Physicists have theoretically shown that it is possible to transmit information from one location to another without transmitting energy. Instead of using real photons, which always carry energy, the technique uses a small, newly predicted quantum afterglow of virtual photons that do not need to carry energy. Although no energy is transmitted, the receiver must provide the energy needed to detect the incoming signal—similar to the way that an individual must pay to receive a collect call.

The physicists, Robert H. Jonsson, Eduardo Martín-Martínez, and Achim Kempf, at the University of Waterloo (Martín-Martínez and Kempf are also with the Perimeter Institute), have published a paper on the concept in a recent issue of Physical Review Letters.

Currently, any protocol also involves transmission. This is because these protocols use real photons to transmit information, and all real photons carry energy, so the information and energy are inherently intertwined.

Most of the time when we talk about electromagnetic fields and photons, we are talking about real photons. The that reaches our eyes, for example, consists only of real photons, which carry both information and energy. However, all contain not only real photons, but also virtual photons, which can be thought of as "imprints on the quantum vacuum." The new discovery shows that, in certain circumstances, virtual photons that do not carry energy can be used to transmit information.

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