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Real-time spectroscopy based on an emerging time-stretch technique can map the spectral information of optical waves into the time domain, opening several fascinating explorations of nonlinear dynamics in mode-locked lasers. However, the self-starting process of mode-locked lasers is quite sensitive to the environmental perturbation, which causes the transient behavior of laser to deviate from the true build-up process of solitons. Here, we optimize the laser system to improve its stability that suppresses the Q-switched lasing induced by the environmental perturbation. We therefore demonstrate the first observation of the entire build-up process of solitons in a mode-locked laser, revealing two possible ways to generate the temporal solitons. One way includes the dynamics of raised relaxation oscillation, quasi mode-locking stage, spectral beating behavior, and finally the stable single-soliton mode-locking. The other way contains, however, an extra transient bound-state stage before the final single-pulse mode-locking operation.

In tunnel junctions between ferromagnets and heavy elements with strong spin orbit coupling the magnetoresistance is often dominated by tunneling anisotropic magnetoresistance (TAMR). This makes conventional DC spin injection techniques impractical for determining the spin relaxation time ($\tau_s$). Here, we show that this obstacle for measurements of $\tau_s$ can be overcome by 2nd harmonic spin-injection-magnetoresistance (SIMR). In the 2nd harmonic signal the SIMR is comparable in magnitude to TAMR, thus enabling Hanle-induced SIMR as a powerful tool to directly determine $\tau_s$. Using this approach we determined the spin relaxation time of Pt and Ta and their temperature dependences. The spin relaxation in Pt seems to be governed by Elliott-Yafet mechanism due to a constant resistivity $\times$spin relaxation time product over a wide temperature range., Comment: 7 pages, 4 figures

The (over)completeness of even and odd nonlinear charge coherent states is proved and their generation explored. They are demonstrated to be generalized entangled nonlinear coherent states. A $D$-algebra realization of the SU$_f$(1,1) generators is given in terms of them. They are shown to exhibit SU$_f$(1,1) squeezing and two-mode $f$-antibunching for some particular types of $f$-nonlinearity, but neither one-mode nor two-mode $f$-squeezing., Comment: 33 pages, 3 figures, minor changes. arXiv admin note: substantial text overlap with arXiv:quant-ph/0306130 and arXiv:quant-ph/0503076

k-Component q-deformed charge coherent states are constructed, their (over)completeness proved and their generation explored. The q-deformed charge coherent states and the even (odd) q-deformed charge coherent states are the two special cases of them as k becomes 1 and 2, respectively. A D-algebra realization of the SU$_q$(1,1) generators is given in terms of them. Their nonclassical properties are studied and it is shown that for $k\geq3$, they exhibit two-mode q-antibunching, but neither SU$_q$(1,1) squeezing, nor one- or two-mode q-squeezing., Comment: LaTeX, 29 pages, 2 Postscript figures, minor changes

Even and odd q-deformed charge coherent states are constructed, their (over)completeness proved and their generation explored. A $D$-algebra realization of the SU$_q$(1,1) generators is given in terms of them. They are shown to exhibit SU$_q$(1,1) squeezing and two-mode $q$-antibunching, but neither one-mode, nor two-mode $q$-squeezing., Comment: LaTeX, 23 pages, no figure, minor changes, final version to be published in PLA

We consider continuous observation of the nonlinear dynamics of single atom trapped in an optical cavity by a standing wave with intensity modulation. The motion of the atom changes the phase of the field which is then monitored by homodyne detection of the output field. We show that the conditional Hilbert space dynamics of this system, subject to measurement induced perturbations, depends strongly on whether the corresponding classical dynamics is regular or chaotic. If the classical dynamics is chaotic the distribution of conditional Hilbert space vectors corresponding to different observation records tends to be orthogonal. This is a characteristic feature of hypersensitivity to perturbation for quantum chaotic systems., Comment: 11 pages, 6 figures

We describe the classical and quantum two dimensional nonlinear dynamics of large blue-detuned eveanescent-wave guiding cold atoms in hollow fiber. We show that chaotic dynamics exists for classic dynamics, when the intensity of the beam is periodically modulated. The two dimensional distributions of atoms in (x,y) plane are simulated. We show that the atoms will accumulate on several annular regions when the system enters a regime of global chaos. Our simulation shows that, when the atomic flux is very small, a similar distribution will be obtained if we detect the atomic distribution once each the modualtion period and integrate the signals. For quantum dynamics, quantum collapses and revivals appear . For periodically modulated optical potential, the variance of atomic position will be supressed compared to the no modulation case. The atomic angular momentum will influnce the evolution of wave function in two dimensional quantum system of hollow fiber., Comment: 14pages, 9 figures

We describe the classical two dimensinal nonlinear dynamics of cold atoms in far-off-resonant donut beams. We show that there chaotic dynamics exists for charge greater than unity, when the intensity of the beam is periodically modulated. The two dimensional distributions of atoms in $(x,y)$ plane for charge two are simulated. We show that the atoms will acumulate on several ring regions when the system enters to regime of global chaos., Comment: 8 pages, 8 figures