A1 Refereed original research article in a scientific journal
Transfer and routing of Gaussian states through quantum complex networks with and without community structure
Authors: Hahto, Markku; Nokkala, Johannes; García-Pérez, Guillermo; Maniscalco, Sabrina; Piilo, Jyrki
Publisher: VEREIN FORDERUNG OPEN ACCESS PUBLIZIERENS QUANTENWISSENSCHAF
Publishing place: WIEN
Publication year: 2025
Journal: Quantum
Journal name in source: QUANTUM
Journal acronym: QUANTUM-AUSTRIA
Article number: 05623
Volume: 9
Number of pages: 19
eISSN: 2521-327X
DOI: https://doi.org/10.22331/q-2025-05-20-1751
Web address : https://doi.org/10.22331/q-2025-05-20-1751
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/492246040
Preprint address: https://arxiv.org/abs/2403.05623v1
The goal in quantum state transfer is to avoid the need to physically transport carriers of quantum information. This is achieved by using a suitably engineered Hamiltonian that induces the transfer of the state of one subsystem to another. A less known generalization of state transfer considers multiple systems such that any pair can exchange quantum information and transfers can take place at any time, starting and stopping independently. This is sometimes called routing of quantum states. State transfer in particular has received a great deal of attention, however the vast majority of results in both state transfer and routing concern qubits transferred in a network of restricted structure. Here we consider routing of single-mode Gaussian states and entanglement through complex networks of quantum harmonic oscillators. We compare a protocol where the transfer is completed in a single step but the effective Hamiltonian only approximately transfers the state with one where the transfer can in principle be perfect but the transfer is done in two steps, and also illustrate the state-dependency of the transfer fidelity with paradigmatic Gaussian states as well as number states. We find that even in a random and homogeneous network, the transfer fidelity still depends on the degree of the nodes for any link density, and that in both random and complex networks it is the community structure that controls the appearance of higher frequency normal modes useful for transfer. Finally, we find that networks of sufficient complexity may have superior routing performance over superficially similar random networks. Our results pave the way for further exploration of the role of community structure in state transfer and related tasks.
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Funding information in the publication:
M.H. acknowledges financial support from Vilho, Yrjö and Kalle Väisälä Foundation. J.N. acknowledges financial support from the Turku Collegium for Science, Medicine and Technology as well as the Academy of Finland under project no. 348854.
