Quenching the Kitaev honeycomb model

This work was presented first in a seminar at the University of Toronto on 18 October 2017. The slides of this presentation can be downloaded here (pptx, 13 MB).

Title: Quenching the Kitaev honeycomb model

Author: Louk Rademaker


Abstract: I studied the non-equilibrium response of an initial Néel state under time evolution with the Kitaev honeycomb model. This time evolution can be computed using a random sampling over all relevant flux configurations. With isotropic interactions the system quickly equilibrates into a steady state valence bond solid. Anisotropy induces an exponentially long prethermal regime whose dynamics are governed by an effective toric code. Signatures of topology are absent, however, due to the high energy density nature of the initial state.


Quantum Thermalization and the Expansion of Atomic Clouds

I also presented this work in the form of a poster at the SPICE workshop ’Non-equilibrium Quantum Matter’, Mainz, Germany, from 30 May to 2 June 2017. The poster can be downloaded here (pdf, 1.3 MB).

Title: Quantum Thermalization and the Expansion of Atomic Clouds

Authors: Louk Rademaker, Jan Zaanen


Abstract: The ultimate consequence of quantum many-body physics is that even the air we breathe is governed by strictly unitary time evolution. The reason that we perceive it nonetheless as a completely classical high temperature gas is due to the incapacity of our measurement machines to keep track of the dense many-body entanglement of the gas molecules. The question thus arises whether there are instances where the quantum time evolution of a macroscopic system is qualitatively different from the equivalent classical system? Here we study this question through the expansion of noninteracting atomic clouds. While in many cases the full quantum dynamics is indeed indistinguishable from classical ballistic motion, we do find a notable exception. The subtle quantum correlations in a Bose gas approaching the condensation temperature appear to affect the expansion of the cloud, as if the system has turned into a diffusive collision-full classical system.



MBL-to-Ergodic Transition from the perspective of Integrals of Motion

At the 16th International Conference on Transport in Interacting Disordered Systems (TIDS16) in Granada, Spain I presented my work done with Miguel Ortuño and Andres Somoza on many-body localization (MBL). Specifically, these are the first large-system results using our method of displacement transformations to find the MBL integrals of motion.

A sneak peek: the accuracy of our method increases order by order and with increasing disorder. Download the full presentation as a pptx file (4.5 MB)


Presentation: Integrals of Motion with Displacement Transformations

15At the KITP conference ‘KITP Conference: Aspects and applications of many-body localization‘ from 16 to 20 November, here in Santa Barbara, my collaborator Miguel Ortuño gave a presentation about the work we have been doing together on MBL.

You can watch the talk on the website of the KITP: http://online.kitp.ucsb.edu/online/mbl-c15/ortuno/

The slides of the presentation can be downloaded here, and the paper that explains our work in more detail is currently on the arXiv.


Presentation: Glassy dynamics in geometrically frustrated Coulomb liquids

mainzAt the SPICE-Workshop on Bad Metal Behavior in Mott Systems (June 29-July 2 2015) in Mainz, Germany, I was invited speaker. I gave a talk about glassy dynamics in theta-RbZn, the organic material that upon fast-cooling can avoid the charge ordering transition and gets into a disorderfree electron glass phase. At the hand of four characteristics of a glass – slow dynamics, a soft gap, short-range correlations and a rugged energy landscape – I discuss the results of our model of hoppings electrons with long-range Coulomb repulsion.

You can download the presentation here (pdf, 10 MB).

The talk has been posted on Youtube: click here to watch it!

Poster: The Tower of States and the Entanglement Spectrum in a Coplanar Antiferromagnet

Poster KITP conferenceFrom June 1 to June 5, 2015, the KITP hosted the conference ‘Closing the entanglement gap: Quantum information, quantum matter, and quantum fields,’ where I presented a poster on my recent (unpublished) work on the entanglement spectrum of a coplanar antiferromagnet. The entanglement entropy attains a logarithmic term from the tower of states, proportional to the number of Goldstone modes, the entanglement spectrum represents the full SO(3) symmetry of the tower of states.

You can download the poster here (pdf, 1.3 MB).

Presentation, Cafe KITP: Quasiparticles


At 7 May 2015 I gave a public outreach talk for Café KITP at Club Soho in Santa Barbara, for a general audience, with the title ‘Quasiparticles – The Dreams That Stuff is Made Of‘. The idea is that I showed how in solid materials all new kind of ‘fundamental’ particles can arise known as ‘quasiparticles’. In fact, we can engineer any kind of particle – even particles that do not exist in the theory of fundamental particles (the Standard Model) like magnetic monopoles and ‘anyons’. The existence of quasiparticles underlies all modern electronic technology and will give rise no new technologies such as quantum computers.

Download the presentation here (pptx, 10 MB)

Presentation: Efros-Shklovskii Gap without disorder

At the APS March Meeting 2015 I presented recent work on the Efros-Shklovskii Gap without disorder.


Abstract: Certain models of frustrated electron systems have been shown to self-generate glassy behavior, in the absence of disorder. Possible candidate materials contain quarter-filled triangular lattices with long-range Coulomb interactions, as found in the θ-family of organic BEDT-TTF crystals. In disordered insulators with localized electronic states, the so-called Coulomb glass, the single particle excitation spectrum displays the well-known Efros-Shklovskii gap. The same excitation spectrum is investigated in a class of models that display self-generated electronic glassiness, showing pseudogap formation related to the Efros-Shklovskii Coulomb gap. Our study suggests universal characteristics of all electron glasses, regardless of disorder.

Download the presentation here (pdf, 5.4 MB).