290S/290K Quantum Materials Seminar speaker Aris Alexandradinata (UC Santa Cruz), Wednesday, May 10 (yes this is May 2023) at 2 pm in Physics South 402

Time/Venue Wednesday, May 10 at 2 pm Physics South 402
Host Joel Moore
Title Nonlinear optical phenomena of topological materials
Abstract
tba

Posted in QM Seminar | Comments Off on 290S/290K Quantum Materials Seminar speaker Aris Alexandradinata (UC Santa Cruz), Wednesday, May 10 (yes this is May 2023) at 2 pm in Physics South 402

290S/290K Quantum Materials Seminar speaker Junyeong Ahn (Harvard), Wednesday, January 18, 2023 at 2 pm in Physics South 402

Time/Venue Wednesday, January 18 at 2:00 pm Pacific Time in Physics South 402 and via Zoom:
https://berkeley.zoom.us/j/99523499113pwd=REovb3pyam03WXQwbEhrU3dqNHZvdz09

Meeting ID: 995 2349 9113 Passcode: 600704
Host Joel Moore
Title tba
Abstract tba

Posted in QM Seminar | Comments Off on 290S/290K Quantum Materials Seminar speaker Junyeong Ahn (Harvard), Wednesday, January 18, 2023 at 2 pm in Physics South 402

290S/290K Quantum Materials Seminar speakers Ryan Day and another speaker tbd (both UC Berkeley) on Wednesday, December 14 at 2:00 pm in Physics South 402

Time/Venue Wednesday, December 14 at 2:00 pm PST in Physics South 402
Host Bob Birgeneau
Speaker Ryan Day (Analytis Group)
Title tbd
Abstract tbd
Speaker tbd
Title
 tbd
Abstract
 tbd

Posted in QM Seminar | Comments Off on 290S/290K Quantum Materials Seminar speakers Ryan Day and another speaker tbd (both UC Berkeley) on Wednesday, December 14 at 2:00 pm in Physics South 402

Special 290S/290K Quantum Materials Seminar speaker Nikita Astrakhantsev (Uni Zürich) Tuesday, November 14 at 11 am in Physics North 325

Time/Venue Monday, November 14 at 11 am in Physics North 325
 and via Zoom:
https://berkeley.zoom.us/j/99523499113pwd=REovb3pyam03WXQwbEhrU3dqNHZvdz09

Meeting ID: 995 2349 9113 Passcode: 600704
Host Joel Moore
Title tba/ physics of pyrochlore Heisenberg model
Abstract tba

Posted in QM Seminar | Comments Off on Special 290S/290K Quantum Materials Seminar speaker Nikita Astrakhantsev (Uni Zürich) Tuesday, November 14 at 11 am in Physics North 325

290S/290K Quantum Materials Seminar speakers Yi Lin and Luke Pritchard Cairns (both UCB) on Wednesday, November 9 at 2:00 pm in Physics South 402

Time/Venue Wednesday, November 9 at 2:00 pm PST in Physics South 402
Host Bob Birgeneau
Speaker Yi Lin (Lanzara Group)
Title 
tbd
Abstract 
tbd
Speaker 
Luke Pritchard Cairns (Analytis Group)
Title 
tbd
Abstract
tbd

Posted in QM Seminar | Comments Off on 290S/290K Quantum Materials Seminar speakers Yi Lin and Luke Pritchard Cairns (both UCB) on Wednesday, November 9 at 2:00 pm in Physics South 402

290S/290K Quantum Materials Seminar speaker Thais Victa Trevisan (new to UCB!) Wednesday, November 2 at 2 pm in Physics North 402

Time/Venue Wednesday, November 2 at 2 pm Pacific time in Physics North 402 and via Zoom:
https://berkeley.zoom.us/j/99523499113pwd=REovb3pyam03WXQwbEhrU3dqNHZvdz09

Meeting ID: 995 2349 9113 Passcode: 600704
Host Joel Moore
Title: tba
Abstract: tba

Posted in QM Seminar | Comments Off on 290S/290K Quantum Materials Seminar speaker Thais Victa Trevisan (new to UCB!) Wednesday, November 2 at 2 pm in Physics North 402

290S/290K Quantum Materials Seminar speaker Peter Lunts (UMD) Wednesday, October 19 at 2 pm in Physics North 402

Time/Venue Wednesday, October 19 at 2 pm Pacific time in Physics North 402 and via Zoom:
https://berkeley.zoom.us/j/99523499113pwd=REovb3pyam03WXQwbEhrU3dqNHZvdz09

Meeting ID: 995 2349 9113 Passcode: 600704
Host Ehud Altman
Title Non-Hertz-Millis scaling of the antiferromagnetic quantum critical metal via scalable Hybrid Monte Carlo
Abstract Over the last decade there has been a surge of activity in studying various quantum phenomena via electronic `constructor models’ that lack the fermion sign problem. Of note are constructor models of quantum phase transitions in metallic systems, where it is easier to find such microscopic models due to the notion of universality. However, this agenda has been hampered due to the expensive scaling with system size of Determinant Quantum Monte Carlo, making it difficult to convincingly extract long-wavelength information from the critical theory.
In this talk I will introduce a Hybrid Monte Carlo (HMC) algorithm with a novel auto-tuning procedure. We apply this method to the O(3) spin-fermion model, a minimal model of the onset of antiferromagnetic order in a two-dimensional metal. Our method allows us to study unprecedentedly large systems of 80×80 sites, even at criticality. To characterize the universality class of the quantum critical point, we extract the scaling exponents and functional form of the static and zero-momentum dynamical spin susceptibility. We find a strong violation of the Hertz-Millis form, contrary to all previous results. The form that we do observe provides strong evidence that the universal scaling is actually governed by the fixed point of [Phys. Rev. X 7, 021010 (2017)], even away from perfect hot-spot nesting. Our results suggest that controlled analytical calculations of the critical theory near perfect hot-spot nesting can be used to make qualitatively correct predictions at larger nesting angles of other observables. Additionally, the HMC method we introduce is generic and can be used to study other fermionic models of quantum criticality, where there is a strong need to simulate large systems.

Posted in QM Seminar | Comments Off on 290S/290K Quantum Materials Seminar speaker Peter Lunts (UMD) Wednesday, October 19 at 2 pm in Physics North 402

290S/290K Quantum Materials Seminar speakers Hongrui Zhang and Shubhayu Chatterjee (both UCB) on Wednesday, October 12 at 2:00 pm PST in Physics South 402

Time/Venue Wednesday, October 12 at 2:00 pm PST in Physics South 402
Host Bob Birgeneau
Speaker Hongrui Zhang (Ramesh Group)
Title 
A layered polar magnet
Abstract 
tbd
Speaker 
Shubhayu Chatterjee (Yao & Zaletel Groups)
Title 
tbd
Abstract 
tbd

Posted in QM Seminar | Comments Off on 290S/290K Quantum Materials Seminar speakers Hongrui Zhang and Shubhayu Chatterjee (both UCB) on Wednesday, October 12 at 2:00 pm PST in Physics South 402

290S/290K Quantum Materials Seminar speaker Dan Borgnia (UCB) Wednesday, October 5 at 2 pm in Physics North 402

Time/Venue Wednesday, October 5 at 2 pm Pacific time in Physics North 402
 and via Zoom:
https://berkeley.zoom.us/j/99523499113pwd=REovb3pyam03WXQwbEhrU3dqNHZvdz09

Meeting ID: 995 2349 9113 Passcode: 600704
Host Joel Moore
Title Localization via Quasi-Periodic Bulk-Bulk Correspondence
Abstract Quasi-periodic systems exhibit rich spectral properties, including topological invariants, mobility edges, and localization transitions. They are one of the few examples of operators we know to have a singular continuous spectrum (a generic, but poorly understood property class of operators). I will report on a new set of tools relating quasi-periodic topology and the spectral measure for the metal-insulator transition (MIT) in the almost-Mathieu operator. By constructing quasi-periodic transfer matrix equations from the limit of rational approximate projected Green’s functions using a 2D parent Hamiltonian, we treat the metal-insulator transition like a gauge transformation and link the eigenfunction localization of the MIT to the chiral edge modes of the Hofstadter Hamiltonian. This implies the localized phase roots in a topological “bulk-bulk” correspondence, a bulk-boundary correspondence between the 1D AAH system (boundary) and its 2D parent Hamiltonian (bulk). These results have exciting consequence in the singular continuous spectrum, including applications to the Dry Ten Martini Problem.

Posted in QM Seminar | Comments Off on 290S/290K Quantum Materials Seminar speaker Dan Borgnia (UCB) Wednesday, October 5 at 2 pm in Physics North 402

Special 290S/290K Quantum Materials Seminar speaker Nathanan Tantivasadakarn (Harvard) Tuesday, October 4 at 11 am in Physics North 402

Time/VenueTuesday, October 4 at 11 am in Pacific time in Physics North 402
 and via Zoom:
https://berkeley.zoom.us/j/99523499113pwd=REovb3pyam03WXQwbEhrU3dqNHZvdz09

Meeting ID: 995 2349 9113 Passcode: 600704
Host Ehud Altman
Title tba
Abstract: tba

Posted in QM Seminar | Comments Off on Special 290S/290K Quantum Materials Seminar speaker Nathanan Tantivasadakarn (Harvard) Tuesday, October 4 at 11 am in Physics North 402