Quantum coherence, which is the core in quantum mechanics, has been used in many fields of quantum physics. The manipulation and conversion of quantum coherence in bipartite or multipartite systems has become a hot topic and the manipulation of coherence in a bipartite system has been discussed when performing assisted distillation of quantum coherence.

The task is considered with protocols where Alice can perform arbitrary operations and Bob is restricted to only incoherent operations while classical communication between Alice and Bob is allowed, which is referred as local quantum-incoherent operations and classical communication (LQICC).

Prof. LI Chuanfeng and Prof. XIANG Guoyong's group from University of Science and Technology of China (USTC) of Chinese Academy of Sciences made progress in experimental investigation of quantum coherence and reported the first experimental test of assisted distillation of quantum coherence, which might be helpful in remote quantum information processing and quantum control. The study was published in Optica. 

A recent theoretical frame work study the task of assisted distillation of quantum coherence and provided a theoretical solution to this problem. To fill the gap of experimental test of the task in assisted distillation of quantum coherence, researchers experimentally implemented a class of such LQICC protocols based on a linear optic system, for extracting the maximal distillable coherence on one subsystem in our single-shot photonic scheme.

The results showed that even in the presence of experimental imperfections and limitations, a maximal increase in distillable coherence can be observed even in the single-copy scenario for pure states. Furthermore, the experimental study with a specific class of mixed states is also reported, which showed that distillable coherence can be increased with less demand than entanglement distillation and also shed light on the strong relationship between quantum coherence and quantum correlation.

Figure: Experimental Set up (Image by LI Chuanfeng & XIANG Guoyong)