RESEARCH
Our research encompasses
a variety of problems and techniques in quantum condensed matter theory.
Our themes range from
the highly exotic, such as long-range entangled states of matter,
to the technologically
relevant, such as the understanding of the fundamental limits to efficiency of
photovoltaic energy generation.
We enjoy collaborating
with experimental groups and are always looking at experiments for inspiration.
Below is a sample of our research.
Quantum spin liquids
and other highly entangled states of matter
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We introduced a new kind of U(1)
‘’pseudo-scalar’’ quantum spin liquids that could explain the vanishing
thermal Hall effect coexisting with quantum oscillations in alpha-RuCl3 (see arXiv).
Our work was highlighted in the Journal
of Condensed Matter Physics. |
By establishing an exact duality map, we computed
the Berry phases that the emergent vison particle acquires when moving in a
plaquette of Z2 spin liquids (see arXiv and also our PRR).
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Depiction of an exact map that we developed
from quantum electric field lines on the six vertex and dimer models onto
one-dimensional quantum spin chains (see arXiv). |
Berry phases and in
non-linear transport and optics
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We found a divergence of the Berry curvature over
an entire line (the “hot-line” ) associated with the Fermi arcs
of Weyl semimetals, which can lead to a variety of interesting observable
effects. Our work was highlighted as an Editor
suggestion in PRL. |
We established the “Quantum Rectifcation Sum Rule” according to which the integral over
frequency of the rectification conductivity of time reversal invariant
materials depends only on the Berry connections of their bands and not of the
energy dispersions. Our work was highlighted in the cover of PRL.
See also predictions for real materials here. |
We introduced the notion of “Berry Curvature
Dipole” and its connection to the non-linear Hall conductivity in time
reversal invariant materials (see PRL). |
Quantum Hall liquids
and novel probes of fractionalization
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We introduced a class of excitonic Laughlin
states that could be potentially relevant to certain Moire
superlattice materials (see PRB). |
We developed a theory of competing Laughlin-like
fractionalized states with broken symmetry relevant for graphene placed on boron
nitride (See PRB). |
We developed a theory of the cyclotron resonance
of the Spinon Fermi surface state that could be
used to pinpoint the presence of these states in correlated materials (see PRB). |
Strongly interacting
gapless fermions
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We found than in the “quantum” limit there is a
remarkable universality of the transverse conductivity of metals and its
associated magnetic noise which can be measured with an NV center spin qubit,
which make them controlled only by the geometrical shape of their fermi surface
(see NJP).
There is also a related behavior for the spinon
fermi surface state (see arXiv). |
We developed a bosonization
map for Q=0 excitations of Dirac fermions in 2+1D and utilized it to non-perturbatively
compute the interaction corrections to their optical conductivity (see PRB). |
We studied a remarkable collective mode of the
strongly interacting Fermi fluids known as the “shear sound mode” and made a
proposal for how to detect it experimentally (see PRB
and PRB). |