Quantum Security via Random Light

Indian defence scientists find novel way to generate perfectly random string of numbers that will boost security in quantum computers

India’s Defence Research and Development Organisation (DRDO) has taken a remarkable step towards quantum computing. Research scientists at DRDO’s Young Scientist Laboratory for Quantum Technologies has come up with a quantum device that can generate a perfect sequence of random numbers through the tracking of light particles. The device leverages a fundamental yet ever-puzzling mystery of optics – the fact that light displays both the properties of a wave and a particle simultaneously.

What’s the big deal about random numbers?

Generating a sequence of truly random numbers, which will present absolute absence of correlation between any two successive numbers, was always a dream event for mathematicians. It was the British scientist Francis Galton who had first proposed a device for this task in 1890. And the gadget he proposed to be the perfect random number generating device was none other than the playing! His logic was correct, but as computing grew increasingly complex, a six-sided cube was obviously not enough, and scientists had been in constant search for the holy grail. Today unique 6-digit authentication codes are routine for any secure online activity. Every split-second almost the whole of humanity is eagerly checking their mobile phones for that elusive code to complete their transaction. Imagine the huge number of random strings that are supposed to be generated relentlessly and transmitted – all within a matter of split seconds. Naturally, the world needed far more sophisticated systems than the dice to keep up to the pace, and computer programmes are currently employed to generate random numbers to fulfil such requirements.

So why the new device?

The fact is, computer programs are not truly random when it comes to producing perfect sequences with no correlation between any two successive numbers unendingly. For any such programming system, a time is bound to come when the sequence of numbers would be repeated. Technically, this is a potential security threat and allows a possible breach to the system concerned – and likely to be exploited by advanced malwares. In short, the sheer volume of data being generated, and the frequency of secure online transactions being performed every moment all over the globe, has rendered the modern PIN- and OTP-generating software as helpless as the ancient dice!

And imagine the plight that will be faced by quantum processors which are being built with the sole purpose of scaling up processing speeds and data volume to unimaginable levels. Thousands of times faster than traditional computing and handling proportionately massive loads of data traffic, they will require nothing short of “the perfect” random number sequence to maintain the same security levels.This is where our home-grown DRDO device scores.

The official press release from DRDO mentions that random numbers are now essential in diverse computational domains including quantum communication, cryptography, scientific simulations, fundamental physics experiments and even lotteries. It appears that the new technology is going to be a trendsetter, as it employs an entirely novel approach.

The science behind the innovation

For their device, the scientists at DRDO used attenuators on a source of laser light in a very controlled manner, to reduce the intensity of the laser to just a single photon. A “photon” is the basic particle of which light is made of. The photons isolated by the attenuating device are then passed through a branched beam splitter with two exit points – one at the termination point of each branch. As the photons reach the end-point of the branches, they are tracked by detecting devices capable of identifying photon signals. Whenever the devices detect a photon, the system generates an electrical pulse that is transmitted to a recording unit. The branches have designated values and the device registers a “zero” (0) if the pulse emanates from one branch, and a “one” (1) if it emanates from the other branch. Thus, a continuous stream of random binary digits keeps on being generated as long as light passes through the system.

And here comes the beauty of harnessing optics to generate random numbers. As photons are particles that are of absolute random in behaviour, it is impossible to predict which branching path a photon will take leading to the generation of what binary digit. This means no existing system can ever guess in advance what string of code such a photon-emanating system would eventually generate. On one hand the extent of randomness makes the code perfectly unique, and on the other it becomes virtually impossible to crack due to the unpredictability factor.

The DRDO press release further confirms: “Based on the encouraging results obtained, it can be stated that the developed Quantum Random Number Generator (QRNG) passes the global randomness testing standards.”