Lotteries, accidents and rolls of dice, the world around us is full of unpredictable events. Yet generating a truly random series of numbers for encryption has remained a surprisingly difficult task.
Now, researchers have used an experiment relying on both Albert Einstein's theory of relativity and quantum ...
Lotteries, accidents and rolls of dice, the world around us is full of unpredictable events. Yet generating a truly random series of numbers for encryption has remained a surprisingly difficult task.
Now, researchers have used an experiment relying on both Albert Einstein's theory of relativity and quantum mechanics, which describes the probabilistic nature of subatomic particles, to produce strings of numbers that are guaranteed to be random.
Computers everywhere use random numbers as keys to lock or unlock encrypted information. Many processes for producing these keys, such as random number generators inside computers, use an algorithm that spits out a seemingly arbitrary string of numbers. Other approaches try to make use of real-world randomness, for instance measuring the length of time between keystrokes or the fluctuating temperature of a computer server, to produce random numbers.
Entangled photons
Quantum mechanics, on the other hand, offers truly random outcomes. For instance, a light particle, or photon, can either be pointing up or pointing down. Before it's measured, the particle is in a superposition state, in which it has a 50 percent chance of pointing up and a 50 percent chance of pointing down once measured. Its eventual outcome is certifiably random, but using this property for number generation has still been somewhat problematic.
Consider a photon in a superposition state of up and down, and upon measurement, the photon turns out to be down, an outcome that nobody should have been able to predict in advance.
But how it could be known that the photon wasn't always down? In other words, there's no way to prove, for any individual photon, that it was in a superposition state before it got measured. To get around this conundrum, pairs of photons were entangled with one another, meaning that their properties were forever tied together.
In their experiment, the researchers then sent the two photons to opposite ends of their lab, separated by a distance of 187 meters, and measured their properties. Because of their entanglement, the photons always returned coordinated results, if one was found to be up, the other was always down.
Because they were so far apart, there's no way for the photons to have discussed their perfect lockstep synchronization unless they could send signals faster than the speed of light, which would violate Einstein's theory of relativity. The two photons therefore serve as a check on one another, guaranteeing that they were actually in a superposition state before being measured and that their results are genuinely random.
This could mean that an ultimate quantum random number generator was just built, but the method took about 10 minutes to produce 1,024 random strings, whereas current cryptographic processes would need far faster number generators.
The new technique's first real-world use will come when it's incorporated into NIST's randomness beacon, a public source of randomness for researchers studying unpredictability, and researchers hope the experimental setup could one day be shrunk enough to fit on a computer chip and help in the creation of "unhackable" messages.
Source:
SPACE.com
