This is a comment on the paper : Quantum Interference between Light Sources Separated by 150 Million Kilometers by Deng et al, PHYSICAL REVIEW LETTERS 123, 080401 (2019)
We report an experiment to test quantum interference, entanglement and nonlocality using two dissimilar photon sources, the Sun and a semiconductor quantum dot on the Earth, which are separated by 150 million kilometers. By making the otherwise vastly distinct photons indistinguishable all degrees of freedom, we observe time-resolved two-photon quantum interference with a raw visibility of 0.796(17), well above the 0.5 classical limit, providing the first evidence of quantum nature of thermal light. Further, using the photons with no common history, we demonstrate post-selected two-photon entanglement with a state fidelity of 0.826(24), and a violation of Bells inequality by 2.20(6). The experiment can be further extended to a larger scale using photons from distant stars, and open a new route to quantum optics experiments at an astronomical scale.
In a recent letter, Gaidarzhy et al. claim to have observed evidence for quantized displacements of a nanomechanical oscillator. We contend that the evidence, analysis, claims, and conclusions presented are contrary to expectations from fundamentals of quantum mechanics and elasticity theory, and that the method used by the authors is unsuitable in principle to observe the quantized energy states of a nanomechanical structure.
In the quest to realize a scalable quantum network, semiconductor quantum dots (QDs) offer distinct advantages including high single-photon efficiency and indistinguishability, high repetition rate (tens of GHz with Purcell enhancement), interconnectivity with spin qubits, and a scalable on-chip platform. However, in the past two decades, the visibility of quantum interference between independent QDs rarely went beyond the classical limit of 50$%$ and the distances were limited from a few meters to kilometers. Here, we report quantum interference between two single photons from independent QDs separated by 302 km optical fiber. The single photons are generated from resonantly driven single QDs deterministically coupled to microcavities. Quantum frequency
The CLAS Collaboration provides a comment on the physics interpretation of the results presented in a paper published by M. Amaryan et al. regarding the possible observation of a narrow structure in the mass spectrum of a photoproduction experiment.
Large-scale integrated quantum photonic technologies will require the on-chip integration of identical photon sources with reconfigurable waveguide circuits. Relatively complex quantum circuits have already been demonstrated, but few studies acknowledge the pressing need to integrate photon sources and waveguide circuits together on-chip. A key step towards such large-scale quantum technologies is the integration of just two individual photon sources within a waveguide circuit, and the demonstration of high-visibility quantum interference between them. Here, we report a silicon-on-insulator device combining two four-wave mixing sources, in an interferometer with a reconfigurable phase shifter. We configure the device to create and manipulate two-colour (non-degenerate) or same-colour (degenerate), path-entangled or path-unentangled photon pairs. We observe up to 100.0+/-0.4% visibility quantum interference on-chip, and up to 95+/-4% off-chip. Our device removes the need for external photon sources, provides a path to increasing the complexity of quantum photonic circuits, and is a first step towards fully-integrated quantum technologies.
Shaul Mukamel
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(2020)
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"Comment on Quantum Interference between Light Sources Separated by 150 Million Kilometers Deng et al. PHYSICAL REVIEW LETTERS 123, 080401 (2019)"
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Shaul Mukamel
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