Communication with quantum catalysts

Abstract Communication is essential for advancing science and technology. Quantum communication, in particular, benefits from the use of catalysts. During the communication process, these catalysts enhance performance while remaining unchanged. Although chemical catalysts that undergo deactivation typically perform worse than those that remain unaffected, quantum catalysts, referred to as embezzling catalysts, can surprisingly outperform their non-deactivating counterparts despite experiencing slight alterations. In this work, we employ embezzling quantum catalysts to enhance the transmission of both quantum and classical information. By utilizing finite-dimensional embezzling catalysts, we guarantee a non-zero catalytic channel capacity for any quantum channel while keeping variations in the catalytic system arbitrarily small. Our protocol also improves long-distance entanglement distribution. Furthermore, we introduce catalytic superdense coding, demonstrating how embezzling catalysts can boost the transmission of classical information. Finally, we explore methods to reduce the dimensionality of catalysts, a step toward making quantum catalysis a practical reality.