From abstract: Here we show that, while in nature the complex conjugation needed for time reversal is exponentially improbable, one can design a quantum algorithm that includes complex conjugation and thus reverses a given quantum state.
"Normally in a quantum computer, if we apply measurement function F to input x so y=F(x), it's impossible to reverse F and turn y into x. However, if we constrain y, we can make a special function G_Y such that x=G_Y(y)"
Whilst I don't have time to really dive through all the sections, this seems weirdly click-baity and IBM-promoting for an academic article.
In the case of a quantum computer simulating something (we can not really do this yet, but we are hard at work building the hardware) that type of reversal might require us to calculate complex conjugates of quantum states. For various reasons this is nontrivial and this paper describes ways to do that.
https://sydney.edu.au/news-opinion/news/2018/07/25/first-eve...
1. This particular work is explicitly relying on the fact that many quantum operations (including the type of time evolution they are considering) are a one-to-one map (not the one-to-many "irreversible" hash functions). Hence this work is explicitly not applicable.
2. Quantum computers do break some form of public key encryption, but this is a solved problem, as there are many other public key encryption protocols that are can not be broken by a quantum computer. Quantum computers do provide modest speedup in all types of brute force searches, like breaking symmetric encryption, but this is trivial to defend against by using a slightly bigger encryption key.