Imaging with quantum states of light

Abstract

The production of pairs of entangled photons simply by focusing a laser beam onto a crystal with a non-linear optical response was used to test quantum mechanics and to open new approaches in imaging. The development of the latter was enabled by the emergence of single photon sensitive cameras able to characterize spatial correlations and high-dimensional entanglement. Thereby new techniques emerged such as the ghost imaging of objectswhere the quantum correlations between photons reveal the image from photons that have never interacted with the object -or the imaging with undetected photons by using nonlinear interferometers. Additionally, quantum approaches in imaging can also lead to an improvement in the performance of conventional imaging systems. These improvements can be obtained by means of image contrast, resolution enhancement that exceed the classical limit and acquisition of sub-shot noise phase or amplitude images. In this review we discuss the application of quantum states of light for advanced imaging techniques.

Resolving starlight: a quantum perspective

“…Unfortunately, in all the problems studied by Helstrom, the improvements predicted by his theory seemed modest at best, rendering the question of quantum limits academic. Quantum opticians turned their attention to nonclassical light sources [30][31][32][33][34][35][36], while classical opticians turned their attention to near-field microscopy [37,38], fluorescence control [37, 39,40], and computational imaging [7,41]. Helstrom's work on incoherent imaging was all but forgotten.…”

“…The application of nonclassical light to sensing and imaging has been an active research topic in quantum optics for many decades [30][31][32][33][34][35][36]117]. It is now well known, however, that nonclassical light is extremely fragile against loss and decoherence [117], and any theoretical advantage can be easily lost in practice, not to mention that the efficient generation and detection of nonclassical light remain challenging.…”

Imaging through noise with quantum illumination

“…The aforementioned demonstration may be seen as a qualitative assessment of the method but a full field imaging implementation of the quantum illumination protocol remains to be demonstrated using a spatially resolved source of single photons and spatially resolved coincidence detections. Furthermore, a demonstration of the quantum illumination protocol in which thermal light, as opposed to a coherent state, is used as the incoming parasitic light so as to better represent environmental light statistics would be a demonstration of the potential real-world applications of the quantum illumination protocol.In quantum imaging, commonly used properties are spatial quantum-correlations, which can be exploited to surpass the classical limits of imaging [12,13,14,15,16]. These quantum-correlations have been used in the case of NOON states for enhanced phase detection [17,18], through the use of definite number of photons, to improve the signal to noise ratio for measuring the absorption of objects through sub-shot-noise measurements [15,19,20,21], and to perform resolution-enhanced imaging by centroid estimation of photon-pairs [22].…”

“…In quantum imaging, commonly used properties are spatial quantum-correlations, which can be exploited to surpass the classical limits of imaging [12,13,14,15,16]. These quantum-correlations have been used in the case of NOON states for enhanced phase detection [17,18], through the use of definite number of photons, to improve the signal to noise ratio for measuring the absorption of objects through sub-shot-noise measurements [15,19,20,21], and to perform resolution-enhanced imaging by centroid estimation of photon-pairs [22].…”

Ghost imaging with engineered quantum states by Hong–Ou–Mandel interference

“…3D ghost images have been reconstructed using single pixel detectors [15], and ghost imaging has even been studied in the presence of turbulence [16]. See [17,18] for comprehensive reviews. Recently, the concept of ghost imaging was extended to entanglement swapped photons, demonstrating ghost imaging with initially independent photons [19].…”