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)
554 2016-04-08 13:30    Theoretical Overview of Iron-based superconductors and its future
553 2016-04-08 16:00    Spectroscopic studies of iron-based superconductors : what have we learned?
552 2016-04-12 16:00    Confinement of Superconducting Vortices in Magnetic Force Microscopy
551 2016-04-18 15:30    First Principles Approaches for Intermolecular Interactions: From Gas-Phase Dimers to Liquid Water and Molecular Crystal Polymorphism file
550 2016-04-19 14:00    Nonlocal collisional electron transport in partially ionized plasma generation, structure, and stability
549 2016-04-26 16:00    Transport spectroscopy for electronic bands in carbon-based nanomaterials with weak-bond contacts
548 2016-04-28 15:00    Lattice/Spin/Charge Coupling in 5d Pyrochlore Cd2Os2O7
547 2016-05-11 16:00    The quest for novel high-temperature superconductors---Prospects and progress in iridates
546 2016-05-13 13:30    Aperiodic crystals in low dimensions
545 2016-05-13 16:00    Graphene analogue in (111)- BaBiO3 bilayer heterostructures for topological electronics
544 2016-05-16 16:00    Tuning microwave cavities with biased nonlinear dielectrics for axion searches
543 2016-05-17 11:00    The CERN Resonant WISP Search: Development, Results and Lesson-Learned
542 2016-05-19 15:00    The CERN Resonant WISP Search: Development, Results and Lesson-Learned
541 2016-05-19 16:00    Nonlinear/quantum optical effect in silicon nano-photonics
540 2016-05-24 16:00    Electronic and magnetic properties of 2D transition-metal thiophosphates and tunability of magnetic order with carrier density
539 2016-05-31 16:00    Understanding 3D tokamak physics towards advanced control of toroidal plasma
538 2016-06-01 10:30    Welcome to Nature Photonics
537 2016-06-01 16:00    Laboratory experiments relevant to mesospheric clouds, Saturn’s rings & astrophysical jets
536 2016-06-14 15:00    No-Insulation High Temperature Superconductor Magnet Technology for Compact, Reliable, and Low-Cost High Field DC Magnets
535 2016-06-14 16:00    Photonic quantum network based on multimode squeezed vacuums and single-photon subtraction