Linköping University researchers have experimentally validated a theoretical connection between quantum mechanics and information theory, specifically confirming a 2014 mathematical proposition from Singapore that links the complementarity principle to entropic uncertainty. This breakthrough bridges fundamental quantum concepts with information theory, opening new possibilities for quantum technology applications.
The research centers on wave-particle duality, a cornerstone of quantum mechanics that traces back to Isaac Newton’s time. This principle establishes that light can exist as both waves and particles, though these properties cannot be simultaneously measured in the same photon. This limitation, formalized by Niels Bohr in the 1920s as the complementarity principle, maintains that the combination of wave and particle characteristics must remain constant.
The Singapore team’s 2014 mathematical work demonstrated that this complementarity principle directly correlates with the degree of unknown information in a quantum system. Their theory proposed that any measurement of wave or particle characteristics would always leave at least one bit of information unknown, representing the unmeasured property.
The Linköping team’s experimental confirmation employed an innovative approach using photons with orbital angular momentum rather than traditional oscillating motion. This choice not only validated the theory but also enhanced the potential for practical applications due to increased information capacity. Their experimental setup utilized an interferometer where photons encounter two beam splitters, with the second one being partially insertable to enable measurements of waves, particles, or combinations thereof.
Led by researcher Guilherme B Xavier, the team collaborated with scientists from Poland and Chile to achieve these results. While Xavier acknowledges that the findings have no immediate practical applications, he emphasizes their significance as foundational research that could enable future developments in quantum information and computing technologies.
The research team, including PhD student Daniel Spegel-Lexne, is now planning follow-up experiments to explore the photon’s behavior when rapidly altering the second crystal’s settings. This next phase could have direct applications in secure encryption key distribution, potentially advancing quantum cryptography.
Published in Science Advances, this work represents a crucial step forward in quantum physics, demonstrating how theoretical quantum mechanical principles can be experimentally verified and potentially harnessed for practical applications in quantum communication, metrology, and cryptography. The research exemplifies how fundamental scientific investigation can lay the groundwork for future technological innovations, even when immediate applications aren’t apparent.
Reference: “Experimental demonstration of the equivalence of entropic uncertainty with wave-particle duality” by Daniel Spegel-Lexne, Santiago Gómez, Joakim Argillander, Marcin Pawłowski, Pedro R. Dieguez, Alvaro Alarcón and Guilherme B. Xavier, 6 December 2024, Science Advances. DOI: 10.1126/sciadv.adr2007
