Entanglement in identical particle systems

F. Benatti, Roberto Floreanini B, Fabio Franchini +1 more

Y. S. Li, Bei Zeng, X. S. Liu +1 more

The definition of entanglement in identical-particle system is introduced. The separability criterion in two-identical-particle system is given. The physical meaning of the definition is analyzed. Applications to two-boson and two-fermion systems are made. It is found that some different entanglement and correlation phenomena in identical-boson systems exist, and they may have applications in the field of quantum information.

Dirk Bouwmeester, Jian-Wei Pan, Matthew Daniell +2 more

Nathan Killoran, M. Cramer, Martin Bodo Plenio

Identical particles and entanglement are both fundamental components of quantum mechanics. However, when identical particles are condensed in a single spatial mode, the standard notions of entanglement, based on clearly identifiable subsystems, break down. This has led many to conclude that such systems have limited value for quantum information tasks, compared to distinguishable particle systems. To the contrary, we show that any entanglement formally appearing amongst the identical particles, including entanglement due purely to symmetrization, can be extracted into an entangled state of independent modes, which can then be applied to any task. In fact, the entanglement of the mode system is in one-to-one correspondence with the entanglement between the inaccessible identical particles. This settles the long-standing debate about the resource capabilities of such states, in particular spin-squeezed states of Bose-Einstein condensates, while also revealing a new perspective on how and when entanglement is generated in passive optical networks. Our results thus reveal new fundamental connections between entanglement, squeezing, and indistinguishability.

Margaret Margaret, Reid, Qiong-Yi +3 more

Donghwa Lee, Tanumoy Pramanik, Seongjin Hong +4 more

Quantum correlations between identical particles are at the heart of quantum technologies. Several studies with two identical particles have shown that the spatial overlap and indistinguishability between the particles are necessary for generating bipartite entanglement. On the other hand, researches on the extension to more than two-particle systems are limited by the practical difficulty to control multiple identical particles in laboratories. In this work, we propose schemes to generate two fundamental classes of genuine tripartite entanglement, i.e., GHZ and W classes, which are experimentally demonstrated using linear optics with three identical photons. We also show that the tripartite entanglement class decays from the genuine entanglement to the full separability as the particles become more distinguishable from each other. Our results support the prediction that particle indistinguishability is a fundamental element for entangling identical particles.