Skip to main content

Publications

Direct visualization of electronic transport in a quantum anomalous Hall insulator

Cornell Affiliated Author(s)
Author
G. Ferguson
Run Xiao
Anthony Richardella
David Low
Nitin Samarth
Katja Nowack
Abstract

A quantum anomalous Hall (QAH) insulator is characterized by quantized Hall and vanishing longitudinal resistances at zero magnetic field that are protected against local perturbations and independent of sample details. This insensitivity makes the microscopic details of the local current distribution inaccessible to global transport measurements. Accordingly, the current distributions that give rise to transport quantization are unknown. Here we use magnetic imaging to directly visualize the transport current in the QAH regime.

Journal
Nature Materials
Date Published
Group (Lab)
Katja Nowack Group

Broken symmetries and excitation spectra of interacting electrons in partially filled Landau levels

Cornell Affiliated Author(s)
Author
Gelareh Farahi
Cheng-Li Chiu
Xiaomeng Liu
Zlatko Papic
Kenji Watanabe
Takashi Taniguchi
Michael Zaletel
Ali Yazdani
Abstract

Interacting electrons in flat bands give rise to a variety of quantum phases. One fundamental aspect of such states is the ordering of the various flavours - such as spin or valley - that the electrons can undergo and the excitation spectrum of the broken symmetry states that they form. These properties cannot be probed directly with electrical transport measurements.

Journal
Nature Physics
Date Published
Group (Lab)
Xiaomeng Liu Group

New perspectives on student reasoning about measurement uncertainty: More or better data

Cornell Affiliated Author(s)
Author
Andy Schang
Matthew Dew
Emily Stump
N. Holmes
Gina Passante
Abstract

Uncertainty is an important and fundamental concept in physics education. Students are often first exposed to uncertainty in introductory labs, expand their knowledge across lab courses, and then are introduced to quantum mechanical uncertainty in upper-division courses. This study is part of a larger project evaluating student thinking about uncertainty across these contexts.

Journal
Physical Review Physics Education Research
Date Published
Group (Lab)
Natasha Holmes Group

A geometrical perspective on development

Cornell Affiliated Author(s)
Author
A. Raju
E.D. Siggia
Abstract

Cell fate decisions emerge as a consequence of a complex set of gene regulatory networks. Models of these networks are known to have more parameters than data can determine. Recent work, inspired by Waddington's metaphor of a landscape, has instead tried to understand the geometry of gene regulatory networks. Here, we describe recent results on the appropriate mathematical framework for constructing these landscapes. This allows the construction of minimally parameterized models consistent with cell behavior.

Journal
Development Growth and Differentiation
Date Published
Research Area
Group (Lab)
Eric Siggia Group

Etoposide promotes DNA loop trapping and barrier formation by topoisomerase II

Cornell Affiliated Author(s)
Author
T.T. Le
M. Wu
J.H. Lee
N. Bhatt
J.T. Inman
J.M. Berger
M.D. Wang
Abstract

Etoposide is a broadly employed chemotherapeutic and eukaryotic topoisomerase II poison that stabilizes cleaved DNA intermediates to promote DNA breakage and cytotoxicity. How etoposide perturbs topoisomerase dynamics is not known. Here we investigated the action of etoposide on yeast topoisomerase II, human topoisomerase IIα and human topoisomerase IIβ using several sensitive single-molecule detection methods. Unexpectedly, we found that etoposide induces topoisomerase to trap DNA loops, compacting DNA and restructuring DNA topology.

Journal
Nature Chemical Biology
Date Published
Research Area
Group (Lab)
Michelle Wang Group

Graph gauge theory of mobile non-Abelian anyons in a qubit stabilizer code

Cornell Affiliated Author(s)
Author
Y.D. Lensky
K. Kechedzhi
I. Aleiner
Eun-Ah Kim
Abstract

Stabilizer codes allow for non-local encoding and processing of quantum information. Deformations of stabilizer surface codes introduce new and non-trivial geometry, in particular leading to emergence of long sought after objects known as projective Ising non-Abelian anyons. Braiding of such anyons is a key ingredient of topological quantum computation. We suggest a simple and systematic approach to construct effective unitary protocols for braiding, manipulation and readout of non-Abelian anyons and preparation of their entangled states.

Journal
Annals of Physics
Date Published
Group (Lab)
Eun-Ah Kim Group

Impact of traditional physics lab instruction on students’ critical thinking skills in a Finnish context

Cornell Affiliated Author(s)
Author
P. Pirinen
A. Lehtinen
N.G. Holmes
Abstract

Recent studies have given incentives to physics departments around the world to revise the learning goals of their lab courses to emphasize experimentation skills over reinforcing lecture content. Evaluation instruments have been developed to measure the achievement of learning goals, and one such instrument is the Physics Lab Inventory of Critical thinking (PLIC). The PLIC measures respondents’ ability to evaluate models, evaluate methods, and to suggest the next steps for an investigation.

Journal
European Journal of Physics
Date Published
Group (Lab)
Natasha Holmes Group

Instabilities induced by mechanical loading determine the viability of chondrocytes grown on porous scaffolds

Cornell Affiliated Author(s)
Author
B. Kim
N. Bouklas
Itai Cohen
L.J. Bonassar
Abstract

Tissue-engineered cartilage constructs have shown promise to treat focal cartilage defects in multiple clinical studies. Notably, products in clinical use or in late-stage clinical trials often utilize porous collagen scaffolds to provide mechanical support and attachment sites for chondrocytes. Under loading, both the local mechanical responses of collagen scaffolds and the corresponding cellular outcomes are poorly understood, despite their wide use.

Journal
Journal of Biomechanics
Date Published
Group (Lab)
Itai Cohen Group