Trapped-ion quantum simulation of excitation transport: Disordered, noisy, and long-range connected quantum networks

Abstract

The transport of excitations governs fundamental properties of matter. Particularly rich physics emerges in the interplay between disorder and environmental noise, even in small systems such as photosynthetic biomolecules. Counterintuitively, noise can enhance coherent quantum transport, which has been proposed as a mechanism behind the high transport efficiencies observed in photosynthetic complexes. This effect has been called "environment-assisted quantum transport" (ENAQT). Here, we propose a quantum simulation of the excitation transport in an open quantum network, taking advantage of the high controllability of current trapped-ion experiments. Our scheme allows for the controlled study of various different aspects of the excitation transfer, ranging from the influence of static disorder and interaction range, over the effect of Markovian and non-Markovian dephasing, to the impact of a continuous insertion of excitations. Our proposal discusses experimental error sources and realistic parameters, showing that it can be implemented in state-of-the-art ion-chain experiments.

Lieb–Robinson bounds for open quantum systems with long-ranged interactions

“…In this work, we have presented a number of Lieb-Robinson bounds that capture the locality of dynamics in long-ranged open quantum systems. Such systems are currently a focus of interest, due to the fact that several platforms for quantum simulators can be described well by open systems of this type [22][23][24][25][26][27][28][29][30][31][32][33]. It is the hope that this works stimulates further research into the static and dynamical properties of such quantum systems, e.g., by showing stability statements [41,42] that follow from Lieb-Robinson bounds of the type we have presented here, or to relate the findings established here to experimental observations of open long-ranged interacting systems out of equilibrium.…”

“…Often these platforms are employed for quantum simulation of unitary dynamics, but it turns out that significant non-unitary effects, like dissipation and decoherence, frequently have to be accounted for as well, or may even act as desirable resources. Examples of experimental realizations of open quantum lattice models with long-ranged interactions include Coulomb crystals of trapped ions [22][23][24][25], lattices of Rydberg atoms [26][27][28][29][30], and laser-driven atomic clouds [31][32][33].…”

Multifractality in random networks with power-law decaying bond strengths

“…We would like to add that the dPBRM model, when interpreted as a model for one-dimensional quantum chains with long-range interactions, has characteristics proper of models currently used in the study of excitation transport [56]: disorder and power-law decaying bond strengths. Furthermore, these characteristics can presumably be implemented and tuned in state-of-theart ion-chain experiments; thus the dPBRM model may find applications related to quantum transport with high efficiencies [56].…”

Two-particle quantum correlations in stochastically-coupled networks

“…The study of quantum random walks in noisy environments have played a fundamental role in understanding non-trivial quantum phenomena observed in an interdisciplinary framework of studies ranging from biology [1,2], chemistry [3], materials science [4] and electronics [5], to photonics [6][7][8][9] and ultracold matter [10,11]. For many years, most of the research efforts had been focused on the propagation of single particles [12]; however, a great interest in describing the dynamics of correlated particles in noisy systems has recently arisen [13][14][15][16], mainly because it has been recognized that many-particle quantum correlations can be preserved in noisy networks by properly controlling the initial state of the particles, their statistics, indistinguishability or their type of interaction [17,18].…”