‘This computer works almost like a guitar’: Fingernail-sized quantum chip uses vibrations to store data

ETH Zurich’s quantum chip sees the superconducting qubit act as a processor and the vibration modes of a fingernail-width acoustic resonator serve as quantum RAM
The approach borrows from classical computer architecture because it completely flips the script on how modern quantum computing could store short-term data.
The team demonstrated a set of universal gates and performed small instances of quantum Fourier transform and period search.

A guitar string essentially stores a note based on how it vibrates, and if it is plucked differently, an entirely different note is played.

A team of researchers from ETH Zurich exploited the same principle to build a quantum chip that stores information by replacing the string with microscopic acoustic resonators.

This allows the chip to significantly increase its working memory, thereby significantly increasing storage capacity, a prohibitively expensive commodity in quantum computing.

A vibration-based quantum storage game

The ETH Zurich research is led by quantum physicist Yiwen Chu, who used tiny mechanical vibrations to store and process information. The vibrations, however, go far beyond the range of human hearing and occur inside a quantum chip where they essentially replace or supplement the working memory of a quantum computer.

The study, published by the Hybrid Quantum Systems group, cites Professor Yiwen Chu, as well as doctoral students Yu Yang and Igor Kladarić, as lead authors and focuses on replicating the division of labor observed in a classical computer.

A superconducting transmon qubit serves as the processor, while the working memory (the quantum equivalent of RAM) is a high harmonic mass acoustic wave resonator, or HBAR, whose many vibration modes each serve as the memory location.

The Qubit essentially exchanges a quantum state of a vibrational mode (reads it, in classical computing terms), manipulates it (modifies it), and exchanges it (writes it). This creates a unique setup that most modern quantum computers do not follow, in which processing and storage are two separate segments; Most designs treat both memory and computation equally.

The approach has advantages, however: Acoustic waves have wavelengths about a hundred thousand times shorter than electromagnetic waves, allowing an entire quantum chip to be extremely small, as the research team states, even though the actual computer will be several times larger.

The chip successfully passed stress tests, including a proof of feasibility, which also included tests using two of the most commonly used methods for evaluating a quantum computer: the quantum Fourier transform and a period search algorithm.

The end game here, as the research team noted, is quantum random access memory (QRAM), which would allow modern quantum computers to access a much larger stock of quantum memory than current specifications allow. The success of this approach depends on both the scalability of the approach and the computing power used.

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