Physicists show time-cloaking device — for 15 trillionths of a second
Physicists Moti Fridman and colleagues at Cornell University (Ithaca, NY) have successfully demonstrated a time-cloaking device that can “hide” time for 15 trillionths of a second. In a paper published in Nature , the researchers describe how they were able to cause light passing through a fiber-optic cable to compress, then decompress, causing a hole or void to exist long enough for there to be a lag between the two.
A pair of “split time lenses” are used to create a “temporal hole” in a probe beam such that any temporal or spectral changes caused by an event within this hole do not occur. The figure is oriented such that the probe light is described by horizontal lines, and lines at different orientations represent different wavelengths.
Light from a probe is sent through special silicon lens in the fiber cable where the index of refraction is manipulated, causing some of the light passing through it to speed up and some to slow down. This causes the waves to divide. Another lens, a little farther up the cable, then causes the light to be put back together. The result is light emerging from the end of the cable that appears to be unaltered, which means, for the little bit of space between the lenses, things have, or could have, gone on with no record of them occurring.
The reason that creating a temporary gap in the light in a fiber-optic cable is considered to be cloaking time is because of the type of duality that exists between space and time in electromagnetic theory, which says in short, that diffraction and dispersion are symmetric in space-time. The technology might be used for signal-processing applications, or if coded messages could be hidden in a series of these cloaks, it would be mighty difficult to intercept them, making for very secure communications.
If the technology could be expanded to real-world size, you could step between two lenses, and do anything you wish, and it would never be recorded in time; for the rest of the world, it would never have happened. The researchers point out that they don’t expect the technique could ever produce a gap that lasts any longer than 120 µs not nearly enough time to do anything fun.
For more information, go to focus.aep.cornell.edu/publications.html.
Learn more about Cornell University