A photon of entangled photons pair interacts with a transparent phase pattern that introduces position dependent shift in polarisation state of photon. A coincidence imaging camera, incorporating measurement outcomes of non-interacting photon generates quantum image.
A transparent polarisation sensitive phase pattern makes a polarisation dependent transformation of quantum state of photons without absorbing them. Such an invisible pattern can be imaged with quantum entangled photons by making joint quantum measurements on photons. This paper shows a long path experiment to quantum image a transparent polarisation sensitive phase pattern with hyper-entangled photon pairs involving momentum and polarisation degrees of freedom. In the imaging configuration, a single photon interacts with the pattern while the other photon, which has never interacted with the pattern, is measured jointly in a chosen polarisation basis and in a quantum superposition basis of its position which is equivalent to measure its momentum. Individual photons of each hyper-entangled pair cannot provide a complete image information. The image is constructed by measuring the polarisation state and position of the interacting photon corresponding to a measurement outcome of the non-interacting photon. This paper presents a detailed concept, theory and free space long path experiments on quantum imaging of polarisation sensitive phase patterns.
A transparent polarisation sensitive phase pattern exhibits a position and polarisation dependent phase shift of transmitted light and it represents a unitary transformation. A quantum ghost image of this pattern is produced with hyper-entangled photons consisting of Einstein-Podolsky-Rosen (EPR) and polarisation entanglement. In quantum ghost imaging, a single photon interacts with the pattern and is detected by a stationary detector and a non-interacting photon is imaged on a coincidence camera. EPR entanglement manifests spatial correlations between an object plane and a ghost image plane, whereas a polarisation dependent phase shift exhibited by the pattern is detected with polarisation entanglement. In this quantum ghost imaging, the which-position-polarisation information of a photon interacting with the pattern is not present in the experiment. A quantum ghost image is constructed by measuring correlations of the polarisation-momentum of an interacting photon with polarisation-position of a non-interacting photon. The experiment is performed with a coincidence single photon detection camera, where a non-interacting photon travels a long optical path length of 17.83 m from source to camera and a pattern is positioned at an optical distance of 19.16 m from the camera.
Holography encodes information using classical light interference with applications ranging from microscopy to data storage. Quantum entanglement enables information processing with capabilities beyond technology based on classical principles. Here we introduce a holographic imaging concept that is conditioned on the coherence, and thus the entanglement, between the qubit terms in a quantum entangled photon state. By harnessing the nonlocal properties of entanglement, we remotely reconstruct an image encoded in the phase of spatial-polarisation hyper-entangled photons. The nonlocal nature of our measurements removes the need for path overlap, resulting in insensitivity to mechanical instabilities, while polarisation encoding provides robustness against random phase disorder. Furthermore, the measurement of correlations removes the sensitivity to the presence of stray light.