Remote Entanglement of Superconducting Qubits via Solid-State Spin Quantum Memories

TL;DR

This paper proposes a novel entanglement distribution scheme for superconducting qubits using solid-state spin quantum memories, avoiding issues of noise and heating associated with direct microwave-to-optical photon conversion.

Contribution

It introduces a quantum memory-based interface for microwave and optical photons, enabling efficient, heralded entanglement distribution without significant heating inside the refrigerator.

Findings

Quantum memory interface enables microwave-optical photon conversion.

Scheme reduces heating compared to direct conversion methods.

Allows heralded entanglement and parallelization with multiple memories.

Abstract

Quantum communication between remote superconducting systems is being studied intensively to increase the number of integrated superconducting qubits and to realize a distributed quantum computer. Since optical photons must be used for communication outside a dilution refrigerator, the direct conversion of microwave photons to optical photons has been widely investigated. However, the direct conversion approach suffers from added photon noise, heating due to a strong optical pump, and the requirement for large cooperativity. Instead, for quantum communication between superconducting qubits, we propose an entanglement distribution scheme using a solid-state spin quantum memory that works as an interface for both microwave and optical photons. The quantum memory enables quantum communication without significant heating inside the refrigerator, in contrast to schemes using high-power optical pumps. Moreover, introducing the quantum memory naturally makes it possible to herald entanglement and parallelization using multiple memories.