visual
visual

세미나

  • HOME
  • >
  • 소식
  • >
  • 세미나
날짜 2016-11-18 10:30 
연사  
장소 #5318(5th fl.) 

Non-equilibrium many-body spin dynamics in diamond

 

Dr. 원, Havard University

Nov. 18th (Fri) 10:30 a.m., #5318(5th fl.)

 

 

Abstract:

In this talk, we will discuss two recent developments in non-equilibrium quantum dynamics of strongly interacting many-body systems: I. critically slow thermalization in a disordered dipolar spin ensemble [1] and II. the observation of discrete time crystalline order [2]. Both of these experiments were enabled by a high density ensemble of nitrogen-vacancy (NV) color centers in diamond [3]. As a mixture of theory and experiments, the talk will be self-contained and pedagogical, reviewing some of basic concepts in many-body localization, Floquet time-crystal, spin properties of NV centers and experimental techniques to manipulate and engineer the dynamics.

Part I:

Statistical mechanics underlies our understanding of macroscopic quantum systems. It is based on the assumption that out-of-equilibrium systems rapidly approach their equilibrium states, forgetting any information about their microscopic initial conditions. This fundamental paradigm is challenged by disordered systems, in which a slowdown or even absence of thermalization is expected. By controlling the spin states of the ~10^6 NV centers, we observe slow, sub-exponential thermalization consistent with power laws that exhibit disorder-dependent exponents; this behavior is modified at late times owing to many-body interactions. These observations are quantitatively explained by a resonance counting theory that incorporates the effects of both disorder and interactions

Part II:

The interplay of periodic driving, disorder, and strong interactions has recently been predicted to result in exotic ``time-crystalline'' phases, which spontaneously break the discrete time-translation symmetry of the underlying drive. We report the experimental observation of such discrete time-crystalline order and the observation of long-lived temporal correlations at integer multiples of the fundamental driving period. We experimentally identify the phase boundary and find that the temporal order is protected by strong interactions; this order is remarkably stable against perturbations, even in the presence of slow thermalization. We provide a theoretical description of approximate Floquet eigenstates of the system based on product state ansatz and predict the phase boundary, which is in qualitative agreement with our observations.

 

[1] G. Kucsko et al, arXiv:1609.08216

[2] S. Choi et al, arXiv:1610.08057

[3] J. Choi et al, arXiv:1608.05471

 

Contact: Eun-Gook Moon, Physics Dept., (egmoon@kaist.ac.kr)

 

번호 날짜 연사 제목
공지 2025-02-24 16:00    2025년 봄학기 콜로키움 안내
공지 2025-02-27 16:00    2025년 봄 물리학과 특별세미나 (광학/응집물리 분야)
425 2022-10-06 13:00    Counting States with Global Symmetry
424 2022-08-12 10:00    Twisted Bilayer Magnets file
423 2022-08-12 10:00    Twisted Bilayer Magnets file
422 2016-04-26 16:00    Transport spectroscopy for electronic bands in carbon-based nanomaterials with weak-bond contacts
421 2018-05-11 16:00    암페어 단위 재정의와 단전자 펌프 소자 개발 file
420 2025-04-22 16:00  Dr. Nanse Esaki (The University of Tokyo)  Spin Nernst and thermal Hall effects of topological triplons in quantum dimer magnets on the maple-leaf and star lattices file
419 2016-06-01 10:30    Welcome to Nature Photonics
418 2018-07-02 15:00    High Precision Magnetic Field Measurement for the Muon g-2 Experiment file
417 2015-10-16 15:00    High Magnetic Fields to Probe the sub-eV range of Particle/Astroparticle Physics - From the OSQAR experiments at CERN up to new perspectives at LNCMI-Grenoble
416 2018-11-09 14:30    Moiré superlattices – from twisted bilayer graphene to quasicrystal file
415 2024-05-30 10:00    Quasiperiodic Effects in Quasicrystals
414 2024-05-16 14:30    [Astrophysics Seminar] Observational Cosmology with Superconducting Sensors
413 2022-03-29 10:00    Non-reciprocal phase transitions file
412 2022-03-31 10:00    Weiss fields for Quantum Spin Dynamics file
411 2020-10-15 17:00    Time crystals, quasicrystals, and time crystal dynamics in the superfluid universe file
410 2023-05-03 16:00    Probing microscopic origins of axions by the chiral magnetic effect
409 2022-11-09 16:00    Radio Astronomy, Radio Interferometry, and Multi-wavelength Studies on Relativistic Jets
408 2017-06-02 16:00    Maxwell's demon in quantum wonderland file
407 2015-12-03 16:00    Hybrid solid state spin qubits in wide bandgap semiconductors
406 2025-01-08 16:00  Dr. SangEun Han  Quantum impurity model for two-stage multipolar ordering and Fermi surface reconstruction