Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Direct access to quantum fluctuations through cross-correlation
  measurements   Detection of the quantum fluctuations by conventional methods meets certain
obstacles, since it requires high frequency measurements. Moreover, quantum
fluctuations are normally dominated by classical noise, and are usually further
obstructed by various accompanying effects such as a detector backaction. In
present work, we demonstrate that these difficulties can be bypassed by
performing the cross-correlation measurements. We propose to use a pair of
two-level detectors, weakly coupled to a collective mode of an electric
circuit. Fluctuations of the current source accumulated in the collective mode
induce stochastic transitions in the detectors. These transitions are then read
off by quantum point contact (QPC) electrometers and translated into two
telegraph processes in the QPC currents. Since both detectors interact with the
same collective mode, this leads to a certain fraction of the correlated
transitions. These correlated transitions are fingerprinted in the
cross-correlations of the telegraph processes, which can be detected at zero
frequency, i.e., with a long time measurements. Concerning the dependance of
the cross-correlator on the detectors' energy splittings, the most interesting
region is at the degeneracy points, where it exhibits a sharp non-local
resonance, that stems from higher order processes. We find that at certain
conditions the main contribution to this resonance comes from the quantum
noise. Namely, while the resonance line shape is weakly broadened by the
classical noise, the height of the peak is directly proportional to the square
of the quantum component of the noise spectral function.

10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
17
The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int