Hardware-efficient quantum random access memory using hybrid quantum acoustic systems*

Hybrid quantum systems where 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 coupling enables the initialization and manipulation of quantum states. In this talk we consider the practical applications of multi-mode quantum acoustic systems as hardware-efficient quantum processors. Quantum gates between different acoustic modes can be implemented using resonant interactions between the phonons and qubit, but such gates are vulnerable to qubit decoherence. As an alternative, we propose the use of off-resonant interactions that only virtually excite the qubit. This virtual approach overcomes limitations placed by qubit decoherence and attains considerably higher fidelities for long-lived acoustic modes. Given advances in performance, we propose a quantum acoustic implementation of a quantum random access memory (qRAM). We show how information can be routed through the system such that data stored in memory modes can be accessed in superposition according to the state of designated address modes—implementing a qRAM on a single chip.