Thermodynamic properties and phase diagrams of spin-1 quantum Ising systems with three-spin interactions

The spin-1 quantum Ising systems with three-spin interactions on two-dimensional triangular lattices are studied by mean-field method. The thermal variations of order parameters and phase diagrams are investigated in detail. The stable, metastable and unstable branches of the order parameters are obtained. According to the stable conditions at critical point, we find that the systems exhibit tricritical points. With crystal field and biquadratic interactions, the system has rich phase diagrams with single reentrant or double reentrant phase transitions for appropriate ranges of the both parameters.Comment: 10 pages, 5 figure

Using Probabilistic Topic Modeling of Library Access Records to Identify Learning Trends in Educational Research

Advances in the architecture of digital library service infrastructure enable the collection of various types of data related to the use of library resources, tools, and services. The Big Data that is being generated provides valuable insight into library operations and has the potential to reshape the future of library work. In this paper, we describe the innovative application of topic modeling (supervised Latent Dirichlet Allocation) of research corpora accessed by patrons through a library proxy server. We found that the underlying topics of this corpus (e.g., psychology, family education, and methodology) converge with the general interests one would expect from a Graduate School of Education. In addition, we discuss the potential and challenges of utilizing library proxy log data in learning analytics research

An efficient system for the production of the medicinally important plant: Asparagus cochinchinensis (Lour.) Merr.

An in vitro cultivation protocol was developed for Asparagus cochinchinensis a species threatened by over collection due to its importance as a medicinal plant in China. Adventitious shoot induction was most successful by using hypocotyls as explants for propagation on Murashige and Skoog (Murashige et al., 1962) medium supplemented with 4.5 μM N6-benzylaminopurine (BA) only as well as with 3.0 μM α- naphthalene acetic acid (NAA) and 4.5 μM BA. For continuous subculture, indole-3-acetic acid (IAA) and BA (μM) at a ratio of 3.0:4.5 or 3.0:9.0 had the best regeneration potential producing approximately four plantlets per nodal explants. Plantlets had 4 – 5 nodes that could be utilized for the following subculture phase to induce axillary shoots. The plantlets were placed on ½-strength MS medium, indole-3-butyric acid (IBA) was included in the media at a concentration of 2.5 or 5.0 M. This propagation regime has the capacity for producing 1000 – 2000 plants from one shoot after 3 months long subculture cycles, making it highly attractive for implementation as an in vitro conservation strategy. The micropropagated plants were easily acclimatized (80%) within a month after rooting in vitro and being planted ex vitro in a sand : soil : peat moss : vermiculite (1:2:1:1; v/v/v/v) mixture.Key words: Medicinal herbs, Asparagus cochinchinensis (Lour.) Merr., micropropagation

Coexistence of multi-photon processes and longitudinal couplings in superconducting flux qubits

In contrast to natural atoms, the potential energies for superconducting flux qubit (SFQ) circuits can be artificially controlled. When the inversion symmetry of the potential energy is broken, we find that the multi-photon processes can coexist in the multi-level SFQ circuits. Moreover, there are not only transverse but also longitudinal couplings between the external magnetic fields and the SFQs when the inversion symmetry of potential energy is broken. The longitudinal coupling would induce some new phenomena in the SFQs. Here we will show how the longitudinal coupling can result in the coexistence of multi-photon processes in a two-level system formed by a SFQ circuit. We also show that the SFQs can become transparent to the transverse coupling fields when the longitudinal coupling fields satisfy the certain conditions. We further show that the quantum Zeno effect can also be induced by the longitudinal coupling in the SFQs. Finally we clarify why the longitudinal coupling can induce coexistence and disappearance of single- and two-photon processes for a driven SFQ, which is coupled to a single-mode quantized field.Comment: 11 pages, 6 figure

Sample-efficient benchmarking of multi-photon interference on a boson sampler in the sparse regime

Verification of a quantum advantage in the presence of noise is a key open problem in the study of near-term quantum devices. In this work, we show how to assess the quality of photonic interference in a linear optical quantum device (boson sampler) by using a maximum likelihood method to measure the strength at which various noise sources are present in the experiment. This allows us to use a sparse set of samples to test whether a given boson sampling experiment meets known upper bounds on the level of noise permissible to demonstrate a quantum advantage. Furthermore, this method allows us monitor the evolution of noise in real time, creating a valuable diagnostic tool. Finally, we observe that sources of noise in the experiment compound, meaning that the observed value of the mutual photon indistinguishability, which is the main imperfection in our study, is an effective value taking into account all sources of error in the experiment

Multi-mode entanglement of N harmonic oscillators coupled to a non-Markovian reservoir

Multi-mode entanglement is investigated in the system composed of $N$ coupled identical harmonic oscillators interacting with a common environment. We treat the problem very general by working with the Hamiltonian without the rotating-wave approximation and by considering the environment as a non-Markovian reservoir to the oscillators. We invoke an $N$-mode unitary transformation of the position and momentum operators and find that in the transformed basis the system is represented by a set of independent harmonic oscillators with only one of them coupled to the environment. Working in the Wigner representation of the density operator, we find that the covariance matrix has a block diagonal form that it can be expressed in terms of multiples of $3\times 3$ and $4\times 4$ matrices. This simple property allows to treat the problem to some extend analytically. We illustrate the advantage of working in the transformed basis on a simple example of three harmonic oscillators and find that the entanglement can persists for long times due to presence of constants of motion for the covariance matrix elements. We find that, in contrast to what one could expect, a strong damping of the oscillators leads to a better stationary entanglement than in the case of a weak damping.Comment: 21 pages, 4 figure

Non-magnetic impurities in two dimensional superconductors

A numerical approach to disordered 2D superconductors described by BCS mean field theory is outlined. The energy gap and the superfluid density at zero temperature and the quasiparticle density of states are studied. The method involves approximate self-consistent solutions of the Bogolubov-de$\,$Gennes equations on finite square lattices. Where comparison is possible, the results of standard analytic approaches to this problem are reproduced. Detailed modeling of impurity effects is practical using this approach. The {\it range} of the impurity potential is shown to be of {\it quantitative importance} in the case of strong potential scatterers. We discuss the implications for experiments, such as the rapid suppression of superconductivity by Zn doping in Copper-Oxide superconductors.Comment: 16 pages, latex, 8 figures( available upon request