The flexibility and high information capacity of entangled states has been so far demonstrated in several areas of quantum communication and quantum computing. We have recently concentrated on the development of several new techniques for high efficiency optical imaging and ultra-precise measurement in telecommunication and nanotechnology. The use of high dimensional quantum states of light helps to outperform traditional optical approaches in resolution and in the amount of information obtained about the system under evaluation.

We consider the benefit of using the high-dimensional Hilbert space of correlated orbital angular momentum (OAM) states. A typical imaging procedure requires a significant amount of energy to be registered pixel-by-pixel by a CCD camera before one could start recognizing the type of object that has registered. The new approach [1] enables one to recognize objects much faster and with less required energy (more information is obtained per detected photon).

The nonlinear process of spontaneous parametric down conversion (SPDC) has often been used as an effective source of optical entanglement, and is capable of generating entangled photon pairs that span higher order OAM states. The correlated (joint) detection of two photons in the OAM basis using coincidence counting reveals that the scattering occurs mainly between OAM states of orbital orders that have symmetry elements resonating with geometric structures present in the object.

Such a fast object recognition technology could become useful in situations where the presence or absence of objects with particular symmetry features must be quickly identified in the field of view. For example, some living cells, drug molecules, or viruses have particular rotational symmetries, so that their IEEE and LEOS.

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