Unitary paradox of cosmological perturbations

If we interpret the Bekenstein-Hawking entropy of the Hubble horizon as thermodynamic entropy, then the entanglement entropy of the superhorizon modes of curvature perturbation entangled with the subhorizon modes will exceed the Bekenstein-Hawking bound at some point; we call this the unitary paradox of cosmological perturbations by analogy with black hole. In order to avoid a fine-tuned problem, the paradox must occur during the inflationary era at the critical time $t_c=\ln(3\sqrt{\pi}/\sqrt{2}\epsilon_HH_{inf})/2H_{inf}$ (in Planck units), where $\epsilon_H= -\dot{H}/H^2$ is the first Hubble slow-roll parameter and $H_{inf}$ is the Hubble rate during inflation. If we instead accept the fine-tuned problem, then the paradox will occur during the dark energy era at the critical time $t_c'=\ln(3\sqrt{\pi}H_{inf}/\sqrt{2}fe^{2N}H_\Lambda^2)/2H_\Lambda$, where $H_\Lambda$ is the Hubble rate dominated by dark energy, $N$ is the total number of e-folds of inflation, and $f$ is a purification factor that takes the range $0<f<3\sqrt{\pi}H_{inf}/\sqrt{2}e^{2N}H_\Lambda^2$.Comment: 13 pages, 3 figures; close to published versio

Inflation with a class of concave inflaton potentials in Randall-Sundrum model

We investigate inflation with a class of concave inflaton potentials of the form $\sim \phi^n$ $(0<n<1)$ in the Randall-Sundrum model with an infinite extra spatial dimension. We show that this class of models is much more in good agreement with observations compared to the standard inflation. We also find the range of the five-dimensional Planck scale ($M_5$) and show that large tensor-to-scalar ratios do not eliminate small-field inflation in braneworld cosmology.Comment: 7 pages, 2 figures; matches EPJC version; comments are welcom

Time-System Entanglement and Special Relativity

We know that space and time are treated almost equally in classical physics, but we also know that this is not the case for quantum mechanics. A quantum description of both space and time is important to really understand the quantum nature of reality. The Page-Wootters mechanism of quantum time is a promising starting point, according to which the evolution of the quantum system is described by the entanglement between it and quantum temporal degrees of freedom. In this paper, we use a qubit clock model to study how the time-system entanglement measures depend on the rapidity when the quantum system is Lorentz boosted. We consider the case of a spin-1/2 particle with Gaussian momentum distribution as a concrete example.Comment: 5 pages, 3 figure

Shaft inflation in Randall-Sundrum model

Shaft inflation is a model in which the inflaton potential approaches a plateau far from the origin, while it resembles chaotic inflation near the origin. Meanwhile, the Randall-Sundrum type II model (RSII) is an interesting extra-dimensional model to study cosmological phenomenology. In this paper, we study shaft inflation in the RSII model. We find that the predictions are in excellent agreement with observation. The fundamental five-dimensional Planck scale is found to be $M_5\simeq 10^{16}$ GeV, which is consistent with the lower bound $M_5\gtrsim 10^{9}$ GeV obtained from experimental Newtonian gravitational bound. This is an important result that can be used to explore further the implications of extra dimension in other contexts.Comment: 14 pages, 5 figures, 2 tables; published version in JCA

Insights of quantum time for quantum evolution

If time is emergent, quantum system is entangled with quantum time as it evolves. If the system contains entanglement within itself, which we can call \textit{internal entanglement} to distinguish it from the ``external" time-system entanglement, the speed of evolution is enhanced. In this paper, we explore the insights of quantum time for the evolution of a system that contains two entangled qubits. We consider two cases: (1) two initially entangled qubits that evolve under local dynamics; (2) two interacting qubits such that entanglement between them is generated over time. In both cases, the key message is that increasing internal entanglement speeds up the evolution and makes the system more entangled with time. This result could be useful to gain new insights of quantum time for black hole evaporation or cosmological perturbations in an expanding Universe, because we also have an evolving entangled bipartite system in those cases.Comment: 12 pages, 4 figure

Constraint on the Higgs-Dilaton potential via Warm inflation in Two-Time Physics

Within the $SP(2,R)$ symmetry, the Two-time model (2T model) has six dimensions with two dimensions of time and the dilaton field that can be identified as inflaton in a warm inflation scenario with potential of the form $\sim\phi^4$. From that consideration, we derive the range of parameters for the Higgs-Dilaton potential, the coupling constant between Higgs and Dialton ($\alpha$) is lager than $1.598$ or smaller than $2.13\times 10^{-7}$ when the mass of Dilaton is lager than $200$ GeV. Therefore, the 2T-model indirectly suggests that extra-dimension can also be a source of inflation.Comment: 11 pages and 2 figure

Investigations of embroidery antennas on polymer substrate

For everyday human life, people desire to stay connected via an advanced wireless network. Although cellular phone is worthy in various applications, people are likely to carry a wide range of mobile devices and constantly connect with each other. Future communication network requires a new class of front-ends electronic devices that are small, light-weight, conformal, multi-functional but also environment-friendly, inexpensive and good performance. In different aspects, once of the key factors to achieve this goal is to integrate the wireless antenna into garments as daily clothes and enhance its durability. Consequently, these wearable antennas need not only possess good RF performance characteristics but also mechanical structure which adaptable to conformity and durability. This dissertation presents a novel class embroidery patch antenna on polymer composite — polydimethylsiloxane (PDMS). By lamination and polymer integration, different structures and feeding techniques of fully embroidered polymer patch antenna with ground plane have been designed, fabricated and tested. Analysis of the effect of conductive patch weight as well as conductive characteristics using different embroidery structures on antenna performance has been carried out. The measured results show that although double embroidered layer on one side of fabric has similar conductivity and identical embroidery properties as two-sided embroidery, the antenna performs better using two-sided embroidery structure in term of reflection coefficient and gain measurement. In respect of conductivity of embroidered layers, the thesis investigates a method to improve the conductivity of embroidered patches used in antennas on polymer composite. Nanopowders which include graphene, zinc oxide (ZnO), aluminum oxide (Al2O3) and copper oxide (CuO) were dispersed in ethanol solvent to prepare as dyeing solutions. The effect of nanopowders on patches resistance has been studied. The measured results show that the patch conductivity improves 11.87% after 7 times dyeing with CuO and 8.14% after 10 times dyeing with ZnO. In contrast, graphene raises up the sheet resistance. The CuO and ZnO dyed conductive patch layers have been laminated and integrated on polymer substrate with embroidered ground plane to analyze the dyeing effect on antenna performance. Although dyeing effect reduces the resonant frequencies, the measured result indicates that dyed patch antennas perform better in term of reflection coefficient level

Investigations of embroidery antennas on polymer substrate

For everyday human life, people desire to stay connected via an advanced wireless network. Although cellular phone is worthy in various applications, people are likely to carry a wide range of mobile devices and constantly connect with each other. Future communication network requires a new class of front-ends electronic devices that are small, light-weight, conformal, multi-functional but also environment-friendly, inexpensive and good performance. In different aspects, once of the key factors to achieve this goal is to integrate the wireless antenna into garments as daily clothes and enhance its durability. Consequently, these wearable antennas need not only possess good RF performance characteristics but also mechanical structure which adaptable to conformity and durability. This dissertation presents a novel class embroidery patch antenna on polymer composite — polydimethylsiloxane (PDMS). By lamination and polymer integration, different structures and feeding techniques of fully embroidered polymer patch antenna with ground plane have been designed, fabricated and tested. Analysis of the effect of conductive patch weight as well as conductive characteristics using different embroidery structures on antenna performance has been carried out. The measured results show that although double embroidered layer on one side of fabric has similar conductivity and identical embroidery properties as two-sided embroidery, the antenna performs better using two-sided embroidery structure in term of reflection coefficient and gain measurement. In respect of conductivity of embroidered layers, the thesis investigates a method to improve the conductivity of embroidered patches used in antennas on polymer composite. Nanopowders which include graphene, zinc oxide (ZnO), aluminum oxide (Al2O3) and copper oxide (CuO) were dispersed in ethanol solvent to prepare as dyeing solutions. The effect of nanopowders on patches resistance has been studied. The measured results show that the patch conductivity improves 11.87% after 7 times dyeing with CuO and 8.14% after 10 times dyeing with ZnO. In contrast, graphene raises up the sheet resistance. The CuO and ZnO dyed conductive patch layers have been laminated and integrated on polymer substrate with embroidered ground plane to analyze the dyeing effect on antenna performance. Although dyeing effect reduces the resonant frequencies, the measured result indicates that dyed patch antennas perform better in term of reflection coefficient level