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Publications

Nanocalorimetry using microscopic optical wireless integrated circuits

Cornell Affiliated Author(s)
Author
Conrad Smart
Alejandro Cortese
B. Ramshaw
Paul McEuen
Abstract

We present in situ calorimetry, thermal conductivity, and thermal diffusivity measurements of materials using temperature-sensing optical wireless integrated circuits (OWiCs). These microscopic and untethered optical sensors eliminate input wires and reduce parasitic effects. Each OWiC has a mass of ∼100 ng, a 100-μm-scale footprint, and a thermal response time of microseconds. We demonstrate that they can measure the thermal properties of nearly any material, from aerogels to metals, on samples as small as 100 ng and over thermal diffusivities covering four orders of magnitude.

Journal
Proceedings of the National Academy of Sciences of the United States of America
Date Published
Group (Lab)
Brad Ramshaw Group
Paul McEuen Group

Universal scaling for disordered viscoelastic matter near the onset of rigidity

Author
Danilo Liarte
Stephen Thornton
Eric Schwen
Itai Cohen
Debanjan Chowdhury
James Sethna
Abstract

The onset of rigidity in interacting liquids, as they undergo a transition to a disordered solid, is associated with a rearrangement of the low-frequency vibrational spectrum. In this Letter, we derive scaling forms for the singular dynamical response of disordered viscoelastic networks near both jamming and rigidity percolation. Using effective-medium theory, we extract critical exponents, invariant scaling combinations, and analytical formulas for universal scaling functions near these transitions.

Journal
Physical Review E
Date Published
Group (Lab)
Debanjan Chowdhury Group
Itai Cohen Group
James Sethna Group

Lorentz electron ptychography for imaging magnetic textures beyond the diffraction limit

Cornell Affiliated Author(s)
Author
Zhen Chen
Emrah Turgut
Yi Jiang
Kayla Nguyen
Matthew Stolt
Song Jin
Daniel Ralph
Gregory Fuchs
David Muller
Abstract

Nanoscale spin textures, especially magnetic skyrmions, have attracted intense interest as candidate high-density and power-efficient information carriers for spintronic devices1,2. Facilitating a deeper understanding of sub-hundred-nanometre to atomic-scale spin textures requires more advanced magnetic imaging techniques3–5. Here we demonstrate a Lorentz electron ptychography method that can enable high-resolution, high-sensitivity magnetic field imaging for widely available electron microscopes.

Journal
Springer Science and Business Media LLC
Date Published
Group (Lab)
Dan C. Ralph Group

Theory of a continuous bandwidth-tuned Wigner-Mott transition

Cornell Affiliated Author(s)
Author
Seth Musser
T. Senthil
Debanjan Chowdhury
Abstract

We develop a theory for a continuous bandwidth-tuned transition at fixed fractional electron filling from a metal with a generic Fermi surface to a "Wigner-Mott"insulator that spontaneously breaks crystalline space-group symmetries. Across the quantum critical point, (i) the entire electronic Fermi surface disappears abruptly upon approaching from the metallic side, and (ii) the insulating charge gap and various order parameters associated with the spontaneously broken space-group symmetries vanish continuously upon approaching from the insulating side.

Journal
Physical Review B
Date Published
Group (Lab)
Debanjan Chowdhury Group

Criticality and entanglement in nonunitary quantum circuits and tensor networks of noninteracting fermions

Cornell Affiliated Author(s)
Author
C.-M. Jian
B. Bauer
A. Keselman
A.W.W. Ludwig
Abstract

Models for nonunitary quantum dynamics, such as quantum circuits that include projective measurements, have recently been shown to exhibit rich quantum critical behavior. There are many complementary perspectives on this behavior. For example, there is a known correspondence between d-dimensional local nonunitary quantum circuits and tensor networks on a [D=(d+1)]-dimensional lattice.

Journal
Physical Review B
Date Published
Group (Lab)
Chao-Ming Jian Group

Mechanisms underlying WNT-mediated priming of human embryonic stem cells

Cornell Affiliated Author(s)
Author
A. Yoney
L. Bai
A.H. Brivanlou
E.D. Siggia
Abstract

Embryogenesis is guided by a limited set of signaling pathways dynamically expressed in different places. How a context-dependent signaling response is generated has been a central question of developmental biology, which can now be addressed with in vitro models of human embryos that are derived from embryonic stem cells (hESCs). Our previous work demonstrated that during early stages of hESC differentiation, cells chronicle signaling hierarchy.

Journal
Development (Cambridge)
Date Published
Research Area

Dynamics of spin helices in the one-dimensional XX model

Cornell Affiliated Author(s)
Author
D. Pereira
E.J. Mueller
Abstract

Motivated by cold-atom experiments and a desire to understand far-from-equilibrium quantum transport, we analytically study the dynamics of spin helices in the one-dimensional XX model. We use a Jordan-Wigner transformation to map the spin chain onto a noninteracting Fermi gas with simple equations of motion. The resulting dynamics are nontrivial, however, as the spin-helix initial condition corresponds to a highly nonequilibrium distribution of the fermions. We find a separation of timescales between the in-plane and out-of-plane spin dynamics.

Journal
Physical Review A
Date Published
Group (Lab)
Erich Mueller Group

Fractional correlated insulating states at one-third filled magic angle twisted bilayer graphene

Cornell Affiliated Author(s)
Author
K. Zhang
Y. Zhang
L. Fu
Eun-Ah Kim
Abstract

The observation of superconductivity and correlated insulating states in twisted bilayer graphene has motivated much theoretical progress at integer fillings. However, little attention has been given to fractional fillings. Here we show that the three-peak structure of Wannier orbitals, dictated by the symmetry and topology of flat bands, facilitates the emergence of a state we name a “fractional correlated insulator” at commensurate fractional filling of ν = n ± 1/3.

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

X-ray nano-imaging of defects in thin film catalysts via cluster analysis

Cornell Affiliated Author(s)
Author
A. Luo
O.Y. Gorobtsov
J.N. Nelson
D.-Y. Kuo
T. Zhou
Z. Shao
R. Bouck
M.J. Cherukara
M.V. Holt
K.M. Shen
D.G. Schlom
J. Suntivich
A. Singer
Abstract

Functional properties of transition-metal oxides strongly depend on crystallographic defects; crystallographic lattice deviations can affect ionic diffusion and adsorbate binding energies. Scanning x-ray nanodiffraction enables imaging of local structural distortions across an extended spatial region of thin samples. Yet, localized lattice distortions remain challenging to detect and localize using nanodiffraction, due to their weak diffuse scattering.

Journal
Applied Physics Letters
Date Published
Group (Lab)
Kyle Shen Group

Hamiltonian reconstruction as metric for variational studies

Cornell Affiliated Author(s)
Author
K. Zhang
S. Lederer
K. Choo
T. Neupert
Giuseppe Carleo
Eun-Ah Kim
Abstract

Variational approaches are among the most powerful techniques to approximately solve quantum many-body problems. These encompass both variational states based on tensor or neural networks, and parameterized quantum circuits in variational quantum eigensolvers. However, self-consistent evaluation of the quality of variational wavefunctions is a notoriously hard task. Using a recently developed Hamiltonian reconstruction method, we propose a multi-faceted approach to evaluating the quality of neural-network based wavefunctions.

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