# Direct Generation and Non-Hermitian Regulation of Energy-Time-Polarization-Hyper-Entangled Quadphotons

## TL;DR

This paper presents a method to generate highly entangled photons using non-Hermitian regulation in a rubidium system, enabling tunable quantum networks with high information capacity.

## Contribution

A novel approach to generate hyper-entangled quadphotons using non-Hermitian regulation and spontaneous eight-wave mixing in hot 85Rb.

## Key findings

- High-dimensional entanglement is achieved through passive non-Hermitian characteristics and EWM-based quadphoton generation.
- Multiple coherent channels and oscillations in quantum correlations are observed, enabling a high-capacity four-body entangled network.
- The system can switch between three working states by regulating non-Hermitian characteristics via polarized dressings.

## Abstract

Entangled multiphoton is an ideal resource for quantum information technology. Here, narrow-bandwidth hyper-entangled quadphoton is theoretically demonstrated by quantizing degenerate Zeeman sub states through spontaneous eight-wave mixing (EWM) in a hot 85Rb. Polarization-based energy-time entanglement (output) under multiple polarized dressings is presented in detail with uncorrelated photons and Raman scattering suppressed. High-dimensional entanglement is contrived by passive non-Hermitian characteristic, and EWM-based quadphoton is genuine quadphoton with quadripartite entanglement. High quadphoton production rate is achieved from co-action of four strong input fields, and electromagnetically induced transparency (EIT) slow light effect. Atomic passive non-Hermitian characteristic provides the system with acute coherent tunability around exceptional points (EPs). The results unveil multiple coherent channels (~8) inducing oscillations with multiple periods (~19) in quantum correlations, and high-dimensional (~8) four-body entangled quantum network (capacity ~65536). Coexistent hyper and high-dimensional entanglements facilitate high quantum information capacity. The system can be converted among three working states under regulating passive non-Hermitian characteristic via triple polarized dressing. The research provides a promising approach for applying hyper-entangled multiphoton to tunable quantum networks with high information capacity, whose multi-partite entanglement and multiple-degree-of-freedom properties help optimize the accuracy of quantum sensors.