Lee, Seung-Woo Kim, Jaewan Nha, Hyunchul 2024-01-19T15:04:04Z 2024-01-19T15:04:04Z 2021-09-05 2021-03-17 2521-327X https://pubs.kist.re.kr/handle/201004/117255 Quantum measurement is a basic tool to manifest intrinsic quantum effects from fundamental tests to quantum information applications. While a measurement is typically performed to gain information on a quantum state, its role in quantum technology is indeed manifold. For instance, quantum measurement is a crucial process element in measurement-based quantum computation. It is also used to detect and correct errors thereby protecting quantum information in error-correcting frameworks. It is therefore important to fully characterize the roles of quantum measurement encompassing information gain, state disturbance and reversibility, together with their fundamental relations. Numerous efforts have been made to obtain the trade-off between information gain and state disturbance, which becomes a practical basis for secure information processing. However, a complete information balance is necessary to include the reversibility of quantum measurement, which constitutes an integral part of practical quantum information processing. We here establish all pairs of trade-off relations involving information gain, disturbance, and reversibility, and crucially the one among all of them together. By doing so, we show that the reversibility plays a vital role in completing the information balance. Remarkably, our result can be interpreted as an information-conservation law of quantum measurement in a nontrivial form. We completely identify the conditions for optimal measurements that satisfy the conservation for each tradeoff relation with their potential applications. Our work can provide a useful guideline for designing a quantum measurement in accordance with the aims of quantum information processors. English VEREIN FORDERUNG OPEN ACCESS PUBLIZIERENS QUANTENWISSENSCHAF Complete Information Balance in Quantum Measurement Article 10.22331/q-2021-03-17-414 1 QUANTUM, v.5 QUANTUM 5 scie scopus 000636646100001 2-s2.0-85104243942 Quantum Science & Technology Physics, Multidisciplinary Physics Article PROBABILISTIC CLONING STATE GAIN REVERSIBILITY SUFFICIENCY DISTURBANCE ENTROPY Quantum Measurement Quantum Information Quantum Computing Quantum Communication