Physicists who work on quantum technologies are always looking for ways to manage decoherence, which occurs when a quantum system unavoidably interacts with the surrounding environment. In the past few years, scientists have discovered that some quantum correlations can be "frozen" in a constant state and remain that way in the presence of noise, potentially offering a protective mechanism against decoherence. So far, however, quantum freezing has been shown to exist only on a case-by-case basis and under certain conditions, and its potential protective effect has not been fully exploited.
Now in a new paper to be published in Nature Scientific Reports, physicists Marco Cianciaruso, Thomas Bromley, Wojciech Roga, Rosario Lo Franco, and Gerardo Adesso have shown that the freezing of quantum correlations is universal—that is, it is independent of the method used for measuring the correlations. While working on this proof, the scientists also found that it may be possible to not just prevent but also reverse the effects of decoherence under certain circumstances, which they show by demonstrating the existence of an intriguing new phenomenon modelled by a global rephasing channel.
"The greatest significance of the work is to show that a general form of quantum correlations must remain frozen and protected in the presence of some, usually detrimental, decoherence effects," Lo Franco, who is with the University of Nottingham, the University of Palermo, and the University of São Paulo, told Phys.org. "This fact implies that any further well-defined measure of quantum correlations must freeze during the evolution under the same conditions. Our work thus appears to settle the debate about the universality of the freezing phenomenon of discord-based quantum correlations."
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