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A Quantum Random Number Generator (QRNG) based on the detection of the arrival time of photons is presented. A stochastic model of the QRNG prototype is derived, showing its consistency with output data sets, in order to estimate the entropy produced by the device. Experimental data, in accord with the model, demonstrates the robustness of the approach versus possible variations of external parameters such as temperature or intensity of the light. [ABSTRACT FROM AUTHOR]

Most bounds on the size of codes hold for any code, whether linear or not. Notably, the Griesmer bound holds only in the linear case and so optimal linear codes are not necessarily optimal codes. In this paper, we identify code parameters $(q,d,k)$ , namely, field size, minimum distance, and combinatorial dimension, for which the Griesmer bound also holds in the (systematic) nonlinear case. Moreover, we show that the Griesmer bound does not necessarily hold for a systematic code by explicit construction of a family of optimal systematic binary codes. On the other hand, we are able to provide some versions of the Griesmer bound holding for all the systematic codes. [ABSTRACT FROM AUTHOR]