Date and Time:  22-Dec-2023  10:30am 

Speaker: Cheng Chen ,Institut d'Optique Graduate School, Palaiseau, France

Host: Li You ( Tsinghua Univ. & BAQIS）

Title: Studying the dipolar XY model with a Rydberg quantum simulator

Venue: Room 320

Abstract: 

We realized a two-dimensional dipolar XY model using a programmable Rydberg quantum simulator. First, we demonstrate the adiabatic preparation of both the dipolar XY ferromagnetic and antiferromagnetic state. In the ferromagnetic case, we characterize the presence of a long-range XY order, a feature prohibited in the absence of long-range dipolar interaction [1]. Second, motivated by recent theoretical works [2,3], we explore the prediction that the two-dimensional dipolar XY model can enable the realization of scalable spin squeezing. Experimentally we demonstrate that quench dynamics from a polarized initial state lead to spin squeezing that improves with increasing system size up to a maximum of ?3.5 ± 0.3 dB (prior to correcting for detection errors, or approximately ?5.0 ± 0.3 dB after correction) [4]. Third, we investigate the quench spectroscopy of the dipolar XY model and extract the dispersion relation from the time evolution of correlations [5]. Respectively starting from a ferromagnetic or an antiferromagnetic initial state, we get significantly different dispersion relations of the two phases, corresponding to ～√(|k|)  and ～|k|, demonstrating the importance of power-law interactions on the excitation spectrum of a many-body spin system [6]. Recently, we investigated on experimental measurement of quantum tomography on our platform and have some preliminary results.

References

[1] C. Chen et al., Nature 616, 691–695 (2023).

[2] T. Comparin et al. Phys. Rev. Lett., 2022, 129.

[3] M. Block et al. arXiv:2301.09636

[4] G. Bornet et al., Nature 621, 728–733 (2023)

[5] in preparation.

[6] D. Peter, et al. Phys. Rev. Lett., 2012, 109.

About the Speaker:

Cheng Chen is currently a postdoctoral researcher in the "Quantum Optics – Atoms" group led by Antoine Browaeys at Institut d'Optique. From 2011 to 2015, he studied at the University of Science and Technology of China and got a Bachelor's degree in physics. From 2015 to 2021, he pursued a Ph.D. at Tsinghua University, with Professor Li You and associate professor Meng Khoon Tey. Since September 2021, he has been a postdoctoral researcher working on experimental quantum simulation using Rydberg atom arrays at Institut d'Optique, France. His current research interests are Rydberg atom arrays, Dipolar XY model, Quantum simulation, and Quantum many-body systems.