korean english


Home > 게시판 > 세미나

다음과 같이 세미나 모임을 개최합니다. 많은 참석 부탁합니다. 

날짜: 2015/ 5/16 () 발표는 10:30부터 시작합니다.

장소: 삼성 학술 정보관 7 Creative Learning Room

연사: 정석범 교수 (서울대)

제목: Searching for Majorana fermions


At the dawn of modern physics, there were two different attempts to reconcile quantum mechanics with special relativity for electrons.  When it was recognized that the earlier attempt by Dirac required  the existence of the anti-particle, a colleague of Fermi, Ettore Majorana, came up with a solution that does not require anti-particles. While this concept for a long time had been considered merely as a possible theory for neutrinos, there recently has been active interest in possibility of  Majorana fermions in condensed matter system as an instance of electron fractionalization. The host system for such Majorana fermions are the superconducting analogues of the topological insulators, known as topological superconductors. I will discuss both the conceptual issues and the experimental progresses of this topological superconductor both in 1D and in higher-D.

연사: 조길영 박사 (과학원)

제목: Geometry of Fractional Quantum Hall states


Fractional quantum Hall (FQH) fluids of two-dimensional electron gases (2DEG) in large magnetic fields are fascinating topological states of matter. As such they are characterized by universal properties such as their fractional quantum Hall conductivity, fractionally charged anyonic excitations and a degeneracy of topological origin on surfaces with the topology of a torus. Quite surprisingly these topological fluids also couple to the geometry on which the 2DEG resides and have universal responses to adiabatic changes in the geometry. These responses are given by a Wen-Zee term (which describes the coupling of the currents to the spin connection of the geometry) and a gravitational Chern-Simons term which reflects the universal energy and momentum transport along the edges of the FQH state. We use a field theory of the FQH  states to derive these universal responses [1, 2]. To account for the coupling to the background geometry, we show that the concept of flux attachment needs to be modified and use it to derive the geometric responses from Chern-Simons theories. We show that the resulting composite particles minimally couple to the spin connection of the geometry [1]. Taking account of the framing anomaly of the quantum Chern-Simons theories [2], we derive a consistent theory of geometric responses from the Chern-Simons effective field theories and from parton constructions, and apply it to both abelian and non-abelian states. If time allows, we will also discuss the implications [3-4] of the geometric responses on the so-called nematic fractional quantum Hall states which is recently found in experiments.

[1] GYC, You, and Fradkin, PRB, 90, 115139 (2014)

[2] Gromov, GYC, You, Abanov, and Fradkin, PRL, 114, 016805 (2014)

[3] GYC, Parrikar, You, Reigh, and Hughes, PRB, 91, 035122 (2014)

[4] You, GYC, and Fradkin, PRX, 4, 041050, (2015)   

번호 제목 날짜 조회 수
공지 2020학년도 1학기 콜로퀴움 일정 2020.01.31 206958
공지 <12/8(Thu.) 11:00am>노벨상 소개 강연 - 2016년 노벨 물리학상: 위상 응집 물리의 탄생 2016.11.28 529809
615 2019학년도 2학기 콜로퀴움 일정 2019.07.17 379203
» <5/16(토)> 세미나 개최 안내 2015.05.18 114527
613 2016학년도 1학기 콜로퀴움 일정 2016.02.03 108573
612 2017학년도 1학기 콜로퀴움 일정 2017.01.05 107194
611 2019학년도 1학기 콜로퀴움 일정 2019.01.08 96002
610 2018학년도 2학기 콜로퀴움 일정 2018.07.03 89664
609 2018학년도 1학기 콜로퀴움 일정 2018.01.03 83209
608 2014학년도 2학기 콜로퀴움 일정 2014.09.11 79844
607 2017학년도 2학기 콜로퀴움 일정 2017.07.04 76926
606 <4/2> Radio Detection of Ultra High Energy Cosmic Rays and Neutrinos in Antarctica 2014.03.26 73882
605 <5/1>In vivo optical imaging of hemodynamic changes 2009.05.06 72445
604 <6/2> The black hole search at the LHC: critical comment 2011.06.01 72273
603 <9/1> 원자핵 자기공명(Nuclear Magnetic Resonance) 해설 - 원자선에서 영상까지 2010.08.30 71998
602 <10/28>Grazing Incidence X-ray Diffraction and Surface X-ray Scattering Study of Hematite (α-Fe2O3) Nano-cube 2011.10.26 71022
601 BK 석학초청 특별세미나 - Frustration and dimensional reduction in multi-orbital systems 2011.10.28 70779
600 <4/19> Nuclear Reaction Theories 2011.04.14 70646
599 <9/15> Resistance Switching Behavior of Epitaxially Grown NiO Thin Films 2009.09.07 70561
598 2016학년도 2학기 콜로퀴움 일정 2016.08.02 69085