Enriched, robust entangling phenomena arising from non-Abelian quantum holonomy

We propose a new method of creating and manipulating highly-entangled superpositions of well-controlled states of light by using an on-chip photonic system that has recently been shown to implement three-dimensional, non-Abelian quantum holonomy. Our calculations indicate that a subset of such entangled superpositions are maximally-entangled states, and that the underlying entanglement can be distilled and purified for applications, such as quantum metrology, quantum networking, and quantum computation. Notably, we show that we can create maximally entangled, bipartite states of qutrits—having log₂3 “e-bits” of entanglement entropy—by tuning the value of the accumulated non-Abelian phase to ≈ 0.48 rad, where the value of the phase is controllable and is determined by the geometric dimensions and inter-waveguide coupling coefficients within the device. Furthermore, the holonomy confers added protection to these entangled states against the environment, since non-Abelian geometrical phases are less susceptible to dephasing-induced decoherence than their dynamical counterparts. We envisage that this robust entangling mechanism could be utilized for realizing universal quantum gates at room temperature with integrated photonic architectures.