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arXiv · 1707.09396

Sequentially generated entanglement, macroscopicity and squeezing in a spin chain

Tahereh Abad·Klaus Mølmer·Vahid Karimipour
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Abstract

We study quantum states generated by a sequence of nearest neighbor bipartite entangling operations along a one-dimensional chain of spin qubits. After a single sweep of such a set of operations, the system is effectively described by a matrix product state (MPS) with the same virtual dimension as the spin qubits. We employ the explicit form of the MPS to calculate expectation values and two-site correlation functions of local observables, and we use the results to study fluctuations of collective observables. Through the so-called macroscopicity and the squeezing properties of the collective spin variables they witness the quantum correlations and multi-particle entanglement within the chain. Macroscopicity only occurs over the entire chain if the nearest neighbor interaction is maximally entangling, while a finite, sequential interaction between nearest neighbor particles leads to squeezing of the collective spin.

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Tahereh Abad, Klaus Mølmer, Vahid Karimipour. 2017-10-12. Sequentially generated entanglement, macroscopicity and squeezing in a spin chain. https://doi.org/10.1103/physreva.96.042337

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