A New Blast May Have Forged Cosmic Gold

For decades, researchers believed that violent supernovas forged gold and other heavy elements. But many now argue for a different cosmic quarry. …

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Scientists evade the Heisenberg uncertainty principle

Researchers report the discovery of a new technique that could drastically improve the sensitivity of instruments such as magnetic resonance imagers (MRIs) and atomic clocks. The study reports a technique to bypass the Heisenberg uncertainty principle. This technique hides quantum uncertainty in atomic features not seen by the instrument, allowing the scientists to make very high precision measurements.

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Does the universe have a rest frame?

Physics is sometimes closer to philosophy when it comes to understanding the universe. Physicists are now attempting to elucidate whether the universe has a resting frame.

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Quantum dots illuminate transport within the cell

Biophysicists have developed a strategy for using light-emitting nanocrystals as a marker in living cells. By recording the movements of these quantum dots, they can clarify the structure and dynamics of the cytoskeleton.

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Finding the ‘ghost particles’ might be more challenging than what we thought

Results from the NEOS experiment on sterile neutrinos differ partly from the theoretical expectations.

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A single-atom quantum memory in silicon

Long coherence times and fast gate operations are desirable but often conflicting requirements for physical qubits. This conflict can be resolved by resorting to fast qubits for operations, and by storing their state in a ‘quantum memory’ while idle. The 31 P donor in silicon comes naturally equipped with a fast qubit (the electron spin) and a long-lived qubit (the 31 P nuclear spin), coexisting in a bound state at cryogenic temperatures. Here, we demonstrate storage and retrieval of quantum information from a single donor electron spin to its host phosphorus nucleus in isotopically enriched 28 Si. The fidelity of the memory process is characterised via both state and process tomography. We report an overall process fidelity ##IMG## [http://ej.iop.org/images/2058-9565/2/1/015009/qstaa63a4ieqn1.gif] {${F}_{p}\approx 81$} %, and memory storage times up to 80 ms. These values are limited by a transient shift of the electron spin r… …

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A quantum router for high-dimensional entanglement

In addition to being a workhorse for modern quantum technologies, entanglement plays a key role in fundamental tests of quantum mechanics. The entanglement of photons in multiple levels, or dimensions, explores the limits of how large an entangled state can be, while also greatly expanding its applications in quantum information. Here we show how a high-dimensional quantum state of two photons entangled in their orbital angular momentum can be split into two entangled states with a smaller dimensionality structure. Our work demonstrates that entanglement is a quantum property that can be subdivided into spatially separated parts. In addition, our technique has vast potential applications in quantum as well as classical communication systems. …

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Three-observer Bell inequality violation on a two-qubit entangled state

Bipartite Bell inequalities can simultaneously be violated by two different pairs of observers when weak measurements and signalling is employed. Here, we experimentally demonstrate the violation of two simultaneous CHSH inequalities by exploiting a two-photon polarisation maximally entangled state. Our results demonstrate that large double violation is experimentally achievable. Our demonstration may have impact for Quantum Key Distribution or certification of Quantum Random Number generators based on weak measurements. …

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