26 research outputs found
Photonic Jackiw-Rebbi states in all-dielectric structures controlled by bianisotropy
Electric and magnetic resonances of dielectric particles have recently
uncovered a range of exciting applications in steering of light at the
nanoscale. Breaking of particle inversion symmetry further modifies its
electromagnetic response giving rise to bianisotropy known also as
magneto-electric coupling. Recent studies suggest the crucial role of
magneto-electric coupling in realization of photonic topological metamaterials.
To further unmask this fundamental link, we design and test experimentally
one-dimensional array composed of dielectric particles with overlapping
electric and magnetic resonances and broken mirror symmetry. Flipping over half
of the meta-atoms in the array, we observe the emergence of interface states
providing photonic realization of the celebrated Jackiw-Rebbi model. We trace
the origin of these states to the fact that local modification of particle
bianisotropic response affects its effective coupling with the neighboring
meta-atoms which provides a promising avenue to engineer topological states of
light.Comment: 5 pages, 5 figure
Matter-Wave Tractor Beams
Optical and acoustic tractor beams are currently the focus of intense research due to their counterintuitive property of exerting a pulling force on small scattering objects. In this Letter we propose a matter-wave tractor beam and utilize the de Broglie waves of nonrelativistic matter particles in analogy to “classical” tractor beams. We reveal the presence of the quantum-mechanical pulling force for the variety of quantum mechanical potentials observing the resonant enhancement of the pulling effect under the conditions of the suppressed scattering known as the Ramsauer-Townsend effect. We also derive the sufficient conditions on the scattering potential for the emergence of the pulling force and show that, in particular, a Coulomb scatterer is always shoved, while a Yukawa (screened Coulomb) scatterer can be drawn. Pulling forces in optics, acoustics, quantum mechanics, and classical mechanics are compared, and the matter-wave pulling force is found to have exclusive properties of dragging slow particles in short-range potentials. We envisage that the use of tractor beams could lead to the unprecedented precision in manipulation with atomic-scale quantum objects
Light emission from strongly driven many-body systems
Strongly driven systems of emitters offer an attractive source of light over
broad spectral ranges up to the X-ray region. A key limitation of these systems
is that the light they emit is for the most part classical. We challenge this
paradigm by building a quantum-optical theory of strongly driven many-body
systems, showing that the presence of correlations among the emitters creates
emission of nonclassical many-photon states of light. We consider the example
of high-harmonic generation (HHG), by which a strongly driven system emits
photons at integer multiples of the drive frequency. In the conventional case
of uncorrelated emitters, the harmonics are in an almost perfectly multi-mode
coherent state lacking any correlation between harmonics. By contrast, a
correlation of the emitters prior to the strong drive is converted onto
nonclassical features of the output light, including doubly-peaked photon
statistics, ring-shaped Wigner functions, and quantum correlations between
harmonics. We propose schemes for implementing these concepts, creating the
correlations between emitters via an interaction between them or their joint
interaction with the background electromagnetic field (as in superradiance). By
tuning the time at which these processes are interrupted by the strong drive,
one can control the amount of correlations between the emitters, and
correspondingly the deviation of the emitted light from a classical state. Our
work paves the way towards the engineering of novel many-photon states of light
over a broadband spectrum of frequencies, and suggests HHG as a diagnostic tool
for characterizing correlations in many-body systems with attosecond temporal
resolution.Comment: 26 pages main (5 figures), 23 pages Supplementary Informatio
Photon-statistics force in ultrafast electron dynamics
In strong-field physics and attosecond science, intense light induces
ultrafast electron dynamics. Such ultrafast dynamics of electrons in matter is
at the core of phenomena such as high harmonic generation (HHG), where these
dynamics lead to emission of extreme UV bursts with attosecond duration. So
far, all ultrafast dynamics of matter were understood to originate purely from
the classical vector potential of the driving light, disregarding the influence
of the quantum nature of light. Here we show that dynamics of matter driven by
bright (intense) light significantly depend on the quantum state of the driving
light, which induces an effective photon-statistics force. To provide a unified
framework for the analysis & control over such a force, we extend the
strong-field approximation (SFA) theory to account for non-classical driving
light. Our quantum SFA (qSFA) theory shows that in HHG, experimentally feasible
squeezing of the driving light can shift & shape electronic trajectories and
attosecond pulses at the scale of hundreds of attoseconds. Our work presents a
new degree-of-freedom for attosecond spectroscopy, by relying on nonclassical
electromagnetic fields, and more generally, introduces a direct connection
between attosecond science and quantum optics
Generation of squeezed high-order harmonics
For decades, most research on high harmonic generation (HHG) considered
matter as quantum but light as classical, leaving the quantum-optical nature of
the harmonics an open question. Here we explore the quantum properties of high
harmonics. We derive a formula for the quantum state of the high harmonics,
when driven by arbitrary quantum light states, and then explore specific cases
of experimental relevance. Specifically, for a moderately squeezed pump, HHG
driven by squeezed coherent light results in squeezed high harmonics. Harmonic
squeezing is optimized by syncing ionization times with the pump's squeezing
phase. Beyond this regime, as pump squeezing is increased, the harmonics
initially acquire squeezed thermal photon statistics, and then occupy an
intricate quantum state which strongly depends on the semi-classical nonlinear
response function of the interacting system. Our results pave the way for the
generation of squeezed extreme-ultraviolet ultrashort pulses, and, more
generally, quantum frequency conversion into previously inaccessible spectral
ranges, which may enable ultrasensitive attosecond metrology