17 research outputs found
Multi-photon nonclassical correlations in entangled squeezed vacuum states
Photon-number correlation measurements are performed on bright squeezed
vacuum states using a standard Bell-test setup, and quantum correlations are
observed for conjugate polarization-frequency modes. We further test the
entanglement witnesses for these states and demonstrate the violation of the
separability criteria, which infers that all the macroscopic Bell states,
containing typically photons per pulse, are polarization entangled. The
study also reveals the symmetry of macroscopic Bell states with respect to
local polarization transformations.Comment: 5 pages, 4 figure
Macroscopic Pure State of Light Free of Polarization Noise
The preparation of completely non-polarized light is seemingly easy: an
everyday example is sunlight. The task is much more difficult if light has to
be in a pure quantum state, as required by most quantum-technology
applications. The pure quantum states of light obtained so far are either
polarized or, in rare cases, manifest hidden polarization: even if their
intensities are invariant to polarization transformations, higher-order moments
are not. We experimentally demonstrate the preparation of the macroscopic
singlet Bell state, which is pure, completely non-polarized, and has no
polarization noise. Simultaneous fluctuation suppression in three Stokes
observables below the shot-noise limit is demonstrated, opening perspectives
for noiseless polarization measurements. The state is shown to be invariant to
polarization transformations. This robust highly entangled isotropic state
promises to fuel important applications in photonic quantum technologies.Comment: 4 pages, 2 figures, 1 tabl
Polarization-Entangled Light Pulses of 10^5 Photons
We experimentally demonstrate polarization entanglement for squeezed vacuum
pulses containing more than 10^5 photons. We also study photon-number
entanglement by calculating the Schmidt number and measuring its operational
counterpart. Theoretically, our pulses are the more entangled the brighter they
are. This promises important applications in quantum technologies, especially
photonic quantum gates and quantum memories.Comment: 8 pages, 6 figure
Generation and Direct Detection of Broadband Mesoscopic Polarization-Squeezed Vacuum
Using a traveling-wave OPA with two orthogonally oriented type-I BBO crystals
pumped by picosecond pulses, we generate vertically and horizontally polarized
squeezed vacuum states within a broad range of wavelengths and angles.
Depending on the phase between these states, fluctuations in one or another
Stokes parameters are suppressed below the shot-noise limit. Due to the large
number of photon pairs produced, no local oscillator is required, and 3dB
squeezing is observed by means of direct detection.Comment: 4 pages, 4 figures, submitted to PR
Raman-free, noble-gas-filled PCF source for ultrafast, very bright twin-beam squeezed vacuum
We report a novel source of twin beams based on modulational instability in
high-pressure argon-filled hollow-core kagom\'e-style photonic-crystal fibre.
The source is Raman-free and manifests strong photon-number correlations for
femtosecond pulses of squeezed vacuum with a record brightness of ~2500 photons
per mode. The ultra-broadband (~50 THz) twin beams are frequency tunable and
contain one spatial and less than 5 frequency modes
Measurement of two-mode squeezing with photon number resolving multi-pixel detectors
The measurement of the two-mode squeezed vacuum generated in an optical
parametric amplifier (OPA) was performed with photon number resolving
Multi-Pixel Photon Counters (MPPCs). Implementation of the MPPCs allows for the
observation of noise reduction in a broad dynamic range of the OPA gain, which
is inaccessible with standard single photon avalanche photodetectors.Comment: Accepted for Optics Letter