
Time-reversal of an unknown quantum state - samizdis
https://phys.org/news/2020-08-time-reversal-unknown-quantum-state.html
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westurner
T-symmetry
[https://en.wikipedia.org/wiki/T-symmetry](https://en.wikipedia.org/wiki/T-symmetry)
> See also links to "reversible computing" but not the "time reversal"
disambiguation page?

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hammock
The "teeter-totter" thought experiment on that page is interesting to me in
that it seems to illustrate how the future has more possibilities than the
past. But it also occurs to me that the future possibilities are fractal with
the past - ie. the toy could fall onto one of many other lower pedestals,
teetering as it was before. In this way the "many arbitrary" possibilities
could be perceived as anything but.

~~~
westurner
Could there be multiple "collapsed" paths which consistently converge at the
current or future measured state?

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lisper
[http://blog.rongarret.info/2014/10/parallel-universes-and-
ar...](http://blog.rongarret.info/2014/10/parallel-universes-and-arrow-of-
time.html)

~~~
codethief
> The punch line is this: the statement that we can't time-travel into the
> past is exactly the same as the statement that we can only remember the
> past.

Note that the author's definition of "time travel" is a very specific one
which, e.g., has nothing to do with the way time travel is defined in General
Relativity.

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kvathupo
The last line: "This procedure is to be implemented on the emergent quantum
computers with the on-demand thermalizable qubits."

As someone with more familiarity with quantum computer science than its
implementation via "computers," I ask: is it feasible to instantaneously swap
states as described on any near-term quantum computers? Of course, ignoring
the issue of needing sufficiently many ancilla to render the reversal
accurate.

It certainly appears to be a novel theoretical result, but I question its
practicality. The title was kind of click-bait lol

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castratikron
Quantum debugger?

