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 [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
