Abstract: Quantum devices could perform some informational tasks with much better performances than classical systems, with profound implications for cryptography, chemistry, material science, and many areas of physics. However, to reach this goal we need to control large quantum systems, where the many-body dynamics becomes fragile and the system quickly heats up to its thermal state.
There are then two key questions: How does a closed quantum system thermalize (thus losing its “quantum power”)? How can we preserve quantum information in the presence of strong interactions?
Using a nuclear spin chain as an exemplary experimental system, and the tools of Hamiltonian engineering, I will show how to choreograph the dynamics in order to prevent the system from heating up, even in the presence of strong interactions among spins.
In particular, I will show how disorder can quench the scrambling of quantum information, a phenomenon known as localization, and thus prevent thermalization. Similarly, engineering quasi-conserved quantities in the system dynamics can induce prethermalization, a long-lived state that thermalizes only exponentially slowly. I will further discuss how metrics of information scrambling, such as out-of-time ordered correlations and echoes, can be used to investigate such phenomena and probe the limits to our quantum control.