Thursday, 28 August 2025

Double-slit experiment with one-atom slits

Researchers have fine-tuned one of the most iconic experiments in physics — the double-slit experiment — using two single atoms as the slits. A photon fired at the atoms is scattered in a version of the familiar pattern that has graced a thousand physics textbooks: ripples of interference in some conditions (in this case, when the atoms were trapped in well-defined positions) or no interference (when they were not). The experiment once again shows how light behaves as both a particle and a wave, while negating some of the concerns about experimental ‘noise’ that worried Albert Einstein. “I think this is a beautiful experiment and a testament to how far our experimental control has come,” says physicist Thomas Hird. “This probably far surpasses what Einstein could have imagined possible.”



Blogger Comments:

This experiment takes the double-slit experiment to a whole new level. Instead of using ordinary slits, researchers used two individual atoms as the “slits” for photons of light. The results are as beautiful as they are revealing.

Quantum Possibilities, Not Fixed Properties

Photons are usually described as either particles or waves. But this experiment shows that a photon doesn’t carry a fixed identity. Its behaviour depends on the quantum system it interacts with—here, the positions of the two atoms.

  • When the atoms are well-positioned, the photon creates the familiar interference pattern, like ripples from overlapping waves.

  • When the atoms are uncertain or wobbly, the pattern disappears, and photons behave more like individual particles.

This tells us that quantum phenomena are context-dependent: what you see depends on how the system is arranged.

Every Detection is an Event

Each photon’s arrival on the detector is a moment of actualisation. The interference pattern doesn’t exist in any single photon—it emerges from the collective behaviour of many photons interacting with the atomic system.

Think of it like a flock of birds: a single bird doesn’t create the wave patterns you see in flight, but the flock as a whole does. Similarly, the interference pattern is a manifestation of the system’s underlying potential.

Why This Matters

  • The experiment shows that quantum properties are not intrinsic; they emerge from relationships between objects.

  • It demonstrates how modern technology can probe quantum potential directly, giving us a cleaner, more precise view than ever before.

  • Most importantly, it reminds us that the world at the quantum level is emergent, relational, and profoundly context-sensitive—things only “appear” in the way they do because of the configuration of the system.

In short: the photon is neither strictly a particle nor a wave—it is potential made actual by the system it meets, and the pattern of outcomes is a collective story told by many such interactions.