Army Scientists Take New Spin On Quantum Research

Army researchers discovered a way to further enhance quantum systems to provide Soldiers with more reliable and secure capabilities on the battlefield.

Specifically, this research informs how future quantum networks will be designed to deal with the effects of noise and decoherence, or the loss of information from a quantum system in the environment.

As one of the U.S. Army’s priority research areas in its Modernization Strategy, quantum research will help transform the service into a multi-domain force by 2035 and deliver on its enduring responsibility as part of the joint force providing for the defense of the United States.

This research effort considers how dispersion, a very common effect found in optical systems, impacts quantum states of three or more particles of light.

Dispersion is an effect where a pulse of light spreads out in time as it is transmitted through a medium, such as a fiber optic. This effect can destroy time correlations in communication systems, which can result in reduced data rates or the introduction of errors.

To understand this, Kirby said, consider the situation where two light pulses are created simultaneously and the goal is to send them to two different detectors so that they arrive at the same time. If each light pulse goes through a different dispersive media, such as two different fiber optic paths, then each pulse will be spread in time, ultimately making the arrival time of the pulses less correlated.

The key to this is something called entanglement, a strong correlation between quantum systems, which is not possible in classical physics, Kirby said.

In this new work, Nonlocal Dispersion Cancellation for Three or More Photons, published in the peer-reviewed Physical Review A, the researchers extend the analysis to systems of three or more entangled photons and identify in what scenarios quantum systems outperform classical ones. This is unique from similar research as it considers the effects of noise on entangled systems beyond two-qubits, which is where the primary focus has been.

Additionally, based on the success of Franson’s initial work on systems of two-photons, it was reasonable to assume that dispersion on one part of a quantum system could always be cancelled out with the proper application of dispersion on another part of the system.

Further, Kirby said, this work is valuable for quantum communications because it allows for increased data rates.

Since Kirby and his colleagues' new work describes how to limit the uncertainty in joint detection times of networks, it will allow subsequent transmissions in quicker succession.

The next step for this research is to determine if these results can be readily verified in an experimental setting.

About CCDC Army Research Laboratory
CCDC Army Research Laboratory is an element of the U.S. Army Combat Capabilities Development Command. As the Army’s corporate research laboratory, ARL discovers, innovates and transitions science and technology to ensure dominant strategic land power. Through collaboration across the command’s core technical competencies, CCDC leads in the discovery, development and delivery of the technology-based capabilities required to make Soldiers more lethal to win the nation’s wars and come home safely. CCDC is a major subordinate command of the U.S. Army Futures Command.