Factorization and Criticality in the Anisotropic XY Chain via Correlations

In this review, we discuss the zero and finite temperature behavior of various bipartite quantum and total correlation measures, the skew information-based quantum coherence, and the local quantum uncertainty in the thermal ground state of the one-dimensional anisotropic XY model in transverse magnetic field. We compare the ability of considered measures to correctly detect or estimate the quantum critical point and the non-trivial factorization point possessed by the spin chain.Comment: 29 pages, 8 figures. A review paper accepted for publication in the special issue Entanglement Entropy in the journal Entrop

Protecting the SWAP\sqrt{SWAP} operation from general and residual errors by continuous dynamical decoupling

We study the occurrence of errors in a continuously decoupled two-qubit state during a $\sqrt{SWAP}$ quantum operation under decoherence. We consider a realization of this quantum gate based on the Heisenberg exchange interaction, which alone suffices for achieving universal quantum computation. Furthermore, we introduce a continuous-dynamical-decoupling scheme that commutes with the Heisenberg Hamiltonian to protect it from the amplitude damping and dephasing errors caused by the system-environment interaction. We consider two error-protection settings. One protects the qubits from both amplitude damping and dephasing errors. The other features the amplitude damping as a residual error and protects the qubits from dephasing errors only. In both settings, we investigate the interaction of qubits with common and independent environments separately. We study how errors affect the entanglement and fidelity for different environmental spectral densities.Comment: Extended version of arXiv:1005.1666. To appear in PR

Iterative actions of normal operators

Let $A$ be a normal operator in a Hilbert space $\mathcal{H}$, and let $\mathcal{G} \subset \mathcal{H}$ be a countable set of vectors. We investigate the relations between $A$, $\mathcal{G}$ , and $L$ that makes the system of iterations $\{A^ng: g\in \mathcal{G},\;0\leq n< L(g)\}$ complete, Bessel, a basis, or a frame for $\mathcal{H}$. The problem is motivated by the dynamical sampling problem and is connected to several topics in functional analysis, including, frame theory and spectral theory. It also has relations to topics in applied harmonic analysis including, wavelet theory and time-frequency analysis.Comment: 14 pages, 0 figure

Quantum Correlations and Coherence in Spin-1 Heisenberg Chains

We explore quantum and classical correlations along with coherence in the ground states of spin-1 Heisenberg chains, namely the one-dimensional XXZ model and the one-dimensional bilinear biquadratic model, with the techniques of density matrix renormalization group theory. Exploiting the tools of quantum information theory, that is, by studying quantum discord, quantum mutual information and three recently introduced coherence measures in the reduced density matrix of two nearest neighbor spins in the bulk, we investigate the quantum phase transitions and special symmetry points in these models. We point out the relative strengths and weaknesses of correlation and coherence measures as figures of merit to witness the quantum phase transitions and symmetry points in the considered spin-1 Heisenberg chains. In particular, we demonstrate that as none of the studied measures can detect the infinite order Kosterlitz-Thouless transition in the XXZ model, they appear to be able to signal the existence of the same type of transition in the biliear biquadratic model. However, we argue that what is actually detected by the measures here is the SU(3) symmetry point of the model rather than the infinite order quantum phase transition. Moreover, we show in the XXZ model that examining even single site coherence can be sufficient to spotlight the second-order phase transition and the SU(2) symmetry point.Comment: 8 pages. 5 figure

Quantum coherence and uncertainty in the anisotropic XY chain

We explore the local quantum coherence and the local quantum uncertainty, based on Wigner-Yanase skew information, in the ground state of the anisotropic spin-1/2 XY chain in transverse magnetic field. We show that the skew information, as a figure of merit, supplies the necessary information to reveal the occurrence of the second order phase transition and the completely factorized ground state in the XY model. Additionally, in the same context, we also discuss the usefulness of a simple experimentally friendly lower bound of local quantum coherence. Furthermore, we demonstrate how the connection between the appearance of non-analyticities in the local quantum uncertainty of the ground state and the quantum phase transitions does not hold in general, by providing explicit examples of the situation. Lastly, we discuss the ability of the local quantum coherence to accurately estimate the critical point of the phase transition, and investigate the robustness of the factorization phenomenon at low temperatures.Comment: 7 pages, 6 figures. Title changed. Close to published versio

Determination of chilling temperature effects on nutrient elements composition and distribution in cole (Brassica oleracea L. Cv. Acephala) using the WDXRF spectroscopic technique

Cole (Brassica oleracea L. cv. Acephala) is a naturally very hardy species to (at) chilling temperatures. It has been observed that the plant species can be viable even under snow during a cold winter. The cole seedlings were grown in soil for one month. Chilling temperatures were then applied to these seedlings under controlled conditions. These seedlings were subsequently, cut into root tip, root middle part, root upper part, hypocotyl, epicotyl, petiole and leaf and sampled randomly. Concentrations of inorganic elements (Al, Si, P, S, Cl, K, Ca, Fe, and Mg) in the parts were measured by wavelength-dispersive X-ray fluorescence (WDXRF) spectrometry to test chilling temperature effects on nutrient accumulation and distribution within these seedlings. Results indicated that the distribution of some inorganic elements among organs (roots, stem and leaves) of cole plants is significantly altered by chilling stress. There was an association between chilling temperatures and distributions, and accumulations of Ca, Fe, P, Cl, S especially Si and Al in cole seedlings. In addition, the WDXRF technique is a simple, fast, economic and accurate tool for biological studies related to the determining of the amount of plant nutritions in ppm level

Computational speed-up with a single qudit

Quantum algorithms are known for providing more efficient solutions to certain computational tasks than any corresponding classical algorithm. Here we show that a single qudit is sufficient to implement an oracle based quantum algorithm, which can solve a black-box problem faster than any classical algorithm. For $2d$ permutation functions defined on a set of $d$ elements, deciding whether a given permutation is even or odd, requires evaluation of the function for at least two elements. We demonstrate that a quantum circuit with a single qudit can determine the parity of the permutation with only one evaluation of the function. Our algorithm provides an example for quantum computation without entanglement since it makes use of the pure state of a qudit. We also present an experimental realization of the proposed quantum algorithm with a quadrupolar nuclear magnetic resonance using a single four-level quantum system, i.e., a ququart.Comment: Combined version of arXiv:1403.5861 [quant-ph] and arXiv:1406.3579 [quant-ph

Affective components of organizational commitment: A comprehensive structural equations model in a public sector organization

&Ouml;rg&uuml;tsel bağlılık, yazında bug&uuml;ne dek &ccedil;ok araştırılmasına rağmen hem bağlam duyarlılığı hem de belirleyicileri ve sonu&ccedil;ları a&ccedil;ısından karmaşıklığı nedeniyle hala ilgi toplayan bir araştırma başlığıdır. &Ccedil;alışmamızın amacı, &ouml;rg&uuml;tsel bağlılığın duygusal bileşenlerinin belirleyicilerinden sayılan &ldquo;iş tatmini&rdquo; ve &ldquo;genel yaşam tatmini&rdquo; gibi fakt&ouml;rler ve sonucu sayılabilecek &ldquo;&ouml;rg&uuml;tsel performans algısı&rdquo; ve &ldquo;ayrılma niyeti&rdquo; gibi diğer fakt&ouml;rlerle eş anlı etkileşimini bir model &ccedil;er&ccedil;evesinde sınamaktır. &Ouml;ncelikle yazın incelemesinden duygu tabanlı &ouml;rg&uuml;tsel bağlılığın belirleyicileri ve sonu&ccedil;ları sentezlenerek bir kuramsal model geliştirilmiş, geliştirilen bu modeldeki nedensellik ilişkileri &ouml;nsavlara d&ouml;n&uuml;şt&uuml;r&uuml;lm&uuml;şt&uuml;r. Bu kuramsal modelin tamamını ve fakt&ouml;rler arası etkileşimleri eş anlı olarak test edebilmek i&ccedil;in yapısal denklem modelleme y&ouml;nteminden faydalanılmış ve AMOS 4.0 yazılım programı kullanılarak test modelleri geliştirilmiştir. Geliştirilen modeller bir kamu kuruluşunda &ccedil;alışan 752 memur personelden soru formu yoluyla toplanan veriler &uuml;zerinde sınanmıştır. Kuramsal modelde duygusal tabanlı &ouml;rg&uuml;tsel bağlılık i&ccedil;in &ouml;ng&ouml;r&uuml;len kompozit fakt&ouml;r yapısı veri setine tam uymayınca iki fakt&ouml;rl&uuml; &ccedil;&ouml;z&uuml;me ge&ccedil;ilmiş, elde edilen iki fakt&ouml;r &ldquo;duygusal aidiyet&rdquo; ve &ldquo;sadakat&rdquo; olarak adlandırılmıştır. &Ccedil;ift fakt&ouml;rl&uuml; yapı belirleyicilik ve sonu&ccedil;lar a&ccedil;ısından test ama&ccedil;lı yapısal denklem modellerine dahil edildiğinde bulgular bazı &ouml;nsavları tamamen, bazılarını kısmen desteklemiş, bazılarını ise hi&ccedil; desteklememiştir. &ldquo;İş tatmini&rdquo;, &ldquo;duygusal aidiyet&rdquo; ve &ldquo;sadakat&rdquo; arasındaki ilişkilerin y&ouml;n ve şiddeti konusunda bu kavramlar arasındaki yoğun &ccedil;oklu bağlantılar nedeniyle berrak bir değerlendirme yapmak zorlaşmıştır. Buna rağmen denilebilir ki &ldquo;iş tatmini&rdquo; genel olarak &ldquo;duygusal aidiyet&rdquo; ve &ldquo;sadakat&rdquo;i, bu ikisinin iş tatminini belirleme d&uuml;zeyinden &ccedil;ok daha fazla belirliyor g&ouml;r&uuml;n&uuml;mdedir. İşinden tatmin olan bir kamu &ccedil;alışanı &ouml;zellikle &ouml;rg&uuml;te karşı duygusal aidiyet geliştirmekte ve bu duygusal aidiyet sadakate yol a&ccedil;maktadır. Ayrıca, yazındaki bulgulara benzer şekilde sadakatin ayrılma niyetini azalttığı, iş tatmininin ise &ouml;rg&uuml;tsel performans algısını arttırdığı g&ouml;zlemlenmiştir.&nbsp;Anahtar Kelimeler: &Ouml;rg&uuml;tsel bağlılık, iş tatmini, ayrılma niyeti, yapısal denklem modelleri.Organizational commitment construct has attained widespread attention from the organizational scholars during the last three decades. Yet, its close relations to other organizational attitudes and behaviors have rendered its causal identification quite complicated. Besides, many recent studies have indicated that the concept might reveal different characteristics in different contexts. Thus, this study attempts to identify and explain the affective component of organizational commitment with regard to a set of correlated organizational attitudes in a Turkish public sector organization. In order to achieve a reliable and causally robust analysis only the affective component of organizational commitment was analyzed. A thorough literature survey was performed to synthesize a theoretical model about the causal linkages of the construct. According to this survey, one of the most important correlates of organizational commitment is job satisfaction and organizational performance. Therefore, job satisfaction and perceived organizational performance was included in the model with two-way causal paths. Life satisfaction was found to be strongly correlated to job satisfaction and thus integrated to the theoretical model. The last construct included in the model was intent-to-leave. Five testable hypotheses were constituted to test the causal paths between the main constructs of the model. As method, we designed self-administrative questionnaires to measure these organizational attitudes. Questionnaire items were developed based on reliable scales for each construct but adapted to the Turkish and public sector domain. We ran a pilot sample and rechecked validity and reliability of our measures. Then we proceeded to apply our questionnaire to the whole civil servant population of a public sector organization. The total of returned questionnaires were 752 (approx. 90% of population), and due to missing values we ended up with 704 usable observations. Before testing our hypothesis, we started to examine the reliability and validity of our constructs. We used Exploratory Factor Analysis (EFA) method and Cronbach's Alpha for testing construct reliability. EFA did not load on a composite factor for affective organizational commitment scale but supported a two-factor solution. Since this was not expected, a confirmatory factor analysis was run to verify this solution. We found considerable support for a two-factor solution of affective organizational commitment construct, which we named "affective belongingness" and "loyalty" respectively. Having confirmed our measures, as a next step, the theoretical model was moved to AMOS 4.0 program to test the whole model simultaneously. Structural Equations Modeling (SEM) technique enables testing of multiple latent (unobserved) constructs and their interactions, using simultaneous structural equations derived from observed variables. Using SEM, we tested our theoretical model but due to the complex two-way interactions between key constructs, two test models were needed to account for all hypothesized relations. The first test model's overall fit, determined by  2 and GFI, was deemed acceptable, but some of the causal paths were observed as insignificant. The second test model fitted poorly to the data and again some paths were found to have insignificant scores. An optimum model with all paths significant and a good overall fit was produced and designated. Test models using SEM revealed that job satisfaction determined affective belongingness and by being emotionally attached to their organizations, public sector civil servants became more loyal. On the other hand, as predicted, loyal civil servants became less inclined to leave their organization. Yet, there were no statistically significant causal relations between affective based commitment and perceived organizational performance. However, test models indicated that the more satisfied the employees became the more inclined they were to rate their organization as performing well. Also, job satisfaction was found to determine life satisfaction more, even though the reverse is also statistically true. Thus, we conclude that job satisfaction has become even more critical a factor for public organizations to create loyal and emotionally charged employees. To increase satisfaction not just tangible categories such as pay system count but also good administrative capabilities matter. Keywords: Organizational commitment, job satisfaction structural equations model, intent-to-leave