Quantum entanglement? That's hot, baby (just not very hot, OK?)

Researchers in Spain and Columbia have shown that quantum entanglement may be possible at much higher temperatures than anyone thought. The trick, according to the work published in Physical Review, Letters, is to set up a system without thermal equilibrium – that is to say, some bits need to be hotter than others.

Oxford-based physicist Vlatko Verdal discusses the findings in Nature, and explains that both theory and experiment over than last decade have shown that systems can be entangled if “the inter action strength between the subsystems is larger than the thermal energy due to their coupling to the environment,” provided the system is in thermal equilibrium with the environment.

But if the system is not in thermal equilibrium, the researchers predict that in fact nanomechanical oscillators could be entangled at much higher temperatures than thought possible, possibly as high as 100 Kelvin.

Although this is still some way off room temperature (you’ll be needing your thermals) it would at least allow researchers to ditch the cryogenic cooling systems.

Verdal told us that the overarching goal of the research is to make a large scale quantum computer – one with more than 1,000 quantum bits.

"It would be very advantageous if such a device could exist at the room temperature, since keeping things cool is very costly, laborious and generates a great deal of heat.

"The paper by Galve et al is just a small first step in showing that entanglement, which is the main ingredient in quantum computation, can be maintained at high temperature by applying a coherent external driving," he explains.

The system described in the research is coupled quantum oscillators. This Verdal says is not directly relevant for computation, "but it serves as an illustration of the basic principle".

The work is published in Physical Review letters here and Verdal’s discussion of the work is in Nature here.