Researchers establish new basis for quantum sensing and communication
Sensing and communication systems based on quantum-mechanical phenomena can greatly outperform today’s systems, in terms of accuracy and reliability, and are considered a pivotal part of developing next-generation networks. Developing quantum information and decision systems that come close to meeting the theoretical quantum advantages has been a longstanding challenge. Now, a team of researchers at MIT and the University of Ferrara (UniFe) in Italy has developed a framework that could open up new ways of pushing such quantum systems all the way to their fundamental limits.
The key to the team’s new approach is the use of what are known as non-Gaussian quantum states. Most works on quantum sensing and communication systems are based on Gaussian states — namely, states of the electromagnetic field that can be described by Gaussian models. However, many quantum systems based on Gaussian states inevitably suffer from limitations that prevent them from achieving the full quantum advantage.
The reason quantum systems employing Gaussian states have dominated the research in this field is because they are much easier to understand and implement. Now, the MIT and UniFe team has come up with a solution that overcomes limitations of Gaussian states and could unleash a significant leap in the development of quantum information and decision systems.
The findings were recently reported in the Journal on Selected Areas in Information Theory, in a paper by MIT Professor Moe Z. Win, UniFe graduate student Andrea Giani (who has been a visiting student at MIT for the past year), and UniFe Professor Andrea Conti.
“While Gaussian states are well known and relatively easy to prepare, they don’t possess some properties that are necessary for achieving the full quantum advantage,” Giani explains. But by leveraging the properties of non-Gaussian states instead, he says, “we can overcome these sorts of limitations.”
He adds that “quantum sensing and communication systems are expected to provide significant advantages with respect to their classical counterparts.” For example, quantum sensing systems can be more sensitive to the variations of an electromagnetic field than existing classical ones. Such quantum systems can be far more powerful than any existing methods for inferring physical quantities in the presence of noise. Such capabilities could be crucial for many areas, ranging from fingerprinting the magnetic field of the Earth to enhancing astrophysical research.
The mathematical basis laid out in this new work “could pave the way for the development of quantum information and decision systems that capitalize on the unique properties of non-Gaussian states,” says Win, who is the Robert R. Taylor Professor in the Department of Aeronautics and Astronautics at MIT and founding director of the Quantum neXus Laboratory. “Now that we have established the theoretical foundation for quantum sensing and communication using these states, the next step is for us to determine how to optimally design these states for a variety of applications,” he says.
The new work proposes a particular category of non-Gaussian states known as photon-varied Gaussian states (PVGSs), which can be produced with current technologies. The team’s findings show that these PVGSs can indeed enhance the accuracy of quantum sensing, as well as improve the reliability of quantum communications. “We provide a unified characterization of PVGSs,” Conti says, “which facilitates the design of optimal quantum states for sensing and communications.” The unified characterization of quantum states not only simplifies theoretical derivations but also enables practical implementations. “We believe that quantum sensing and communication systems employing PVGSs will become a reality in the near future,” he says.
“All systems, classical or quantum, have a fundamental performance limit,” Win says, “and the use of quantum-mechanical phenomena will unleash new quantum limits” that far surpass classical limits. “Our research philosophy,” he says, “is to establish such limits, from which we develop efficient design methodologies for quantum systems and networks that are reasonable from a perspective of implementation.”
At MIT, Win is a principal investigator at the Laboratory for Information and Decision Systems and is also affiliated with the Institute for Data, Systems, and Society; the MIT School of Engineering; MIT Schwarzman College of Computing; and the Institute for Soldier Nanotechnologies. He formerly worked at AT&T Research Laboratories and NASA’s Jet Propulsion Laboratory. Win regularly collaborates with Conti at the University of Ferrara, and “we have developed a successful long-term relationship over multiple decades,” he says. The goal of their current research effort is to unleash the potential of quantum information and decision systems, expediting their maturation toward practical utility.
The research was supported by the Robert R. Taylor Professorship at MIT, the U.S. National Science Foundation, the Ministero dell’Università e della Ricerca, and the European Union NextGenerationEU.
