Classical computers are typically connected through optical fibers, because optical radiation is robust against disturbances that could corrupt or destroy data. In order to apply this technology to quantum computers, a link that can convert the quantum computer’s microwave photons to optical information carriers, or a device that generates entangled microwave-optical fields as a resource for quantum teleportation, would be required. Such a link or device could serve as a bridge between the room- temperature optical and the cryogenic quantum world. “What we have built is a prototype for a quantum link,” researcher Shabir Barzanjeh said.
![This is an illustration of a prototype of what may, in the future, serve as a link to connect quantum computers. Courtesy of IST Austria/Philip Krantz, Krantz NanoArt.](https://www.photonics.com/images/Web/Articles/2019/6/28/REAS_IST_Austria_Building_a_bridge_to_the_quantum_world.jpg)
In addition to its practical value, the experiment to generate entangled radiation using a mechanical oscillator interested the researchers at a fundamental level. With a length of 30 μm and a composition of about a trillion (1012) atoms, the silicon beam created by the group would be considered large by quantum standards. “The question was: Can one use such a large system to produce nonclassical radiation? Now we know that the answer is yes,” Barzanjeh said.
The research was published in Nature (https://doi.org/10.1038/s41586-019-1320-2).