Superconducting qubits possess outstanding capabilities for processing quantum information in the microwave domain; however they have limited coherence times. An interface between photons and phonons could allow quantum information to be stored in long-lived mechanical oscillators. Here, we introduce a platform that relies on electrostatic forces in nanoscale structures to achieve strong coupling between a superconducting qubit and a nanomechanical oscillator with an energy decay time (T1) of approximately 25 ms, well beyond those achieved in integrated superconducting circuits. We use quantum operations in this system to investigate the microscopic origins of mechanical decoherence and mitigate its impact. By using two-pulse dynamical decoupling sequences, we can extend the coherence time (T2) from 64 μs to 1 ms. These findings establish that mechanical oscillators can act as quantum memories for superconducting devices, with potential future applications in quantum computing, sensing and transduction.
Read the full article: Alkım B. Bozkurt, Omid Golami, Yue Yu, Hao Tian & Mohammad Mirhosseini, A mechanical quantum memory for microwave photons, Nature Physics (August 13, 2025)
A scanning electron microscope image highlighting a single mechanical oscillator, “tuning fork,” from the new work. The false-colored golden lines in the image indicate the location of electrodes that transfer electrical signals between the superconducting qubit and the mechanical oscillator.
Credit: Omid Golami
Mirhosseini and his colleagues have fabricated a superconducting qubit on a chip and connected it to a tiny device that scientists call a mechanical oscillator. Essentially a miniature tuning fork, the oscillator consists of flexible plates that are vibrated by sound waves at gigahertz frequencies. When an electric charge is placed on those plates, the plates can interact with electrical signals carrying quantum information. This allows information to be piped into the device for storage as a “memory” and be piped out, or “remembered,” later.
The researchers carefully measured how long it took for the oscillator to lose its valuable quantum content once information entered the device. “It turns out that these oscillators have a lifetime about 30 times longer than the best superconducting qubits out there,” Mirhosseini says.
Learn more in the Caltech Media story Using Sound to Remember Quantum Information
