Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Valley coherent exciton-polaritons in a monolayer semiconductor   Two-dimensional transition metal dichalcogenide (TMD) semiconductors provide
a unique possibility to access the electronic valley degree of freedom using
polarized light, opening the way to valley information transfer between distant
systems. Excitons with a well-defined valley index (or valley pseudospin) as
well as superpositions of the exciton valley states can be created with light
having circular and linear polarization, respectively. However, the generated
excitons have short lifetimes (ps) and are also subject to the electron-hole
exchange interaction leading to fast relaxation of the valley pseudospin and
coherence. Here we show that control of these processes can be gained by
embedding a monolayer of WSe$_2$ in an optical microcavity, where
part-light-part-matter exciton-polaritons are formed in the strong light-matter
coupling regime. We demonstrate the optical initialization of the valley
coherent polariton populations, exhibiting luminescence with a linear
polarization degree up to 3 times higher than that of the excitons. We further
control the evolution of the polariton valley coherence using a Faraday
magnetic field to rotate the valley pseudospin by an angle defined by the
exciton-cavity-mode detuning, which exceeds the rotation angle in the bare
exciton. This work provides unique insight into the decoherence mechanisms in
TMDs and demonstrates the potential for engineering the valley pseudospin
dynamics in monolayer semiconductors embedded in photonic structures.

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The categories of this paper are: quant-ph
28
The categories of this paper are: alg-geom
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The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: econ
30
The categories of this paper are: q-alg
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The categories of this paper are: adap-org
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The categories of this paper are: hep-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-fin
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The categories of this paper are: stat