Reheating constraints on mutated hilltop inflation

Future research studies of cosmic microwave background polarization seems likely to provide a more improved upper bound of $r \le 0.03$ on the tensor-to-scalar ratio(r). In our work, we have done the reheating study of mutated hilltop inflation(MHI), a model falling in the broad category of small field inflation. We have parameterized reheating in terms of various parameters like reheating duration $N_{\text{rh}}$, reheating temperature $T_{\text{rh}}$ and effective equation of state $\overline{\omega }_{\text{rh}}$ using observationally viable values of scalar power spectrum amplitude $A_{\text{s}}$ and scalar spectral index $n_{\text{s}}$. In our study, working over a range of $\overline{\omega }_{\text{rh}}$, we found that the MHI potential is well consistent with combined Planck and BK18 observations for $\overline{\omega }_{\text{rh}} > 0$ within a particular range of model's parameter space and the lower values of the model parameter in MHI generate considerably smaller r compared to normal hilltop potential without any incompatibility of $n_s$ with observational data, making MHI a better choice in accordance to recent and future studies

Density Fluctuations in the Oscillatory Phase of Nonclassical Inflaton in FRW Universe

Using coherent and squeezed state formalisms of quantum optics for a minimally coupled non-classical inflaton in the FRW mertic is studied, in semiclassical theory of gravity. The leading order solution for the semiclassical Einstein equations in the coherent, squeezed and squeezed vacuum states are obtained perturbatively and are exhibit powerlaw expansion behaviour. The validity of the semiclassical theory is examined in the squeezed vacuum state in the oscillatory phase of the inflaton. The semiclassical theory in the oscillatory phase of the non-classical inflaton holds only if the associated squeezing parameter is much less compared to unity. Quantum fluctuations of the inflaton is also examined in coherent and squeezed state formalisms.Comment: 14 pages, 2 figures, To appear in Int.J.Mod.Phys.

Reheating constraints on modified quadratic chaotic inflation

The Reheating era of inflationary Universe can be parameterized by various parameters like reheating temperature $T_{\text{re}}$, reheating duration $N_{\text{re}}$ and average equation of state parameter $\overline{\omega }_{\text{re}}$, which can be constrained by observationally feasible values of scalar power spectral amplitude $A_{\text{s}}$ and spectral index $n_{\text{s}}$. In this work, by considering the quadratic chaotic inflationary potential with logarithmic-correction in mass, we examine the reheating era in order to place some limits on model's parameter space. By investigating the reheating epoch using Planck's 2018 data, we show that even a small correction can make the quadratic chaotic model consistent with latest cosmological observations. We also find that the study of reheating era helps to put much tighter constraints on model and effectively improves accuracy of model

Anisotropic Compact Star Model on Finch-Skea Spacetime

In this study, we demonstrate a new anisotropic solution to the Einstein field equations in Finch-Skea spacetime. The physical features of stellar configuration are studied in previous investigations. We create a model that meets all physical plausibility conditions for a variety of stars and plot graphs for \textbf{4U 1820-30}.Comment: 9 figures, 1 table and 7 page

Design and simulation of logic gates using single electron transistors at room temperature

The Single Electron Transistor (SET) is a nanoscale three terminal device that provides current conduction characteristics comparable to a MOSFET and can be used for developing nanoscale logic circuits. In this paper, we have determined the design parameters of an SET to observe current oscillations at room temperature. These parameters have been used to design SET-based logic gates for room temperature operation. The circuit architectures of the proposed SET-based logic gates are identical to the corresponding CMOS gates. Complementary operations of an SET as n- and p-type devices were achieved by controlling the charge on the SET island by using the appropriate tuning gate voltages. We have proposed room temperature designs for the NOT, NOR, NAND, And-Or-Inven (AOI) and Or-And-Invert (OAI) gates. Their operations have been verified by simulations with a SPICE package which includes the SET-SPICE model. Copyright © 2006 Inderscience Enterprises Ltd

Design and simulation of logic circuits with hybrid architectures of single electron transistors and conventional devices

Single electron transistor is a nanoelectronic three terminal device. It provides current conduction characteristics comparable to a MOSFET. In this paper, we have designed and simulated logic circuit architectures with a combination of SET and conventional devices such as MOSFETs and comparators. The performances of these hybrid architectures and their advantages and disadvantages with SET standalone circuits have also been studied. © 2006 IEEE

Design and simulation of logic circuits with hybrid architectures of single-electron transistors and conventional MOS devices at room temperature

Single-electron transistors (SETs) provide current conduction characteristics comparable to CMOS technology and research shows that these devices can be used to develop logic circuits. It has been observed while building logic circuits that comprise only of SETs the voltage at the gate input had to be much higher than the power supply for the SET to have acceptable switching characteristics. This limitation in the gate and power supply voltages makes it practically inappropriate to build circuits. In this paper, we propose a hybrid architecture to overcome this limitation by combining conventional MOS devices with SETs. Three different types of hybrid circuits have been proposed and their characteristics have been studied using SPICE-based simulation tool which includes a SET-SPICE model. © 2008 Elsevier Ltd

Validity of semiclassical limit to quantum gravity in two-mode oscillating quantized massive scalar field quantum cosmology

Semiclassical Einstein equations are used to describe the interaction of the back-reaction of the classical gravitational field with quantum matter fields in semiclassical gravity. We in our previous studies have made use of the semiclassical approximation to demonstrate the phenomenon of particle production, often called preheating/reheating of the universe, which occurs after the inflationary epoch during the oscillatory phase of two-mode quantized scalar field of chaotic inflationary model. During this oscillatory phase, back-reaction effects from the created particles, on account of the quantum nature of the states considered, could be significant and one might be concerned about the validity of the semiclassical approximation in these two-mode quantum optical states. The validity of the semiclassical approximation in these states is examined and it is presented how the magnitude of states parameter draws limit on the applicability and reliability of semiclassical theory of gravity. It is argued that semiclassical theory to gravity is a good approximation for states which are closer to coherent states i.e., with coherent parameters greater than unity and with squeezed parameter much smaller than unity