58 research outputs found
Compressive ghost imaging
We describe an advanced image reconstruction algorithm for pseudothermal
ghost imaging, reducing the number of measurements required for image recovery
by an order of magnitude. The algorithm is based on compressed sensing, a
technique that enables the reconstruction of an N-pixel image from much less
than N measurements. We demonstrate the algorithm using experimental data from
a pseudothermal ghost-imaging setup. The algorithm can be applied to data taken
from past pseudothermal ghost-imaging experiments, improving the
reconstruction's quality.Comment: Comments are welcom
Quantum Correlations in Two-Particle Anderson Localization
We predict the quantum correlations between non-interacting particles
evolving simultaneously in a disordered medium. While the particle density
follows the single-particle dynamics and exhibits Anderson localization, the
two-particle correlation develops unique features that depend on the quantum
statistics of the particles and their initial separation. On short time scales,
the localization of one particle becomes dependent on whether the other
particle is localized or not. On long time scales, the localized particles show
oscillatory correlations within the localization length. These effects can be
observed in Anderson localization of non-classical light and ultra-cold atoms.Comment: 4 pages, 4 figures, comments welcom
Development of a density inversion in driven granular gases
Granular materials fluidized by a rapidly vibrating bottom plate often
develop a fascinating density inversion: a heavier layer of granulate supported
by a lower-density region. We employ the Navier-Stokes granular hydrodynamics
to follow a density inversion as it develops in time. Assuming a dilute
low-Mach-number flow, we derive a reduced time-dependent model of the late
stage of the dynamics. The model looks especially simple in the Lagrangian
coordinates. The time-dependent solution describes the growth of a density peak
at an intermediate height. A transient temperature minimum is predicted to
develop in the region of the density peak. The temperature minimum disappears
at later times, as the system approaches the steady state. At late times, the
predictions of the low-Mach-number model are in good agreement with a numerical
solution of the full hydrodynamic equations. At an early stage of the dynamics,
pressure oscillations are predicted.Comment: 13 pages, 6 figures. To appear in "Granular Gas Dynamics", ed. by T.
Poeschel and N. Brilliantov, vol. 624 of "Lecture Notes in Physics", Springe
Bloch oscillations of Path-Entangled Photons
We show that when photons in N-particle path entangled |N,0> + |0,N> state
undergo Bloch oscillations, they exhibit a periodic transition between
spatially bunched and antibunched states. The transition occurs even when the
photons are well separated in space. We study the scaling of the
bunching-antibunching period, and show it is proportional to 1/N.Comment: An error in figure 1b of the original manuscript was corrected, and
the period was redefine
Spectral Polarization and Spectral Phase Control of Time and Energy Entangled Photons
We demonstrate a scheme to spectrally manipulate a collinear, continuous
stream of time and energy entangled photons to generate beamlike,
bandwidth-limited fuxes of polarization-entangled photons with
nearly-degenerate wavelengths. Utilizing an ultrashort-pulse shaper to control
the spectral phase and polarization of the photon pairs, we tailor the shape of
the Hong-Ou-Mandel interference pattern, demonstrating the rules that govern
the dependence of this interference pattern on the spectral phases of the
photons. We then use the pulse shaper to generate all four polarization Bell
states. The singlet state generated by this scheme forms a very robust
decoherence-free subspace, extremely suitable for long distance fiber-optics
based quantum communication.Comment: 5 pages, 3 figure
Quantum Walk of Two Interacting Bosons
We study the effect of interactions on the bosonic two-particle quantum walk
and its corresponding spatial correlations. The combined effect of interactions
and Hanbury-Brown Twiss interference results in unique spatial correlations
which depend on the strength of the interaction, but not on its sign. The
results are explained in light of the two-particle spectrum and the physics of
attractively and repulsively bound pairs. We experimentally measure the weak
interaction limit of these effects in nonlinear photonic lattices. Finally, we
discuss an experimental approach to observe the strong interaction limit using
single atoms in optical lattices.Comment: 4 pages, 5 figures. Comments wellcom
Resource-efficient photonic quantum computation with high-dimensional cluster states
Quantum computers can revolutionize science and technology, but their
realization remains challenging across all platforms. A promising route to
scalability is photonic measurement-based quantum computation, where
single-qubit measurements on large cluster states, together with feedforward,
enable fault-tolerant quantum computation. However, generating large cluster
states at high rates is notoriously difficult, as detection probabilities drop
exponentially with the number of photons comprising the state. We tackle this
challenge by encoding multiple qubits on each photon through high-dimensional
spatial encoding, generating cluster states with over nine qubits at a rate of
100Hz. Additionally, we demonstrate that high-dimensional encoding
substantially reduces the computation duration by enabling instantaneous
feedforward between qubits encoded in the same photon. Our findings pave the
way for resource-efficient measurement-based quantum computation using
high-dimensional entanglement
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