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Recent documents in Physicsen-usMon, 22 Jul 2013 13:29:49 PDT3600Effects of Fluctuating Energy Input on the Small Scales in Turbulence
http://wesscholar.wesleyan.edu/etd_hon_theses/1122
http://wesscholar.wesleyan.edu/etd_hon_theses/1122Mon, 03 Jun 2013 05:26:06 PDTChen-chi ChienAsymmetric Light Propagation in Active Photonic Structures
http://wesscholar.wesleyan.edu/etd_hon_theses/1106
http://wesscholar.wesleyan.edu/etd_hon_theses/1106Mon, 03 Jun 2013 05:25:54 PDT
This thesis will present a theoretical and numerical analysis of optical systems exhibiting non-reciprocity, with potential applications in the field of integrated opto-electronic circuits. We will carefully engineer structures with highly-asymmetric transport properties, where traits such as reflectance and transmittance are dependent upon the incident direction of the interrogating waves. This will be achieved through appropriately engineered amplifying and attenuating mechanisms in spatial arrangements obeying parity-time symmetries, as well as the implementation of magneto-optical elements. It will be demonstrated that such structures are good candidates for the development of novel devices serving the purposes of optical isolators and unidirectional lasers in integrated photonic technologies.
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Samuel Abraham KalishRotational Dynamics of Anisotropic Particles in Turbulence: Measurements of Lagrangian Vorticity and the Effects of Alignment with the Velocity Gradient
http://wesscholar.wesleyan.edu/etd_hon_theses/1065
http://wesscholar.wesleyan.edu/etd_hon_theses/1065Mon, 03 Jun 2013 05:25:24 PDTGuy GeyerRunning Shor's Algorithm on a complete, gate-by-gate implementation of a virtual, universal quantum computer
http://wesscholar.wesleyan.edu/etd_hon_theses/950
http://wesscholar.wesleyan.edu/etd_hon_theses/950Tue, 19 Jun 2012 09:26:46 PDTYunseong NamExploiting Wave Transport in PT Symmetric Media
http://wesscholar.wesleyan.edu/etd_hon_theses/930
http://wesscholar.wesleyan.edu/etd_hon_theses/930Tue, 19 Jun 2012 09:18:35 PDT
This thesis will present an integrated experimental and theoretical effort toward managing wave transport and introducing novel methods for signal manipulation. This will be achieved by developing a new circuitry design that exploits both absorption and gain mechanisms via judicious spatial arrangements of active elements that exhibit space-time reflection, or PT symmetries. We will show that the resulting structures, display intriguing behaviour that holds promises for the creation of new synthetic matter with novel functionalities. The playing field will be photonic and electronic circuits with complex potentials corresponding to complex refraction index and active impedances respectively.
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Zin LinTwo Point Correlations Between Velocity Sums and Differences, and Their Implications for Large-Small Scale Correlations in Fluid Turbulence
http://wesscholar.wesleyan.edu/etd_hon_theses/885
http://wesscholar.wesleyan.edu/etd_hon_theses/885Tue, 19 Jun 2012 09:01:11 PDTNicholas Joseph RotileTrends in Time-of-Flight Parameters with Application to Autoionization Lifetime Measurements
http://wesscholar.wesleyan.edu/etd_hon_theses/839
http://wesscholar.wesleyan.edu/etd_hon_theses/839Tue, 19 Jun 2012 08:45:12 PDTSeth Michael HafferkampExtraction of Atom-Diatom Collision Properties by Least Squares Fitting
http://wesscholar.wesleyan.edu/etd_hon_theses/769
http://wesscholar.wesleyan.edu/etd_hon_theses/769Thu, 02 Jun 2011 13:36:44 PDTJames Paris WamplerExperimental Measurement of the Stress Tensor in a Quasi-2D Granular Gas
http://wesscholar.wesleyan.edu/etd_hon_theses/745
http://wesscholar.wesleyan.edu/etd_hon_theses/745Thu, 02 Jun 2011 13:29:47 PDTWan Jun YangDynamic Vortex Drag
http://wesscholar.wesleyan.edu/etd_hon_theses/734
http://wesscholar.wesleyan.edu/etd_hon_theses/734Thu, 02 Jun 2011 13:27:24 PDT
This thesis explores the concept of dynamic vortex drag resulting from Kelvin wave excitations on vortex cores in thin films of superfluid ^{4}He. In this system, vortex drag is commonly accepted as a significant mechanism for the dissipation of third sound wave motion; however, current models implementing a static drag force have been unable to quantitatively explain anomalous third sound free decay results found in the literature. In this thesis, many possible manifestations of Kelvin wave agitation are explored and are shown to correct the deficiencies of existing static drag theories. It is therefore concluded that vortex drag in thin films of superfluid ^{4}He is most likely a dynamic, and not a static, process.
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Nicholas Everett JacksonChaos at the Crossroads of Spontaneous Symmetry Breakings: Novel Universality Classes
http://wesscholar.wesleyan.edu/etd_hon_theses/653
http://wesscholar.wesleyan.edu/etd_hon_theses/653Thu, 02 Jun 2011 13:10:42 PDT
This thesis investigates quantum systems with underlying classically chaotic dynam- ics in the framework of spontaneous symmetry-breaking transitions. The main emphases are on: (i) Quantum-Classical correspondence in systems at a metal-to-insulator tran- sition as seen through dynamical stability with respect to external perturbations, and (ii) the spontaneous breaking of combined parity and time-reversal symmetry in non- Hermitian systems across the localization-delocalization transition. By studying such crossroads between a critical phase transition and a parametric system change (quan- tum to classical or localized to delocalized) we are able to develop results for entire universality classes.
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Carl Tonner WestEffect of Valency on the Dynamics and Thermodynamics of DNA-linked Nanoparticles Materials
http://wesscholar.wesleyan.edu/etd_hon_theses/572
http://wesscholar.wesleyan.edu/etd_hon_theses/572Thu, 17 Jun 2010 11:35:37 PDT
Nanoparticles (NP) functionalized with single-stranded DNA (ssDNA) offer a route to custom-designed, self-assembled nanomaterials with potentially unusual properties. We explore the phase behavior and structure of a model for NP functionalized with between 3 and 6 short ssDNA through simulations, allowing us to examine both the role of the number of attached strands (valency) and their relative orientations. We find that 3 to 5-functionalized NP form amorphous systems, with 4 and 5-functionalized NP constructing an unusual multitude of liquid phases, or polyamorphism, through interpenetration of networks. The 6-functionalized NP with octahedral symmetry form at least six crystalline structures, consisting of up to six interpenetrating simple cubic lattices. The crystallization dynamics of the 6-functionalized system follows the conventional two-step pathway, demonstrating that such mechanism applies to our NP system with complex interactions.
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Wei DaiStability of DNA-Linked Nanoparticle Crystals
http://wesscholar.wesleyan.edu/etd_hon_theses/556
http://wesscholar.wesleyan.edu/etd_hon_theses/556Thu, 17 Jun 2010 11:35:12 PDT
In this thesis, a coarse-grained molecular dynamics model is used to address three factors which impact the kinetic and thermodynamic stability of BCC and FCC crystals formed in DNA-linked nanoparticle systems: (i) surface mobility, (ii) the number of attached strands, and (iii) the size of the nanoparticle core. The model predicts that systems with surface mobility form crystals with lower free energy, but also a lower heat of fusion. FCC crystals have a higher kinetic melting temperature when formed in systems with low surface mobility, but BCC crystals have a lower kinetic melting temperature when formed in systems with low surface mobility. The model demonstrates that the kinetic melting temperature of BCC and FCC systems increases with increasing number of strands, but that it decreases with increasing core size. The results presented here are intended to provide guidance in the choice of parameters when experimentally forming crystals.
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Olivia Padovan-MerharNon-Hermitian Dynamics: Examples from Disordered Microwave Cavities and Classical Optics
http://wesscholar.wesleyan.edu/etd_hon_theses/515
http://wesscholar.wesleyan.edu/etd_hon_theses/515Thu, 17 Jun 2010 11:34:08 PDT
This thesis investigates dynamics in leaking systems with and without amplification. On the one hand, we introduce and investigate both theoretically and experimentally a new measure of Anderson localization in random media which takes absorption into account. On the other hand, we study wave propagation in a new class of synthetic optical materials (periodic or random) where gain and loss are judiciously tailored. These two seemingly different types of problems are nicely brought together in the framework of non-Hermitian Hamiltonian formalism.
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Mei Chai ZhengExperimental Study of Lagrangian Velocity and Energy Statistics in Inhomogeneous Turbulence
http://wesscholar.wesleyan.edu/etd_hon_theses/506
http://wesscholar.wesleyan.edu/etd_hon_theses/506Thu, 17 Jun 2010 11:33:53 PDT
We study Lagrangian statistics in a flow stirred by two oscillating grids. We quantify the dependence of small scales on the inhomogeneous large scales in a complex flow. We also describe the method we developed to study the measurement volume bias while investigating Lagrangian structure functions. We identify the important factors in energy transport by estimating the terms of the turbulent kinetic energy equation.
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Surendra Bahadur KunwarGranular Gravitational Collapse in Realistically Simulated Granular Gases
http://wesscholar.wesleyan.edu/etd_hon_theses/497
http://wesscholar.wesleyan.edu/etd_hon_theses/497Thu, 17 Jun 2010 11:33:39 PDT
Gravitational granular collapse (GGC) occurs whenever a granular gas is allowed to evolve freely in gravity without the additional input of kinetic energy. The system dissipates its remaining energy through inelastic collisions as it settles into a granular solid at rest at the bottom of its enclosure in &amp;#64257;nite time. We are interested in the reasons for an observed divergence between experimental and theoretical results of the rate of decay. The use of realistic simulations con&amp;#64257;rms that, even in more closely ideal settings, the theory is not as universal as expected. We test the relative e&amp;#64256;ects of a variety of system parameters on GGC dynamics and conclude that the second-power granular temperature decay law during GGC theoretically derived involves the somewhat unphysical approximation of particles that interact with a constant coe&amp;#64259;cient of resititution that is very far into the elastic limit.
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Samuel Benjamin KachuckSelf-Assembly of DNA-Linked Nanoparticles
http://wesscholar.wesleyan.edu/etd_hon_theses/464
http://wesscholar.wesleyan.edu/etd_hon_theses/464Thu, 17 Jun 2010 11:32:50 PDT
Nanoparticles (NP) tethered with DNA strands can self-assemble into highly organized structures through complementary bonding of base pairs. Such materials are promising building blocks for the bottom-up nanotechnology. This thesis investigates (a) the phase diagram of NP tethered with four DNA strands, (b) lattice models that reveal the insights behind the unusual phase behavior, and (c) a theoretical description for the self-assembly. All of our studies are based on a combination of theory and simulations. We report the discovery of a hierarchy of amorphous networked phases that has never been observed in other materials. The mechanism behind the multitude of phases is studied in detail using various approaches. Lastly, we present a comprehensive theoretical framework that quantitatively describes the equilibrium clustering and dynamics, as well as the self-assembly kinetics. The theoretical predictions yield striking agreement with our molecular modeling.
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Chia Wei HsuInvestigation of Stark Broadening in LIBS of Hydrogen Balmer emission lines n = 3 to 15
http://wesscholar.wesleyan.edu/etd_hon_theses/373
http://wesscholar.wesleyan.edu/etd_hon_theses/373Wed, 27 May 2009 12:36:25 PDT
This thesis investigates Stark broadening hydrogen Balmer emission lines n = 4 to 15 subsequent to nanosecond laser induced optical breakdown of hydrogen gas from Nd:YAG Q-switched laser operated at 1064 nm. Data for 1, 2 and 4 µs delay times after the plasma initiation was Abel inverted for Balmer emission lines from n = 3 to 10. Trends in Area and FWHM under the fitted Lorentzian to these curves were plotted as a function of radius and for three separate delays. Temperature of 5000 to 10000 K was calculated. Electron number of density of 5×&amp;#12310;10&amp;#12311;^16 to 1×&amp;#12310;10&amp;#12311;^15/&amp;#12310;cm&amp;#12311;^(-3)was referred from the theory. This work was able to observe distinguishable hydrogen Balmer emission lines from plasma for n = 3 to 15.
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Yudhishthir Prasad KandelVortex Dissipation in Superfluid Third Sound Flows
http://wesscholar.wesleyan.edu/etd_hon_theses/336
http://wesscholar.wesleyan.edu/etd_hon_theses/336Wed, 27 May 2009 12:34:07 PDT
This thesis probes possible mechanisms behind anomalous freedecays commonly observed in superfluid helium third sound flows. Several models, based on vortex dissipation, for the additional dissipation these anomalous freedecays imply are constructed, tested, and modified to be consistent with the observed characteristics. This work concludes that these simple models involving only vortex friction and a creation energy are insufficient to explain the observed characteristics. From this conclusion a model is proposed that holds promise for future study.
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Anand SwaminathanWave-packet Dynamics in Unconventional RMT Models
http://wesscholar.wesleyan.edu/etd_hon_theses/327
http://wesscholar.wesleyan.edu/etd_hon_theses/327Wed, 27 May 2009 12:33:35 PDT
We analyze the wave-packet dynamics scenario produced by Random Matrix Theory models with unconventional band-profile structures. Our motivation is to understand the energy spreading of quantum systems with complex dynamics. Examples of such systems include complex nuclei, atoms and molecules, quantum dots, and Bose-Einstein Condensates in optical traps, which, under the influence of an external perturbation, experience an energy redistribution of the initially prepared state. Such a perturbation could be due to an external electric or magnetic field, a change in the confining geometry, or a residual interaction, among other things. Of special interest in our analysis is the investigation of the time relaxation properties of a prepared state into a sea of other states (the continuum). We find that, for a large family of power spectra characterized by a non-flat profile, the survival probability $P(t)$ might exhibit either exponential-like or power-law decay.
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James Maxwell Aisenberg