Publications with Fulltext

Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/6

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    PublicationOpen Access
    Hamilton-Jacobi formulation of the thermodynamics of Einstein-Born-Infeld-AdS black holes
    (Institute of Physics (IOP) Publishing, 2019) Department of Physics; Dereli, Tekin; Ünlütürk, Kıvanç İbrahim; PhD Student; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; 201358; N/A
    A Hamilton-Jacobi formalism for thermodynamics was formulated by Rajeev (Ann. Phys., 323 (2008) 2265) based on the contact structure of the odd-dimensional thermodynamic phase space. This allows one to derive the equations of state of a family of substances by solving a Hamilton-Jacobi equation (HJE). In the same work it was applied to changeless non-rotating black holes, and the use of Born-Infeld electromagnetism was proposed to apply it to charged black holes as well. This paper fulfills this suggestion by deriving the HJE for charged non-rotating black holes using the Born-Infeld theory and a negative cosmological constant. The most general solution of this HJE is found. It is shown that there exist solutions which are distinct from the equations of state of the Einstein-Born-Infeld-AdS (EBIAdS) black hole. The meaning of these solutions is discussed.
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    PublicationOpen Access
    The covariant description of electromagnetically polarizable media
    (Elsevier, 2007) Gratus, J; Tucker, R.W.; Department of Physics; Dereli, Tekin; Faculty Member; Department of Physics; College of Sciences; 201358
    The form of the phenomenological stress-energy-momentum tensor for the electromagnetic field in a class of inhomogeneous, anisotropic magneto-electric media is calculated from first principles, leading to a coherent understanding of the phenomenological stresses and energy-momentum exchanges induced by electromagnetic interactions with such matter in terms of a fully relativistic covariant variational framework.
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    PublicationOpen Access
    Non-minimally coupled Einstein-Yang-Mills field equations and Wu-Yang monopoles in Bertotti-Robinson spacetimes
    (Institute of Physics (IOP) Publishing, 2021) Department of Physics; Dereli, Tekin; Şenikoğlu, Yorgo; Researcher; Department of Physics; College of Sciences; 201358; N/A
    Bertotti-Robinson spacetimes are topologically AdS(2) x S-2 and described by a conformally flat metric. Together with the Coulomb electric potential, they provide a class of static, geodetically complete Einstein-Maxwell solutions. We show here that the Bertotti-Robinson metric together with Wu-Yang magnetic pole potentials give a class of static solutions of a system of non-minimally coupled Einstein-Yang-Mills equations that may be relevant for investigating vacuum polarization effects in a first-order perturbative approach to quantum fields.
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    PublicationOpen Access
    Erratum: Geometric phase, bundle classification, and group representation
    (American Institute of Physics (AIP) Publishing, 1999) Department of Mathematics; Department of Physics; Mostafazadeh, Ali; Faculty Member; Department of Mathematics; Department of Physics; College of Sciences; 4231
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    PublicationOpen Access
    Quantum mechanics of a photon
    (American Institute of Physics (AIP) Publishing, 2017) Department of Physics; Department of Mathematics; Babaei, Hassan; Mostafazadeh, Ali; Faculty Member; Department of Physics; Department of Mathematics; Graduate School of Sciences and Engineering; N/A; 4231
    A first-quantized free photon is a complex massless vector field A = (A(mu)) whose field strength satisfies Maxwell's equations in vacuum. We construct the Hilbert space H of the photon by endowing the vector space of the fields A in the temporal-Coulomb gauge with a positive-definite and relativistically invariant inner product. We give an explicit expression for this inner product, identify the Hamiltonian for the photon with the generator of time translations in H, determine the operators representing the momentum and the helicity of the photon, and introduce a chirality operator whose eigenfunctions correspond to fields having a definite sign of energy. We also construct a position operator for the photon whose components commute with each other and with the chirality and helicity operators. This allows for the construction of the localized states of the photon with a definite sign of energy and helicity. We derive an explicit formula for the latter and compute the corresponding electric and magnetic fields. These turn out to diverge not just at the point where the photon is localized but on a plane containing this point. We identify the axis normal to this plane with an associated symmetry axis and show that each choice of this axis specifies a particular position operator, a corresponding position basis, and a position representation of the quantum mechanics of a photon. In particular, we examine the position wave functions determined by such a position basis, elucidate their relationship with the Riemann-Silberstein and Landau-Peierls wave functions, and give an explicit formula for the probability density of the spatial localization of the photon.
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    PublicationOpen Access
    A photonic Carnot engine powered by a spin-star network
    (European Physical Society (EPS), 2017) Türkpençe, Deniz; Paternostro, Mauro; Department of Physics; Altıntaş, Ferdi; Müstecaplıoğlu, Özgür Esat; Researcher; Faculty Member; Department of Physics; College of Sciences; N/A; 1674
    We propose a spin-star network, where a central spin-(1/2), acting as a quantum fuel, is coupled to N outer spin-(1/2) particles. If the network is in thermal equilibrium with a heat bath, the central spin can have an effective temperature, higher than that of the bath, scaling nonlinearly with N. Such temperature can be tuned with the anisotropy parameter of the coupling. Using a beam of such central spins to pump a micromaser cavity, we determine the dynamics of the cavity field using a coarse-grained master equation. We find that the central-spin beam effectively acts as a hot reservoir to the cavity field and brings it to a thermal steady state whose temperature benefits from the same nonlinear enhancement with N and results in a highly efficient photonic Carnot engine. The validity of our conclusions is tested against the presence of atomic and cavity damping using a microscopic master equation method for typical microwave cavity-QED parameters. The role played by quantum coherence and correlations on the scaling effect is pointed out. An alternative scheme where the spin-(1/2) is coupled to a macroscopic spin-(N/2) particle is also discussed. Copyright (C) EPLA, 2017
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    PublicationOpen Access
    A comparison of the LVDP and {\Lambda} CDM cosmological models
    (Springer, 2012) Department of Physics; Akarsu, Özgür; Dereli, Tekin; Faculty Member; Department of Physics; College of Sciences; N/A; 201358
    We compare the cosmological kinematics obtained via our law of linearly varying deceleration parameter (LVDP) with the kinematics obtained in the Lambda CDM model. We show that the LVDP model is almost indistinguishable from the Lambda CDM model up to the near future of our universe as far as the current observations are concerned, though their predictions differ tremendously into the far future.
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    PublicationOpen Access
    New improved massive gravity
    (European Physical Society (EPS), 2016) Yetişmişoğlu, Cem; Department of Physics; Dereli, Tekin; Faculty Member; Department of Physics; College of Sciences; 201358
    We derive the field equations for topologically massive gravity coupled with the most general quadratic curvature terms using the language of exterior differential forms and a first-order constrained variational principle. We find variational field equations both in the presence and absence of torsion. We then show that spaces of constant negative curvature (i.e. the anti de-Sitter space AdS(3)) and constant torsion provide exact solutions.
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    PublicationOpen Access
    SU(4) description of bilayer skyrmion-antiskyrmion pairs
    (Institute of Physics (IOP) Publishing, 2020) Department of Physics; Almasri, Mohammad Walid; PhD Student; Department of Physics; College of Sciences
    The antiferromagnetic coupling and entanglement between skyrmion lattices are treated in magnetic bilayer systems. We first formulate the problem of large bilayer skyrmions using the-theory. We have considered bilayer skyrmions under the presence of Dzyaloshinskii-Moriya (DMI) and Zeeman interactions confined in a two-dimensional chiral magnet such as Fe0.5Co0.5Si. We parametrize bilayer skyrmions using the SU(4) representation, and represent each skyrmion and antiskyrmion using the Schmidt decomposition. The reduced density matrices for skyrmion and antiskyrmion have been calculated. The conditions for maximal, partial entanglement and separable bilayer skyrmions are presented. Our results can be used for generating entanglement in systems with a large number of spins.
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    PublicationOpen Access
    Non-Hermitian quantum dynamics and entanglement of coupled nonlinear resonators
    (European Physical Society (EPS), 2014) Altıntaş, Ferdi; Department of Physics; Güven, Kaan; Karakaya, Evren; Müstecaplıoğlu, Özgür Esat; Faculty Member; Faculty Member; Department of Physics; College of Sciences; 52290; N/A; 1674
    We consider a generalization of a recently proposed non-Hermitian model for resonant cavities coupled by a chiral mirror by taking into account number non-conservation and nonlinear interactions. We analyze non-Hermitian quantum dynamics of populations and entanglement of the cavity modes. We find that the interplay between initial coherence and non-Hermitian coupling leads to a counterintuitive population transfer. While an initially coherent cavity mode is depleted, the other empty cavity can be populated more than or less than the initially filled one. Moreover, the presence of nonlinearity yields population collapse and revival as well as bipartite entanglement of the cavity modes. In addition to coupled cavities, we point out that similar models can be found in PT -symmetric Bose-Hubbard dimers of Bose-Einstein condensates or in coupled soliton-plasmon waveguides. We specifically illustrate the quantum dynamics of populations and entanglement in a heuristic model that we propose for a soliton-plasmon system with soliton amplitude-dependent asymmetric interaction. Degree of asymmetry, nonlinearity and coherence are examined to control plasmon excitations and soliton-plasmon entanglement. Relations to PT -symmetric lasers and Jahn-Teller systems are pointed out.