Quantum Theory & Quantum computing have ZERO inpact or effect on the theories of Special and General Relativity. Layman's Terms: Time doesn't change because of quantum theory. It flows as it does on the macro scale. As a matter of fact, Quantum Mechanics have zero affect on spacetime which was firmly established by Einstein.
Quantum mechanics, as it’s been conventionally understood for the past 93 years, in no way whatsoever involves time travel into the past. Indeed, it’s sometimes been remarked that, for all of quantum mechanics’ revolutionary implications, time is ironically one of the few concepts that it didn’t change at all! In standard quantum mechanics (that is, without relativity), time is just a continuous parameter that flows at the same rate everywhere in the universe. Special relativity & General relativity, not quantum mechanics, established that time might be mutable; time dilation stems from, for instance, traveling close to the speed of light or flying by a black hole