In a recent study published in Physical Review Letters, a research team led by academician Guo Guangcan, Prof. Li Chuanfeng, and Prof. Liu Biheng from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS), along with Prof. Giulio Chiribella from the University of Hong Kong, has made groundbreaking progress in the field of quantum information science. The team has successfully constructed a coherent superposition of quantum evolution with two opposite directions in a photonic system, showcasing the advantages of characterizing input-output indefiniteness.
The concept of time reversal has long been a topic of interest in quantum information science. While the idea that time flows inexorably from the past to the future is deeply ingrained in our minds, the laws of physics at the microscopic level do not inherently favor any specific direction of time. Both classical and quantum mechanics feature reversible equations of motion, allowing for valid evolution processes even when the direction of time is altered. This principle, known as time reversal symmetry, forms the basis of the team’s research.
One of the major challenges in quantum research has been the experimental realization of time reversal. To address this issue, the research team extended the concept of time reversal to the input-output inversion of a quantum device in a photonic setup. By exchanging the input and output ports of the device, the team was able to simulate time-reversal properties and demonstrate the coherence of quantum evolution and its inverse.
Using quantum witness techniques, the team was able to characterize the structures of the quantum evolution processes and quantify the advantages of quantizing the evolution time direction. The results showed that the coherent superposition of quantum evolution and its inverse provided significant benefits in quantum channel identification. In fact, the team achieved a 99.6% success rate in distinguishing between two sets of quantum channels using the time-reversal simulator, compared to a maximum success rate of only 89% with a definite time direction strategy.
The study sheds light on the potential of input-output indefiniteness as a valuable resource for advancements in quantum information and photonic quantum technologies. By leveraging the advantages of quantum evolution coherence, researchers may be able to revolutionize the field of quantum information science and pave the way for cutting-edge innovations in photonic systems.
The research team’s innovative approach to quantum evolution coherence represents a significant step forward in the field of quantum information science. By challenging conventional notions of time direction and harnessing the power of quantum superposition, the team has demonstrated the potential for quantum technologies to reach new heights of efficiency and accuracy.
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