Classical computers separate processing from memory, pairing a processor with RAM. Quantum computers have largely lacked that architecture, but researchers led by Yiwen Chu, head of the Hybrid Quantum Systems Group at ETH Zurich, have now built one: a chip that couples superconducting qubits to tiny mechanical resonators whose vibrations store quantum information. The work, with doctoral student Igor Kladaric among the authors, is published in Science and marks the first such combination.
In the new design, the qubit retrieves a stored vibrational state, processes or modifies it and writes it back, just as a processor works with memory. Each resonator supports many distinct vibrational modes, and each mode serves as a memory slot, so mechanical memory stores more information in less space than electromagnetic alternatives and keeps quantum states stable for longer. The entire chip measures about 7.5 by 2.5 millimetres, roughly the width of a small fingernail.
The team demonstrated that the architecture is genuinely programmable, running basic operations as well as the quantum Fourier transform and period finding, routines at the heart of many quantum algorithms. The result is a proof of feasibility for a general-purpose quantum computer with dedicated working memory; the open challenge now is scaling the approach to larger numbers of qubits and resonators.