New techniques improve quantum communication, entangle phonons

Phys.org  June 17, 2020
A team of researchers in the US (University of Chicago, Argonne National Laboratory, UC Santa Barbara) developed a system that entangled two communication nodes using microwave photons through a microwave cable about a meter in length. By turning the system on and off in a controlled manner, they were able to quantum-entangle the two nodes and send information between them without ever having to send photons through the cable. In principle, this would also work over a much longer distance. Using a system built to communicate with phonons, they entangled two microwave phonons. They used one of the phonons as a “herald,” which was used to affect how their quantum system used the other phonon. The herald allowed the team to perform a so-called “quantum eraser” in which information is erased from a measurement, even after the measurement has been completed. The phonons interact strongly with several solid-state quantum systems that may not interact strongly with photons. Phonons could provide a better way to couple to these systems…read more. TECHNICAL ARTICLE
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