visual
visual

세미나

  • HOME
  • >
  • 소식
  • >
  • 세미나
날짜 2016-11-18 10:30 
일시 Nov. 18th (Fri) 10:30 a.m. 
장소 #5318(5th fl.) 
연사 Dr. 최 순 원, Havard University 

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 장소 제목
400 2018-05-11 16:00  E6-2. 1st fl. #1323  암페어 단위 재정의와 단전자 펌프 소자 개발 file
399 2018-10-12 16:00  E6-2. 1st fl. #1323  Direct observation of a two-dimensional hole gas at oxide interfaces file
398 2018-12-07 14:30  E6-2. 1st fl. #1323  Spin generation from heat and light in metals file
397 2018-12-16 16:00  E6-2. 1st fl. #1323  Lectures on 2d Conformal Field Theory file
396 2018-03-16 14:30  E6-2. 1st fl. #1323  산화물 다층박막에서의 다양한 물리현상 file
395 2018-03-16 14:30  E6-2. 1st fl. #1323  산화물 다층박막에서의 다양한 물리현상 file
394 2018-05-11 14:30  E6-2. 1st fl. #1323  Disordered Floquet topological insulators file
393 2018-04-09 11:00  E6-2. 1st fl. #1323  Doublon-holon origin of the subpeaks at the Hubbard band edges file
392 2019-03-29 14:30  E6-2. 1st fl. #1323  Epitaxial Multifunctional Oxide Thin Films for Novel Electronics file
391 2019-09-10 15:00  E6-2. 1st fl. #1323  Two-Stage Kondo Effect file
390 2019-11-01 14:30  E6-2. 1st fl. #1323  Squeezing the best out of 2D materials file
389 2018-12-07 16:00  E6-2. 1st fl. #1323  Novel probes of interacting electrons in 2D systems file
388 2017-09-22 16:00  E6-2. 1st fl. #1323  Unexpected Electron-Pairing in Integer Quantum Hall Effect file
387 2018-06-01 11:00  E6-2. 1st fl. #1323  Topological phases in low-dimensional quantum materials file
386 2016-10-18 15:00  E6-2. 1st fl. #1323  “Hybrid quantum systems with mechanical oscillators”
385 2019-09-27 16:00  E6-2. 1st fl. #1323  0D/1D/2D/3D III-V materials grown by MBE for Optelectronics file
384 2018-05-17 13:30  E6-2. 1st fl. #1323  Quantum Spin Liquid in Kitaev Materials file
383 2018-11-09 16:00  E6-2. 1st fl. #1323  Quantum sensing and imaging with diamond defect centers for nano-scale spin physics file
382 2018-12-27 16:00  E6-2. 1st fl. #1323  Quantum Innovation (QuIN) Laboratory file
381 2016-04-12 16:00  E6-2. 1st fl. #1323  Confinement of Superconducting Vortices in Magnetic Force Microscopy