Articles
http://nur.nu.edu.kz:80/handle/123456789/908
2021-10-24T18:08:57ZGRAVITY WITH SCALAR FIELD VISCOUS FLUID
http://nur.nu.edu.kz:80/handle/123456789/5770
GRAVITY WITH SCALAR FIELD VISCOUS FLUID
Myrzakul, S R; Imankul, M; Arzimbetova, M; Myrzakul, T R
We focus on a viable teleparallel cosmological model with a scalar field in a flat
Friedman-Robertson-Walker universe. The Lagrangian and equations of motion are obtained.
The case of an inhomogeneous viscous dark energy is considered and the cosmological
parameters associated with the viscosity parameter are determined. It is shown that when
considering constant viscosity and state parameter, the Universe expands exponentially
2021-01-01T00:00:00ZMOVING MIRROR MODEL FOR QUASITHERMAL RADIATION FIELDS
http://nur.nu.edu.kz:80/handle/123456789/5708
MOVING MIRROR MODEL FOR QUASITHERMAL RADIATION FIELDS
Good, Michael R. R.; Linder, Eric V.; Wilczek, Frank
We analyze the flow of energy and entropy emitted by a class of moving mirror trajectories which
provide models for important aspects of the radiation fields produced by black hole evaporation.
The mirror radiation fields provide natural, concrete examples of processes that follow thermal
distributions for long periods, accompanied by transients which are brief and carry little net energy,
yet ultimately represent pure quantum states. A burst of negative energy flux is a generic feature
of these fields, but it need not be prominent.
2020-01-30T00:00:00ZRELATIVISTIC CORRECTIONS TO PHOTONIC ENTANGLED STATES FOR THE SPACE-BASED QUANTUM NETWORK
http://nur.nu.edu.kz:80/handle/123456789/5707
RELATIVISTIC CORRECTIONS TO PHOTONIC ENTANGLED STATES FOR THE SPACE-BASED QUANTUM NETWORK
Ilo-Okeke, Ebubechukwu O.; Ilyas, Batyr; Tessler, Louis; Takeoka, Masahiro; Jambulingam, Segar; Dowling, Jonathan P.; Byrnes, Tim
In recent years there has been a great deal of focus on a globe-spanning quantum network,
including linked satellites for applications ranging from quantum key distribution to distributed
sensors and clocks. In many of these schemes, relativistic transformations may have deleterious
effects on the purity of the distributed entangled pairs. In this paper, we make a comparison of
several entanglement distribution schemes in the context of special relativity. We consider three
types of entangled photons states: polarization, single photon, and Laguerre-Gauss mode entangled
states. All three types of entangled states suffer relativistic corrections, albeit in different ways.
These relativistic effects become important in the context of applications such as quantum clock
synchronization where high fidelity entanglement distribution are required
2020-02-15T00:00:00ZRADIATION FROM AN INERTIAL MIRROR HORIZON
http://nur.nu.edu.kz:80/handle/123456789/5506
RADIATION FROM AN INERTIAL MIRROR HORIZON
Good, Michael; Abdikamalov, Ernazar
The purpose of this study is to investigate radiation from asymptotic zero acceleration motion where a horizon is formed and subsequently detected by an outside witness. A perfectly reflecting moving mirror is used to model such a system and compute the energy and spectrum. The trajectory is asymptotically inertial (zero proper acceleration)—ensuring negative energy flux (NEF), yet approaches light-speed with a null ray horizon at a finite advanced time. We compute the spectrum and energy analytically.
2020-08-01T00:00:00ZNeutrino-driven Convection in Core-collapse Supernovae: High-resolution Simulations
http://nur.nu.edu.kz:80/handle/123456789/4811
Neutrino-driven Convection in Core-collapse Supernovae: High-resolution Simulations
Radice, David; Ott, Christian D.; Abdikamalov, Ernazar; Couch, Sean M.; Haas, Roland; Schnetter, Erik
We present results from high-resolution semiglobal simulations of neutrino-driven convection in core-collapse supernovae. We employ an idealized setup with parameterized neutrino heating/cooling and nuclear dissociation at the shock front. We study the internal dynamics of neutrino-driven convection and its role in redistributing energy and momentum through the gain region. We find that even if buoyant plumes are able to locally transfer heat up to the shock, convection is not able to create a net positive energy flux and overcome the downward transport of energy from the accretion flow. Turbulent convection does, however, provide a significant effective pressure support to the accretion flow as it favors the accumulation of energy, mass, and momentum in the gain region. We derive an approximate equation that is able to explain and predict the shock evolution in terms of integrals of quantities such as the turbulent pressure in the gain region or the effects of nonradial motion of the fluid. We use this relation as a way to quantify the role of turbulence in the dynamics of the accretion shock. Finally, we investigate the effects of grid resolution, which we change by a factor of 20 between the lowest and highest resolution. Our results show that the shallow slopes of the turbulent kinetic energy spectra reported in previous studies are a numerical artifact. Kolmogorov scaling is progressively recovered as the resolution is increased.
2016-03-01T00:00:00ZTurbulent chimeras in large semiconductor laser array
http://nur.nu.edu.kz:80/handle/123456789/4807
Turbulent chimeras in large semiconductor laser array
Shena, J.; Hizanidis, J.; Kovanis, V.; Tsironis, G.P.
Semiconductor laser arrays have been investigated experimentally and theoretically from the viewpoint of temporal and spatial coherence for the past forty years. In this work, we are focusing on a rather novel complex collective behavior, namely chimera states, where synchronized clusters of emitters coexist with unsynchronized ones. For the first time, we find such states exist in large diode arrays based on quantum well gain media with nearest-neighbor interactions. The crucial parameters are the evanescent coupling strength and the relative optical frequency detuning between the emitters of the array. By employing a recently proposed figure of merit for classifying chimera states, we provide quantitative and qualitative evidence for the observed dynamics. The corresponding chimeras are identified as turbulent according to the irregular temporal behavior of the classification measure.
2017-02-01T00:00:00Z