Academic Positions

  • Assistant professor2013

    General Courses and Basic Sciences

  • Assistant professor2017

    Physics Department

Educations

  • -0001Bachelor of Science

    Solid state physics

    Sistan and Baluchestan

  • -0001Master of Science

    Physics

    Shahid Beheshti University

  • 2017Ph.D

    Physics

    Shahid Beheshti University

Executives

Favouriates

Filter by type:

Sort by year:

Holography from quantum cosmology

Mehdi Rashki,شهرام جلال زاده
USA , PHYSICAL REVIEW D , Year : 2015 , Pages: 23501-23501, ISSN:1550-7998 Journal Paper

Abstract

The Weyl-Wigner-Groenewold-Moyal formalism of deformation quantization is applied to the closed Friedmann-Lemaître-Robertson-Walker cosmological model.We show that the phase space average for the surface of the apparent horizon is quantized in units of the Planck’s surface, and that the total entropy of the Universe is also quantized. Taking into account these two concepts, it is shown that ’t Hooft conjecture on the cosmological holographic principle in radiation and dust dominated quantum universes is satisfied as a manifestation of quantization. This suggests that the entire Universe (not only inside the apparent horizon) can be seen as a two-dimensional information structure encoded on the apparent horizon.

The Quantum State of the Universe from Deformation Quantization and Classical-Quantum Correlation

شهرام جلال زاده,Mehdi Rashki
Netherlands , General Relativity and Gravitation , Year : 2017 , Pages: 1-14, ISSN:0001-7701 Journal Paper

Abstract

In this paper we study theIn this paper we study the quantum cosmology of homogeneous and isotropic cosmology, via the Weyl–Wigner–Groenewold–Moyal formalism of phase space quantization, with perfect fluid as a matter source. The corresponding quantum cosmology is described by theMoyal–Wheeler-DeWitt equation which has exact solutions in Moyal phase space, resulting in Wigner quasiprobability distribution functions peaking around the classical paths for large values of scale factor. We show that the Wigner functions of these models are peaked around the non-singular universes with quantum modified density parameter of radiation. of homogeneous and isotropic cosmology, via the Weyl–Wigner–Groenewold–Moyal formalism of phase space quantization, with perfect fluid as a matter source. The corresponding quantum cosmology is described by the Moyal–Wheeler-DeWitt equation which has exact solutions in Moyal phase space, resulting in Wigner quasiprobability distribution functions peaking around the classical paths for large values of scale factor. We show that the Wigner functions of these models are peaked around the non-singular universes with quantum modified density parameter of radiation.

Interacting Dark Side of Universe Through Generalized Uncertainty Principle

Mehdi Rashki,مجید فتحی,بهرنگ مستقل,شهرام جلال زاده
Singapore , International Journal of Modern Physics D , Year : 2019 , Pages: 1950081-1950081, ISSN:0218-2718 Journal Paper

Abstract

We investigate the impact of the generalized uncertainty principle proposed by some approaches to quantum gravity such as string theory and doubly special relativity on the cosmology. Using generalized Poisson brackets, we obtain the modi fied Friedmann and Raychaudhuri equations and suggest a dynamical dark energy to explain the late time acceleration of the Universe. After considering the interaction between dark matter and dark energy, originated from the minimal length, we obtain the effective cosmological parameters and equation of state parameter for dark matter and dark energy. Finally, we show that the resulting model is equivalent to the Phantom and Tachyon fi elds.

Solving a nonlinear fractional Schrödinger equation using cubic B-splines

Majid Erfanian,Mehdi Rashki,H. Zeidabadi,H. Borzoui
Egypt , Advances in Difference Equations , Year : 2020 , Pages: 344-364, ISSN:1687-1847 Journal Paper

Abstract

We study the inhomogeneous nonlinear time-fractional Schrödinger equation for linear potential, where the order of fractional time derivative parameter α varies between 0 < α < 1. First, we begin from the original Schrödinger equation, and then by the Caputo fractional derivative method in natural units, we introduce the fractional time-derivative Schrödinger equation. Moreover, by applying a finite-difference formula to time discretization and cubic B-splines for the spatial variable, we approximate the inhomogeneous nonlinear time-fractional Schrödinger equation; the simplicity of implementation and less computational cost can be mentioned as the main advantages of this method. In addition, we prove the convergence of the method and compute the order of the mentioned equations by getting an upper bound and using some theorems. Finally, having solved some examples by using the cubic B-splines for the spatial variable, we show the plots of approximate and exact solutions with the noisy data in figures

تاثیرات اصل عدم قطعیت تعمیم یافته در عالم تاریک

مهدی راشکی,مجید فتحی,بهرنگ مستقل,شهرام جلال زاده
همایش ملی گرانش و کیهان شناسی ، سال : 2016 مقاله کنفرانسی

چکیده

وجود طول کمینه توسط نظریه های متفاوتی نظیر فیزیک سیاه چاله، نظریه ریسمان و نظریه نسبیت خاص دوگان پیش بینی شده .[ است، که به تعمیم اصل عدم قطعیت هایزنبرگ منجر میشود [ 1 اخیراً مشاهدات کیهانشناسی نشان داده است که عالم در فاز انبساط شتاب دار است[ 2]، که این می تواند یک گواه برای وجود انرژی تاریک عالم می باشد. پیشنهادات متعددی برای توضیح منشأ انرژی تاریک ارائه شده است. ساده ترین نامزد برای توضیح دینامیک انرژی تاریک، ثابت کیهانشناسی است و سپس معروف ترین نامزد برای توضیح منشأ انرژی تاریک، میدان های نرده ای مانند کوئینت اسنس و شبح می باشند.

  •    Direct Phone: _
  •    Internal Phone: _
  •    Fax: _
  •    Email: mahdirashki@uoz.ac.ir