From bipartite to many-particle entanglement of ultracold atoms
Final Report Abstract
The field of quantum physics has experienced a continuous growth since its invention in the beginning of the 20th century. Over the years, the technological advances enabled a constant improvement of the control of microscopic quantum systems, by resolving the quantization, by exploiting the superposition principle, and by creating entanglement in multi-particle systems. These experimental achievements are deeply connected with an improved theoretical understanding of large quantum systems. In addition to the scientific benefit, the gained understanding has led to the development of industrial applications, with a broad range of possible products in the future. The project “From bipartite to many-particle entanglement of ultracold atoms” explored the generation and application of entanglement between ultra-cold neutral atoms. These ultra-cold atoms are prepared in a Bose-Einstein condensate, where all particles are indistinguishable and thus share the same quantum-mechanical state. The project now exploits a process, where collisions between these atoms generate pairs of atoms, where one atom has a spin pointing up and the other a spin pointing down. The fact that these atoms are always created in pairs, together with the fundamental indistinguishability of the atoms, leads to the generation of entanglement. In the project, we could show that this process allows for the generation of Einstein-Podolsky-Rosen entanglement. This type of entanglement refers to a famous article by Einstein, Podolsky and Rosen in 1935, where the concept of entanglement was investigated for the first time. In the course of the project, the created entanglement was also demonstrated to be of practical relevance. It was shown that it can be employed to improve the resolution of atomic microwave clocks beyond the fundamental limit of unentangled atoms. Further investigations included the proof of entanglement between spatially separated atomic clouds and the realization of the analogue of a prominent quantum optical effect, the Dynamical Casimir Effect.
Publications
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Improvement of an atomic clock using squeezed vacuum, Phys. Rev. Lett. 117, 143004 (2016)
I. Kruse, K. Lange, J. Peise, B. Lücke, L. Pezzè, J. Arlt, W. Ertmer, C. Lisdat, L. Santos, A. Smerzi, and C. Klempt
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Creation of entangled atomic states by an analogue of the Dynamical Casimir effect, New J. Phys. 20, 103017 (2018)
K. Lange, J. Peise, B. Lücke, T. Gruber, A. Sala, A. Polls, W. Ertmer, B. Julià-Dìaz, L. Santos, and C. Klempt
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Entanglement between two spatially separated atomic modes, Science 360, 416 (2018)
K. Lange, J. Peise, B. Lücke, I. Kruse, G. Vitagliano, I. Apellaniz, M. Kleinmann, G. Tóth, and C. Klempt
