Researcher: Müstecaplıoğlu, Özgür Esat
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Müstecaplıoğlu, Özgür Esat
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Publication Metadata only Environment-assisted modulation of heat flux in a bio-inspired system based on collision model(Mdpi, 2022) N/A; N/A; Department of Physics; Pedram, Ali; Müstecaplıoğlu, Özgür Esat; PhD Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; N/A; 1674The high energy transfer efficiency of photosynthetic complexes has been a topic of research across many disciplines. Several attempts have been made in order to explain this energy transfer enhancement in terms of quantum mechanical resources such as energetic and vibration coherence and constructive effects of environmental noise. The developments in this line of research have inspired various biomimetic works aiming to use the underlying mechanisms in biological light harvesting complexes for the improvement of synthetic systems. In this article, we explore the effect of an auxiliary hierarchically structured environment interacting with a system on the steady-state heat transport across the system. The cold and hot baths are modeled by a series of identically prepared qubits in their respective thermal states, and we use a collision model to simulate the open quantum dynamics of the system. We investigate the effects of system-environment, inter-environment couplings and coherence of the structured environment on the steady state heat flux and find that such a coupling enhances the energy transfer. Our calculations reveal that there exists a non-monotonic and non-trivial relationship between the steady-state heat flux and the mentioned parameters.Publication Metadata only Dynamical properties of a coupled nonlinear dielectric waveguide - surface-plasmon system as a new type of josephson junction(IEEE, 2011) N/A; Department of Physics; N/A; Department of Physics; Müstecaplıoğlu, Özgür Esat; Özok, Yasa Ekşioğlu; Güven, Kaan; Faculty Member; PhD Student; Faculty Member; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; 1674; 237974; 52290We demonstrate that a weakly-coupled nonlinear dielectric waveguide surface-plasmon (DWSP-JJ) system can be formulated as in analogy to bosonic Josephson junction of atomic condensates, yet the inherently dynamic coupling parameter generates novel features in the phase space.Publication Metadata only Survival probability in a quantum walk on a one-dimensional lattice with partially absorbing traps(American Scientific Publishers, 2013) Gonulol, Meltem; Aydiner, Ekrem; Shikano, Yutaka; Department of Physics; Müstecaplıoğlu, Özgür Esat; Faculty Member; Department of Physics; College of Sciences; 1674Time dependence of the survival probability in a one dimensional lattice with randomly distributed and partial absorbing traps is analyzed as a function of concentration and absorption probability of the traps. The short and long time behaviors of the non-interacting quantum walks are identified with stretched exponentials. Dynamical scaling laws of the short and long time regimes as well as the crossover time between them are characterized. It is found that the short time behavior is more sensitive to the absorption probability and the crossover takes longer time for more transparent traps. Moreover, the stretching exponents increase with the transparency of the traps.Publication Metadata only Unified trade-off optimization of quantum harmonic otto engine and refrigerator(American Physical Society (APS), 2022) Singh, Varinder; Singh, Satnam; Abah, Obinna; Department of Physics; Müstecaplıoğlu, Özgür Esat; Faculty Member; Department of Physics; College of Sciences; 1674We investigate quantum Otto engine and refrigeration cycles of a time-dependent harmonic oscillator operating under the conditions of maximum Q function, a trade-off objective function which represents a compromise between energy benefits and losses for a specific job, for both adiabatic and nonadiabatic (sudden) frequency modulations. We derive analytical expressions for the efficiency and coefficient of performance of the Otto cycle. For the case of adiabatic driving, we point out that in the low-temperature regime, the harmonic Otto engine (refrigerator) can be mapped to Feynman's ratchet and pawl model which is a steady-state classical heat engine. For the sudden switch of frequencies, we obtain loop-like behavior of the efficiency-work curve, which is characteristic of irreversible heat engines. Finally, we discuss the behavior of cooling power at maximum Q function.Publication Metadata only Irreversible work and internal friction in a quantum otto cycle of a single arbitrary spin(Springer, 2017) Gencten, Azmi; Department of Physics; Department of Physics; Department of Physics; Çakmak, Selçuk; Altıntaş, Ferdi; Müstecaplıoğlu, Özgür Esat; Other; Researcher; Faculty Member; Department of Physics; College of Sciences; College of Sciences; College of Sciences; 301753; 126883; 1674We propose an arbitrary driven spin as the working fluid of a quantum Otto cycle in the presence of internal friction. The role of total allocated time to the adiabatic branches of the cycle, generated by different control field profiles, on the extractable work and the thermal efficiency are analyzed in detail. The internal friction is characterized by the excess entropy production and quantitatively determined by studying the closeness of an actual unitary process to an infinitely long one via quantum relative entropy. It is found that the non-ideal, finite-time adiabatic transformations negatively effect the work output and the thermal efficiency of the quantum heat engine. The non-monotone dependence of the work output, thermal efficiency, entropy production and the internal friction on the total adiabatic time are elucidated. It is also found that almost frictionless adiabatic transformations with small entropy production can be obtained in a short adiabatic time. Complete frictionless solutions for finite adiabatic times, possible implementation of our engine in NMR setups and the estimation of the power output have also been analyzed.Publication Metadata only Enhancing capacity of coherent optical information storage and transfer in a Bose-Einstein condensate(2007) N/A; Department of Physics; Department of Physics; Müstecaplıoğlu, Özgür Esat; Tarhan, Devrim; Faculty Member; Other; Department of Physics; College of Sciences; College of Sciences; 1674; N/AThe coherent optical information storage capacity of an atomic Bose-Einstein condensate is examined. The theory of slow light propagation in atomic clouds is generalized to the short-pulse regime by taking into account group velocity dispersion. It is shown that the number of stored pulses in the condensate can be optimized for a particular coupling laser power, temperature, and interatomic interaction strength. Analytical results are derived for a semi-ideal model of the condensate using the effective uniform density zone approximation. Detailed numerical simulations are also performed. It is found that the axial density profile of the condensate protects the pulse against group velocity dispersion. Furthermore, taking into account the finite radial size of the condensate, multimode light propagation in an atomic Bose-Einstein condensate is investigated. The number of modes that can be supported by a condensate is found. The single-mode condition is determined as a function of experimentally accessible parameters including trap size, temperature, condensate number density, and scattering length. Quantum coherent atom-light interaction schemes are proposed for enhancing multimode light propagation effects.Publication Metadata only Heat transport and rectification via quantum statistical and coherence asymmetries(American Physical Society (APS), 2022) Palafox, Stephania; Roman-Ancheyta, Ricardo; Çakmak, Barış; Department of Physics; Müstecaplıoğlu, Özgür Esat; Faculty Member; Department of Physics; College of Sciences; 1674Recent experiments at the nanoscales confirm that thermal rectifiers, the thermal equivalent of electrical diodes, can operate in the quantum regime. We present a thorough investigation of the effect of different particle exchange statistics, coherence, and collective interactions on the quantum heat transport of rectifiers with two-terminal junctions. Using a collision model approach to describe the open system dynamics, we obtain a general expression of the nonlinear heat flow that fundamentally deviates from the Landauer formula whenever quantum statistical or coherence asymmetries are present in the bath particles. Building on this, we show that heat rectification is possible even with symmetric medium-bath couplings if the two baths differ in quantum statistics or coherence. Furthermore, the associated thermal conductance vanishes exponentially at low temperatures as in the Coulomb-blockade effect. However, at high temperatures it acquires a power-law behavior depending on the quantum statistics. Our results can be significant for heat management in hybrid open quantum systems or solid-state thermal circuits.Publication Metadata only Vortex lattice of a Bose-Einstein condensate as a photonic band gap material(Institute of Physics (IOP) Publishing, 2009) Tasgin, M. E.; Oktel, M. O.; Department of Physics; Müstecaplıoğlu, Özgür Esat; Faculty Member; Department of Physics; College of Sciences; 1674Photonic crystal behavior of a rotating Bose-Einstein condensate with a triangular vortex lattice is reviewed and a scheme for getting much wider band gaps is proposed. It is shown that photonic band gaps can be widened an order of magnitude more by using a Raman scheme of index enhancement, in comparison to previously considered upper level microwave scheme.Publication Metadata only Scattering of short laser pulses from trapped atoms in a double well potential(Elsevier, 2004) N/A; Department of Physics; Müstecaplıoğlu, Özgür Esat; Faculty Member; Department of Physics; College of Sciences; 1674We investigate scattering of short laser pulses from trapped two level atoms in a double well potential. We have found that in contrast to the unique scattering cross section profiles obtained in the atoms trapped in single quantum wells, different angular distributions of scattered photons are possible in the case of double well traps depending on the time of arrival of laser pulses to the trap, geometry of the scattering determined by the alignment of the double wells with respect to the incoming laser direction and the initial preparation of the atomic subsystem.Publication Metadata only Dispersive propagation of ultras low pulses in an atomic Bose-Einstein condensate(Polish Acad Sciences Inst Physics, 2011) Tarhan, Devrim; Sefi, Seçkin; Department of Physics; Müstecaplıoğlu, Özgür Esat; Faculty Member; Department of Physics; College of Sciences; 1674One-dimensional propagation of ultraslow optical pulses in an atomic Bose-Einstein condensate taking into account the dispersion and the spatial inhomogeneity is investigated. Analytical and semi-analytical solutions of the dispersive inhomogeneous wave equation modeling the ultraslow pulse propagation are developed and compared against the standard wave equation solvers based upon Cranck-Nicholson and pseudo-spectral methods. The role of curvature of the trapping potential of the condensate on the amount of dispersion of the ultraslow pulse is pointed out.