17 research outputs found
Numerical simulation of a Controlled-Controlled-Not (CCN) quantum gate in a chain of three interacting nuclear spins system
We present the study of a quantum Controlled-Controlled-Not gate, implemented
in a chain of three nuclear spins weakly Ising interacting between all of them,
that is, taking into account first and second neighbor spin interactions. This
implementation is done using a single resonant -pulse on the initial state
of the system (digital and superposition). The fidelity parameter is used to
determine the behavior of the CCN quantum gate as a function of the ratio of
the second neighbor interaction coupling constant to the first neighbor
interaction coupling constant (). We found that for we can
have a well defined CCN quantum gate.Comment: 9 pages, 5 fugure
Masking of Time-Frequency Patterns in Applications of Passive Underwater Target Detection
Spectrogram analysis of acoustical sounds for underwater target classification is utilized when loud nonstationary interference sources overlap with a signal of interest in time but can be separated in time-frequency (TF) domain. We propose a signal masking method which in a TF plane combines local statistical and morphological features of the signal of interest. A dissimilarity measure D of adjacent TF cells is used for local estimation of entropy H, followed by estimation of ΔH=Htc−Hfc entropy difference, where Hfc is calculated along the time axis at a mean frequency fc and Htc is calculated along the frequency axis at a mean time tc of the TF window, respectively. Due to a limited number of points used in ΔH estimation, the number of possible ΔH values, which define a primary mask, is also limited. A secondary mask is defined using morphological operators applied to, for example, H and ΔH. We demonstrate how primary and secondary masks can be used for signal detection and discrimination, respectively. We also show that the proposed approach can be generalized within the framework of Genetic Programming