Work Package 2: Quantum speed limits in many-body systems
More, as was famously noted, is different. When dealing with quantum many-body systems this statement becomes particularly insightful as we can see the emergence of criticality, where despite a well defined microscopic description, non-trivial and singular behaviours can be exhibited. The use of one-dimensional spin systems as archetypal registers for quantum processing devices means developing a clear understanding of criticality is of utmost importance and equally developing effective techniques to control these systems is paramount. The discovery by Lieb and Robinson showing that communication along nearest neighbour interacting spin systems is bounded by an effective “space-time cone”, somewhat in analogy to the causal light cone, has led to profound developments in the understanding and simulation of complex many-body quantum systems. Interestingly, the quantum speed limit also has been shown to be fundamental in revealing the dynamical features, such as the critical slowing down, when transitioning a critical point in the same systems and recent advances have indicated the dominant role the quantum speed limit plays when attempting to realise precisely these dynamics.
Objective and impact: The main goal of WP2 is to use these two fundamental bounds to develop effective control methods requiring the minimal resources. We will analyse the tools necessary to control critical systems, offering a clear framework for their experimental feasibility. WP2 is thus endowed with broad fundamental and practical relevance. Regarding the former, it will deepen the understanding of criticality and unite two fundamental principles in quantum physics. While for the latter, it will establish the minimal experimental resources necessary to simulate these most remarkable systems.