arXiv (Cornell University),
Год журнала:
2023,
Номер
unknown
Опубликована: Янв. 1, 2023
Accessing
the
low-energy
non-equilibrium
dynamics
of
materials
and
their
polaritons
with
simultaneous
high
spatial
temporal
resolution
has
been
a
bold
frontier
electron
microscopy
in
recent
years.
One
main
challenges
lies
ability
to
retrieve
extremely
weak
signals
while
simultaneously
disentangling
amplitude
phase
information.
Here,
we
present
Free-Electron
Ramsey
Imaging
(FERI),
approach
based
on
light-induced
modulation
that
enables
coherent
amplification
optical
near-fields
imaging.
We
provide
time-,
space-,
phase-resolved
measurements
micro-drum
made
from
hexagonal
boron
nitride
membrane
visualizing
sub-cycle
2D
polariton
wavepackets
therein.
The
reveals
vortex-anti-vortex
singularities
wavefronts,
together
an
intriguing
phenomenon
traveling
wave
mimicking
profile
standing
wave.
Our
experiments
show
20-fold
near-field
signal
compared
conventional
imaging,
resolving
peak
field
intensities
order
~W/cm2,
corresponding
amplitudes
few
kV/m.
As
result,
our
work
paves
way
for
spatio-temporal
biological
specimens
quantum
materials,
exciting
yet
delicate
samples
are
currently
difficult
investigate.
Physical Review Letters,
Год журнала:
2024,
Номер
132(8)
Опубликована: Фев. 23, 2024
We
demonstrate
a
silicon-based
electron
accelerator
that
uses
laser
optical
near
fields
to
both
accelerate
and
confine
electrons
over
extended
distances.
Two
dielectric
(DLA)
designs
were
tested,
each
consisting
of
two
arrays
silicon
pillars
pumped
symmetrically
by
pulse
front
tilted
beams,
designed
for
average
acceleration
gradients
35
$50\text{
}\text{
}\mathrm{MeV}/\mathrm{m}$,
respectively.
The
DLAs
are
act
as
alternating
phase
focusing
(APF)
lattices,
where
electrons,
depending
on
the
electron-laser
interaction
phase,
will
alternate
between
opposing
longitudinal
transverse
defocusing
forces.
By
incorporating
fractional
period
drift
sections
alter
synchronous
$\ifmmode\pm\else\textpm\fi{}60\ifmmode^\circ\else\textdegree\fi{}$
off
crest,
captured
in
bucket
experience
half
peak
gradient
while
also
experiencing
strong
confinement
forces
enable
long
lengths.
APF
accelerators
with
lengths
up
$708\text{
}\mathrm{\ensuremath{\mu}}\mathrm{m}$
energy
gains
$23.7\ifmmode\pm\else\textpm\fi{}1.07\text{
}\mathrm{keV}$
FWHM,
25%
increase
from
starting
energy,
demonstrating
ability
achieve
substantial
subrelativistic
DLA.
Physical Review Letters,
Год журнала:
2025,
Номер
134(4)
Опубликована: Янв. 31, 2025
The
emerging
field
of
free-electron
quantum
optics
enables
electron-photon
entanglement
and
holds
the
potential
for
generating
nontrivial
photon
states
information
processing.
Although
recent
experimental
studies
have
entered
regime,
rapid
theoretical
developments
predict
that
qualitatively
unique
phenomena
only
emerge
beyond
a
certain
interaction
strength.
It
is
thus
pertinent
to
identify
maximal
strength
materials,
geometries,
particle
energies
enable
one
approach
it.
We
derive
an
upper
limit
vacuum
between
free
electrons
single-mode
photons,
which
illuminates
conditions
strongest
interaction.
Crucially,
we
obtain
explicit
energy
selection
recipe
photons
achieve
at
arbitrary
separations
two
optimal
regimes
favoring
either
fast
or
slow
over
those
with
intermediate
velocities.
validate
by
analytical
numerical
calculations
on
canonical
geometries
provide
near-optimal
designs
indicating
feasibility
strong
interactions.
Our
findings
offer
fundamental
intuition
maximizing
practical
design
rules
future
experiments
electron-mediated
photon-photon
entanglement.
They
should
also
evaluation
key
metrics
applications
such
as
maximum
power
radiation
sources
acceleration
gradient
dielectric
laser
accelerators.
The
Jaynes-Cummings
Hamiltonian
is
at
the
core
of
cavity
quantum
electrodynamics;
however,
it
relies
on
bound-electron
emitters
fundamentally
limited
by
binding
Coulomb
potential.
In
this
work,
we
propose
theoretically
a
new
approach
to
realizing
model
using
low-energy
free
electrons
coupled
dielectric
microcavities
and
exemplify
several
technologies
made
possible
approach.
Using
recoil,
large
detuning
inhibits
emission
multiple
consecutive
photons,
effectively
transforming
electron
into
few-level
system
mode.
We
show
that
can
be
used
for
generation
single
photon
pairs,
even
SWAP
gate
between
electron,
with
unity
efficiency
high
fidelity.
Tunable
their
kinetic
energy,
are
inherently
versatile
an
engineerable
wavelength.
Hence,
they
pave
way
toward
possibilities
interconnects
photonic
platforms
disparate
spectral
regimes.
ACS Photonics,
Год журнала:
2024,
Номер
11(8), С. 3401 - 3411
Опубликована: Июль 29, 2024
A
central
challenge
in
the
emerging
field
of
free-electron
quantum
optics
is
to
achieve
strong
interaction
and
single-photon
nonlinearity
between
a
flying
free
electron
photonic
mode.
Existing
schemes
are
intrinsically
limited
by
diffraction,
which
puts
an
upper
bound
on
length
and,
therefore,
strength
coupling
nonlinearity.
Here,
we
propose
"free-electron
fibers":
effectively
one-dimensional
systems
where
electrons
copropagate
with
two
guided
modes.
The
first
mode
applies
ponderomotive
trap
electron,
removing
limitations
due
diffraction.
second
strongly
couples
enhanced
that
orders
magnitude
larger
than
previous
designs.
extended
lengths
enabled
our
scheme
allow
for
nonlinearities
mediated
electrons.
We
predict
novel
effects
system
such
as
deterministic
emission
nonlinear
multimode
dynamics.
Our
proposal
paves
way
toward
realization
heralded
macroscopic
nonclassical
light
generation,
sources,
gates
controlled
free-electron–photon
interactions.
We
reveal
a
mechanism
to
enhance
particle-matter
interactions
by
exploiting
the
pseudo-Brewster
effect
of
gain
materials,
presenting
an
enhancement
at
least
four
orders
magnitude
for
light
emission.
This
is
enabled
emergence
unprecedented
phase
diagram
that
maps
all
phenomena
free-electron
transition
radiation
into
three
distinct
phases
in
gain-thickness
parameter
space,
namely,
conventional,
intermediate,
and
Brewster
phases,
when
electron
penetrates
dielectric
slab
with
modest
finite
thickness.
Essentially,
our
revealed
corresponds
phase,
which
also
features
ultrahigh
directionality,
always
angle,
regardless
velocity.
Counterintuitively,
we
find
intensity
this
Brewster-transition
insensitive
Fabry-Pérot
resonance
condition
and,
thus,
variation
thickness,
moreover,
weaker
could
lead
stronger
Physical Review Letters,
Год журнала:
2024,
Номер
132(25)
Опубликована: Июнь 17, 2024
An
essential
component
for
quantum-enhanced
measurements
with
free
electrons
is
an
electron
resonator.
We
report
stable
guiding
of
at
50
eV
energy
up
to
seven
round
trips
in
a
linear
autoponderomotive
structure,
which
realized
two
microstructured
printed
circuit
boards
that
generate
the
required
electromagnetic
fields.
Free
are
laser
triggered
from
sharp
tungsten
needle
tip
and
coupled
front
resonator
help
sub-nanosecond-fast
switchable
mirrors.
After
variable
time
delay,
we
open
rear
mirror
measure
number
trapped
delay-line
detector.
demonstrate,
simulate,
show
ways
optimizing
simulations,
will
enable
``interaction-free''
measurement
setups,
including
multipass
quantum-Zeno
effect
based
schemes,
helping
realize
quantum
microscope.
Journal of Applied Physics,
Год журнала:
2025,
Номер
137(3)
Опубликована: Янв. 15, 2025
This
study
investigates
an
anti-symmetrically
positioned
nanophotonic
dual-pillar
structure,
in
which
the
dielectric
and
vacuum
components
are
evenly
distributed
along
direction
of
electron
propagation,
with
each
pillar
facing
a
region.
Our
numerical
simulation
results
show
that
previously
proposed
symmetric
grating
where
pillars
other
alternated
gaps,
is
accompanied
by
deceleration
region,
preventing
achievement
high
gradients
during
acceleration
process.
By
contrast,
anti-symmetric
structure
eliminates
field
generates
uniformly
field.
requires
two
oppositely
directed
laser
beams
crossing
transverse
region
must
have
phase
shift
π
case.
has
significant
potential
for
accelerating
sub-relativistic
beams.
In
this
simulation,
initial
energy
selected
as
79
keV.
The
gradient
provided
design
electrons
approximately
70
MeV/m;
however,
can
provide
maximum
up
to
∼430
MeV/m.
Optics Express,
Год журнала:
2025,
Номер
33(7), С. 14737 - 14737
Опубликована: Март 14, 2025
The
dielectric
laser
accelerator
(DLA)
is
an
innovative
on-chip
particle
that
employs
a
periodic
structure
to
modulate
beam,
generating
longitudinal
accelerating
field
propel
particles.
Leveraging
the
high
laser-induced
damage
threshold
of
materials,
DLAs
can
achieve
significantly
higher
acceleration
gradients
compared
traditional
accelerators.
Current
inverse
design
approaches
for
DLAs,
based
on
adjoint
variable
method
(AVM),
overlook
impact
changes
in
electron
velocity,
which
result
dephasing
between
electrons
and
over
long
distances.
To
address
this
limitation,
we
propose
improved
incorporates
velocity
variations
into
objective
function,
specifically
tailored
long-distance
structures.
Using
incident
electric
amplitude
1.2
GV/m,
designed
20
µm
DLA
capable
26.6
keV
with
average
gradient
347
MeV/m.
Our
ensures
sustained
across
entire
structure,
surpassing
energy
gain
limits
imposed
by
original
approach.
Furthermore,
optimal
initial
closely
aligns
target
value
(26.6
keV),
demonstrating
issue
has
been
effectively
resolved.
This
advancement
paves
way
more
efficient
robust
acceleration.