Modeling of ions energy distribution profile of electronegative plasma discharges with an efficient Monte Carlo simulator

The crucial role that Ions Energy Distribution Function (IEDF) at the electrodes plays in plasma processing of semiconductor materials demands that this quantity be predicted with high accuracy and with low noise levels in any plasma simulator. In this work, an efficient Particle-in-cell/Monte-Carlo (PIC/MC) simulator is developed to model IEDF at the electrodes of electronegative plasma discharges. The simulator uses an effective method to increase the number of MC particles in regions of low particle density by splitting the particles and by adjusting their statistical weight. This statistical enhancement technique, which does not require interprocessor communication, is particularly suitable for parallel processing. The simulator is used to model an electronegative rf discharge at a pressure of 25 mTorr. The IEDF obtained from this simulator has good statistics with low noise levels, whereas the IEDF calculated by standard PIC/MC simulator is jammed with stochastic noise.Comment: LaTeX file, 19 pages, 16 figure

A simple quantum oblivious transfer protocol

A simple and efficient protocol for quantum oblivious transfer is proposed. The protocol can easily be implemented with present technology and is secure against cheaters with unlimited computing power provided the receiver does not have the technology to store the particles for an arbitrarily long period of time. The proposed protocol is a significant improvement over the previous protocols. Unlike the protocol of Cr\'epeau and Kilian which is secure if only if the spin of the particle is measured along the $x$ or the $y$ axis, the present protocol is perfectly secure no matter along which axes the spin of the particles are measured, and unlike the protocol of Bennett et al. which requires tens of thousand of particles, the present protocol requires only two particles.Comment: 11 pages, LaTeX file, no figures. The structure of the OT protocol is the same as before: Alice sends two particles to Bob, with the spin of the particles along the horizontal or vertical axis. The proof of the security of the protocol has been made more clear. Some new references have been adde

A Quantum Bit Commitment Protocol Based on EPR States

A protocol for quantum bit commitment is proposed. The protocol is feasible with present technology and is secure against cheaters with unlimited computing power as long as the sender does not have the technology to store an EPR particle for an arbitrarily long period of time. The protocol is very efficient, requiring only tens of particles.Comment: LaTeX file, 10 pages, no figures. It is shown how a cheating sender who has the technology to store an EPR particle for an arbitrarily long period of time can break the proposed protocol. Some recent references have been adde

Simulation and analysis of electron cyclotron resonance discharges

We describe in detail the method for Particle-in cell/Monte-Carlo simulation of electron cyclotron resonance (ECR) discharges. In the simulation, electric and magnetic fields are obtained by solving Maxwell equations, and electrons and ions are accelerated by solving equations of motion. We consider two different cases: (i) propagation of electromagnetic wave in the presence of a constant external magnetic field; (ii) propagation of electromagnetic wave in the presence of a linearly decreasing magnetic field which corresponds to a realistic ECR discharge. The simulation results indicate that at the resonance layer, the electrons are heated by the electromagnetic wave, and the incoming wave amplitude is pronouncedly damped, with the wave hardly propagating through the ECR layer.Comment: LaTeX file, 13 pages, 11 Figure

A Bell inequality which can be used to test locality more simply than Clauser-Horne inequality and which is violated by a larger magnitude of violation than Clauser-Horne-Shimony-Holt inequality

A correlation inequality is derived from local realism and a supplementary assumption. Unlike Clauser-Horne (CH) inequality [or Clauser-Horne-Shimony-Holt (CHSH) inequality] which is violated by quantum mechanics by a factor of $\sqrt 2$, this inequality is violated by a factor of 1.5. Thus the magnitude of violation of this inequality is approximately 20.7% larger than the magnitude of violation of previous inequalities. Moreover, unlike CH (or CHSH) inequality which requires the measurement of five detection probabilities, the present inequality requires the measurement of only two detection probabilities. This inequality can therefore be used to test locality more simply than CH or CHSH inequality.Comment: LaTeX file, 18 pages, no figure

Maximal violation of Bell's inequality in the case of real experiments

Einstein's locality is invoked to derive a correlation inequality. In the case of ideal experiments, this inequality is equivalent to Bell's original inequality of 1965 which, as is well known, is violated by a maximum factor of 1.5. The crucial point is that even in the case of real experiments where polarizers and detectors are non-ideal, the present inequality is violated by a factor of 1.5, whereas previous inequalities such as Clauser-Horne-Shimony-Holt inequality of 1969 and Clauser-Horne inequality of 1974 are violated by a factor of $\sqrt 2$. The larger magnitude of violation can be of importance for the experimental test of locality. Moreover, the supplementary assumption used to derive this inequality is weaker than Garuccio-Rapisarda assumption. Thus an experiment based on this inequality refutes a larger family of hidden variable theories than an experiment based on Garuccio-Rapisarda inequality.Comment: Latex file, 16 pages, no figure

Quantum oblivious transfer protocols based on EPR states

We describe efficient protocols for quantum oblivious transfer and for one-out-of-two quantum oblivious transfer. These protocols, which can be implemented with present technology, are secure against general attacks as long as the cheater can not store the bit for an arbitrarily long period of time.Comment: The EPR states that Alice sends to Bob are no longer orthogonal. Thus the modified protocol is secure even if Bob has the technology to determine which state was sent to him. The new protocol is efficient, feasible with present technology, and is secure against general attacks as long as Bob can not store the bit for an arbitrarily long period of tim

Bell's theorem, quantum mechanical non-locality and atomic cascade photons

Bell's theorem of 1965 is a proof that all realistic interpretations of quantum mechanics must be non-local. Bell's theorem consists of two parts: first a correlation inequality is derived that must be satisfied by all local realistic theories; second it is demonstrated that quantum mechanical probabilities violate this inequality in certain cases. In the case of ideal experiments, Bell's theorem has been proven. However, in the case of real experiments where polarizers and detectors are non-ideal, the theorem has not yet been proven since the proof always requires some arbitrary and {\em ad hoc} supplementary assumptions. In this paper, we state a new and rather weak supplementary assumption for the ensemble of photons that emerge from the polarizers, and we show that the conjunction of Einstein's locality with this assumption leads to validity of an inequality that is violated by a factor as large as 1.5 in the case of real experiments. Moreover, the present supplementary assumption is considerably weaker and more general than Clauser, Horne, Shimony, Holt supplementary assumption.Comment: Latex file, 11 pages, no figure

Analysis of low pressure electro-positive and electro-negative rf plasmas with Monte Carlo method

Particle-in-cell/Monte Carlo technique is used to simulate low pressure electro-negative and electro-positive plasmas at a frequency of 10 MHz. The potential, electric field, electron and ion density, and currents flowing across the plasma are presented. To compare the physical properties of the electro-positive gas with those of an electro-negative gas, the input voltage was decreased from 1000 Volts to 350 Volts. The simulation results indicate that the introduction of negative ions induces dramatic effects on the spatial and temporal variation of the electric field and on the behavior of the electron, ion, and displacement currents. In particular, the numerical modeling predicts the formation of double-layer at the plasma-sheath boundary of electro-negative discharge.Comment: Latex file, 14 pages, 19 figure

Maximal violation of Bell's inequality and atomic cascade photons

A correlation inequality is derived from local realism and a supplementary assumption. This inequality is violated by a factor of 1.5 in the case of real experiments, whereas previous inequalities such as Clauser-Horne-Shimony-Holt inequality of 1969 and Clauser-Horne inequality of 1974 are violated by a factor of $\sqrt 2$. Thus the magnitude of violation of this inequality is approximately 20.7% larger than the magnitude of violation of previous inequalities. Moreover, the present inequality can be used to test locality very simply because it requires the measurements of only two detection probabilities. In contrast, Clauser-Horne inequality requires the measurements of five detection probabilities.Comment: LaTeX file, 18 pages, no figures. The paper has been significantly modified. It is shown that the in the case of ideal experiments, the inequality derived in this paper is equivalent to Bell's original inequality of 1965 which, as is well known, is violated by a factor of 1.5. The crucial point is that even in the case of real experiments where polarizers and detectors are non-ideal, the present inequality is violated by a factor of 1.5, whereas previous inequalities such as CHSH inequality of 1969 and CH inequality of 1974 are violated by a factor of $\sqrt 2