SQUEEZING light may be the key to teleporting energy across vast distances – although the amount of energy that could theoretically be transmitted is only several hundred microelectronvolts.
For years physicists have been smashing distance records for quantum teleportation, which exploits quantum entanglement to send encrypted information. Entangled particles remain linked no matter how far apart they are, and a change to one particle always affects its partner.
In experiments, for example, a pair of entangled particles is separated and each partner is sent to a different location. When someone measures the particle at point A, its quantum state is decided and that immediately causes a corresponding change in the particle at point B. No matter is transmitted, and nothing is travelling faster than light. But the person at point B can recreate the photon at point A using only information about the observed changes – effectively teleporting the photon.
Masahiro Hotta of Tohoku University in Sendai, Japan, wondered if it would be possible to use quantum entanglement to teleport energy instead.
Theory has it that a vacuum is not truly empty – it is filled with a quantum field, and tiny fluctuations in that field cause particles to pop in and out of existence. These particles emerge in entangled pairs and, crucially, the two partners can appear great distances apart.
The quantum field in a vacuum is usually at its lowest energy level. But if someone measures the field, the quantum system in that region – call it region A – gains energy and becomes excited. Hotta suggests using the information gained from that measurement to create an electric current that is tuned to this quantum change. Because particles spread across the vacuum are entangled with each other, sending this tuned current through another part of the vacuum – region B – will allow the current to extract "hidden" energy from the quantum system in that region. In other words, particles from region A will teleport some of their energy to region B, without the need for a physical transmission line.
Hotta's original theory suggested this would work only over tens of nanometres. To get greater reach, he and his team have applied a twist to their theory that adds "squeezed" light to the vacuum (arxiv.org/abs/1305.3955v2). In quantum mechanics, there is a limit to how precisely we can know multiple values in a physical system. Physicists can exploit this rule by increasing the uncertainty of one value on purpose, allowing them to better pin down a different, target property.
To squeeze light, you use this effect to get the best possible value for its amplitude, which is proportional to the number of photons travelling together. That forces more photons to travel in pairs. When such squeezed light is sent through the space between two target regions, it enhances the entanglement between them, allowing energy to be teleported across greater distances.
This article appeared in print under the headline "Teleport energy via quantum squeeze"
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