Bulletin of the American Physical Society
52nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 66, Number 6
Monday–Friday, May 31–June 4 2021; Virtual; Time Zone: Central Daylight Time, USA
Session X03: Information Propagation with Long-range InteractionsInvited Live
|
Hide Abstracts |
Chair: Alexey Gorshkov, JQI |
Friday, June 4, 2021 8:00AM - 8:30AM Live |
X03.00001: Lieb-Robinson bound and information propagation in long-range interacting systems Invited Speaker: Tomotaka Kuwahara A fundamental principle of many-body physics is causality, that is, strict prohibition of information propagation outside the light cone. However, in non-relativistic systems, it is often unclear whether such a light cone can be well-defined. In 1972, this problem was completely solved by Lieb and Robinson in short-range interacting systems. The existence of the effective light-cone was proven; outside of it, the amount of information decays exponentially with the distance. This effective light-cone is characterized in the form of a ``Lieb-Robinson bound,'' and it is linear with respect to time. In the case where the interaction length is short-range, it is quite natural to expect that the information propagation is constrained by a finite velocity. However, beyond short-range interactions, the situation becomes highly non-trivial. In particular, for long-range interactions, information easily propagates to an arbitrarily distant point. Here, long-range interaction indicates that the interaction strength between separated sites demonstrates a power-law decay as $R^{-\alpha}$ for distance $R$. This intuitively leads to an impression that the linear-light cone can no longer be obtained in long-range interacting systems, as has been shown by Hastings and Koma [1]. Nevertheless, depending on the power-law exponent, it has been numerically [2] and experimentally [3] observed that a linear light cone still remains even under long-range interactions. This motivates the following linear light cone problem: ``what is the critical power-law exponent to induce the linear light cone?'' Owing to its importance and simplicity, the problem has received significant interest from researchers of various backgrounds. In this talk, we give the solution of the linear light cone problem [4]. Our result provides the complete proof of the linear light cone for $\alpha>2D+1$ in generic long-range interacting systems of arbitrary dimensions. The present study proves the optimality of our condition $\alpha>2D+1$ by showing an explicit counterexample which violates the linear light cone for $\alpha<2D+1$. In addition, we demonstrate that for $\alpha>D$ a polynomial form of the effective light cone still retains as long as if the out-of-time-order correlators are considered [5]. [1] M. B. Hastings and T. Koma, Communications in Mathematical Physics 265, 781 (2006). [2] P. Hauke and L. Tagliacozzo, Phys. Rev. Lett. 111, 207202 (2013). [3] P. Richerme, et al., Nature (London) 511, 198 (2014). [4] T. Kuwahara and K. Saito, Phys. Rev. X 10, 031010 (2020). [5] T. Kuwahara and K. Saito, Phys. Rev. Lett. 126, 030604 (2021). |
Friday, June 4, 2021 8:30AM - 9:00AM Live |
X03.00002: Speed limits on quantum dynamics with long-range interactions Invited Speaker: Andrew Lucas In 1972, Lieb and Robinson proved that quantum information propagates with a finite velocity in quantum many-body systems with local interactions. Yet most physically realized systems have long-range interactions, that decay as a power law with the distance between two particles. Are there still meaningful speed limits on the propagation of quantum information in these physically realized systems? |
Friday, June 4, 2021 9:00AM - 9:30AM Live |
X03.00003: Quantum Chaos with Power-law Interactions Invited Speaker: Brian Swingle I will present a theory of quantum chaos and quantum information spreading in systems with long-range power-law interactions. Depending on the exponent of the power-law interactions, our theory predicts that information can spread ballistically, super-ballistically, or even exponentially fast. I will present a large-N mean field model in which our proposed phase diagram can be explicitly checked. Finally, I will argue that systems with dipolar interactions are a natural experimental testbed and I will discuss our theory in light of existing nuclear magnetic resonance data on adamantane. Based on work with Tianci Zhou, Xiao Chen, Andrew Guo, and Shenglong Xu. |
Friday, June 4, 2021 9:30AM - 10:00AM Live |
X03.00004: Lieb-Robinson bounds in long range interacting spin chains Invited Speaker: David Luitz Lieb-Robinson bounds quantify the maximal speed of information spreading in nonrelativistic quantum systems. We discuss the relation of Lieb-Robinson bounds to out-of-time order correlators, which correspond to different norms of commutators $C(r,t)=[A_i(t),B_{i+r}]$ of local operators. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700