32,390 research outputs found
Polarization and valley switching in monolayer group-IV monochalcogenides
Group-IV monochalcogenides are a family of two-dimensional puckered materials
with an orthorhombic structure that is comprised of polar layers. In this
article, we use first principles calculations to show the multistability of
monolayer SnS and GeSe, two prototype materials where the direction of the
puckering can be switched by application of tensile stress or electric field.
Furthermore, the two inequivalent valleys in momentum space, which are dictated
by the puckering orientation, can be excited selectively using linearly
polarized light, and this provides an additional tool to identify the
polarization direction. Our findings suggest that SnS and GeSe monolayers may
have observable ferroelectricity and multistability, with potential
applications in information storage
2D materials and van der Waals heterostructures
The physics of two-dimensional (2D) materials and heterostructures based on
such crystals has been developing extremely fast. With new 2D materials, truly
2D physics has started to appear (e.g. absence of long-range order, 2D
excitons, commensurate-incommensurate transition, etc). Novel heterostructure
devices are also starting to appear - tunneling transistors, resonant tunneling
diodes, light emitting diodes, etc. Composed from individual 2D crystals, such
devices utilize the properties of those crystals to create functionalities that
are not accessible to us in other heterostructures. We review the properties of
novel 2D crystals and how their properties are used in new heterostructure
devices
Controlling chaos in the quantum regime using adaptive measurements
The continuous monitoring of a quantum system strongly influences the
emergence of chaotic dynamics near the transition from the quantum regime to
the classical regime. Here we present a feedback control scheme that uses
adaptive measurement techniques to control the degree of chaos in the
driven-damped quantum Duffing oscillator. This control relies purely on the
measurement backaction on the system, making it a uniquely quantum control, and
is only possible due to the sensitivity of chaos to measurement. We quantify
the effectiveness of our control by numerically computing the quantum Lyapunov
exponent over a wide range of parameters. We demonstrate that adaptive
measurement techniques can control the onset of chaos in the system, pushing
the quantum-classical boundary further into the quantum regime
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