Cavity-Enhanced Collective Quantum Processing with Polarization-Encoded Qubits

Researchers have introduced a novel cavity-enhanced optical architecture designed for collective quantum processing, where logical qubits are encoded within the polarization subspace of recirculating intracavity modes. This approach explicitly separates the physical carrier from the computational degree of freedom. Harmonic cavity bundles serve as a stable resonant substrate, while programmable polarization transformations facilitate single-qubit operations. Furthermore, a polarization-selective nonlinear interaction in the entanglement region generates tunable controlled-phase gates, thereby enabling a universal gate set. Parameter-scaling analysis demonstrates that order-unity conditional phases can be achieved in centimeter-scale cavities using experimentally accessible solid-state nonlinear media. Notably, this method does not require extreme nonlinear coefficients, millisecond photon lifetimes, or sub-hertz laser stabilization. The findings suggest that resonant recirculation offers a physically plausible and practical platform for developing cavity-based collective quantum architectures, potentially advancing the field of quantum computing by reducing stringent hardware requirements.