Device transmits radio waves with almost no power – without violating the laws of physics

This sounds like the receiver sucking the signal from the transmitter. The analogy used is a heat pump, and they effective suck heat from the source and dump it where needed, they do not create heat (i.e., convert a different form of energy to heat).

Touch credit cards do not have a power source. They send information using energy harvested from the electromagnetic field produced by the reader device.

Anyway, all very interesting if you're a tech nerd.

Seems plausible. Thermocouples are long proven heat-to-electricity generators, albeit, not very efficient.

It would be interesting to see more of this invention and if it's viable or not.

One area for future work is to improve our system’s data rate and range, and to test it in applications such as implanted devices. 

It would seem to have abundant applications for RFT implanted in biological tissue given its modalities.

This tech has, I believe, significant military applications. Radio / radar emissions can be geolocated and targeting, making the emitter vulnerable to attack. But if you can transmit on such low powers there could be opportunities for short range comms, say within a naval force at sea or a ground unit operating clandestinely, that is not detectable from afar.

you can't violate the laws of physics

Ask Schrödinger's cat!!

If you interact with the cat, you'll have messed up the experiment. Schrödinger won't be pleased. :-)

If you interact with the cat, you'll have messed up the experiment. Schrödinger won't be pleased. :-)

Lol. Once the experiment is done, Fluffy does interviews...

you can't violate the laws of physics

Laws of "classical" physics can be violated in Quantum physics.

Ask Schrödinger's cat!!

There's been many nice ideas over the Centuries, though very few actually turn out to be practical.