Research conducted by physicists at Leiden University has successfully replicated the renowned double-slit experiment, originally performed with light, using sound waves for the first time. This groundbreaking study, published in the journal Optics Letters on November 13, 2025, provides new insights that could significantly impact technology, particularly in the realm of 5G devices and the emerging field of quantum acoustics.
The study, led by Ph.D. student Thomas Steenbergen and his colleague Löffler, explored how sound behaves at a microscopic level. Steenbergen explained, “We saw that sound waves in materials behave in the same way as light, but also slightly differently. With a mathematical model, we can now explain and predict this behavior.”
The original double-slit experiment, conducted by Thomas Young in 1801, demonstrated that light can exhibit both wave-like and particle-like properties. In this experiment, light passing through two narrow slits produced an interference pattern of alternating bright and dark stripes due to the reinforcement and cancellation of light waves.
By adapting this experiment for sound, Steenbergen and his team aimed to uncover the nuances of sound wave behavior. Their experimental setup extended earlier work by physics bachelor student Krystian Czerniak. The research employed gigahertz sound waves, vibrating at one billion cycles per second—far beyond human hearing capabilities.
The experiment utilized a small piece of gallium arsenide, a semiconductor commonly found in electronic devices. In a precise setup, colleague Matthijs Rog carved two minute grooves in the material using an ion beam. Steenbergen elaborated, “We then measure the sound with an extremely precise optical scanner. This device can measure sound literally everywhere, including in and in front of the slits. We can measure the height of the sound waves with picometer precision—that’s one millionth of a micrometer.”
As anticipated, the researchers observed an interference pattern similar to that produced by light. However, they noted distinct differences. Steenbergen remarked, “If you look closely, you also see that the pattern is not completely symmetrical. Sound waves don’t move the same way in all directions. The speed of the waves depends on the angle at which they pass through the material.” By developing a mathematical model, the team explained these differences and made accurate predictions about sound wave behavior.
The implications of this study extend beyond academic curiosity. Gigahertz sound waves are integral to telecommunications, particularly in 5G technology. The findings could enhance the performance and design of electronic devices and sensors that utilize sound. Furthermore, the research contributes valuable knowledge to the fledgling field of quantum acoustics, which explores how sound waves at the quantum level can transmit information.
This innovative research shows how a classic experiment from centuries ago continues to open new avenues of exploration in modern science and technology. The work of Steenbergen and his colleagues marks a significant step in understanding the fundamental principles governing sound, with potential applications that could shape future technological advancements.
