Bulletin of the American Physical Society
APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014; Denver, Colorado
Session Z12: Invited Session: Application of Synchronization in the Micro and Macro World |
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Sponsoring Units: GSNP DBIO Chair: Juan Restrepo, University of Colorado, Boulder Room: 205 |
Friday, March 7, 2014 11:15AM - 11:51AM |
Z12.00001: Quantum synchronization and the no-photon laser Invited Speaker: Murray Holland This talk will present a new approach to lasers that is based on the quantum synchronization of many atoms. Such lasers are predicted to produce light of unprecedented spectral purity and coherence, some two orders of magnitude better than any system available today. The idea is based on superradiant emission, where an ensemble of atoms with an extremely narrow atomic transition can phase-lock and form a macroscopic dipole that radiates light collectively. This is quite unlike a typical laser where atoms essentially act independently. The resulting light source is expected to have a spectral linewidth of just a few millihertz and could lead to more accurate and stable atomic clocks. Atomic clocks based on optical transitions have improved tremendously in recent years, giving clocks that tick $10^{15}$ times per second, and can have a fractional stability exceeding one part in $10^{16}$. This new sharper light source aims to push the frontier even further, so that fundamental tests of physics, such as the time variation of constants and tests of gravity, might even be possible. [Preview Abstract] |
Friday, March 7, 2014 11:51AM - 12:27PM |
Z12.00002: Theory of injection locking and mutual synchronization of non-isochronous auto-oscillators in the presence of noise Invited Speaker: Andrei Slavin A theory of injection locking and mutual synchronization of non-isochronous (having oscillation frequency dependent on the oscillation amplitude) auto-oscillators (AO) in the presence of thermal noise is developed and illustrated on the examples of spin-torque and spin-Hall nano-oscillators. It is demonstrated that all the characteristics of the injection locking and mutual synchronization of AO (such as phase-locking and synchronization frequency bands and transition times to a phase-locked state after application of a driving signal) are determined by the non-isochronous parameters of an AO : damping rate of amplitude fluctuations $\Gamma_{p} $ and dimensionless nonlinearity coefficient $\nu $ (see Eqs. (27b) and (33) in [1]). It is also shown that the influence of the thermal noise leads to the appearance of an apparent threshold amplitude of the driving signal in the process of injection locking. The developed theory is used to quantitatively explain the phenomena of fractional [2] and parametric [3] synchronization observed in strongly non-isochronous spin-torque [2, 3] and spin-Hall [4] microwave nano-oscillators based on magnetic nano-structures and driven by either spin-polarized charge current or pure spin current. \\[4pt] [1] A. Slavin and V. Tiberkevich, IEEE Trans. Magn. \textbf{45}, 1875 (2009). \\[0pt] [2] S. Urazhdin et al., Phys. Rev.Lett. \textbf{105, }104101 (2010). \\[0pt] [3] S. Urazhdin et al., Phys. Rev. Lett. \textbf{105}, 237204 (2010). \\[0pt] [4] V. E. Demidov et al., Nature Materials \textbf{11}, 1028, doi:10.1038/nmat3459 (2012). [Preview Abstract] |
Friday, March 7, 2014 12:27PM - 1:03PM |
Z12.00003: Synchronization of Degrade-and-Fire Oscillations in Synthetic Gene Circuits Invited Speaker: Lev Tsimring This talk reviews our recent work on the synchronization of synthetic gene oscillators operating in the degrade-and-fire regime. Computational modeling and theoretical analysis show that the key mechanism of oscillations is a small delay in the negative feedback loop. In a strongly nonlinear regime, this time delay can lead to long-period oscillations in gene expression that can be characterized by ``degrade and fire'' dynamics. I will present experimental, analytical, and computational results for the intra-cellular as well as population-wide synchronization when oscillators are coupled either by common protease enzymes or by coupling the oscillators to a quorum sensing machinery that produces chemical inducers freely diffusing through cell membranes. [Preview Abstract] |
Friday, March 7, 2014 1:03PM - 1:39PM |
Z12.00004: Unusual synchronization behaviors during the electropolishing of silicon wafers: experiments and theory Invited Speaker: Katharina Krischer The electrodissolution of silicon wafers exhibits a variety of oscillatory spatio-temporal patterns. Most typically, rather peculiar cluster patterns emerge, which always exhibit a pronounced oscillation of the uniform mode. In addition, the spontaneous formation of synchronously and incoherently oscillating domains, i.e., a chimera-type state, is observed. I will first give an overview of the experimentally observed oscillatory states with emphasis on their synchronization behavior and then discuss the current theoretical understanding of their emergence. In particular, I will show that the patterns can be well reproduced with a modified complex Ginzburg-Landau equation with nonlinear global (amplitude) coupling. To elucidate the role of the nonlinear global coupling, the dynamics of an ensemble of identical nonlinearly coupled Stuart-Landau oscillators is also discussed. [Preview Abstract] |
Friday, March 7, 2014 1:39PM - 2:15PM |
Z12.00005: Equivalence of phase oscillator models Invited Speaker: Antonio Politi Various types of phase-oscillator models are discussed to identify mutual analogies and differences. In particular, an ensemble of leaky-integrate-and-fire neurons is compared with both Winfree- and Kuramoto-type models, showing that, contrary to the common belief, relevant differences are maintained even in the weak coupling limit. The comparison is mostly made by studying the linear stability of the splay state and its possible bifurcations. [Preview Abstract] |
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