arXiv subjects

Joe Bailey

Publications and source records attributed to Joe Bailey.

4 recordsLinked to original sources

arXiv2022

Multiband condensate of magnons in two dimensions

Wavelike bosonic particles can accumulate in a single mode characterized by a particular wavelength, and such condensates are at the heart of phenomena such as superconductivity and superfluidity where usually a single complex number describes their state. If there are several flavors of excitations or particles, a vector containing several complex numbers can characterize multicomponent condensation, thus opening new possibilities for textures, dynamics, and devices. Thus far, multicomponent condensates have long represented a rewarding subfield of cold atom physics, as well as a theme for research on exotic superconductors where the constituent bosons are not atoms but electron pairs. Here we consider the case where the bosons are magnons (collective spin excitations), injected by microwaves into high-quality yttrium iron garnet (YIG) crystals. Recent advances in fabrication yield thin (128 nm) films of sufficiently high quality to display multiple magnon bands quantized along the film normal. Microwave pumping can populate these bands, providing a new two-dimensional multiband condensate optimized in a narrow range of powers and frequencies due to a four-magnon scattering resonance. We establish a phase diagram for this magnonic system, reminiscent of that for exotic superconductors, revealing both single and multiband condensation.

cond-mat.quant-gas↗

arXiv2017

Impact Of Urban Technology Deployments On Local Commercial Activity

While smart city innovations seem to be a common and necessary response to increasing challenges of urbanization, foreseeing their impact on complex urban system is critical for informed decision making. Moreover, often the effect of urban interventions goes beyond the original expectations, including multiple indirect impacts. The present study considers the impact of two urban deployments, Citi Bike (bike sharing system) and LinkNYC kiosks, on the local commercial activity in the affected neighborhoods of New York City. The study uses anonymized and aggregated insights provided through a grant from the Mastercard Center for Inclusive Growth in order to provide initial data-driven evidence towards the hypothesis that proximity of Citi Bike stations incentivizes local sales at eating places, while LinkNYC kiosks help people, especially visitors, to navigate local businesses and thus incentivize commercial activity in different business categories.

cs.CY↗

arXiv2012

Bistable collective behavior of polymers tethered in a nanopore

Polymer-coated pores play a crucial role in nucleo-cytoplasmic transport and in a number of biomimetic and nanotechnological applications. Here we present Monte Carlo and Density Functional Theory approaches to identify different collective phases of end-grafted polymers in a nanopore and to study their relative stability as a function of intermolecular interactions. Over a range of system parameters that is relevant for nuclear pore complexes, we observe two distinct phases: one with the bulk of the polymers condensed at the wall of the pore, and the other with the polymers condensed along its central axis. The relative stability of these two phases depends on the interpolymer interactions. The existence of the two phases suggests a transport mechanism in which marginal changes in these interactions, possibly induced by nuclear transport receptors, cause the pore to transform between open and closed configurations.

cond-mat.soft↗

arXiv2010

Coined quantum walks on percolation graphs

Quantum walks, both discrete (coined) and continuous time, form the basis of several quantum algorithms and have been used to model processes such as transport in spin chains and quantum chemistry. The enhanced spreading and mixing properties of quantum walks compared with their classical counterparts have been well-studied on regular structures and also shown to be sensitive to defects and imperfections in the lattice. As a simple example of a disordered system, we consider percolation lattices, in which edges or sites are randomly missing, interrupting the progress of the quantum walk. We use numerical simulation to study the properties of coined quantum walks on these percolation lattices in one and two dimensions. In one dimension (the line) we introduce a simple notion of quantum tunneling and determine how this affects the properties of the quantum walk as it spreads. On two-dimensional percolation lattices, we show how the spreading rate varies from linear in the number of steps down to zero, as the percolation probability decreases to the critical point. This provides an example of fractional scaling in quantum walk dynamics.

quant-ph↗