- ETH Zurich’s quantum chip sees a superconducting qubit acting as a CPU and the vibration modes of a fingernail-width acoustic resonator serving as quantum RAM
- The approach borrows from classical computer architecture as it completely flips the script on how modern quantum computing could store short-term data.
- The team demonstrated a set of universal gates and ran small instances of the quantum Fourier transform and period search.
Basically, a guitar string stores a note based on how it vibrates, and if one plays it differently, a completely different note sounds.
A team of researchers at ETH Zurich has leveraged 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, essentially 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 small 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, lists Professor Yiwen Chu, along with PhD students Yu Yang and Igor Kladarić, as lead authors and focuses on replicating the division of labor seen on a classical computer.
A superconducting transmon qubit serves as the CPU, while the working memory (the quantum equivalent of RAM) is a high-pitch massive acoustic wave resonator, or HBAR, whose numerous vibration modes each serve as a memory slot.
Basically, the Qubit exchanges a quantum state from a vibrational mode (reads it, in classical computing terms), manipulates it (modifies it), and exchanges it again (writes it). This creates a unique configuration that most modern quantum computers do not follow, in which processing and storage are two distinct segments; most designs treat both memory and computation similarly.
However, the approach has advantages: Acoustic waves have wavelengths about a hundred thousand times shorter than electromagnetic ones, allowing an entire quantum chip to be extremely small, as the research team claims, even if the actual computer will be many orders of magnitude larger.
The chip passed stress tests, including a feasibility test, which also included testing using two of the most widely used methods for benchmarking a quantum computer: the quantum Fourier transform and a period search algorithm.
The goal here, as the research team noted, is quantum random access memory (QRAM), which would allow modern quantum computers to access much larger quantum memory storage than current specifications allow. Whether this will be successful depends on both the scalability of the approach and the computational power at play.
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