7,088 research outputs found
Nonclassicality of noisy quantum states
Nonclassicality conditions for an oscillator-like system interacting with a
hot thermal bath are considered. Nonclassical properties of quantum states can
be conserved up to a certain temperature threshold only. In this case,
affection of the thermal noise can be compensated via transformation of an
observable, which tests the nonclassicality (witness function). Possibilities
for experimental implementations based on unbalanced homodyning are discussed.
At the same time, we demonstrate that the scheme based on balanced homodyning
cannot be improved for noisy states with proposed technique and should be
applied directly.Comment: 15 pages, 3 figure
Dual problem of nonclassicality
We show that nonclassicality of phase-space quasi-probability distributions
is tied to violations of principles of physical reality in device-dependent
scenarios. In this context, the nonclassicality problem has its dual form
expressed as a device-dependent analog of Bell inequalities. This approach is
applicable even to systems with only one spatial party. The derived
inequalities are employed for testing nonclassicality with emblematic optical
measurements: photocounting including the case of realistic photon-number
resolution; unbalanced, balanced, and eight-port homodyne detection.Comment: 13 pages, 6 figure
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