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Quantum Communications: Using the Laws of Physics to Find the Holy Grail of Security

By Joe Lukens
Co-authored by Paula Reinman

“I think I can safely say that no one understands quantum mechanics.”

Richard FeynmanWinner of the Nobel Prize in Physics

Innovators often see opportunities where others see problems. Take the matter of light: intuition about classical physics does not hold true when it comes to light. Light comes in particles called photons, which lack even the simplest common-sense properties, such as specific location. They are difficult to isolate and difficult to measure.

While the randomness of light makes it impossible for us to apply our tried and true intuition from the everyday world, these properties also can be used to our advantage because of their complexity and unpredictability. Nowhere could these innovations be more important than in security. Given the amount of information on the internet and the highly connected nature of our world, we are more vulnerable than ever to security breeches. In fact, rarely a week goes by when we do not hear about a major commercial or government security break. While today’s security is based on complex codes, all of which could be hacked with current or future code-breaking algorithms, tomorrow’s security will likely be based on the laws of physics, which are complex enough to keep us safe against the most sophisticated threats.

The Beauty of Light

This is the world of quantum communications. It is a world inhabited by scientists who live to understand that which defies explanation, such as the researchers in the Quantum Information Science Group at Oak Ridge National Laboratory. This team includes Joe Lukens, 2015 Marconi Society Paul Baran Young Scholar with a PhD from Purdue University and a BS from the University of Alabama. Lukens, who has focused on security for years, was recognized as a Paul Baran Young Scholar in part for his research to create highly secure quantum key distribution. He has expanded this work as a Wigner Fellow at Oak Ridge.

Quantum physicists identify and solve problems anywhere there is room for improvement by using quantum properties. The random characteristics of light become opportunities for improved security. For example, one of the strange consequences of quantum mechanics is that a measurement disturbs the system being measured. In the case of a single photon, this means that it is impossible to figure out its properties from one measurement, since the measurement itself changes the original state forever. While long-viewed as a problem (how can something that is so uncertain be useful?), researchers have turned this idea on its head. Because measurement disturbs the system, anyone who tries to tamper with a photon intended to be sent secretly to someone else will change the photon’s properties—therefore it is known for sure whether an eavesdropper is tapping into these communications.

From the Grid to the Airport

Researchers are testing and applying quantum communications to applications that make sense now, without adding a lot of cost or unnecessary limitations to the solution. One example is the electric grid, which could be a commercial application in the near future. The stability of the current grid relies on being able to distribute very accurate GPS timing signals in order to synchronize and respond to demand fluctuations or supply interruptions over large distances. Lack of signal or accuracy can cause a serious loss of power on the grid, affecting businesses and consumers over a wide area. Today, it is possible to cause blackouts by spoofing a signal, making the electric grid a potential target for hackers. Rather than using GPS timing signals, researchers are investigating quantum keys to ensure that the grid is communicating only with the right partners. Since quantum key generation and exchange is highly secure but not yet very fast, this is a perfect application since securing the electric grid does not require high speeds.

Another area where the properties of light will make us all more secure is through quantum sensing. Today we use optical sensors to look for dangerous materials, such as toxic chemicals or materials being smuggled into the country. These sensors use laser beams and the sensing accuracy of those lasers is limited by something called shot noise.  Since each photon arrives randomly, the photons create statistical noise, causing a variety of unpredictable results unless they are averaged over a long period of time. But quantum properties make it possible to generate “squeezed” light to beat this limitation. Squeezing reduces the noise from one of the photon’s properties (such as intensity) by increasing the noise somewhere else (such as the phase). Doing this significantly lowers the noise in a given optical measurement, vastly improving the speed and accuracy of a particular sensor.

Researchers are doing table top experiments using components available in today’s communications systems to understand how we can start using quantum communications in practical ways to solve today’s security problems. Because security guaranteed by the laws of physics1 should always beat security based on even the most sophisticated code.

1. Quantum Information Science Group, Oak Ridge National Laboratory