A key to making a practical quantum computer is protecting entanglement from decoherence caused by unavoidable coupling with the environment, which leads to degrad-ation of quantum co-herence.

Professor Yoon-Ho Kim of the Department of Physics successfully curbed decoherence by making use of quantum measurement itself. The paper, titled “Protecting entanglement from decoherence using weak measurement and quantum measurement reversal,” appeared in Nature Physics published online on Dec. 18, 2011.

In quantum physics, one of the greatest challenges is controlling quantum decoherence, which isolates the system from its environment. Prof. Kim resolved this by utilizing the concept of weak quantum measurement, originally discussed for quantum error correction.

Prof. Kim noted “Although quantum computing is in the early step, it harnesses the possibility of changing the paradigm of the information-based society. The research results set the theoretical fundaments of the development of quantum information tech-nology.”