Light Pulses Under Control: A New Chip for Quantum Communication express
Light can act as a courier carrying secret messages. But to ensure the courier doesn't lose a single letter, you need to meet and check it very quickly. The new chip made from a thin film of lithium niobate is like a turnstile that opens and closes in billionths of a second, letting light pulses through at just the right moment.
Previously, such turnstiles were bulky and slow. Here, light hits the chip, and an electric field instantly changes its path. The switching speed exceeds 30 billion times per second — faster than a fly's wingbeat. This allows the chip to route photons to different outputs based on their arrival time.
In practice, this means a secret key can be transmitted over optical fiber without pauses or delays. In the experiment, the key was generated at 25,000 bits per second and ran steadily for 12 hours straight. That's like typing 25,000 characters per second for 12 hours without a single mistake.
The device can also choose how to measure the incoming light, like adjusting the turnstile for different widths. This closes the main loophole through which an eavesdropper could listen in. Now communication becomes not only fast but truly secure.
Lithium niobate is a transparent crystal that changes its optical properties under an electric field. That's why it became the basis for ultra-fast light switches.
In Star Trek, subspace is used for instant long-distance communication. Here, we're talking about earthly fiber-optic networks, but the speed and security are already almost like science fiction.