5 research outputs found
Quantum enhanced imaging and sensing with correlated light
No full textWithout light, there would be no sight. Light acts as a probe in various measurement techniques ranging from imaging to spectroscopy, from small scale cantilever displace- ment measurement in atomic force microscopy to large scale mirror motion in interfer- ometry, light detection and ranging (LIDAR) and many other fields. As the light probe intensity rises, it not only allows reducing the background noise effect, but it also aids precision to the measurement by reducing the photon noise (shot-noise) contribution. However, increasing intensity beyond certain threshold level is not always advantageous for ultra sensitive measurements. For example in the detection of gravitational waves, the current power circulating in the large scale interferometers can not be increased further without introducing other noise sources like thermal effects on the mirrors, un- wanted scattered photons, and back action due to radiation pressure. In the imaging of delicate photo sensitive sample, high power can causes cell damage or it may lead to disturb the regular process under investigation, viz. favouring certain biochemical reaction, which do not correspond to natural in vitro behaviour. At low intensity, pho- ton noise is an important concern and quantum states of light with correlated photon fluctuation can ideally represent a fruitful way to build specific measurement strategies to surpass the limitation of standard approach based on classical light sources, offering an avenue of solutions for ultra sensitive measurements. This thesis work focuses on two application of quantum enhanced measurement strate- gies. The first part of the thesis work has been dedicated to the realization of the first wide-field microscope with Sub Shot Noise (SSN) sensitivity. This is based on the ex- ploitation of quantum correlations in the Squeezed Vacuum state. In the second part, the investigations have made on the role of the quantum correlated beams in an unusual interferometric scheme, in which two identical optical interferometers are subject to the same phase fluctuation. The scheme, in the classical regime, has been already imple- mented in a large scale experiment devoted to the search of possible quantum gravity (QG) effects at Fermilab
Realization of the first sub-shot-noise wide field microscope
No full textRecently, several proof of principle experiments have demonstrated the advantages of quantum technologies over classical schemes. The present challenge is to surpass the limits of proof of principle demonstrations to approach real applications. This letter presents such an achievement in the field of quantum enhanced imaging. In particular, we describe the realization of a sub-shot-noise wide field microscope based on spatially multi-mode non-classical photon number correlations in twin beams. The microscope produces realtime images of 8000 pixels at full resolution, for a 500 μm2 field of view, with noise reduced to 80% of the shot noise level (for each pixel), which is suitable for absorption imaging of complex structures. By fast post-elaboration, specifically applying a quantum enhanced median filter, the noise can be further reduced (to <30% of the shot noise level) by setting a trade-off with the resolution, thus achieving the best sensitivity per incident photon reported in absorption microscopy
Improving interferometers by quantum light: toward testing quantum gravity on an optical bench
No full textWe analyze in detail a system of two interferometers aimed at the detection of extremely faint phase uctuations. The idea behind is that a correlated phase-signal like the one predicted by some phenomenological theory of Quantum Gravity (QG) could emerge by correlating the output ports of the interferometers, even when in the single interferometer it confounds with the background. We demonstrated that 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. Our results conrms the benet of using squeezed beams together with strong coherent beams in interferometry, even in this correlated case. On the other hand, our results concerning the possible use of photon number entanglement in twin beam state pave the way to interesting and probably unexplored areas of application of bipartite entanglement and, in particular, the possibility of reaching surprising uncertainty reduction exploiting new interferometric congurations, as in the case of the system described here
Realization of a twin beam source based on four wave mixing in Cesium
No full textFour-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 ð3Þ 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 1) even in the CW pump regime, which is not the case for PDC ð2Þ phenomenon in nonlinear crystals. So, 4WM is well suited for atom-light interaction and atombased quantum-protocols. Here, we present the ¯rst realization of a source of 4-wave mixing exploiting D2 line of Cesium atoms
One- and two-mode squeezed light in correlated interferometry
No full textWe study in detail a system of two interferometers aimed at detecting 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, as in the case of so-called
holographic noise. The signature of this kind of noise emerges as a correlation between the output signals
of the interferometers. On the other hand, when holographic noise is absent one expects uncorrelated signals
since the time-averaged fluctuations due to shot noise and other independent contributions vanish (though limiting
the overall sensitivity).We showhowinjecting 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 the use of both the two-mode squeezed vacuum and two independent squeezed states. Our results confirm
the benefit of using squeezed beams together with strong coherent beams in interferometry. We also investigate
the possible use of the two-mode squeezed vacuum, discovering interesting and unexplored areas of application
of bipartite entanglement, in particular the possibility of reaching in principle a surprising uncertainty reduction
