Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Coherent-Classical Estimation for Linear Quantum Systems   We study a coherent-classical estimation scheme for a class of linear quantum
systems, where the estimator is a mixed quantum-classical system that may or
may not involve coherent feedback. We show that when the quantum plant or the
quantum part of the estimator (coherent controller) is an annihilation operator
only system, coherent-classical estimation without coherent feedback can
provide no improvement over purely-classical estimation. Otherwise,
coherent-classical estimation without feedback can be better than
classical-only estimation for certain homodyne detector angles, although the
former is inferior to the latter for the best choice of homodyne detector
angle. Moreover, we show that coherent-classical estimation with coherent
feedback is no better than classical-only estimation, when both the plant and
the coherent controller are annihilation operator only systems. Otherwise,
coherent-classical estimation with coherent feedback can be superior to
purely-classical estimation, and in this case, the former is better than the
latter for the optimal choice of homodyne detector angle.

21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
4
The categories of this paper are: cond-mat
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con