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Experimental demonstration of beating the channel capacity limit for superdense coding with high-dimensional entanglement.

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We study the birefringence of the quantized polarized light in a magneto-optically manipulated atomic ensemble as a generalized Stern-Gerlach effect of light. To explain this engineered birefringence microscopically, we derive an effective Shrödinger equation for the spatial motion of two orthogonally polarized components, which behave as a spin with an effective magnetic moment leading to a Stern-Gerlach split in a nonuniform magnetic field. We show that electromagneticallyinduced-transparency mechanism can enhance the magneto-optical Stern-Gerlach effect of light in the presence of a control field with a transverse spatial profile and a nonuniform magnetic field.

Today's software systems often use many different computation features and span different abstraction levels (e.g., user code and runtime-system code). To build foundational certified systems, it is hard to have a single verification system supporting all computation features. In this paper we present an open framework for foundational proof-carrying code (FPCC). It allows program modules to be specified and certified separately using different type systems or program logics. Certified modules (i.e., code and proof) can be linked together to build fully certified systems. The framework supports modular verification and proof reuse. It is also expressive enough so that invariants established in specific verification systems are preserved even when they are embedded into our framework. Our work presents the first FPCC framework that systematically supports interoperation between different verification systems. It is fully mechanized in the Coq proof assistant with machine-checkable soundness proof.

The physical impact and the testability of the Kochen-Specker (KS) theorem is debated because of the fact that perfect compatibility in a single quantum system cannot be achieved in practical experiments with finite precision. Here, we follow the proposal of A. Cabello and M. T. Cunha [Phys. Rev. Lett. 106, 190401 (2011)], and present a compatibility-loophole-free experimental violation of an inequality of noncontextual theories by two spatially separated entangled qutrits. A maximally entangled qutrit-qutrit state with a fidelity as high as 0.975±0.001 is prepared and distributed to separated spaces, and these two photons are then measured locally, providing the compatibility requirement. The results show that the inequality for noncontextual theory is violated by 31 standard deviations. Our experiments pave the way to close the debate about the testability of the KS theorem. In addition, the method to generate high-fidelity and high-dimension entangled states will provide significant advantages in high-dimension quantum encoding and quantum communication.