Macroscopic entanglement

Entanglement is the most striking feature of quantum mechanics, but is it limited to the microscopic world only? Is there a fundamental limit to how “macroscopic” entanglement can be? This question is as old as quantum mechanics itself. Recent theoretical and experimental progress in quantum optics is now opening new and tantalizing ways to explore the ramification of this question.

We studying several questions pertaining to this theme. First and foremost, we need to understand what can be rightfully called macroscopic entanglement, how it can be created and revealed, and how sensitive it is to loss and decoherence. This, in return, could lead to the creation of new quantum-enhanced metrological techniques. Recent publications are:

Our recent progress in developing solid-state quantum memories based on rare-earth-ion doped crystals for quantum repeaters also offer ways to transfer optical macroscopic entanglement to solid objects, into which the state of single photons are mapped to the collective state of billions of atoms. This opens new possibilities to study entanglement that is macroscopic in terms of the number of stored modes, bits of entanglement, dimensionality of the quantum states and the number of crystals used for storage.

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Team: Peter Strassmann, Alexey Tiranov, Emmanuel Zambrini Cruzeiro, Florian Fröwis, Mikael Afzelius, Nicolas Gisin