576,823 research outputs found
Synthesizing a Fractional v=2/3 State from Particle and Hole States
Topological edge-reconstruction occurs in hole-conjugate states of the
fractional quantum Hall effect. The frequently studied polarized state of
filling factor v=2/3 was originally proposed to harbor two counter-propagating
edge modes: a downstream v=1 and an upstream v=1/3. However, charge
equilibration between these two modes always led to an observed downstream
v=2/3 charge mode accompanied by an upstream neutral mode (preventing an
observation of the original proposal). Here, we present a new approach to
synthetize the v=2/3 edge mode from its basic counter-propagating charged
constituents, allowing a controlled equilibration between the two
counter-propagating charge modes. This novel platform is based on a carefully
designed double-quantum-well, which hosts two populated electronic sub-bands
(lower and upper), with corresponding filling factors, vl & vu. By separating
the 2D plane to two gated intersecting halves, each with different fillings,
counter-propagating chiral modes can be formed along the intersection line.
Equilibration between these modes can be controlled with the top gates' voltage
and the magnetic field. Our measurements of the two-terminal conductance G2T
and the presence of a neutral mode allowed following the transition from the
non-equilibrated charged modes, manifested by G2T=(4/3)e2/h, to the fully
equilibrated modes, with a downstream charge mode with G2T=(2/3)e2/h
accompanied by an upstream neutral mode.Comment: 16 pages,4 figure
Switch between critical percolation modes in city traffic dynamics
Percolation transition is widely observed in networks ranging from biology to
engineering. While much attention has been paid to network topologies, studies
rarely focus on critical percolation phenomena driven by network dynamics.
Using extensive real data, we study the critical percolation properties in city
traffic dynamics. Our results suggest that two modes of different critical
percolation behaviors are switching in the same network topology under
different traffic dynamics. One mode of city traffic (during nonrush hours or
days off) has similar critical percolation characteristics as small world
networks, while the other mode (during rush hours on working days) tends to
behave as a 2D lattice. This switching behavior can be understood by the fact
that the high-speed urban roads during nonrush hours or days off (that are
congested during rush hours) represent effective long-range connections, like
in small world networks. Our results might be useful for understanding and
improving traffic resilience.Comment: 8 pages, 4 figures, Daqing Li, Ziyou Gao and H. Eugene Stanley are
the corresponding authors ([email protected], [email protected],
[email protected]
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