Detecting quantum entanglement in multiparticle systems (notice the new date!!)

DIPC Seminars

Geza Toth (UPV/EHU Leioa, Ikerbasque)
Donostia International Physics Center (DIPC). Paseo Manuel de Lardizabal, 4, Donostia
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Detecting quantum entanglement in multiparticle systems (notice the new date!!) G. Toth (UPV/EHU Leioa, Ikerbasque): Detecting quantum entanglement in multiparticle systems The verification of the presence of quantum entanglement is perhaps one of the most interesting fields in quantum information science [1]. Its importance is due to the fact that entangled states can outperform non-entangled ones in several quantum information processing algorithms. Moreover, quantum entanglement is also a resource even in quantum metrology [2]. Thus, creating large-scale entanglement and verifying its presence by simple measurements became a goal of many recent experiments. Detecting entanglement is a hard task. In practice, various sufficient conditions for entanglement exist, such as entanglement witness operators. Some of these conditions can identify not only entanglement, but also various forms of multipartite entanglement that can be very useful even when studying the thermal ground states of spin chains. After reviewing the basics of the field, an example will be shown where a sufficient condition for entanglement has been used in a physical system [3]. Concretely, entanglement between many thousands of neutral atoms has been created in a cold gas experiment. A criterion developed by us has been used to estimate the amount of entanglement based on a measurement of the global spin. It outperforms previous criteria and applies to a wide class of entangled states. [1] O. Gühne and G. Tóth, Entanglement detection, Phys. Rep. 474, 1 (2009). [2] G. Tóth and I. Apellaniz, Quantum metrology from a quantum information science perspective, J. Phys. A: Math. Theor. 47, 424006 (2014), special issue "50 years of Bell's theorem". [3] B. Lücke et al., Phys. Rev. Lett. 112, 155304 (2014), Editors' Suggestion, Synopsis at