Enhancing quantum entropy in vacuum-based quantum random number generator

Information-theoretically provable unique true random numbers, which cannot be correlated or controlled by an attacker, can be generated based on quantum measurement of vacuum state and universal-hashing randomness extraction. Quantum entropy in the measurements decides the quality and security of the random number generator. At the same time, it directly determine the extraction ratio of true randomness from the raw data, in other words, it affects quantum random numbers generating rate obviously. In this work, considering the effects of classical noise, the best way to enhance quantum entropy in the vacuum-based quantum random number generator is explored in the optimum dynamical analog-digital converter (ADC) range scenario. The influence of classical noise excursion, which may be intrinsic to a system or deliberately induced by an eavesdropper, on the quantum entropy is derived. We propose enhancing local oscillator intensity rather than electrical gain for noise-independent amplification of quadrature fluctuation of vacuum state. Abundant quantum entropy is extractable from the raw data even when classical noise excursion is large. Experimentally, an extraction ratio of true randomness of 85.3% is achieved by finite enhancement of the local oscillator power when classical noise excursions of the raw data is obvious.Comment: 12 pages,8 figure

Electronically reconfigurable binary phase liquid crystal reflectarray metasurface at 108 GHz

We have proposed a preliminary design and computation results of a 20 by 20 elements reconfigurable liquid crystal (LC) based binary phase reflectarray metasurface for applications in THz wireless communication. Specifically, we performed full-wave simulations and theoretical calculations on the far-field patterns of our proposed device, and we also developed optimisation routines for both the antenna unit cell design as well as far-field pattern synthesis algorithms. The LC used was modelled after Merk's model GT3-23001. At optimal operation frequency of 108 GHz, the phase difference between ON and OFF state is 177 degrees, and the reflection amplitudes of both states are 0.88. We were able to demonstrate 60 degrees of beam steering, which was achieved together with a (single beam) RCS of -5.8 dBm2, when the device dimension is only 20mm by 20mm. The operational bandwidth is plus or minus 2 GHz from central frequency of 108 GHz

Synchronization Recovery of Chaotic Wave Through an Imperfect Channel

We present a novel idea to recover synchronization using the genetic algorithm after a chaotic wave passes through an imperfect channel with constant attenuation and offset. The compensation block, which is added before the receiver, is used to compensate the distortion of the imperfect channel. A new concept, the synchronization mismatch is defined and used as the cost function in genetic algorithm to design the compensation block. The validity of this approach is suggested by numerical simulations

Optimality Conditions and Duality of Three Kinds of Nonlinear Fractional Programming Problems

Some assumptions for the objective functions and constraint functions are given under the conditions of convex and generalized convex, which are based on the F-convex, ρ-convex, and (F,ρ)-convex. The sufficiency of Kuhn-Tucker optimality conditions and appropriate duality results are proved involving (F,ρ)-convex, (F,α,ρ,d)-convex, and generalized (F,α,ρ,d)-convex functions