Quantum computing just got a major boost from an unexpected source – sound.
In a leap forward for the storage of quantum information, scientists at Caltech have developed a hybrid system that converts delicate quantum states from superconducting qubits into vibrations, preserving them up to 30 times longer than current methods.
This breakthrough could help bridge one of the biggest gaps in quantum technology: keeping information stable long enough to tackle problems that today’s computers cannot solve.
From bits to qubits, and beyond
Conventional computers process data as bits – binary values of 0 or 1.
Quantum computers, however, rely on qubits, which can exist as both 0 and 1 at the same time thanks to a phenomenon called superposition. This property allows quantum systems to handle problems too complex for classical machines.
Many of today’s quantum computers are built on superconducting circuits, where electrons flow without resistance at ultra-low temperatures.
These superconducting qubits excel at rapid calculations, but they are poor at storing quantum information for extended periods.
To solve this, scientists have been searching for reliable ‘quantum memories’ that can hold quantum states without losing their integrity.
Turning electricity into sound
The Caltech team, led by graduate students Alkim Bozkurt and Omid Golami under the guidance of electrical engineering and applied physics professor Mohammad Mirhosseini, took an unconventional approach.
Their solution involves converting electrical signals carrying quantum states into sound waves.
These sound waves, made of phonons, the quantum particles of vibration, are stored in a device called a mechanical oscillator.
This oscillator, similar in concept to a microscopic tuning fork, uses vibrating plates that operate at gigahertz frequencies, compatible with superconducting qubits. The plates can hold and later release the stored quantum information without significant loss.
Why sound beats electricity for storage
The research reveals why phonons offer such an advantage. Unlike electromagnetic waves, sound waves travel much more slowly and remain confined within the device, preventing energy leakage and interference from nearby systems.
When tested, the mechanical oscillators preserved quantum states roughly 30 times longer than state-of-the-art superconducting qubits.
This extended storage time opens the door to more complex quantum algorithms that require information to be temporarily ‘parked’ before further processing.
Compact, scalable, and future-ready
Because acoustic waves are slower than light, the devices can be much smaller while still functioning efficiently.
This compactness means multiple oscillators, each acting as an independent memory unit, could be integrated onto a single chip. Such scalability is a key step toward building larger, more powerful quantum computers.
However, the team acknowledges that improvements are still needed. The current system can store and retrieve quantum information, but the transfer rates must be increased by a factor of three to ten to meet the demands of real-world quantum computing.
The road ahead for quantum memories
The research group is already exploring ways to boost the interaction between electrical and acoustic waves to achieve faster and more efficient transfers.
If successful, this hybrid quantum memory design could become a cornerstone technology for future quantum processors.
By demonstrating that sound can outperform electricity as a medium for storing quantum information, the Caltech researchers have added a powerful new tool to the quantum engineer’s toolkit, bringing us one step closer to practical, large-scale quantum computers.
