Gapped quantum criticality gains long-time quantum correlations

¹ Asia Pacific Center for Theoretical Physics (APCTP) - Pohang, Gyeongbuk, 790-784, Korea
² Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS) - Zanjan 45137-66731, Iran
³ Department of Physics, POSTECH - Pohang, Gyeongbuk 790-784, Korea
⁴ Max Planck POSTECH Center for Complex Phase Materials, POSTECH - Pohang 790-784, Korea

Received: 21 May 2015
Accepted: 8 July 2015

Abstract

We show that gapped critical environment could remarkably prevent an enhanced decay of decoherence factor and quantum correlations at the critical point, which is non-trivially different from the ones in a gapless critical environment (Quan H. T. et al., Phys. Rev. Lett., 96 (2006) 140604). The quantum correlations display very fast decaying to their local minimum at the critical point while maximum decaying occurs away from this point. In particular, our results imply that the collapse of the decoherence factor is not an indicator of a quantum phase transition of the environment as opposed to what happens in a gapless criticality. In the weak-coupling regime, the relaxation time, at which the quantum correlations touch rapidly local minima, shows a power-law singularity as a function of the gap. Furthermore, quantum correlations decay exponentially with the second power of the relaxation time. Our results are important for a better understanding and characterisation of the gap critical environment and its ability as entangler in open quantum systems.