Quantum study harnesses wave-particle duality for innovative imaging

A groundbreaking quantum study from Stevens Institute of Technology has created a formula that precisely quantifies the “wave-ness” and “particle-ness” of quantum objects, enabling innovative quantum imaging with undetected photons

For a century, quantum mechanics has unveiled a universe stranger than fiction, where particles can simultaneously behave as waves and alter their state simply by being observed. Now, a groundbreaking study from Stevens Institute of Technology has not only deepened our understanding of this fundamental concept – wave-particle duality – but has also leveraged it to power a novel imaging technique.

This peer-reviewed research, published in Physical Review Research, introduces a precise mathematical framework that quantifies the intricate relationship between a quantum object’s “wave-ness” and “particle-ness,” opening new avenues for quantum information and computing.

Quantifying the elusive dance of wave and particle

The concept of wave-particle duality is a cornerstone of quantum mechanics, describing how subatomic entities exhibit characteristics of both waves (like interference patterns) and particles (like a defined position or path). For decades, researchers have strived to quantify these dual behaviours.

Previous models expressed this relationship as an inequality, suggesting that the sum of an object’s wave-like and particle-like behaviours was less than or equal to one. While insightful, this formulation had a critical flaw: it could permit scenarios where both wave-like and particle-like behaviours simultaneously increased, contradicting their inherently exclusive nature.

Dr. Xiaofeng Qian, Assistant Professor of Physics at Stevens and lead author of the paper, explains, “Researchers have been working to quantify wave-particle duality for half a century, but this is the first complete framework to fully quantify wave-like and particle-like behaviors with optimum quantitative measures that are relevant at the quantum level.”

The Stevens team’s breakthrough lies in introducing a crucial new variable: the coherence of the quantum object. “Coherence is a tricky concept, but it’s essentially a hidden description of the potential for wave-like interference,” Qian clarifies. By incorporating and compensating for coherence alongside conventional measures of wave-ness and particle-ness, the researchers discovered a precise, closed mathematical relationship. “When we quantify and compensate for coherence… we find they add up to exactly one,” states Qian.

This elegant formula allows for the calculation of both wave-ness and particle-ness with unprecedented precision, moving beyond mere inequalities to exact values. Graphically, this relationship can be beautifully depicted as a perfect quarter-circle for a perfectly coherent system, transforming into a flatter ellipse as coherence diminishes.

From theory to application: Powering quantum imaging

Beyond its profound implications for foundational physics, this new understanding of wave-particle duality has significant practical applications, particularly in quantum information and quantum computing. To demonstrate this, Qian’s team applied their theory to a technique known as quantum imaging with undetected photons (QIUP).

In QIUP, an object is scanned using one photon from an entangled pair. If this “scanning” photon passes unimpeded through an aperture, its coherence remains high. However, if it collides with the aperture’s walls, its coherence sharply decreases. By then measuring the wave-ness and particle-ness of its entangled partner-photon, Qian’s team could deduce the coherence of the scanning photon and, in turn, map the shape of the aperture. “This shows that the wave-ness and particle-ness of a quantum object can be used as a resource in quantum imaging, and potentially many other quantum information or computational tasks,” Qian affirms.

Remarkably, the team found that imaging remained possible even when external factors like temperature or vibrations degraded the overall coherence within the quantum system. Since such factors equally affect both high and low coherence situations, the crucial difference in coherence between the two scenarios remains detectable. “The ellipse gets squeezed, but we’re still able to extract the information of the object we need,” Qian explains, highlighting the robustness of their approach.

While this study represents a significant leap forward, further research is needed, particularly to explore how wave-particle duality manifests in more complex multipath quantum scenarios. As Qian concludes, “The mathematics make it look simple, but we’re a long way from exhausting the weirdness of quantum mechanics. There are still plenty of frontiers left for us to explore.”

This pioneering work by the Stevens team not only enriches our fundamental understanding of the quantum world but also lays the groundwork for transformative advancements in quantum technologies.