Entropy, information and quantum measurements

Masashi Ban

Masashi Ban

Information obtained by a quantum measurement process performed on a physical system and the entropy change of the measured physical system are considered in detail. It is shown that the condition for the amount of information obtained by the quantum measurement process to be represented by the Shannon mutual entropy is that the intrinsic observable of the measured physical system commutes with the operational observable defined by the quantum measurement process. When some measurement outcome is obtained, the decrease of the Shannon entropy of the measured system is compared with that of the von Neumann entropy. Furthermore, a condition is established under which the amount of information that can be established by the quantum measurement process becomes equal to the decrease of the Shannon entropy of the measured physical system.

Jincheng Zhang

This paper investigates the optimization of quantum state measurement using the principles of information entropy. The core idea is to treat quantum state measurement as an information entropy problem, aiming to maximize the information gained from the measurement process. Traditional quantum measurement techniques often rely on probabilistic outcomes, lacking control and inherent optimization. This work proposes a novel approach that leverages information entropy to design and optimize measurement schemes. The theoretical framework centers around quantifying uncertainty associated with quantum states and formulating measurement strategies to minimize this uncertainty, thereby maximizing the information obtained. Specifically, we explore the relationship between measurement outcomes, entropy, and the achievable precision. The proposed methodology offers a pathway to more efficient and accurate quantum state determination, with potential applications in quantum sensing, quantum communication, and fundamental quantum information theory. The key contributions of this research lie in the systematic application of information entropy to guide measurement selection and the development of a quantifiable metric for evaluating the effectiveness of measurement strategies. The final result is a framework that allows for controlled optimization of quantum measurements, moving beyond purely probabilistic approaches.

Subhash C. Kak

Zijing Li, Jiangnan Deng, Bing Hai Zhou +2 more

Under uncertain environment, it is very difficult to measure the entropy of quantum information system, because there is no effective method to model the randomness. First, different from the traditional classic uncertainty, a quantum uncertain model is proposed to simulate a quantum information system under uncertain environment, and to simplify the entropy measurement of quantum information system. Second, different from the classic random seed under uncertain environment which is often called as pseudo-random number, here the quantum random is employed to provide us a true random model for the entropy of quantum information system. Third, the complex interaction and entangling activity of uncertain factors of quantum information is modeled as quantum binary instead of classic binary, which can help us to evaluate the entropy of uncertain environment, to analyze the entropy divergence in quantum information system. This work presents a non-classic risk factor measurement for quantum information system and a helpful entropy measurement.

Nilanjana Datta