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arXiv:1707.08969 · Physical Review Letters

Harvesting Multiqubit Entanglement from Ultrastrong Interactions in Circuit Quantum Electrodynamics

Federico Armata, Giuseppe Calajò, Tuomas Jaako, M. S. Kim, Peter Rabl

Published Nov 1, 2017• 38 citations
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Abstract

We analyze a multiqubit circuit QED system in the regime where the qubit-photon coupling dominates over the system's bare energy scales. Under such conditions a manifold of low-energy states with a high degree of entanglement emerges. Here we describe a time-dependent protocol for extracting these quantum correlations and converting them into well-defined multipartite entangled states of noninteracting qubits. Based on a combination of various ultrastrong-coupling effects, the protocol can be operated in a fast and robust manner, while still being consistent with experimental constraints on switching times and typical energy scales encountered in superconducting circuits. Therefore, our scheme can serve as a probe for otherwise inaccessible correlations in strongly coupled circuit QED systems. It also shows how such correlations can potentially be exploited as a resource for entanglement-based applications.

DOI
10.1103/physrevlett.119.183602

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