On Friday, May 4, 2018 at 8:21:52 AM UTC-5, Bruce wrote: > > > Unfortunately, it is not the case that you can implement absolutely any > unitary transformation in this way. For instance, you cannot implement the > unitary transformation that would reverse a totally decohered event. Your > quantum computer ceases to function if there is any decoherence! For > example, you cannot implement a unitary transformation that would resurrect > my dead grandfather, even though his life and death were entirely unitary. > So you cannot reverse a recorded measurement. > > Bruce >
Weak measurements are or come close to being reversible. There is an effort to know what the limits are on this, So far the boundary between a hard and weak measurement appears flexible. This means that if one had some vast master equation for all the reservior of interacting states that a hard measurement might be reversible. Of course from a practical perspective this becomes implausible. LC -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
