Electric field excitation suppression in cold atoms

In this article, the atom excitation suppression is studied in two ways. The first way of exploring the excitation suppression is by an external DC electric field. The second way is to study the excitation suppression caused by electric field generated by free charges, which are created by ionizing atoms. This suppression is called Coulomb blockade. Here the Coulomb forces are created by ions through ionizing atoms by a UV laser. The theory shows that the interaction, which causes the suppression, is primarily caused by charge-dipole interactions. Here the charge is the ion, and the dipole is an atom. In this experiment, we use $^{85}$Rb atoms. The valence electron and the ion core are the two poles of an electric dipole. The interaction potential energy between the ion and the atom is proportional to $\frac{1}{R^2}$, and the frequency shift caused by this interaction is proportional to $\frac{1}{R^4}$, where $R$ is the distance between the ion and the dipole considered. This research can be used for quantum information storage, remote control, creating hot plasmas using cold atoms, as well as electronic devices.Comment: 12 pages, 7 figure

Strong experimental guarantees in ultrafast quantum random number generation

We describe a methodology and standard of proof for experimental claims of quantum random number generation (QRNG), analogous to well-established methods from precision measurement. For appropriately constructed physical implementations, lower bounds on the quantum contribution to the average min-entropy can be derived from measurements on the QRNG output. Given these bounds, randomness extractors allow generation of nearly perfect "{\epsilon}-random" bit streams. An analysis of experimental uncertainties then gives experimentally derived confidence levels on the {\epsilon} randomness of these sequences. We demonstrate the methodology by application to phase-diffusion QRNG, driven by spontaneous emission as a trusted randomness source. All other factors, including classical phase noise, amplitude fluctuations, digitization errors and correlations due to finite detection bandwidth, are treated with paranoid caution, i.e., assuming the worst possible behaviors consistent with observations. A data-constrained numerical optimization of the distribution of untrusted parameters is used to lower bound the average min-entropy. Under this paranoid analysis, the QRNG remains efficient, generating at least 2.3 quantum random bits per symbol with 8-bit digitization and at least 0.83 quantum random bits per symbol with binary digitization, at a confidence level of 0.99993. The result demonstrates ultrafast QRNG with strong experimental guarantees.Comment: 11 pages, 9 figure

Fish and freshwater crayfish in streams in the Cape Naturaliste region and Wilyabrup Brook

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