221 research outputs found
Two-mode squeezed vacuum and squeezed light in correlated interferometry
We study in detail a system of two interferometers aimed to the detection of
extremely faint phase-fluctuations. This system can represent a breakthrough
for detecting a faint correlated signal that would remain otherwise
undetectable even using the most sensitive individual interferometric devices,
that are limited by the shot noise. If the two interferometers experience
identical phase-fluctuations, like the ones introduced by the so called
"holographic noise", this signal should emerge if their output signals are
correlated, while the fluctuations due to shot noise and other independent
contributions will vanish. We show how the injecting quantum light in the free
ports of the interferometers can reduce the photon noise of the system beyond
the shot-noise, enhancing the resolution in the phase-correlation estimation.
We analyze both the use of two-mode squeezed vacuum or twin-beam state (TWB)
and of two independent squeezing states. Our results basically confirms the
benefit of using squeezed beams together with strong coherent beams in
interferometry, even in this correlated case. However, mainly we concentrate on
the possible use of TWB, discovering interesting and probably unexplored areas
of application of bipartite entanglement and in particular the possibility of
reaching in principle surprising uncertainty reduction
Realization of a twin beam source based on four-wave mixing in Cesium
Four-wave mixing (4WM) is a known source of intense non-classical twin beams.
It can be generated when an intense laser beam (the pump) and a weak laser beam
(the seed) overlap in a medium (here cesium vapor), with
frequencies close to resonance with atomic transitions. The twin beams
generated by 4WM have frequencies naturally close to atomic transitions, and
can be intense (gain ) even in the CW pump regime, which is not the case
for PDC phenomenon in non-linear crystals. So, 4WM is well suited
for atom-light interaction and atom-based quantum protocols. Here we present
the first realization of a source of 4-wave mixing exploiting line of
Cesium atoms.Comment: 10 pages, 10 figure
Quantum Correlation Bounds for Quantum Information Experiments Optimization: the Wigner Inequality Case
Violation of modified Wigner inequality by means binary bipartite quantum
system allows the discrimination between the quantum world and the classical
local-realistic one, and also ensures the security of Ekert-like quantum key
distribution protocol. In this paper we study both theoretically and
experimentally the bounds of quantum correlation associated to the modified
Wigner's inequality finding the optimal experimental configuration for its
maximal violation. We also extend this analysis to the implementation of
Ekert's protocol
Toward third order ghost imaging with thermal light
Recently it has been suggested that an enhancement in the visibility of ghost
images obtained with thermal light can be achieved exploiting higher order
correlations [3]. This paper reports on the status of an higher order ghost
imaging experiment carried on at INRIM labs exploiting a pseudo-thermal source
and a CCD camera.Comment: To be published in Proceedings of Recent advances in Foundations of
Quantum Mechanics and Quantum Informatio
Single-phase and correlated-phase estimation with multiphoton annihilated squeezed vacuum states: An energy-balancing scenario
partially_open3In recent years, several works have demonstrated the advantage of photon-subtracted Gaussian states for various quantum optics and information protocols. In most of these works, the relation between the advantages and the usual increasing energy of the quantum state related to photon subtraction was not clearly investigated. In this paper, we study the performance of an interferometer injected with multiphoton-annihilated squeezed vacuum states mixed with coherent states for both single- and correlated-phase estimations. For single-phase estimation, although the use of multiphoton-annihilated squeezed vacuum states at low mean photons per mode provides an advantage compared to classical strategy, when the total input energy is held fixed, the advantage due to photon subtraction is completely lost. However, for the correlated case in the analogous scenario, some advantage appears to come from both the energy rise and improvement in photon statistics. In particular quantum enhanced sensitivity with photon-subtracted states appears more robust to losses, showing an advantage of about 30% with respect to the squeezed vacuum state in the case of a realistic value of the detection efficiency.openN. Samantaray; I. Ruo Berchera; I. P. DegiovanniSamantaray, N.; Ruo Berchera, I.; Degiovanni, I. P
- …