Quantum steering based weak entanglement detection

Quantum entanglement is a unique phenomenon of quantum mechanics and the core of many quantum technologies. Although entanglement is often observed in small-scale systems, detecting weak entanglement in large or noisy systems remains a major challenge, as experimental flaws can easily destroy fragile quantum correlations. A new weak entanglement detection criterion based on quantum steering has recently been proposed as a potential alternative to traditional entanglement witnesses. In this work, we provide a theoretical analysis by comparing the detection capabilities of the steering-based criterion with those of traditional entanglement witnesses under realistic measurement errors. The results show that the steering-based approach offers improved sensitivity for detecting weak entanglement. We further experimentally verify the feasibility of this steering-based criterion by using a linear optical setup. The experimental results align well with theoretical predictions, confirming the practicality and reliability of the method. These findings provide the steering-based criterion as a promising and accessible tool for detecting weak entanglement, and are expected to have potential applications in quantum communication, quantum computing, and other areas of quantum information science.