Quantum State Transfer in Engineered Spin Chain under Influence of Spatially Distributed Environment

Hui Zhou, Xi Chen, Xinfang Nie +4 more

Zhou Lan, Jing Lu, Shi Tao

It has been shown that a quantum state could be perfectly transferred via a spin chain with engineered “always-on interaction". In this paper, we study a more realistic problem for such a quantum state transfer (QST) protocol, how the efficacy of QST is reduced by the quantum decoherence induced by a spatially distributed environment. Here, the environment is universally modeled as a bath of fermions located in different positions. By making use of the irreducible tensor method in angular momentum theory, we investigate the effect of environment on the efficiency of QST for both cases at zero and finite temperatures. We not only show the generic exponential decay of QST efficiency as the number of sites increase, but also find some counterintuitive effect, the QST can be enhanced as temperature increases in some cases.

Edward B. Fel’dman, Alexander Ivanovich Zenchuk

Lan Zhou, Jing Lü, Tao Shi +1 more

A perfect quantum state transfer(QST) has been shown in an engineered spin chain with "always-on interaction". Here, we consider a more realistic problem for such a protocol, the quantum decoherence induced by a spatially distributed environment, which is universally modeled as a bath of harmonic oscillators. By making use of the irreducible tensor method in angular momentum theory, we investigate the effect of decoherence on the efficiency of QST for both cases at zero and finite temperatures. We not only show the generic exponential decay of QST efficiency as the number of sites increase, but also find some counterintuitive effect, the QST can be enhanced as temperature increase.

Martin Sandberg, Emanuel H. Knill, Eliot Kapit +2 more

Jan Jeske, Nicolas Vogt, Jared H. Cole

We investigate the influence of environmental noise on spin networks and spin chains. In addition to the common model of an independent bath for each spin in the system we also consider noise with a finite spatial correlation length. We present the emergence of decoherence-free subspaces and different dynamics with increasing correlation length for both dephasing and dissipating environments. This leads to relaxation blocking of one spin by uncoupled surrounding spins. We then consider perfect state transfer through a spin chain in the presence of decoherence and discuss the dependence of the transfer quality on spatial noise correlation length. We identify qualitatively different features for dephasing and dissipative environments in spin-transfer problems.