Walking with coffee: Why does it spill?

LM13443 - In our busy lives, almost all of us have to walk with a cup of coffee. While often we spill that precious liquid, this familiar phenomenon has never been explored systematically. Here we report on the results of an experimental study of the conditions under which coffee spills for various walking speeds and initial liquid levels in the cup. These observations are analyzed from the dynamical systems and fluid mechanics viewpoints as well as with the help of a model developed here. Particularities of the common cup sizes, coffee properties, and biomechanics of walking proved to be responsible for the spilling phenomena. The studied problem represents an example of the interplay between the complex motion of a cup, due to biomechanics of a walking individual, and the low viscosity liquid dynamics in it.

Holographic Storage of Biphoton Entanglement

LP13000 - Coherent and reversible storage of multi-photon entanglement with a multimode quantum memory is essential for scalable all-optical quantum information processing. Although single photon has been successfully stored in different quantum systems, storage of multi-photon entanglement remains challenging because of the critical requirement for coherent control of photonic entanglement source, multimode quantum memory, and quantum interface between them. Here we demonstrate a coherent and reversible storage of biphoton Bell-type entanglement with a holographic multimode atomic- ensemble-based quantum memory. The retrieved biphoton entanglement violates Bell's inequality for 1 microsecond storage time and a memory-process fidelity of 98% is demonstrated by quantum state tomography. Our work makes the first step towards holographic storage of multi-photon entanglement.