In a quantum measurement, an operator projects the system into one of its eigenstates with a specific eigenvalue as the readout. Once the measurement is done, the unknown initial state of the system is destroyed, and in general there is no way to recover it from the result. However, such quantum measurement, the so-called strong or von Neumann measurement, is only part of the story. There is another type of quantum measurement called weak measurement, in which the outcome is not precise or sharp but nevertheless reveals some information about the system. Since this weak measurement does not totally collapse the system, the information of the initial state is passed over to the final state. If such retained information is complete, it would be possible to recover the initial state with some operations. In this talk, I shall discuss the processes and the issues related to protecting quantum coherence and entanglement.
M. Suhail Zubairy is a University Distinguished Professor of Physics and the holder of the Munnerlyn-Heep Chair in Quantum Optics at the Texas A&M University. He received his Ph.D. from the University of Rochester in 1978. He served as Professor of Electronics and the founding Chairman of the Department of Electronics at the Quaid-i-Azam University before joining Texas A&M University in 2000. Prof. Zubairy’s research interests include quantum optics and laser physics. He has published over 300 research papers on topics such as precision microscopy and lithography, quantum computing, noise-free amplification, and atomic coherence effects. He is the co-author of two books, one on Quantum Optics and the other on Quantum Computing Devices. He has received many honors including the Willis E. Lamb Award for Laser Science and Quantum Optics, Alexander von Humboldt Research Prize, the Outstanding Physicist Award from the Organization of Islamic Countries, the Abdus Salam Prize in Physics, the International Khwarizmi Award from the President of Iran, the Orders of Hilal-e-Imtiaz and Sitara-e-Imtiaz from the President of Pakistan, and the George H. W. Bush Award for Excellence in International Research. He is an elected member of the Pakistan Academy of Sciences and a Fellow of the American Physical Society and the Optical Society.