Sharif Digital Repository

We propose an experiment to investigate the possibility of long-distance thermodynamic relationships between two entangled particles. We consider a pair of spin-12 particles prepared in an entangled singlet state in which one particle is sent to Alice and the other to her distant mate Bob, who are spatially separated. Our proposed experiment consists of three different setups: First, both particles are coupled to two heat baths with various temperatures. In the second setup, only Alice’s particle is coupled to a heat bath and finally, in the last setup, only Bob’s particle is coupled to a heat bath. We study the evolution of an open quantum system using the first law of thermodynamics based... 

One of the most prominent issues in fully adiabatic circuits is the breaking reversibility problem; i.e., non-adiabatic energy dissipation in the last stage adiabatic gates whose outputs are connected to external circuits. In this paper, we show that the breaking reversibility problem can result in significant energy dissipation. Subsequently, we propose an efficient technique to address the breaking reversibility problem, which is applicable to the usual fully adiabatic logic such as 2LAL, SCRL, and RERL. Detailed SPICE simulations are used to evaluate the proposed technique. The experimental results show that the proposed technique can considerably reduce (e.g., about 74% for RERL, 35% for... 

In the present study, two-phase refrigerant flow is simulated using drift flux model for straight and helical capillary tubes. The conservation equations of mass, energy and momentum are solved using the 4th order Runge-Kutta method. This model is validated by previously published experimental and numerical results and also by experimental results presented in this work. The effect of various parameters such as inlet pressure, inlet temperature, sub-cooling degree, and geometric dimensions are studied. The results of the present study show that for the same length and under similar conditions, mass flux through helical capillary tube with coil diameter of 40 mm are about 11% less than that... 

In this paper, an analytic model of the energy consumption of the Stepwise Adiabatic Circuits (SAC) when it is possible to discharge the load capacitor is proposed. Using this model, analytical derivations are calculated which shows us the power saving of the SACs. Using analytical derivations, the sizing of a capacitor tank is determined for a desired energy saving. For example, the derivations predict that if the sizing of the 3-step series tank capacitors is equal to the load capacitor, the power saving is 55%. Also, if the sizing of the tank is very large the energy saving of a 3-step stepwise charging is equal to 66.7%. Several Simulations in 0.18μm CMOS technology prove the accuracy of... 

Micro-machining of face centered cubic (FCC) metallic materials is simulated via the theory of rate-dependent crystal plasticity. This approach accounts for slip systems and crystallographic orientations in its constitutive framework in order to accurately model the evolution of localized shear band formed during severe plastic deformation of crystalline materials. Through developing a user-defined subroutine in the ABAQUS/Explicit FE platform, the constitutive model is implemented and used to study the influence of workpiece crystallographic orientation on the cutting and thrust specific energies of the process. Due to the high rate of deformation, mechanical properties of texture can be... 

In this study, a comprehensive three-dimensional dynamic model was developed for simulating the flow behavior and catalytic coupling reactions for direct synthesis of dimethyl ether (DME) from syngas including CO2 in a fixed bed reactor at commercial scale under both adiabatic and isothermal conditions. For this purpose, a computational fluid dynamic (CFD) simulation was carried out through which the standard k-e{open} model with 10% turbulence tolerations was implemented. At first, an adiabatic fixed bed reactor was simulated and the obtained results were compared with those of an equivalent commercial slurry reactor. Then the concentration and temperature profiles along the reactor were... 

It is shown that in a controlled adiabatic homotopy between two Hamiltonians, H0 and H1, the gap or "anti- crossing" phenomenon can be viewed as the development of cusps and swallow tails in the region of the complex plane where two critical value curves of the quadratic map associated with the numerical range of H0 + i H 1 come close. The "near crossing" in the energy level plots happens to be a generic situation, in the sense that a crossing is a manifestation of the quadratic numerical range map being unstable in the sense of differential topology. The stable singularities that can develop are identified and it is shown that they could occur near the gap, making those singularities of... 

Laser excitation pulses that lead to perfect adiabatic state transfer in an ensemble of three-level ladder atoms lead to highly entangled states of many atoms if their highest excited state is subject to Rydberg blockade. Solution of the Schrödinger equation shows that it is increasingly difficult to ensure the adiabatic evolution as the number of atoms increases. A diminishing energy gap, significant variations in collective observables, and increased work fluctuations link the critical slowing down of the adiabatic evolution with a quantum-phase-transition-like behavior of the system. © 2018 American Physical Society  

Quantum computing and quantum simulation can be implemented by concatenation of one- and two-qubit gates and interactions. For most physical implementations, however, it may be advantageous to explore state components and interactions that depart from this universal paradigm and offer faster or more robust access to more advanced operations on the system. In this article, we show that adiabatic passage along the dark eigenstate of excitation exchange interactions can be used to implement fast multiqubit Toffoli (Ck-NOT) and fan-out (C-NOTk) gates. This mechanism can be realized by simultaneous excitation of atoms to Rydberg levels, featuring resonant exchange interaction. Our theoretical... 

Adiabatic quantum algorithms are characterized by their run time and accuracy. The relation between the two is essential for quantifying adiabatic algorithmic performance yet is often poorly understood.We study the dynamics of a continuous time, adiabatic quantum search algorithm and find rigorous results relating the accuracy and the run time. Proceeding with estimates, we show that under fairly general circumstances the adiabatic algorithmic error exhibits a behavior with two discernible regimes: The error decreases exponentially for short times and then decreases polynomially for longer times.We show that the well-known quadratic speedup over classical search is associated only with the... 

In this paper, the path independent interaction integral has been implemented in the framework of the extended finite element method for mixed mode adiabatic cracks under thermo-mechanical loadings particularly in orthotropic non-homogenous materials. The mesh insensitivity and increased accuracy due to the thermal and displacement asymptotic analytical solutions are discussed and the contour independency of the interaction integral is investigated in different examples. Finally, the problem of crack propagation in orthotropic FGM materials under the thermal loading is investigated to assess the accuracy and robustness of proposed approach  

A new switching method for the stabilisation of a one-dimensional capacitor array tank for the stepwise charging of a load capacitor is presented. In this method, the tank capacitor configuration is rearranged in a circular manner once the charging process of a load capacitor finishes and before the charging process of a new load capacitor begins. Unlike previously reported methods, this method does not require backward switching for the stabilisation of tank capacitor voltages. Hence, the proposed method reduces the number of charging process steps by a factor of up to 2 compared with the conventional method. Moreover, since the tank recycles its charge inherently, the capacitive load can... 

The mutual interaction of two oscillating gas bubbles in different concentrations of sulfuric acid is numerically investigated. A nonlinear oscillation for spherical symmetric bubbles with equilibrium radii smaller than 10 μm at a frequency of 37 kHz in a strong driving acoustical field Pa =1.8 bar is assumed. The calculations are based on the investigation of the secondary Bjerknes force with regard to adiabatic model for the bubble interior which appears as repulsion or attraction interaction force. In this work the influence of the various concentrations of sulfuric acid in uncoupled and coupled distances between bubbles has been investigated. It is found that the sign and value of the... 

This work defines density factor as the ratio of before ignition density to after ignition density of the ignition mixture. This work provides an estimation method for explosive limits of various fuels under room temperature and pressure by showing that for a large universe of fuels, constant adiabatic flame temperature and density factor are appropriate approximations at the lower explosive limit while only a constant density factor might be an appropriate approximation at the upper explosive limit. Thus the assumption of a constant adiabatic flame temperature can be used in calculating lower explosive limit while the assumption of a constant density factor can be used in approximating... 

Flammability limits are important safety parameters of each flammable material. Thermal theory of flame propagation suggests existence of a threshold temperature above which a flame propagates. Density theory of flame propagation suggests existence of a threshold density factor above which a flame propagates; density factor is defined as the ratio of before ignition to after ignition density. Based on a general version of thermal theory of flame propagation, constancy of values of adiabatic flame temperature at each flammability limit can be used to predict flammability limits. Similarly, based on a general version of the density theory of flame propagation, constancy of values of density... 

In reply to the comment of Lu and An on our publication paper [Phys. Rev. E 70, 016304 (2004)], we show that the consideration of water vapor exchange at the bubble interface is essential for obtaining our results and the adiabatic model is too simple to produce the differences. Moreover, in spite of smallness of the compressional viscosity term at the collapse, the illustrated differences are reasonable due to the strong nonlinearity of the bubble dynamics at the collapse and its sensitivity to even small perturbations. We emphasize on the correctness of our calculation results and our simulation programs are now available on the web. © 2005 The American Physical Society  

Equal channel angular pressing is an outstanding method for imposing large plastic deformation to metallic materials without any decreasing in cross section area of as processed samples. In this paper, the effect of working temperature, ram speed and the number of passes on the formation of adiabatic shear bands in Al6061 during equal channel angular pressing was investigated. Billets of the alloy were processed up to four passes via route BC from room temperature to 200°C with two ram speeds using a die that imparts an effective strain of ∼1.1 per pass. The results have demonstrated that the onset of the adiabatic shear banding in this alloy strongly depends on the ram speed: more...