arXiv subjects

Roland E. S. Otadoy

Publications and source records attributed to Roland E. S. Otadoy.

5 recordsLinked to original sources

arXiv2026

Entanglement and confinement: A new pairing mechanism in high-T_{C} cuprates

We demonstrate that entanglement and confinement hole pairing (ECHP) is a precise physics of the entanglement framework of the RVB theory of high-Tc cuprates. Our novel strong ECHP mechanism explains the entire phase diagram of both electron and hole-doped cuprates, notably the linearly decreasing T* at the pseudogap but with "T*-singularity" at the peak of the superconducting (SC) dome, the Tc=T* at the optimum doping and the rest of the overdoped regions of the SC dome, the duality of the spin gap and strange metal phase, the presence of the parallel superconducting stripes in the CuO plane (spin-polarized and spin-unpolarized channels), and the linear-T resistivity of the strange metal phase above the overdoped regions of the SC dome. This also explains the experimental spin textures of the cuprates. We refer to our new ECHP model as a resonating entanglement and confinement hole pair (RECHP) theory. Based on RECHP theory, we were able to provide a conceptual and comprehensive semiquantitative explanation of the entire phase diagram, thus providing the sought-after pairing mechanism responsible for the entire phase diagram of high-T_{C} cuprates.

cond-mat.supr-con↗

arXiv2023

An inverter-chain link implementation of quantum teleportation and superdense coding

A new perspective in terms of inverter-chain link (ICL) diagrams of quantum entanglement faithfully captures the fundamental concept of quantum teleportation and superdense coding. The ICL may be considered a series of σ_{x} Pauli-matrix operations, where a physical/geometric representation provides the mysterious link raised by EPR. Here, we employ discrete phase space and ICL analyses of quantum entanglement as a resource for quantum teleportation and superdense coding. We underscore the quantum superposition principle and Hadamard transformation under a local single-qubit operation. On the fundamental question posed by EPR, our result seems to lend support to the geometric nature of quantum entanglement. In concluding remarks, we discuss very briefly a bold conjecture in physics aiming to unify general relativity with quantum mechanics, namely, ER=EPR.

quant-ph↗

arXiv2020

On quantum Hall effect, Kosterlitz-Thouless phase transition, Dirac magnetic monopole, and Bohr-Sommerfeld quantization

We addressed quantization phenomena in transport and vortex/precession-motion of low-dimensional systems, stationary quantization of confined motion in phase space due to oscillatory dynamics or compacti fication of space and time for steady-state systems (e.g., particle in a box or torus, Brillouin zone, and Matsubara time zone or Matsubara quantized frequencies), and the quantization of sources. We discuss how the self-consistent Bohr-Sommerfeld quantization condition permeates the relationships between the quantization of integer Hall effect, fractional quantum Hall effect, the Berezenskii-Kosterlitz-Thouless vortex quantization, the Dirac magnetic monopole, the Haldane phase, contact resistance in closed mesoscopic circuits of quantum physics, and in the monodromy (holonomy) of completely integrable Hamiltonian systems of quantum geometry. In quantum transport of open systems, quantization occurs in fundamental units of quantum conductance, other closed systems in quantum units dictated by Planck's constant, and for sources in units of discrete vortex charge and Dirac magnetic monopole charge. The thesis of the paper is that if we simply cast the B-S quantization condition as a U(1) gauge theory, like the gauge field of the topological quantum field theory (TQFT) via the Chern-Simons gauge theory, or specifically as in topological band theory (TBT) of condensed matter physics in terms of Berry connection and curvature to make it self-consistent, then all the quantization method in all the physical phenomena treated in this paper are unified.

cond-mat.mes-hall↗

arXiv2019

Generalized Nonequilibrium Quantum Transport of Spin and Pseudospins: Entanglements and Topological Phases

General nonequilibrium quantum transport equations are derived for a coupled system of charge carriers, Dirac spin, isospin (or valley spin), and pseudospin, such as either one of the band, layer, impurity, and boundary pseudospins. Limiting cases are obtained for one, two or three different kinds of spin ocurring in a system. We show that a characteristic integer number $N_{s}$ determines the formal form of spin quantum transport equations, irrespective of the type of spins or pseudospins, as well as the maximal entanglement entropy. The results may shed a new perspective on the mechanism leading to zero modes and chiral/helical edge states in topological insulators, integer quantum Hall effect topological insulator (QHE-TI), quantum spin Hall effect topological insulator (QSHE-TI) and Kondo topological insulator (Kondo-TI). It also shed new light in the observed competing weak localization and antilocalization in spin-dependent quantum transport measurements. In particular, a novel mechanism of localization and delocalization, as well as the new mechanism leading to the onset of superconductivity in bilayer systems seems to emerge naturally from torque entanglements in nonequilibrium quantum transport equations of spin and pseudospins. Moreover, the general results may serve as a foundation for engineering approximations of the quantum transport simulations of spintronic devices based on graphene and other 2-D materials such as the transition metal dichalcogenides (TMDs), as well as based on topological materials exhibiting quantum spin Hall effects. The extension of the formalism to spincaloritronics and pseudo-spincaloritronics is straightforward.

cond-mat.mes-hall↗

arXiv2016

Magnetic Susceptibility of Dirac Fermions, Bi-Sb Alloys, Interacting Bloch Fermions, Dilute Nonmagnetic Alloys, and Kondo Alloys

Wide ranging interest in Dirac Hamiltomian is due to the emergence of novel materials, namely, graphene, topological insulators and superconductors, the newly-discovered Weyl semimetals, and still actively-sought after Majorana fermions in real materials. We give a brief review of the relativistic Dirac quantum mechanics and its impact in the developments of modern physics. The quantum band dynamics of Dirac Hamiltonian is crucial in resolving the giant diamagnetism of bismuth and Bi-Sb alloys. Quantitative agreement of the theory with the experiments on Bi-Sb alloys has been achieved, and physically meaningful contributions to the diamagnetism has been identified. We also treat relativistic Dirac fermion as an interband dynamics in uniform magnetic fields. For the interacting Bloch electrons, the role of translation symmetry for calculating the magnetic susceptibility avoids any approximation to second order in the field. The magnetic susceptibility of Hubbard model and those of Fermi liquids are readily obtained as limiting cases. The expressions for magnetic susceptibility of dilute nonmagnetic alloys give a firm theoretical foundation of the empirical formulas used in fitting experimental results. For completeness, the magnetic susceptibility of dilute magnetic or Kondo alloys is also given for high and low temperature regimes.

cond-mat.mes-hall↗