Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Scattering Experiments with Microwave Billiards at an Exceptional Point
  under Broken Time Reversal Invariance   Scattering experiments with microwave cavities were performed and the effects
of broken time-reversal invariance (TRI), induced by means of a magnetized
ferrite placed inside the cavity, on an isolated doublet of nearly degenerate
resonances were investigated. All elements of the effective Hamiltonian of this
two-level system were extracted. As a function of two experimental parameters,
the doublet and also the associated eigenvectors could be tuned to coalesce at
a so-called exceptional point (EP). The behavior of the eigenvalues and
eigenvectors when encircling the EP in parameter space was studied, including
the geometric amplitude that builds up in the case of broken TRI. A
one-dimensional subspace of parameters was found where the differences of the
eigenvalues are either real or purely imaginary. There, the Hamiltonians were
found PT-invariant under the combined operation of parity (P) and time reversal
(T) in a generalized sense. The EP is the point of transition between both
regions. There a spontaneous breaking of PT occurs.

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The categories of this paper are: bayes-an
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The categories of this paper are: chao-dyn
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The categories of this paper are: quant-ph
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The categories of this paper are: q-alg
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The categories of this paper are: math-ph
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The categories of this paper are: eess
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The categories of this paper are: q-bio
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The categories of this paper are: hep-lat
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The categories of this paper are: atom-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: solv-int
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: plasm-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: patt-sol