Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum-enhanced multi-parameter estimation for unitary photonic systems   Precise device characterization is a fundamental requirement for a large
range of applications using photonic hardware, and constitutes a
multi-parameter estimation problem. Estimates based on measurements using
single photons or classical light have precision which is limited by
shot-noise, while quantum resources can be used to achieve sub-shot-noise
precision. However, there are many open questions with regard to the best
quantum protocols for multi-parameter estimation, including the ultimate limits
to achievable precision, as well as optimal choices for probe states and
measurements. In this paper, we develop a formalism based on Fisher information
to tackle these questions for set-ups based on linear-optical components and
photon-counting measurements. A key ingredient of our analysis is a mapping for
equivalent protocols defined for photonic and spin systems, which allows us to
draw upon results in the literature for general finite-dimensional systems.
Motivated by the protocol in X.-Q. Zhou, et al., Optica 2, 510 (2015), we
present new results for quantum-enhanced tomography of unitary processes,
including a comparison of Holland-Burnett and NOON probe states.

37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
3
The categories of this paper are: physics
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
23
The categories of this paper are: solv-int
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph