Student Cracks the High-Dimensional Quantum Code & Reveals Hidden Structures of Quantum Entangled States

(SciTechDaily) Isaac Nape, an emerging South African talent in the study of quantum optics, is part of a crack team of Wits physicists who led an international study that revealed the hidden structures of quantum entangled states.
Now Nape and his colleagues at Wits, together with collaborators from Scotland and Taiwan offer a new and fast tool for quantum computing and communication. “Quantum states that are entangled in many dimensions are key to our emerging quantum technologies, where more dimensions mean a higher quantum bandwidth (faster) and better resilience to noise (security), crucial for both fast and secure communication and speed up in error-free quantum computing.
“What we have done here is to invent a new approach to probing these ‘high-dimensional’ quantum states, reducing the measurement time from decades to minutes,” Nape explains.
Nape worked with Distinguished Professor Andrew Forbes, lead investigator on this study and Director of the Structured Light Laboratory in the School of Physics at Wits, as well as postdoctoral fellow Dr. Valeria Rodriguez-Fajardo, visiting Taiwanese researcher Dr. Hasiao-Chih Huang, and Dr. Jonathan Leach, and Dr. Feng Zhu from Heriot-Watt University in Scotland.
In their paper titled: Measuring dimensionality and purity of high-dimensional entangled states, the team outlined a new approach to quantum measurement, testing it on a 100 dimensional quantum entangled state.
“Our work circumvented the problem by a chance discovery, that there is a set of measurements that is not a tomography and not a Bell measurement, but that holds important information of both,” says Nape. “In technical parlance, we blended these two measurement approaches to do multiple projections that look like a tomography but measuring the visibilities of the outcome, as if they were Bell measurements. This revealed the hidden information that could be extracted from the strength of the quantum correlations across many dimensions.”