44 research outputs found
Experimental generation and characterization of single-photon hybrid ququarts based on polarization-orbital angular momentum encoding
High-dimensional quantum states, or qudits, represent a promising resource in
the quantum information field. Here we present the experimental generation of
four-dimensional quantum states, or ququarts, encoded in the polarization and
orbital angular momentum of a single photon. Our novel technique, based on the
q-plate device, allows to prepare and measure the ququart in all five mutually
unbiased bases. We report the reconstruction of the four dimensional density
matrix through the tomographic procedure for different ququart states.Comment: 7 pages, 5 figure
Experimental Detection of Quantum Channels
We demonstrate experimentally the possibility of efficiently detecting
properties of quantum channels and quantum gates. The optimal detection scheme
is first achieved for non entanglement breaking channels of the depolarizing
form and is based on the generation and detection of polarized entangled
photons. We then demonstrate channel detection for non separable maps by
considering the CNOT gate and employing two-photon hyperentangled states.Comment: 8 pages, 9 figure
Two-particle bosonic-fermionic quantum walk via 3D integrated photonics
Quantum walk represents one of the most promising resources for the
simulation of physical quantum systems, and has also emerged as an alternative
to the standard circuit model for quantum computing. Up to now the experimental
implementations have been restricted to single particle quantum walk, while
very recently the quantum walks of two identical photons have been reported.
Here, for the first time, we investigate how the particle statistics, either
bosonic or fermionic, influences a two-particle discrete quantum walk. Such
experiment has been realized by adopting two-photon entangled states and
integrated photonic circuits. The polarization entanglement was exploited to
simulate the bunching-antibunching feature of non interacting bosons and
fermions. To this scope a novel three-dimensional geometry for the waveguide
circuit is introduced, which allows accurate polarization independent
behaviour, maintaining a remarkable control on both phase and balancement.Comment: 4 pages, 5 figures + supplementary informatio
Integrated optical waveplates for arbitrary operations on polarization-encoded single-qubits
Integrated photonic technologies applied to quantum optics have recently
enabled a wealth of breakthrough experiments in several quantum information
areas. Path encoding was initially used to demonstrate operations on single or
multiple qubits. However, a polarization encoding approach is often simpler and
more effective. Two-qubits integrated logic gates as well as complex
interferometric structures have been successfully demonstrated exploiting
polarization encoding in femtosecond-laser-written photonic circuits. Still,
integrated devices performing single-qubit rotations are missing. Here we
demonstrate waveguide-based waveplates, fabricated by femtosecond laser pulses,
capable to effectively produce arbitrary single-qubit operations in the
polarization encoding. By exploiting these novel components we fabricate and
test a compact device for the quantum state tomography of two
polarization-entangled photons. The integrated optical waveplates complete the
toolbox required for a full manipulation of polarization-encoded qubits
on-chip, disclosing new scenarios for integrated quantum computation, sensing
and simulation, and possibly finding application also in standard photonic
devices