A tiny hiding hole in time

Ars Technica : An event at a specific point in time can now be hidden from observation. Alexander Gaeta of Cornell University and colleagues created a “time lens” that shifts light entering it to bluer, faster wavelengths and then shifts the light to redder wavelengths that travel more slowly. The result is a gap in the beam of light as the blue light races ahead of the slower red light. The light is then sent through a dispersive medium with the opposite effect, so that the wavelength shifts are reversed. Any events that took place during the gap never happened, as far as the beam of light is concerned. When the device was off, a separate laser pulse that interacted with the light created a clear signal; when the device was on, that signal dropped to background levels. Although the apparent gap in time is only about 15 picoseconds long—too short for any human action to take place—the technique could be used in fiber-optic data transmission and data processing applications.