Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Short-pulse cross-phase modulation in an
  electromagnetically-induced-transparency medium   Electromagnetically-induced transparency (EIT) has been proposed as a way to
greatly enhance cross-phase modulation, with the possibility of leading to
few-photon-level optical nonlinearities. This enhancement grows as the
transparency window width, \Delta_EIT, is narrowed. Decreasing \Delta_EIT,
however, increases the response time of the effect, suggesting that for pulses
of a given duration, there could be a fundamental limit to the strength of the
nonlinearity. We show that in the regimes of most practical interest - narrow
EIT windows perturbed by short signal pulses- the enhancement offered by EIT is
not only in the magnitude of the nonlinear phase shift but in fact also in its
increased duration. That is, for the case of signal pulses much shorter
(temporally) than the inverse EIT bandwidth, the narrow window serves to
prolong the effect of the passing signal pulse, leading to an integrated phase
shift that grows linearly with \Delta_EIT even though the peak phase shift may
saturate; the continued growth of the integrated phase shift improves the
detectability of the phase shift, in principle without bound. For many
purposes, it is this detectability which is of interest, more than the absolute
magnitude of the peak phase shift. We present analytical expressions based on a
linear time-invariant model that accounts for the temporal behavior of the
cross-phase modulation for several parameter ranges of interest. We conclude
that in order to optimize the detectability of the EIT-based cross-phase shift,
one should use the narrowest possible EIT window, and a signal pulse that is as
broadband as the excited state linewidth and detuned by half a linewidth.

4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
26
The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys