# Hardware-efficient quantum random access memory with hybrid quantum acoustic systems

## TL;DR

This paper proposes a hardware-efficient quantum random access memory (QRAM) scheme using hybrid quantum acoustic systems, leveraging high-Q phonon modes and engineered couplings for improved fidelity and superposition data access.

## Contribution

It introduces a novel QRAM implementation utilizing multimode quantum acoustic systems with off-resonant drives, enhancing gate fidelity over existing methods.

## Key findings

- Engineered phonon-phonon couplings enable superposition data access.
- The scheme offers substantial fidelity improvements for long-lived acoustic modes.
- QRAM can be implemented on a single chip using this approach.

## Abstract

Hybrid quantum systems in which acoustic resonators couple to superconducting qubits are promising quantum information platforms. High quality factors and small mode volumes make acoustic modes ideal quantum memories, while the qubit-phonon coupling enables the initialization and manipulation of quantum states. We present a scheme for quantum computing with multimode quantum acoustic systems, and based on this scheme, propose a hardware-efficient implementation of a quantum random access memory (QRAM). Quantum information is stored in high-Q phonon modes, and couplings between modes are engineered by applying off-resonant drives to a transmon qubit. In comparison to existing proposals that involve directly exciting the qubit, this scheme can offer a substantial improvement in gate fidelity for long-lived acoustic modes. We show how these engineered phonon-phonon couplings can be used to access data in superposition according to the state of designated address modes--implementing a QRAM on a single chip.