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Photonic Quantum Simulators
Quantum simulators are controllable quantum systems that can be used to mimic other quantum systems. They have the potential to enable the tackling of problems that are intractable on conventional computers. The photonic quantum technology available today is reaching the stage where significant advantages arise for the simulation of interesting problems in quantum chemistry, quantum biology and solid-state physics. In addition, photonic quantum systems also offer the unique benefit of being mobile over free space and in waveguide structures, which opens new perspectives to the field by enabling the natural investigation of quantum transport phenomena. Here, we review recent progress in the field of photonic quantum simulation, which should break the ground towards the realization of versatile quantum simulators.Chemistry and Chemical Biolog
Tapering of fs Laser-written Waveguides
The vast development of integrated quantum photonic technology enables the
implementation of compact and stable interferometric networks. In particular
laser-written waveguide structures allow for complex 3D-circuits and
polarization-encoded qubit manipulation. However, the main limitation for the
scale-up of integrated quantum devices is the single-photon loss due to
mode-profile mismatch when coupling to standard fibers or other optical
platforms. Here we demonstrate tapered waveguide structures, realized by an
adapted femtosecond laser writing technique. We show that coupling to standard
single-mode fibers can be enhanced up to 77% while keeping the fabrication
effort negligible. This improvement provides an important step for processing
multi-photon states on chip
Gravitationally induced phase shift on a single photon
The effect of the Earth's gravitational potential on a quantum wave function
has only been observed for massive particles. In this paper we present a scheme
to measure a gravitationally induced phase shift on a single photon travelling
in a coherent superposition along different paths of an optical fiber
interferometer. To create a measurable signal for the interaction between the
static gravitational potential and the wave function of the photon, we propose
a variant of a conventional Mach-Zehnder interferometer. We show that the
predicted relative phase difference of radians is measurable even in
the presence of fiber noise, provided additional stabilization techniques are
implemented for each arm of a large-scale fiber interferometer. Effects arising
from the rotation of the Earth and the material properties of the fibers are
analysed. We conclude that optical fiber interferometry is a feasible way to
measure the gravitationally induced phase shift on a single-photon wave
function, and thus provides a means to corroborate the equivalence of the
energy of the photon and its effective gravitational mass.Comment: 13 pages, 5 figure
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