Odd Pair Research Articles

First-principles investigation of two-dimensional topological insulators BiX (X=H, F, O)

In order to exploit the nontrivial topological phase of matter for realizing room temperature transport applications, two-dimensional (2D) topological insulators (TIs) with large bulk band gaps are necessary. Based on first-principles calculations, the electronic and topological properties of 2D large gap TIs BiX (X = H, F, O) have been thoroughly investigated. We confirmed their nontrivial topological nature by calculating topological invariant (using Fu-Kane method) and observed odd number pairs of topologically protected gapless edge states from band structures of their zigzag nanoribbons. The strong spin–orbit coupling effect arising from heavy bismuth atoms not only affects the electronic structures, but also obviously influences the structural parameters such as lattice constant, bond length and buckling height. The key role of orbital filtering effect of X atoms in the electronic and topological properties has been illustrated by employing atomic-orbital-resolved band structures. Furthermore, we proposed a large band gap substrate, hexagonal boron nitride (h-BN), in a BiF/h-BN heterostructure, in which the h-BN substrate preserves the nontrivial topological behavior of BiF. To the best of our knowledge, BiF/h-BN with the gap of 1.041 eV has the largest band gap among all previously studied TI/substrate heterostructures. These findings make this structure a promising platform for high temperature low-dissipation spintronic nanodevices.

Nodeless superconducting gap induced by odd parity pair density wave in underdoped cuprates

We present a theoretical model to show that the transition from an antiferromagnetic (AFM) phase to the dx2−y2-wave superconductivity occurs through a robust companion of a finite momentum pairing between (k,↑) and (−k−Q,↓) electrons, namely a pair-density wave (PDW) state, where Q=(π,π) is the AFM wavevector. Interestingly, the spatial structure of the PDW is constrained to be a p+ip-wave symmetry, which follows pk=p−k−Q under fermions exchange in cuprates, dictating a spin–singlet pairing. Furthermore, the PDW state produces a fully gapped quasiparticle spectrum which explains recent observations of the fully gapped quasiparticle structure of lightly doped cuprates in the hole doping side. We study the stability of all three phases within the self-consistent mean-field theory. Finally, we calculate the superfluid density to propose its exponential temperature dependence as a test to the superconducting origin of this fully gapped state, while the phase modulation of the PDW state can be visualized by scanning probes.

Zigzag approach to higher key rate of sending-or-not-sending twin field quantum key distribution with finite-key effects

Odd-parity error rejection (OPER), in particular the method of actively odd parity pairing (AOPP), can drastically improve the asymptotic key rate of sending-or-not-sending twin-field (SNS-TF) quantum key distribution (QKD). However, in practice, the finite-key effects have to be considered for the security. Here, we propose a zigzag approach to verify the phase-flip error of the survived bits after OPER or AOPP. Based on this, we can take all the finite-key effects efficiently in calculating the non-asymptotic key rate. Numerical simulation shows that our approach here produces the highest key rate over all distances among all existing methods, improving the key rate by more than 100% to 3000% in comparison with different prior art methods with typical experimental setting. These verify the advantages of the AOPP method with finite data size. Also, with our zigzag approach here, the non-asymptotic key rate of SNS-TF QKD can by far break the absolute bound of repeater-less key rate with whatever detection efficiency. We can even reach a non-asymptotic key rate more than 40 times of the practical bound and 13 times of the absolute bound with 1012 pulses.

Non-real eigenvalues of the harmonic oscillator perturbed by an odd, two-point interaction

In this paper, we consider the perturbations of the Harmonic Oscillator Operator by an odd pair of point interactions: $z (\delta(x - b) - \delta(x + b))$. We study the spectrum by analyzing a convenient formula for the eigenvalue. We conclude that if $z = ir$, $r$ real, as $r \to \infty$, the number of non-real eigenvalues tends to infinity.

Kinds of Ghosts

105 MY TRAN Kinds of Ghosts  ouse ghost. Barn ghost. Ghost of the field—also known as field ghost. Durational ghost; ghost of the evening. Ghost of the hour, the time it takes a woman to tip her misery into a bowl. Dinner ghost. Ghost who haunts things. Tables, chairs. The odd pair of jewels and a necklace. Ghost in a dress hanging in midair like a bird. Ghost who runs down your neck, cold. Ghost ahead, ghost behind. Ghost in the clouds, up and about. Ghosts who can fly. Bird ghost. Pigeon ghosts in giant fleets pecking away at the winter field are a hungry lot. Ghost of the farmer. Ghosts who are quiet. Ghost who chats away at the telephone booth, never runs out of quarters. Ghost who has never known of a telephone booth. Ghost who has never left the house—agoraphobic ghost. Ghosts who are frightened of people. Ghosts who are rid of their worst fears. No more putting on shoes and getting down to the bus stop and waiting for the bus again, no more getting up and getting groceries, no more wringing washcloths of soaps and water. Ghosts of a thousand breezes, O so carefree. Schizophrenic ghost. Ghost of Artaud. Ghost who spends most of her time traveling to cities she’s never visited—they say Venice is going to drown, better make it a priority. Ghost of a town that was marginally above water. Ghost of the water. Ghosts of the people who stayed home when the town poured in through their front doors. Ghost who cooked dinner, went to sleep, brushed her teeth, stove left burning. Might as well take a warm bath while at it. Ghost who died clean and washed and relaxed. Ghost at the beach, pulling shells into amusing patterns, portends. Ghost washing up and knocking your sandcastle down. Childish ghost. Ghosts of children. Momma’s ghost. Ghost of the tree she remembers, the color of grass in the shade. Her shade. Ghost of her love for the sun at noon. The dog running a lap. The dog is also her ghost. h ...

Influence of electron–phonon coupling strength on signatures of even and odd-frequency superconductivity

The recently discovered APt3P (A=Sr,Ca,La) family of superconductors offers a platform to study frequency dependent superconducting phenomena as the electron–phonon coupling varies from weak to strong. Here we perform ab initio Eliashberg theory calculations to investigate two such phenomena, the occurrence of dip-hump structures in the tunneling spectra and the magnetic field induced coexistence of even and odd frequency superconductivity in these compounds. By calculating the superfluid density, we make materials specific predictions for the occurrence of the paramagnetic Meissner effect as a hallmark of odd frequency pairing. Our results provide a link between two seemingly uncorrelated aspects of even and odd frequency superconductivity and provide theoretical guidance for the future experimental identification of bulk odd frequency superconductivity in this materials’ family.

Spin-orbit coupling and spin-triplet pairing symmetry in Sr2RuO4

Spin-orbit coupling (SOC) plays a crucial role in determining the spin structure of an odd parity psedospin-triplet Cooper pairing state. Here, we present a thorough study of how SOC lifts the degeneracy among different p-wave pseudospin-triplet pairing states in a widely used microscopic model for $\mathrm{Sr_2 Ru O_4}$, combining a Ginzburg-Landau (GL) free energy expansion, a symmetry analysis of the model, and numerical weak-coupling renormalization group (RG) and random phase approximation (RPA) calculations. These analyses are then used to critically re-examine previous numerical results on the stability of chiral p-wave pairing. The symmetry analysis can serve as a guide for future studies, especially numerical calculations, on the pairing instability in $\mathrm{Sr_2 Ru O_4}$ and can be useful for studying other multi-band spin-triplet superconductors where SOC plays an important role.

A Wide Air Gap Flux Switching Bearingless Motor With Odd and Even Pole Pair Numbers

This paper introduces a bearingless motor topology with a magnet-free rotor that provides a higher rotor torque density and wider magnetic air gap compared to previously published topologies. The stray flux is minimized by using a stator with only eight teeth in temple configuration that contain permanent magnets. The motor performance is analyzed based on experimental prototypes, that were designed using 3D FEM simulations, for even and odd rotor pole pair numbers of six and nine, respectively. Control schemes that compensate parasitic radial forces to achieve stable magnetic levitation of the rotors are presented. The implemented prototypes reached a rotational speed of 2000 rpm and a maximum torque of 8 Nm.

Kinds of Ghosts

105 MY TRAN Kinds of Ghosts  ouse ghost. Barn ghost. Ghost of the field—also known as field ghost. Durational ghost; ghost of the evening. Ghost of the hour, the time it takes a woman to tip her misery into a bowl. Dinner ghost. Ghost who haunts things. Tables, chairs. The odd pair of jewels and a necklace. Ghost in a dress hanging in midair like a bird. Ghost who runs down your neck, cold. Ghost ahead, ghost behind. Ghost in the clouds, up and about. Ghosts who can fly. Bird ghost. Pigeon ghosts in giant fleets pecking away at the winter field are a hungry lot. Ghost of the farmer. Ghosts who are quiet. Ghost who chats away at the telephone booth, never runs out of quarters. Ghost who has never known of a telephone booth. Ghost who has never left the house—agoraphobic ghost. Ghosts who are frightened of people. Ghosts who are rid of their worst fears. No more putting on shoes and getting down to the bus stop and waiting for the bus again, no more getting up and getting groceries, no more wringing washcloths of soaps and water. Ghosts of a thousand breezes, O so carefree. Schizophrenic ghost. Ghost of Artaud. Ghost who spends most of her time traveling to cities she’s never visited—they say Venice is going to drown, better make it a priority. Ghost of a town that was marginally above water. Ghost of the water. Ghosts of the people who stayed home when the town poured in through their front doors. Ghost who cooked dinner, went to sleep, brushed her teeth, stove left burning. Might as well take a warm bath while at it. Ghost who died clean and washed and relaxed. Ghost at the beach, pulling shells into amusing patterns, portends. Ghost washing up and knocking your sandcastle down. Childish ghost. Ghosts of children. Momma’s ghost. Ghost of the tree she remembers, the color of grass in the shade. Her shade. Ghost of her love for the sun at noon. The dog running a lap. The dog is also her ghost. h ...

Group-theoretical classification of superconducting states of strontium ruthenate

The possible superconducting states of strontium ruthenate (Sr$_2$RuO$_4$) are organized into irreducible representations of the point group $D_{4h}$, with a special emphasis on nodes occurring within the superconducting gap. Our analysis covers the cases with and without spin-orbit coupling and takes into account the possibility of inter-orbital pairing within a three-band, tight-binding description of Sr$_2$RuO$_4$. No dynamical treatment if performed: we are confining ourselves to a group-theoretical analysis. The case of uniaxial deformations, under which the point group symmetry is reduced to $D_{2h}$, is also covered. It turns out that nodal lines, in particular equatorial nodal lines, occur in most representations. We also highlight some results specific to multiorbital superconductivity. Among other things, we find that odd inter-orbital pairing allows to combine singlet and triplet superconductivity whithin the same irreducible representation, that pure inter-orbital superconductivity leads to nodal surfaces and that the notion of nodes imposed by symmetry is not clearly defined.

Robust Twin Pairs of Weyl Fermions in Ferromagnetic Oxides.

The ferromagnetic Weyl semimetals with inversion symmetry usually possess odd pairs of Weyl fermions. Here, we present an inversion eigenvalue argument to dictate the existence of even pairs of ferromagnetic Weyl fermions. We show, by a combination of first-principles calculations and symmetry analyses, that this exotic topological feature can be verified in ferromagnetic oxides in different space groups. In particular, a realistic candidate, i.e., hollandite RbCr_{4}O_{8} with a high Curie temperature (∼295 K), hosts intriguing twin pairs of Weyl fermions, which are robustly stable against perturbations. Moreover, our effective model and symmetry analysis show that the twin pairs of Weyl fermions originate from a mirrored nodal ring pair. The nontrivial surface states and Fermi arcs of RbCr_{4}O_{8} are clearly visible, further revealing the topological features. This work strengthens the understanding of the parity analysis in exploring ferromagnetic topological materials with unconventional fermionic excitations.

Can Cat and Bird Be Friends? by Coll Muir

Reviewed by: Can Cat and Bird Be Friends? by Coll Muir Deborah Stevenson, Editor Muir, Coll Can Cat and Bird Be Friends?; written and illus. by Coll Muir. Harper, 2019 [32p] ISBN 978-0-06-286593-9 $17.99 Reviewed from galleys R Gr. 1-2 "Are you a bird? . . . Then I must eat you," says the black cat formally to the white bird he's just encountered. The bird politely suggests that they could become friends instead, noting that he knows lots of cat-pleasing possibilities ("'I know the best car for a cat to hide under.' 'I agree. This is a fantastic car to hide under'"); in turn, the cat offers bird delights such as a hot spot for juicy worms ("These worms are totally tasty!"). They sadly realize they don't have much common ground, though, and regretfully plan to part ways—until they realize they both like painting, so they can be friends after all. While there's validity to the point about friendship coming from sharing experiences rather than categorization, the fun here lies largely in the comically solemn dialogue (conveniently color-coded) and the tour of cat and bird experiences. The speech-only text, repetition, and spare, funny prose make this a treat for beginning readers, but picture-book audiences will relish the goofy friendship story as well. The streamlined digital art adds to the humor: palette is limited to black and white on taupe backgrounds, and while there's some soft shad-ing on and around the added objects, they largely have the crisp-edged simplicity of collage. This hits the sweet spot for dry humor that's still kid accessible, and youngsters looking for a change from the more voluble beginning readers about odd pairings will offer appreciative snickers. [End Page 445] Copyright © 2019 The Board of Trustees of the University of Illinois

Memory Inscribed in Bones: Examining a Diasporic Perspective in Michael Ondaatje’s Anil’s Ghost

Focusing on Michael Ondaatje’s novel Anil’s Ghost, set in Sri Lanka during the late 1980s and early 90s, this article tries to re-examine the current meaning and status of diaspora. In the novel, Anil Tissera, a forensic pathologist, who has returned to her homeland after fifteen years’ absence, investigates alleged human rights abuses during the civil war. While describing the ways in which a diaspora sponsored by international human rights organization intervenes into the internal conflicts of the once colonial nation, Ondaatje suggests that the international interests could lie behind the seemingly inter-ethnic conflicts and that the perspective of diaspora, native yet foreign, can easily be manipulated in the complicating nexus of socio-political issues in Sri Lanka. Inviting questions about the controversial role of diaspora in the age of globalization, the writer suggests an “archaeological understanding” of the local, which underlines a proper understanding of the complex nature of the place. Interestingly, Ondaatje relates the archaeological understanding to the presence of ghost: both archaeology and ghost unbury what is buried. Through the “odd pairing” of an forensic pathologist Anil and an archaeologist Sarath, the novel pays particular attention to the ways in which a diaspora engages in his/her homeland unearthing what is lost in history.

Adaptive playfair cipher Crypto algorithm

A well known cryptographic techniques is Playfair Cryptography, it is considered one of the classical method. After the invention of different techniques, it is easy to break Playfair. This paper proposed some way for removal of the traditional Playfair drawbacks. The Adaptive playfair algorithm proposed in this paper, add more security and complexity to the classical playfair algorithm. In addition to the use of two keys in form of matrices to encrypt the message, the proposed method works depending on using the odd even positions for the every pairs of the letters. The odd pairs encrypt through the first matrix key and the even pairs encrypt by using the second matrix, then applying XOR function with the third key to the result. The resulting cipher text will be in binary form, the plain text obtained by run proposed step backwards.

Polyhedral results on the stable set problem in graphs containing even or odd pairs

Even and odd pairs are important tools in the study of perfect graphs and were instrumental in the proof of the Strong Perfect Graph Theorem. We suggest that such pairs impose a lot of structure also in arbitrary, not just perfect graphs. To this end, we show that the presence of even or odd pairs in graphs imply a special structure of the stable set polytope. In fact, we give a polyhedral characterization of even and odd pairs.

Charge- 4e superconductors: A Majorana quantum Monte Carlo study

Many features of charge-4e superconductors remain unknown because even the "mean-field Hamiltonian" describing them is an interacting model. Here we introduce an interacting model to describe a charge-4e superconductor (SC) deep in the superconducting phase, and explore its properties using quantum Monte Carlo (QMC) simulations. The QMC is sign-problem-free, but only when a Majorana representation is employed. As a function of the chemical potential we observe two sharply-distinct behaviors: a "strong" quarteting phase in which charge-4e quartets are tightly bound (like molecules) so that charge-2e pairing does not occur even in the temperature $T \to 0$ limit, and a "weak" quarteting phase in which a further transition to a charge-2e superconducting phase occurs at a lower critical temperature. Analogous issues arise in a putative Z4 spin-liquid with a pseudo-Fermi surface and in characterizing charge-2e SCs with "odd frequency pairing" (or equivalently with a "composite order parameter") and metallic spin-nematics. Under certain circumstances, we also identified a stable T=0 charge-4e SC phase with gapless nodal quasiparticles. We further discuss possible relevance of our results to various experimental observations in 1/8-doped LBCO.

Pure odd-frequency superconductivity at the cores of proximity vortices

After more than a decade, direct observation of the odd frequency triplet pairing state in super- conducting hybrid structures remains elusive. We propose an experimentally feasible setup that can unambiguously reveal the zero energy peak due to proximity-induced equal spin superconducting triplet correlations. We theoretically investigate a two dimensional Josephson junction in the diffu- sive regime. The nanostructure consists of a normal metal sandwiched between two ferromagnetic layers with spiral magnetization patterns. By applying an external magnetic field perpendicular to the junction plane, vortices nucleate in the normal metal. The calculated energy and spatially resolved density of states, along with the pair potential, reveal that remarkably, only triplet Cooper pairs survive in the vortex cores. These isolated odd frequency triplet correlations result in well defined zero energy peaks in the local density of states that can be identified through tunneling spectroscopy experiments. Moreover, the diffusive regime considered here rules out the possibility of Andreev bound states in the vortex core as contributors to the zero energy peaks.

Nietzsche, Sport, and Contemporary Culture

The word ‘sport’ next to Nietzsche’s name may raise eyebrows among many Nietzsche readers. ‘What an odd pairing?’ one may ask. We prefer Nietzsche and arts or something from the domain of the Geist. Sport is embedded in mass culture and Nietzsche detests anything that has to do with masses; fandom, an important part of sport culture, is nothing Nietzsche would look at favourably but call it a manifestation of the herd instinct. Besides, clubs and sports organizations control this sporting culture through political and economic apparatuses. On the other hand, modern sports, far from producing higher types and the overhuman, appeal to the lowest common denominator, the person on the street and all athletes are equal. All of these objections notwithstanding, one may still speak of a sporting spirit that embodies play, ecstasy in the sense of Dionysian, inventiveness, agonism, grand spectacle, festivity, a specific type of aesthetics and a form of askesis of the body, and a specific outlet for enactment of active justice and a Gestalt of power relations. Playfulness and game-making are crucial in sports, and play is key to Nietzsche’s thought. Sport is a form of letting go, losing oneself in the game, and can be construed as a field for Dionysian forces. Agonism, a significant aspect of Nietzsche’s thought, applies to all competitive sports. Furthermore, sport constitutes one of the major types of spectacles in our age. Finally, sport belongs to the regime of the body, a form of askesis, which Nietzsche would have supported as opposed to the ascetic idealism. In what ways do Nietzsche’s ideas on interpretation shed light on sport and its various aspects as listed above? What hermeneutic tools do we have to interpret sport as a field of culture? These were the guiding questions for this essay.

Topological Septet Pairing with Spin-32Fermions: High-Partial-Wave Channel Counterpart of theHe3−BPhase

We systematically generalize the exotic ^{3}He-B phase, which not only exhibits unconventional symmetry but is also isotropic and topologically nontrivial, to arbitrary partial-wave channels with multicomponent fermions. The concrete example with four-component fermions is illustrated including the isotropic f-, p-, and d-wave pairings in the spin septet, triplet, and quintet channels, respectively. The odd partial-wave channel pairings are topologically nontrivial, while pairings in even partial-wave channels are topologically trivial. The topological index reaches the largest value of N^{2} in the p-wave channel (N is half of the fermion component number). The surface spectra exhibit multiple linear and even high order Dirac cones. Applications to multiorbital condensed matter systems and multicomponent ultracold large spin fermion systems are discussed.

Book Review: Renewing Moral Theology: Christian Ethics as Action, Character and Grace

Renewing Moral Theology: Christian Ethics as Action, Character and Grace. By Daniel A. Westberg. Downers Grove, 111.: IVP Academic, 2015. 281 pp. $25.00 (paper).Daniel Westbergs most recent offering is intended for the general reader interested in the discipline of Christian moral theology. It stands apart from other works in the field, however, not least because it combines two distinctive elements: it is at once Thomistic and Anglican. This may strike some readers as an odd pairing, but in fact it reflects a prominent stream of twentieth-century Anglican theology. The author deftly situates his project within this stream while also taking it in a slightly new direction. While he relies on Thomas Aquinas's moral theology as a starting point, he gracefully draws upon Anglican divines and numerous contemporary authors to weave an updated tapestry for Christian moral reflection. One of the many merits of this book is that it rises above the level of a popular introduction without becoming overly technical. It displays deep familiarity with centurieslong debates in moral theology without assuming that the reader shares this familiarity.The text is neatly divided into two parts. Part 1 is comprised of chapters that touch on some of the more theoretical and foundational aspects of Christian ethical reasoning (action, character, sin, grace, conversion, and law). Chapters 2 through 5 draw upon Westberg's earlier, more technical work and provide a clear and accessible analysis of practical reason and how we ought to understand human actions. Part 2 is devoted to analyses of the virtues, with each of the seven classical virtues receiving its own chapter. Each of these succinct treatments contains helpful everyday examples and concludes with suggestions for further reading. Reading the text from beginning to end, it becomes clear how the author's Anglican and Thomistic commitments work together to provide cohesion to the book's sixteen chapters.While this distinct set of commitments provides coherence to the overall project, there are some areas in which it leads to an inevitable tension. One example pertains to Westbergs treatment of sin. The inclusion of an entire chapter on the subject is admirable and fills a significant lacuna in much contemporary moral theology. An immediate difficulty arises, however, when one attempts to rehabilitate the Thomistic distinction between mortal and venial sins outside of a context in which sacramental confession is regularly practiced, let alone mandated. Westberg is well aware of this reality, and he does not go so far as to suggest that the mortal/venial distinction should become a normative principle of pastoral practice, as it has been in the Roman Catholic Church. …