Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Accurate Lindblad-Form Master Equation for Weakly Damped Quantum Systems
  Across All Regimes   Realistic models of quantum systems must include dissipative interactions
with an environment. For weakly-damped systems the Lindblad-form Markovian
master equation is invaluable for this task due to its tractability and
efficiency. This equation only applies, however, when the frequencies of any
subset of the system's transitions are either equal (degenerate), or their
differences are much greater than the transitions' linewidths (far-detuned).
Outside of these two regimes the only available efficient description has been
the Bloch-Redfield (B-R) master equation, the efficacy of which has long been
controversial due to its failure to guarantee the positivity of the density
matrix. The ability to efficiently simulate weakly-damped systems across all
regimes is becoming increasingly important, especially in the area of quantum
technologies. Here we solve this long-standing problem. We discover that a
condition on the slope of the spectral density is sufficient to derive a
Lindblad form master equation that is accurate for all regimes. We further show
that this condition is necessary for weakly-damped systems to be described by
the B-R equation or indeed any Markovian master equation. We thus obtain a
replacement for the B-R equation over its entire domain of applicability that
is no less accurate, simpler in structure, completely positive, allows
simulation by efficient quantum trajectory methods, and unifies the previous
Lindblad master equations. We also show via exact simulations that the new
master equation can describe systems in which slowly-varying transition
frequencies cross each other during the evolution. System identification tools,
developed in systems engineering, play an important role in our analysis. We
expect these tools to prove useful in other areas of physics involving complex
systems.

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The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
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The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
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The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys
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The categories of this paper are: supr-con
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: q-fin
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The categories of this paper are: ao-sci
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The categories of this paper are: gr-qc