Quantum Noise Silenced by Mirror Trick

Researchers at Swansea University have found a way to significantly reduce quantum noise using mirrors — a discovery that feels almost like magic, but is firmly grounded in the principles of quantum physics.

Figure 1. Silencing Quantum Noise: The Mirror Experiment Changing Physics.

Measuring incredibly small objects, like nanoparticles, poses a major challenge for scientists: the very act of observation disturbs the particles. This happens because photons — the particles of light used to observe them — nudge the nanoparticles upon contact, a phenomenon known as "backaction." Figure 1 shows Silencing Quantum Noise: The Mirror Experiment Changing Physics.

In a recent study published in Physical Review Research, the University’s Physics Department revealed a surprising twist: the interaction isn't one-sided. The particles influence the photons, too.

Mirror, Mirror: Cancelling Out Quantum Disturbance

Rafal Gajewski, a PhD student at Swansea University and lead author of the study, explained: “Our research shows that if you can engineer a situation where measurement becomes fundamentally impossible, the quantum disturbance disappears as well.”

By placing a nanoparticle at the exact center of a hemispherical mirror, the team discovered that under the right conditions, the particle becomes indistinguishable from its mirror image. “In this scenario,” Gajewski noted, “you can’t extract any position information from the scattered light — and as a result, the quantum backaction is eliminated.”

This discovery opens up exciting possibilities, including:

• Generating quantum states with objects far larger than atoms
• Probing the fundamentals of quantum mechanics on unprecedented scales
• Investigating the interplay between quantum mechanics and gravity
• Creating ultra-sensitive instruments capable of detecting minuscule forces

The research could prove especially valuable for cutting-edge initiatives like MAQRO (Macroscopic Quantum Resonators) — a proposed space mission designed to test quantum phenomena with larger-scale objects than ever before.

Counterintuitive Physics: When Light Brings Silence

Dr. James Bateman, the research supervisor, highlighted the deeper implications of the findings: “This study uncovers a fundamental link between information and disturbance in quantum mechanics. What’s truly unexpected is that quantum backaction vanishes exactly when light scattering is at its peak — completely contrary to what we’d normally expect.”

He added, “By carefully designing the environment around a quantum object, we can control the information that can be extracted about it — and in doing so, manage the quantum noise it experiences. This breakthrough paves the way for new types of quantum experiments and could lead to even more precise measurement techniques.”

Shaping the Next Generation of Quantum Sensors

The team is now focused on experimental demonstrations and investigating real-world applications that could usher in a new era of quantum sensing technology.

Their work contributes to the rapidly advancing field of levitated optomechanics—a technique that uses lasers to trap and manipulate microscopic particles in a vacuum. Recent breakthroughs have already succeeded in cooling these particles to their quantum ground state, highlighting the extraordinary level of control researchers can now achieve in these systems.

Source: SciTECHDaily

Cite this article:

Priyadharshini S (2025), Quantum Noise Disappears: Inside the Mirror Experiment That’s Rewriting Physics, AnaTechMaz, pp. 287