6,404 research outputs found
Pseudo Hermitian interactions in the Dirac Equation
We consider dimensional massless Dirac equation in the presence of
complex vector potentials. It is shown that such vector potentials (leading to
complex magnetic fields) can produce bound states and the Dirac Hamiltonians
are -pseudo Hermitian. Some examples have been explicitly worked out.Comment: 8 pages, NO figure
dimensional Dirac equation with non Hermitian interaction
We study dimensional Dirac equation with non Hermitian interactions,
but real energies. In particular, we analyze the pseudoscalar and scalar
interactions in detail, illustrating our observations with some examples. We
also show that the relevant hidden symmetry of the Dirac equation with such an
interaction is pseudo supersymmetry.Comment: 9 page
Deconstructing non-dissipative non-Dirac-hermitian relativistic quantum systems
A method to construct non-dissipative non-Dirac-hermitian relativistic
quantum system that is isospectral with a Dirac-hermitian Hamiltonian is
presented. The general technique involves a realization of the basic canonical
(anti-)commutation relations involving the Dirac matrices and the bosonic
degrees of freedom in terms of non-Dirac-hermitian operators, which are
hermitian in a Hilbert space that is endowed with a pre-determined
positive-definite metric. Several examples of exactly solvable non-dissipative
non-Dirac-hermitian relativistic quantum systems are presented by
establishing/employing a connection between Dirac equation and supersymmetryComment: 11 pages, LaTeX, no figure
(1+1)-Dirac particle with position-dependent mass in complexified Lorentz scalar interactions: effectively PT-symmetric
The effect of the built-in supersymmetric quantum mechanical language on the
spectrum of the (1+1)-Dirac equation, with position-dependent mass (PDM) and
complexified Lorentz scalar interactions, is re-emphasized. The signature of
the "quasi-parity" on the Dirac particles' spectra is also studied. A Dirac
particle with PDM and complexified scalar interactions of the form S(z)=S(x-ib)
(an inversely linear plus linear, leading to a PT-symmetric oscillator model),
and S(x)=S_{r}(x)+iS_{i}(x) (a PT-symmetric Scarf II model) are considered.
Moreover, a first-order intertwining differential operator and an
-weak-pseudo-Hermiticity generator are presented and a complexified
PT-symmetric periodic-type model is used as an illustrative example.Comment: 11 pages, no figures, revise
Pseudo-Hermitian Interactions in Dirac Theory: Examples
We consider a couple of examples to study the pseudo-Hermitian interaction in
relativistic quantum mechanics. Rasbha interaction, commonly used to study the
spin Hall effect, is considered with imaginary coupling. The corresponding
Dirac Hamiltonian is shown to be parity pseudo-Hermitian. In the other example
we consider parity pseudo-Hermitian scalar interaction with arbitrary parameter
in Dirac theory. In both the cases we show that the energy spectrum is real and
all the other features of non-relativistic pseudo-Hermitian formulation are
present. Using the spectral method the positive definite metric operator
() has been calculated explicitly for both the models to ensure positive
definite norms for the state vectors.Comment: 13 pages, Latex, No figs, Revised version to appear in MPL
Photonic Dirac Waveguides
The Dirac equation is a paradigmatic model that describes a range of
intriguing properties of relativistic spin-1/2 particles, from the existence of
antiparticles to Klein tunneling. However, the Dirac-like equations have found
application far beyond its original scope, and has been used to comprehend the
properties of graphene and topological phases of matter. In the field of
photonics, the opportunity to emulate Dirac physics has also enabled
topological photonic insulators. In this paper, we demonstrate that judiciously
engineered synthetic potentials in photonic Dirac systems can offer physical
properties beyond both the elementary and quasi-particles, and topological
realms. Specifically, we introduce a new class of optical Dirac waveguides,
whose guided electromagnetic modes are endowed with pseudo-spin degree of
freedom. Pseudo-spin coupled with the ability to engineer synthetic gauge
potentials acting on it, enables control over the guided modes which is
unattainable in conventional optical waveguides. In particular, we use a
silicon nanophotonic metasurface that supports pseudo-spin degree of freedom as
a testing platform to predict and experimentally confirm a spin-full nature of
the Dirac waveguides. We also demonstrate that, for suitable trapping
potentials, the guided modes exhibit spin-dependent field distributions, which
gives rise to their distinct transport and radiative properties. Thereby, the
Dirac waveguides manifest spin-dependent radiative lifetimes - the
non-Hermitian spin-Hall effect - and open new avenues for spin-multiplexing,
controlling characteristics of guided optical modes, and tuning light-matter
interactions with photonic pseudo-spins.Comment: 16 pages, 5 figure
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