Quantum Time Reversal
Quantum time reversal is the notion of inverting the flow of time in a quantum system by a mathematical operation. As a result, if a quantum system is developing in one way, then turning back the hands of time should lead it to evolve in the other direction, at least in principle.
Some attempts at experimental time reversal in quantum systems have been made. In 2019, for instance, scientists from the Moscow Institute of Physics and Technology claimed to have seen time reversal in a quantum system made up of a superconducting qubit. However, there is some disagreement among scientists about whether or not this experiment proved the existence of time reversal or whether or not it involved some other physical phenomenon with similar effects.
The notion of time reversal in quantum systems is intricate and yet mostly theoretical, and it is the topic of much continuing study and discussion. The future of research in this field has much promise.