A flutter in time: Quantum mechanics is immune to the butterfly effect
1. Researchers set the value of qubit X to zero<p>2. They pressed rewind on all qubits<p>3. They scrambled the value of qubit X<p>4. They pressed “play”<p>5. They checked the value of qubit X to see how close it was to zero. Turns out it was very very close to zero.<p>This calls for an explanation of the recovery of the final value of qubit X despite the destruction of its initial state during step 3. The article proposes that the information necessary to recover the final value is encoded in the qubits with which X is entangled.<p>I don’t know enough about QM to understand how the system is able to use this information to “set” the qubit to the value that it “should” be. Do the researchers’ actions influence the values of the qubits with which X is entangled in such a way that the forward evolution results in a system where X recovers its initial (final) value?<p>My background is in deep learning. If I look at the activations in the final layer of a network, and want to achieve an output for a particular element, I can set that element to the desired value and run the network backward to reconstruct an input that would give that value. If I perturb that input slightly, the network will produce a slightly different activation pattern. If I take an adversarial approach, I can have what would appear to be an outsized influence on the final layer activations. I wonder if such an adversarial perturbation has a quantum analogue.