Spin quantum computing, spin quantum cognition

Over two decades ago, Bruce Kane proposed that spin-half phosphorus nuclei embedded in a spin-zero silicon substrate could serve as a viable platform for spin-based quantum computing. These nuclear spins exhibit remarkably long coherence times, making them ideal candidates for qubits. Despite this advantage, practical realisation of spin quantum computing remains a challenge. More recently, physicist Matthew Fisher proposed a hypothesis linking nuclear spin dynamics, specifically those of phosphorus nuclei within the spin-zero matrix of calcium phosphate molecules, to neural activation and, potentially, cognition. The theory has generated both interest and scepticism, with some fundamental questions remaining. We review this intersection of quantum computing and quantum biology by outlining the similarities between these models of quantum computing and quantum cognition. We then address some of the open questions and the lessons that might be learned in each context. In doing so, we highlight a promising bidirectional exchange: not only might quantum computing offer tools for understanding quantum biology, but biological models may also inspire novel strategies for quantum information processing.