249 research outputs found
Quantum Illumination with Multiplexed Photodetection
No full textThe advantages of using quantum states of light for object detection are often highlighted in schemes that use simultaneous and optimal measurements. Here, we describe a theoretical but experimentally realizable quantum illumination scheme based on nonsimultaneous and nonoptimal measurements, which can maintain this advantage. In particular, we examine the multiclick-heralded two-mode-squeezed vacuum state as a probe signal in a quantum illumination process. The increase in conditioned signal intensity associated with multiclick heralding is greater than that from a single detector-heralded signal. Our results show, for lossy external conditions, the presence of the target object can be revealed earlier using multiclick measurements. We demonstrate this through sequential shot measurements based on Monte Carlo simulation
Poissonian twin-beam states and the effect of symmetrical photon subtraction in loss estimations
No full textWe have devised an experimentally realizable model generating twin-beam states whose individual beam photon statistics are varied from thermal to Poissonian (by temporal mode averaging) keeping the nonclassical mode correlation intact. We have studied the usefulness of these states for loss measurement by considering three different estimators, comparing with the correlated thermal twin-beam states generated from spontaneous parametric down conversion or four-wave mixing. We then incorporated the photon subtraction operation into the model and demonstrated their performance in loss estimations with respect to unsubtracted states at both fixed squeezing and per photon exposure of the absorbing sample. For instance, at fixed squeezing, for two photon subtraction, up to three times advantage is found. An unexpected result in the latter case is that in some operating regimes the photon subtraction scheme can also give up to 20% advantage over the correlated thermal beam result and no advantages are obtained when the statistics of each beam turns to Poissonian. We have also made a comparative study of these estimators for finding the best measurement for loss estimations. We present results for all the values of the model parameters changing the statistics of twin-beam states from thermal t
Single-phase and correlated-phase estimation with multiphoton annihilated squeezed vacuum states: An energy-balancing scenario
No full textIn 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
Improving resolution-sensitivity trade off in sub-shot noise quantum imaging
No full textOne of the challenges of quantum technologies is realizing the quantum advantage, predicted for ideal systems, in real applications, which have to cope with decoherence and inefficiencies. In quantum metrology, sub-shot-noise quantum imaging (SSNQI) and sensing methods can provide genuine quantum enhancement in realistic situations. However, wide-field SSNQI schemes realized so far suffer a trade-off between the resolution and the sensitivity gain over a classical counterpart: small pixels or integrating area are necessary to achieve high imaging resolution, but larger pixels allow a better detection efficiency of quantum correlations, which means a larger quantum advantage. Here, we show how the SSNQI protocol can be optimized to significantly improve the resolution without giving up the quantum advantage in sensitivity. We show a linear resolution improvement (up to a factor 3) with respect to the simple protocol used in previous demonstrations
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
Comparison of two ventilation modes in post-cardiac surgical patients
No full textBackground: The cardiopulmonary bypass (CPB)-associated atelectasis accounted for most of the marked post-CPB increase in shunt and hypoxemia. We hypothesized that pressure-regulated volume-control (PRVC) modes having a distinct theoretical advantage over pressure-controlled ventilation (PCV) by providing the target tidal volume at the minimum available pressure may prove advantageous while ventilating these atelactic lungs. Methods: In this prospective study, 36 post-cardiac surgical patients with a PaO 2 /FiO 2 (arterial oxygen tension/Fractional inspired oxygen) < 300 after arrival to intensive care unit (ICU), (n = 34) were randomized to receive either PRVC or PCV. Air way pressure (Paw ) and arterial blood gases (ABG) were measured at four time points [T1: After induction of anesthesia, T2: after CPB (in the ICU), T3: 1 h after intervention mode, T4: 1 h after T3]. Oxygenation index (OI) = [PaO 2 / {FiO 2 × mean airway pressure (Pmean )}] was calculated for each set of data and used as an indirect estimation for intrapulmonary shunt. Results: There is a steady and significant improvement in OI in both the groups at first hour [PCV, 27.5(3.6) to 43.0(7.5); PRVC, 26.7(2.8) to 47.6(8.2) (P = 0.001)] and second hour [PCV, 53.8(6.4); PRVC, 65.8(7.4) (P = 0.001)] of ventilation. However, the improvement in OI was more marked in PRVC at second hour of ventilation owing to significant low mean air way pressure compared to the PCV group [PCV, 8.6(0.8); PRVC, 7.7(0.5), P = 0.001]. Conclusions: PRVC may be useful in a certain group of patients to reduce intrapulmonary shunt and improve oxygenation after cardiopulmonary bypass-induced perfusion mismatch
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
Efficacy of inhibitory learning theory-based exposure and response prevention and selective serotonin reuptake inhibitor in obsessive-compulsive disorder management: A treatment comparison
No full textBackground: The majority of treatment research on obsessive-compulsive disorder (OCD) has focused on emotional processing theory (EPT)-based exposure-based interventions. Despite the outcomes of EPT-based exposure and response prevention (ERP), a sizeable percentage of patients do not respond whereas 50%–60% of those who respond experience at least partial relapse at follow-up assessments. Inhibitory learning theory (ILT) provides a novel foundation for understanding how exposure therapy can be maximized to overcome such deficits but has not been adequately studied and compared to other evidence-based management in OCD. Aim: The aim of this study was to compare ILT-based ERP plus selective serotonin reuptake inhibitor (SSRI) with only SSRI treatment in OCD patients. Materials and Methods: The present study is pretest/posttest control group design with single masking, where participants (n = 32) diagnosed with OCD were randomly assigned into two treatment groups, namely ILT-based ERP plus SSRI and SSRI alone. Yale-Brown obsessive-compulsive scale was primary outcome measure. Intervention was done for 3 months. Thereafter, the participants were followed up for 6 months. Results: ILT-based ERP and SSRI are both effective treatments. There was no significant difference in treatment effects between combined treatments of SSRI plus ILT-based ERP and SSRI alone in immediate post assessment. However, combined treatment of SSRI plus ILT-based ERP had significantly better treatment effects on follow-ups than SSRI alone. Conclusions: SSRI combined with ILT-based strategies to maximize ERP is significantly better than SSRI alone in the treatment of OCD
Amiodarone and reperfusion ventricular fibrillation
No full text[No abstract available]Ayoub CM, 2009, EUR J ANAESTH, V26, P1056, DOI 10.1097-EJA.0b013e32832f0dfb; NANAS JN, 1995, CIRCULATION, V91, P451; SAMANTARAY A, 2009, J CARDIOTHORAC VASC1
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