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Register a new userExperimental Observation of Quantum Holographic Imaging
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We report the first experimental observation of quantum holographic imaging with entangled photon pairs, generated in a spontaneous parametric down-conversion process. The signal photons play both roles of object wave and reference wave in holography but are recorded by a point detector providing only encoding information, while the idler photons travel freely and are locally manipulated with spatial resolution. The holographic image is formed by the two-photon correlation measurement, although both the signal and idler beams are incoherent. According to the detection regime of the signal photons, we analyze three types of quantum holography schemes: point detection, coherent detection and bucket detection, which can correspond to classical holography using a point source, a plane-wave coherent source and a spatially incoherent source, respectively. Our experiment demonstrates that the two-photon holography in the point detection regime is equivalent to the one-photon holography using a point source. Physically, the quantum holography experiment verifies that a pair of non-commutable physical quantities, the amplitude and phase components of the field operator, can be nonlocally measured through two-photon entanglement.
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Weak measurement has been shown to play important roles in the investigation of both fundamental and practical problems. Anomalous weak values are generally believed to be observed only when post-selection is performed, i.e, only a particular subset of the data is considered. Here, we experimentally demonstrated an anomalous weak value can be obtained without discarding any data by performing a sequential weak measurement on a single-qubit system. By controlling the blazing density of the hologram on a spatial light modulator, the measurement strength can be conveniently controlled. Such an anomalous phenomenon disappears when the measurement strength becomes strong. Moreover, we find that the anomalous weak value can not be observed without post-selection when the sequential measurement is performed on each of the components of a two-qubit system, which confirms that the observed anomalous weak value is based on sequential weak measurement of two noncommutative operators.
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