12 research outputs found
Quantum interferometry with three-dimensional geometry
Quantum interferometry uses quantum resources to improve phase estimation
with respect to classical methods. Here we propose and theoretically
investigate a new quantum interferometric scheme based on three-dimensional
waveguide devices. These can be implemented by femtosecond laser waveguide
writing, recently adopted for quantum applications. In particular, multiarm
interferometers include "tritter" and "quarter" as basic elements,
corresponding to the generalization of a beam splitter to a 3- and 4-port
splitter, respectively. By injecting Fock states in the input ports of such
interferometers, fringe patterns characterized by nonclassical visibilities are
expected. This enables outperforming the quantum Fisher information obtained
with classical fields in phase estimation. We also discuss the possibility of
achieving the simultaneous estimation of more than one optical phase. This
approach is expected to open new perspectives to quantum enhanced sensing and
metrology performed in integrated photonic.Comment: 7 pages (+4 Supplementary Information), 5 figure
Direct laser-writing of ferroelectric single-crystal waveguide architectures in glass for 3D integrated optics
Direct three-dimensional laser writing of amorphous waveguides inside glass has been studied intensely as an attractive route for fabricating photonic integrated circuits. However, achieving essential nonlinear-optic functionality in such devices will also require the ability to create high-quality single-crystal waveguides. Femtosecond laser irradiation is capable of crystallizing glass in 3D, but producing optical-quality single-crystal structures suitable for waveguiding poses unique challenges that are unprecedented in the field of crystal growth. In this work, we use a high angular-resolution electron diffraction method to obtain the first conclusive confirmation that uniform single crystals can be grown inside glass by femtosecond laser writing under optimized conditions. We confirm waveguiding capability and present the first quantitative measurement of power transmission through a laser-written crystal-in-glass waveguide, yielding loss of 2.64âdB/cm at 1530ânm. We demonstrate uniformity of the crystal cross-section down the length of the waveguide and quantify its birefringence. Finally, as a proof-of-concept for patterning more complex device geometries, we demonstrate the use of dynamic phase modulation to grow symmetric crystal junctions with single-pass writing
Three-photon bosonic coalescence in an integrated tritter
The main features of quantum mechanics reside in interference deriving from
the superposition of different quantum objects. While current quantum optical
technology enables two-photon interference both in bulk and integrated systems,
simultaneous interference of more than two particles, leading to richer quantum
phenomena, is still a challenging task. Here we report the experimental
observation of three-photon interference in an integrated three-port
directional coupler realized by ultrafast laser-writing. By exploiting the
capability of this technique to produce three-dimensional structures, we
realized and tested in the quantum regime a three-port beam splitter, namely a
tritter, which allowed us to observe bosonic coalescence of three photons.
These results open new important perspectives in many areas of quantum
information, such as fundamental tests of quantum mechanics with increasing
number of photons, quantum state engineering, quantum sensing and quantum
simulation.Comment: 7+13 pages, 5+5 figure