Entangled Light, Quantum Money

Photo: Two Nodes of a quantum network that Caltech researchers created by halting entangled photons within two ensembles of cesium atoms housed in an ultrahigh-vacuum system. Temporarily storing entanglement provides a basis for quantum data storage, which might be useful for various applications, including quantum cryptography.
Credit: Nara Cavalcanti

From Technology Review:

A breakthrough explores the challenges--and suggests the financial possibilities--of creating quantum networks.

In recent years, the Austrian physicist Anton Zeilinger has bounced entangled photons off orbiting satellites and made 60-atom fullerene molecules exist in quantum superposition--essentially, as a smear of all their possible positions and energy states across local space-time. Now he hopes to try the same stunt with bacteria hundreds of times larger. Meanwhile, Hans Mooij of the Delft University of Technology, with Seth Lloyd, who directs MIT's Center for Extreme Quantum Information Theory, has created quantum states (which occur when particles or systems of particles are superpositioned) on scales far above the quantum level by constructing a superconducting loop, visible to the human eye, that carries a supercurrent whose electrons run simultaneously clockwise and counterclockwise, thereby serving as a quantum computing circuit.

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