White noise, lousy sound — all of these are technical issues that can impact our daily lives. Almost on a daily basis, we’re talking on our phones. Whether it’s for work, family, or friends, we can’t deny that good audio is crucial to communication in the modern world.
But while many methods for correcting bad audio try to resolve technical issues, such as adjusting mic sensitivity, gain, and volume (or buying a new microphone altogether), physicists are looking towards a different solution: quantum microphones.
There have been many solutions to problems with signal-to-noise ratios. Many of these have even been effective in significantly reducing noise and making pleasant audio recordings.
The issue, according to researcher Florian Kaiser, stems from the fundamental noise level that comes from the quantum nature of any measurement, which includes sound. So, even if one eliminated all technical noise by altering the signal, for example, there would still be a baseline level of noise that could affect the sound.
Although some might say these noises are imperceptible, sound engineers and scientists alike are dedicated to improving anything that could possibly be improved.
The closest one gets to crystal clear sound in a microphone is the laser mic. However, these are mostly used in industrial machines and espionage.
What physicists aim for is beating these laser microphones, performance-wise. This is where quantum microphones come in.
Quantum microphones are hyper-sensitive devices that can detect even the tiniest sound particles.
“Entangled photons can make use of quantum correlations to measure small displacements with an improved signal-to-noise ratio compared to laser light. However, the generally complex experimental setting of quantum physics experiments leads to a tremendous resource overhead and complicated data processing, which results in measurement rates of a few data points per second, at most,” Kaiser writes in his paper.
To solve this problem, their research team discovered a method to create a quantum optical displacement sensor that works below the regular noise limit. This method combines various fundamental concepts of quantum optics, creating something robust and simple.
While most researchers may not go the extra mile to prove their theory, Kaiser made sure that its measuring rate was actually functional. Through rigorous testing, they were able to show that quantum light from their membrane was able to improve the signal-to-noise ratio of a medically-approved speech recognition test.
To take it a step further, the team went to a local sound research lab in a hospital to conduct a speech recognition test on 45 patients.
“Our data showed that more than 71% of the subjects were able to hear the improvement provided by the quantum microphone,” Kaiser writes. Operating on a reduced 0.57 dB pressure level, patients were able to clearly and accurately understand the words in the recording.
The success of their testing has made the team eager to develop a “compact version” of this project, present it at various exhibitions, and allow an even wider audience to experience the improved sound quality that quantum microphones can provide.