Polarization and frequency disentanglement of photons via stochastic polarization mode dispersion

We investigate the quantum decoherence of frequency and polarization variables of photons via polarization mode dispersion in optical fibers. By observing the analogy between the propagation equation of the field and the Schr\"odinger equation, we develop a master equation under Markovian approximation and analytically solve for the field density matrix. We identify distinct decay behaviors for the polarization and frequency variables for single-photon and two-photon states. For the single photon case, purity functions indicate that complete decoherence for each variable is possible only for infinite fiber length. For entangled two-photon states passing through separate fibers, entanglement associated with each variable can be completely destroyed after characteristic finite propagation distances. In particular, we show that frequency disentanglement is independent of the initial polarization status. For propagation of two photons in a common fiber, the evolution of a polarization singlet state is addressed. We show that while complete polarization disentanglement occurs at a finite propagation distance, frequency entanglement could survive at any finite distance for gaussian states.Comment: 2 figure

Gamification for Teamwork Skills: Can a Challenge-based Online Tournament Help Students Learn New Knowledge Collaboratively in Teams?

The interest in deploying innovative technologies with gamification to engage student learning in enjoyable style has been growing. This study aimed to investigate whether a purposely designed eTournament with the integration of concepts of gamification and team development could help the participating tertiary education students (N=416) from a variety of backgrounds in terms of culture and discipline to learn to work in teams collaboratively in a challenge-based online game. The qualitative data collected from the top 10 teams’ online discussions supported that the thoughtful design of the eTournament did facilitate their development of teamwork skills. In addition, quantitative data collected from two of the Post-game Questionnaire questions indicated that over 79% of the respondents strongly agree or agree that they enjoyed the eTournamentin general, and over 84% of respondents strongly agree or agree that they become more aware of the seventeen United Nations Sustainable Development Goals because of the eTournament. Notwithstanding, findings in this study show little evidence in supporting team-playing in PaGamO due to the design of the game regardless of the teamwork skills developed in the early stage of the eTournament. Suggestions to address the limitations of this study are also presented for future improvement

Quantum fluctuations in coupled dark solitons in trapped Bose-Einstein condensates

We show that the quantum fluctuations associated with the Bogoliubov quasiparticle vacuum can be strongly concentrated inside dark solitons in a trapped Bose Einstein condensate. We identify a finite number of anomalous modes that are responsible for such quantum phenomena. The fluctuations in these anomalous modes correspond to the `zero-point' oscillations in coupled dark solitons.Comment: 4 pages, 3 figure

Statistics of level spacing of geometric resonances in random binary composites

We study the statistics of level spacing of geometric resonances in the disordered binary networks. For a definite concentration $p$ within the interval $[0.2,0.7]$, numerical calculations indicate that the unfolded level spacing distribution $P(t)$ and level number variance $\Sigma^2(L)$ have the general features. It is also shown that the short-range fluctuation $P(t)$ and long-range spectral correlation $\Sigma^2(L)$ lie between the profiles of the Poisson ensemble and Gaussion orthogonal ensemble (GOE). At the percolation threshold $p_c$, crossover behavior of functions $P(t)$ and $$ is obtained, giving the finite size scaling of mean level spacing $\delta$ and mean level number $n$, which obey the scaling laws, $$ and $n=0.911L^{1.970}$.Comment: 11 pages, 7 figures,submitted to Phys. Rev.

Investigating Mainstreaming Strategies of Hot Cryptocurrencies-wallet

The proliferation of cryptocurrencies in recent years has prompted the launching of many hot cryptocurrencies-wallets (known as hot crypto-wallet , permanently connected to the Internet) services to facilitate the management of cryptocurrencies assets. However, the dark side of cryptocurrencies, such as possible illegal activities and difficulties of key management, may hinder the broader cryptocurrency adoption. Therefore, some hot crypto-wallet services providers have adopted different measures to mainstream their services. Using a qualitative approach, we identified four mainstreaming strategies of hot crypto-wallet services, which may hint at some practical implications for hot cryptowallet service providers

Exploring the structure of digital literacy competence assessed using authentic software applications

Digital literacy competence (DL) is an important capacity for students' learning in a rapidly changing world. However, little is known about the empirical structure of DL. In this paper, we review major DL assessment frameworks and explore the dimensionality of DL from an empirical perspective using assessment data collected using authentic software applications, rather than simulated assessment environments. Secondary analysis on representative data collected from primary and secondary school students in Hong Kong using unidimensional and multidimensional item response theory reveals a general dimension of digital literacy performance and four specific, tool-dependent dimensions. These specific DL dimensions are defined by the software applications that students use and capture commonality among students' performance that is due to their familiarity with the assessment tools and contexts. The design of DL assessment is discussed in light of these findings, with particular emphasis on the influence of the nature of digital applications and environments used in assessment on the DL achievement scores measured

The quantum mechanical geometric phase of a particle in a resonant vibrating cavity

We study the general-setting quantum geometric phase acquired by a particle in a vibrating cavity. Solving the two-level theory with the rotating-wave approximation and the SU(2) method, we obtain analytic formulae that give excellent descriptions of the geometric phase, energy, and wavefunction of the resonating system. In particular, we observe a sudden $\pi$-jump in the geometric phase when the system is in resonance. We found similar behaviors in the geometric phase of a spin-1/2 particle in a rotating magnetic field, for which we developed a geometrical model to help visualize its evolution.Comment: 15pages,6figure

The Schrodinger particle in an oscillating spherical cavity

We study a Schrodinger particle in an infinite spherical well with an oscillating wall. Parametric resonances emerge when the oscillation frequency is equal to the energy difference between two eigenstates of the static cavity. Whereas an analytic calculation based on a two-level system approximation reproduces the numerical results at low driving amplitudes, epsilon, we observe a drastic change of behaviour when epsilon > 0.1, when new resonance states appear bearing no apparent relation to the eigenstates of the static system.Comment: 9 pages, 6 figures, corrected typo

Conformational analysis of the Streptococcus pneumoniae hyaluronate lyase and characterization of Its hyaluronan-specific carbohydrate-binding module

For a subset of pathogenic microorganisms, including Streptococcus pneumoniae, the recognition and degradation of host hyaluronan contributes to bacterial spreading through the extracellular matrix and enhancing access to host cell surfaces. The hyaluronate lyase (Hyl) presented on the surface of S. pneumoniae performs this role. Using glycan microarray screening, affinity electrophoresis, and isothermal titration calorimetry we show that the N-terminal module of Hyl is a hyaluronan-specific carbohydrate-binding module (CBM) and the founding member of CBM family 70. The 1.2 Å resolution x-ray crystal structure of CBM70 revealed it to have a β-sandwich fold, similar to other CBMs. The electrostatic properties of the binding site, which was identified by site-directed mutagenesis, are distinct from other CBMs and complementary to its acidic ligand, hyaluronan. Dynamic light scattering and solution small angle x-ray scattering revealed the full-length Hyl protein to exist as a monomer/dimer mixture in solution. Through a detailed analysis of the small angle x-ray scattering data, we report the pseudoatomic solution structures of the monomer and dimer forms of the full-length multimodular Hyl