Quantum Sound Waves

Phonons are to sound what photons are to light – basically quantum packets of the vibrational energy that make up sound waves. Scientists have hypothesized that phonons could be useful in quantum computer processing systems but, until recently, they haven’t been able to detect them without destroying them. Now a team of researchers has tuned the energy of a quantum circuit (or superconducting qubit) so that phonons can be detected and measured.

Phonons of various wavelengths were passed between sound-reflecting “mirrors.” By measuring the time it takes for them to travel back and forth, phonons of multiple wavelengths could be precisely controlled. Because sound travels much slower than light, the mirrors needed to be separated by only a hair’s width; doing something similar with light would require a separation of 12 meters (approximately 40 feet).

The lifespan of the phonons was a mere 600 nanoseconds, so although this is considered to be a breakthrough in phonon research, much work remains before the applications for quantum computing will be fully understood.