse and thus can be manipulated individually. Using a unique addressing-pulse technique, the intra-cavity pulses can be selectively erased. The remaining pulses that are invariantly trapped in the optoacoustic lattice form a stable optomechanical bound-state which be preserved in the cavity for indefinitely long time. The arbitrarily-controlled on-and off-states of the pulses in different time-slots of the optoacoustic lattice have led to the realization of an all-optical bit-storage in the fibre laser cavity. The interplay between the optoacoustic effects and the dispersive wave perturbations, both being weak long-range interactions between intra-cavity solitons, has led to the generation of stable supramolecular assemblies of optical solitons in the fibre laser. The balance between the carefully-tailored long-range forces of attraction and repulsion, induced by the optoacoustic effects and the dispersive wave perturbations respectively, has enabled stable binding of multi-solitons within each time-slot, while their internal spacings can be over a hundred times of their individual durations. A diversity of long-range bound-states of solitons trapped within different lattice periods have constituted a highly-ordered structure that is distributed throughout the entire laser cavity, with features that resemble the chemical supramolecules, including configurational diversity, reversibility, structural flexibility and dynamic stability