Abstract:We introduce a novel ghost reflection ellipsometer for a spectral characterization of homogeneous thin films and interfaces. The device makes use of a uniform, spatially incoherent, unpolarized light source with Gaussian statistics and of the detection of intensity correlations. Unlike traditional ellipsometers, no source or detector calibration and reference sample are needed. The method is also insensitive to instrumentation errors. The ellipsometer that we present here is a classical analog of a quantum twi… Show more
“…Though the sensitivity of phase difference δ△ can not be obtained from intensity measurements for Fock states or NOON state, we are still able to study the same through the information encoded in the density matrix ρ(t). As shown in ( 21) and (32), only the off-diagonal terms contain the phase parameter △. The fidelity, i.e.…”
Section: Projective Measurements To Obtain Ord Ie Relative Phasementioning
confidence: 99%
“…Several other studies have shown advantages of using squeezed light with tailored beams; SPDC photons in ellipsometry [39,40]. The ellipsometry with classically correlated beams was discussed in [32]. We briefly outline the organization of the paper here.…”
Circular dichroism (CD) is a widely used technique for investigating optically chiral molecules, especially for biomolecules. It is thus of great importance that these parameters be estimated precisely so that the molecules with desired functionalities can be designed. In order to surpass the limits of classical measurements, we need to probe the system with quantum light. We develop quantum Fisher information matrix (QFIM) for precision estimates of the circular dichroism and the optical rotary dispersion for a variety of input quantum states of light that are easily accessible in laboratory. The Cramer-Rao bounds, for all four chirality parameters are obtained, from QFIM for (a) single photon input states with a specific linear polarization and for (b) NOON states having two photons with both either left polarized or right polarized. The QFIM bounds, using quantum light, are compared with bounds obtained for classical light beams i.e., beams in coherent states. Quite generally, both the single photon state and the NOON state exhibit superior precision in the estimation of absorption and phase shift in relation to a coherent source of comparable intensity, especially in the weak absorption regime. In particular, the NOON state naturally offers the best precision among the three. We compare QFIM bounds with the error sensitivity bounds, as the latter are relatively easier to measure whereas the QFIM bounds require full state tomography.
“…Though the sensitivity of phase difference δ△ can not be obtained from intensity measurements for Fock states or NOON state, we are still able to study the same through the information encoded in the density matrix ρ(t). As shown in ( 21) and (32), only the off-diagonal terms contain the phase parameter △. The fidelity, i.e.…”
Section: Projective Measurements To Obtain Ord Ie Relative Phasementioning
confidence: 99%
“…Several other studies have shown advantages of using squeezed light with tailored beams; SPDC photons in ellipsometry [39,40]. The ellipsometry with classically correlated beams was discussed in [32]. We briefly outline the organization of the paper here.…”
Circular dichroism (CD) is a widely used technique for investigating optically chiral molecules, especially for biomolecules. It is thus of great importance that these parameters be estimated precisely so that the molecules with desired functionalities can be designed. In order to surpass the limits of classical measurements, we need to probe the system with quantum light. We develop quantum Fisher information matrix (QFIM) for precision estimates of the circular dichroism and the optical rotary dispersion for a variety of input quantum states of light that are easily accessible in laboratory. The Cramer-Rao bounds, for all four chirality parameters are obtained, from QFIM for (a) single photon input states with a specific linear polarization and for (b) NOON states having two photons with both either left polarized or right polarized. The QFIM bounds, using quantum light, are compared with bounds obtained for classical light beams i.e., beams in coherent states. Quite generally, both the single photon state and the NOON state exhibit superior precision in the estimation of absorption and phase shift in relation to a coherent source of comparable intensity, especially in the weak absorption regime. In particular, the NOON state naturally offers the best precision among the three. We compare QFIM bounds with the error sensitivity bounds, as the latter are relatively easier to measure whereas the QFIM bounds require full state tomography.
“…The technique has particular potential for imaging under turbulent [4][5][6][7] or low-light-level conditions [8] as well as in harsh environments where conventional imaging methods are hard or impossible to implement [9]. Recently, ghost imaging has been demonstrated in such diverse applications as x-ray [10], atom [11], and neutron [12] imaging, as well as in encryption [13], spectroscopy [14], ellipsometry [15,16], and polarimetry using Stokes correlations [17].…”
We introduce a phase-contrast ghost-imaging scheme for the characterization of temporal phase objects in terms of intensity correlations at two photodetectors. The technique is analogous to Zernike's phase-contrast imaging method and is based on utilizing a suitable filter function which renders the small-amplitude phase variations visible in the intensity correlation function. The approach is insensitive to temporal distortions and offers a promising method to analyze the phases of optical pulses.
“…The object is characterized through multiple coincidence or correlation measurements [17] that can deliver a better signal-to-noise ratio compared to classical imaging systems, and also enable imaging with a very low number of photons [18,19]. However, there remains a fundamental limitation of traditional ghost polarimetry approaches due to a need for multiple reconfigurable elements such as rotating waveplates [20][21][22][23][24][25][26][27]. Yet, the unique capabilities of polarization control with metasurfaces towards potential singleshot ghost imaging configurations remains largely untapped, so far limited to the incorporation of metasurfaces for hologram generation [28].…”
We develop a concept of metasurface-assisted ghost imaging for non-local discrimination between a set of polarization objects. The specially designed metasurfaces are incorporated in the imaging system to perform parallel state transformations in general elliptical bases of quantum-entangled or classically-correlated photons. Then, only four or fewer correlation measurements between multiple metasurface outputs and a simple polarization-insensitive bucket detector after the object can allow for the identification of fully or partially transparent polarization elements and their arbitrary orientation angles. We rigorously establish that entangled photon states offer a fundamental advantage compared to classical correlations for a broad class of objects. The approach can find applications for real-time and low-light imaging across diverse spectral regions in dynamic environments.
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