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1.
Opt Express ; 28(24): 35427-35437, 2020 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-33379657

RESUMO

Optical interrogation of tissues is broadly considered in biomedical applications. Nevertheless, light scattering by tissue limits the resolution and accuracy achieved when investigating sub-surface tissue features. Light carrying optical angular momentum or complex polarization profiles, offers different propagation characteristics through scattering media compared to light with unstructured beam profiles. Here we discuss the behaviour of structured light scattered by tissue-mimicking phantoms. We study the spatial and the polarization profile of the scattered modes as a function of a range of optical parameters of the phantoms, with varying scattering and absorption coefficients and of different lengths. These results show the non-trivial trade-off between the advantages of structured light profiles and mode broadening, stimulating further investigations in this direction.


Assuntos
Microscopia de Polarização/métodos , Imagens de Fantasmas , Espalhamento de Radiação , Biomimética , Luz , Modelos Biológicos
2.
Opt Express ; 27(24): 35245-35256, 2019 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-31878697

RESUMO

Enzymes are essential to maintain organisms alive. Some of the reactions they catalyze are associated with a change in reagents chirality, hence their activity can be tracked by using optical means. However, illumination affects enzyme activity: the challenge is to operate at low-intensity regime avoiding loss in sensitivity. Here we apply quantum phase estimation to real-time measurement of invertase enzymatic activity. Control of the probe at the quantum level demonstrates the potential for reducing invasiveness with optimized sensitivity at once. This preliminary effort, bringing together methods of quantum physics and biology, constitutes an important step towards full development of quantum sensors for biological systems.


Assuntos
Luz , Teoria Quântica , beta-Frutofuranosidase/metabolismo , Lasers , Fótons , Saccharomyces cerevisiae/enzimologia
3.
Phys Rev Lett ; 123(23): 230502, 2019 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-31868431

RESUMO

Introducing quantum sensors as a solution to real world problems demands reliability and controllability outside of laboratory conditions. Producers and operators ought to be assumed to have limited resources readily available for calibration, and yet, they should be able to trust the devices. Neural networks are almost ubiquitous for similar tasks for classical sensors: here we show the applications of this technique to calibrating a quantum photonic sensor. This is based on a set of training data, collected only relying on the available probe states, hence reducing overhead. We found that covering finely the parameter space is key to achieving uncertainties close to their ultimate level. This technique has the potential to become the standard approach to calibrate quantum sensors.

4.
Phys Rev Lett ; 121(16): 160602, 2018 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-30387653

RESUMO

The Clausius inequality has deep implications for reversibility and the arrow of time. Quantum theory is able to extend this result for closed systems by inspecting the trajectory of the density matrix on its manifold. Here we show that this approach can provide an upper and lower bound to the irreversible entropy production for open quantum systems as well. These provide insights on how the information on the initial state is forgotten through a thermalization process. Limits of the applicability of our bounds are discussed and demonstrated in a quantum photonic simulator.

5.
Opt Lett ; 43(16): 4045-4048, 2018 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-30106948

RESUMO

The simplicity of a question, such as wondering whether or not correlations characterize a certain system, collides with the experimental difficulty of accessing such information. Here we present a low-demanding experimental approach that refers to the use of a metrology scheme to obtain a conservative estimate of the strength of frequency correlations. Our test bed is the widespread case of a photon pair produced per downconversion. The theoretical architecture used to put the correlation degree on a quantitative ground is also described.

6.
Sci Rep ; 7(1): 7247, 2017 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-28775259

RESUMO

Not much, in the end. Here we put forward some considerations on how Hong-Ou-Mandel interferometry provides signatures of frequency entanglement in the two-photon state produced by parametric down-conversion. We find that some quantitative information can be inferred in the limit of long-pulse pumping, while the short-pulse limit remains elusive.

7.
Phys Rev Lett ; 118(13): 130502, 2017 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-28409967

RESUMO

Standard thermometry employs the thermalization of a probe with the system of interest. This approach can be extended by incorporating the possibility of using the nonequilibrium states of the probe and the presence of coherence. Here, we illustrate how these concepts apply to the single-qubit thermometer introduced by Jevtic et al. [Phys. Rev. A 91, 012331 (2015)PLRAAN1050-294710.1103/PhysRevA.91.012331] by performing a simulation of the qubit-environment interaction in a linear-optical device. We discuss the role of the coherence and how this affects the usefulness of nonequilibrium conditions. The origin of the observed behavior is traced back to how the coherence affects the propensity to thermalization. We discuss this aspect by considering the availability function.

8.
Opt Lett ; 40(7): 1208-11, 2015 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-25831294

RESUMO

Using a zero-offset carrier-envelope locking technique, we have synthesized an octave-spanning composite frequency comb exhibiting 132-attosecond timing jitter between the constituent pulses over a one-second observation window. In the frequency domain, this composite comb has a modal structure and coherence which are indistinguishable from those of a comb that might be produced by a hypothetical single mode locked oscillator of equivalent bandwidth. The associated phase stability enables the participating multi-color pulse sequences to be coherently combined, representing an example of multi-pulse synthesis using a femtosecond oscillator.

9.
Opt Lett ; 38(24): 5299-302, 2013 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-24322242

RESUMO

We demonstrate a novel interferometric characterization scheme that allows the complete reconstruction of two interfering electric fields. The phase profiles of both beams, and their relative phase, can be retrieved simultaneously as a function of any degree of freedom in which it is possible to shear one of the beams. The method has applications in wavefront sensing or ultrashort-pulse measurement, especially also in the domain of extreme light sources where it is difficult to generate a reference field or to replicate the beam in order to perform a self-referencing measurement. We demonstrate the technique experimentally by measuring simultaneously two ultrashort pulses in a single laser shot.

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