Dilute measurement-induced cooling into many-body ground states

Abstract

Cooling a quantum system to its ground state is important for the characterization of 
non-trivial interacting systems, and in the context of a variety of quantum information 
platforms. In principle, this can be achieved by employing measurement-based passive 
steering protocols, where the steering steps are predetermined and are not based on 
measurement readouts. However, measurements, i.e., coupling the system to auxiliary 
quantum degrees of freedom, is rather costly, and protocols in which the number of 
measurements scales with system size will have limited practical applicability. Here, we 
identify conditions under which measurement-based cooling protocols can be taken to the 
dilute limit. For two examples of frustration-free one-dimensional spin chains, we show that 
steering on a single link is sufficient to cool these systems into their unique ground states. 
We corroborate our analytical arguments with finite-size numerical simulations and discuss 
further applications.