Quantum information science is a rapidly growing interdisciplinary field exploring new ways of storing, manipulating and communicating information. Researchers aim to create powerful computational capabilities using new hardware that operates on quantum physics principles.

For the army, these new quantum paradigms could potentially lead to transformational capabilities in fast, efficient and secure collecting, exchanging and processing vast amounts of information on dynamic battlefields in the future. 

As part of their research, Drs Dan Jones, Brian Kirby and Michael Brodsky from the US Army Combat Capabilities Development Command’s Army Research Laboratory, joined by Gabriele Riccardi and Professor Cristian Antonelli from the University of L’Aquila in Italy, studied sources of noise in quantum communication channels.

Noise is a “common plague” of any communication. “Anyone who has ever used a radio, a walkie-talkie or a phone experienced noisy reception now and then,” Brodsky said.

Communication engineers have devised intricate schemes to remove the noise and to clean the transmitted signal as much as possible.  

Quantum communications are no different in their susceptibility to noise in communication channels, Brodsky said, stressing even more so than regular classic communications because the quantum signals are extremely low power.

“To engineer a useful quantum network, we need to understand how far, how fast and how reliably we could send quantum information,” Brodsky explained. “That requires an understanding of the noise in communication channels.”

As the team modelled, emulated, characterised and measured different types of noise in quantum channels, the researchers found that while some quantum noise types are impossible to filter out, others could be removed easily.

The researchers found that the bad noise could be converted into good noise by adding a cheap extra component to the quantum channel. Having this extra control allows them to tweak the channel and to adjust the properties of the noise that masks the transmitted signal.

The overall focus of the lab’s Quantum Networking Group is to experimentally explore the most efficient and secure ways to create, store and process quantum information based on state-of-the-art photonic technologies at present. 

Researchers use the quantum testbed to test-drive various photonic technological approaches to the fast and robust delivery of quantum information over large distances.

“We approach our research quite uniquely by wearing system engineer hats,” Jones said.

The research scope of the group spans developing the architecture and operational principles of quantum networks, as well as understanding and mapping technological limitations to its practical implementation. It also invents methods and techniques to engineer around these limitations, to which the current research results belong. 

“Our research results are a step towards arming the warfighter of the future with quantum advantages and a good example of how operationalising science results in transformational overmatch,” Brodsky said.

The researchers said the next projects in the pipeline focus on demonstrating a way of completely error-free transmission of quantum information. 

Further down the line, they aim to create a multi-user quantum network testbed, deployed in the field, and to demonstrate secure secret sharing protocols between two distance metropolitan campuses.