Trions,
charged excitons that are reminiscent of hydrogen and positronium
ions, have been intensively studied for energy harvesting, light-emitting
diodes, lasing, and quantum computing applications because of their
inherent connection with electron spin and dark excitons. However,
these quasi-particles are typically present as a minority species
at room temperature making it difficult for quantitative experimental
measurements. Here, we show that by chemically engineering the well
depth of sp3 quantum defects through a series of alkyl
functional groups covalently attached to semiconducting carbon nanotube
hosts, trions can be efficiently generated and localized at the trapping
chemical defects. The exciton-electron binding energy of the trapped
trion approaches 119 meV, which more than doubles that of “free”
trions in the same host material (54 meV) and other nanoscale systems
(2–45 meV). Magnetoluminescence spectroscopy suggests the absence
of dark states in the energetic vicinity of trapped trions. Unexpectedly,
the trapped trions are approximately 7.3-fold brighter than the brightest
previously reported and 16 times as bright as native nanotube excitons,
with a photoluminescence lifetime that is more than 100 times larger
than that of free trions. These intriguing observations are understood
by an efficient conversion of dark excitons to bright trions at the
defect sites. This work makes trions synthetically accessible and
uncovers the rich photophysics of these tricarrier quasi-particles,
which may find broad implications in bioimaging, chemical sensing,
energy harvesting, and light emitting in the short-wave infrared.
We present a theoretical study of the interplay between topological p-wave superconductivity, orbital magnetic fields and quantum Hall phases in coupled wire systems. First, we calculate the phase diagram and physical observables of a fermionic ladder made of two coupled Kitaev chains, and discuss the presence of two and four Majorana zero modes. Second, we analyze hybrid systems consisting of a Kitaev chain coupled to a Luttinger liquid. By tuning the magnetic field and the carrier density, we identify quantum Hall and charge density wave phases, as well as regimes in which superconductivity is induced in the second chain by proximity effect. Finally, we consider two-dimensional systems made of weakly coupled ladders. There, we engineer a p+ip superconductor and describe a generalization of the ν = 1/2 fractional quantum Hall phase. These phases might be realized in solid-state or cold-atom nanowires. arXiv:1910.04816v1 [cond-mat.str-el]
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