Spontaneous evolution to classicalization in interacting quantum systems

Bei Zeng, Xie Chen, D. L. Zhou +1 more

Marek Gwóźdź, Lech Jakóbczyk

We consider local time evolution given by spontaneous emission in the system of independent two-level atoms. It is shown that all classically correlated initial states are driven into the states with transient non-zero quantum discord. Thus local creation of genuine quantum correlations can be observed in a simple physical system of non-interacting atoms which are not completely isolated from the environment.

Blanchard Ph, Michele Pasquini, Maurizio Serva

We introduce a model for a two configurations system, and we study the transition from quantum to classical behaviour. We first consider the effect of the interaction with the environment as an external noise and we show that it produces decoherence and suppression of tunnelling. These features are necessary ingredients for classicality, but we believe that classicality also implies that quantum delocalized states spontaneously evolve into localized ones. We then show that this evolution takes place only when both noise and non linearity in the equations are present.

O. Furtmaier

Chang-Kang Hu, Guixu Xie, Kasper Poulsen +11 more

Quantum simulators are ideal platforms to investigate quantum phenomena that are inaccessible through conventional means, such as the limited resources of classical computers to address large quantum systems or due to constraints imposed by fundamental laws of nature. Here, through a digitized adiabatic evolution, we report an experimental simulation of antiferromagnetic (AFM) and ferromagnetic (FM) phase formation induced by spontaneous symmetry breaking (SSB) in a three-generation Cayley tree-like superconducting lattice. We develop a digital quantum annealing algorithm to mimic the system dynamics, and observe the emergence of signatures of SSB-induced phase transition through a connected correlation function. We demonstrate that the signature of a transition from classical AFM to quantum FM-like phase state happens in systems undergoing zero-temperature adiabatic evolution with only nearest-neighbor interacting systems, the shortest range of interaction possible. By harnessing properties of the bipartite Rényi entropy as an entanglement witness, we observe the formation of entangled quantum FM and AFM phases. Our results open perspectives for new advances in condensed matter physics and digitized quantum annealing. Recently, spontaneous symmetry breaking was reported in 1D and 2D lattices with long-range interactions on analogue quantum simulators. Here, using a digital quantum annealing algorithm, Hu et al. observe this effect in a tree-like superconducting qubit lattice with short-range interactions at zero temperature.

Subhashish Banerjee