“Time Cloak” Makes A Hole In Time; Makes Events Invisible

Time has finally been punched through, even though for a very short period of time. Scientists, using the technology for making invisibility cloaks’, have bent light in a tight circle, creating a time cloak. The effect lasts for 40 trillionths of a second.

The art of invisibility

This is the basic idea: If you can make sure that light doesn’t scatter off or reflect of a certain object, that object is invisible. Now, assume that an event occurs, but the lights are switched off at that precise point of time. You don’t register that event. What researchers mean to do is to create this gap in the continuum of light, which then becomes akin to making a small hole in time itself.

Cornell physicist and study co-author Alex Gaeta explains better:

Imagine that you could divert light in time slow it down, speed it up so that you create a gap in the light beam in time. In this case, any event that occurs at that instant of time won’t lead to scattering of light. It appears as if the event never occurred.

He goes on splendidly:

If a device would perhaps speed up a portion of the beam and slow down another portion of it so that there is an instant of time with no beam. You could pass through, and then [on the other side of the event] the device would do the opposite—speed up the part that had been slowed and slow the part that had been sped up. That would put the beam of light back together, so to speak, so that the detector never recognizes that anything has happened.


Bending light in the temporal dimension

Gaeta and colleagues have used a device called a time lens’. It bends light, not in spatial directions, but in temporal direction. It uses the trick described above, only with higher sophistication and precision to create gaps in the continuum.

Tweaking time with light might be more than just a gimmick in terms of technological value. It might be used in cryptography, using the time lens to create gaps in codes, passed through optical fibres and then reverse them using a second laser source. The information can be sent and received perfectly, but during the transit, it will be highly coded.

Making the hole in space and time a bit bigger and more stable is the current focus. Also, the team is looking to make a three dimensional hole in space (along with the one in time) and this will require great synchronization from six different lasers, rather than just the two used for the one-dimensional case.

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