3,124 research outputs found
Weak value amplification: a view from quantum estimation theory that highlights what it is and what isn't
Weak value amplification (WVA) is a concept that has been extensively used in
a myriad of applications with the aim of rendering measurable tiny changes of a
variable of interest. In spite of this, there is still an on-going debate about
its true nature and whether is really needed for achieving high sensitivity.
Here we aim at solving the puzzle, using some basic concepts from quantum
estimation theory, highlighting what the use of the WVA concept can offer and
what it can not. While WVA cannot be used to go beyond some fundamental
sensitivity limits that arise from considering the full nature of the quantum
states, WVA can notwithstanding enhance the sensitivity of real detection
schemes that are limited by many other things apart from the quantum nature of
the states involved, i.e. technical noise. Importantly, it can do that in a
straightforward and easily accessible manner.Comment: 2 pages, 5 figure
Highly-efficient noise-assisted energy transport in classical oscillator systems
Photosynthesis is a biological process that involves the highly-efficient
transport of energy captured from the sun to a reaction center, where
conversion into useful biochemical energy takes place. Even though one can
always use a quantum perspective to describe any physical process, since
everything follows the laws of Quantum Mechanics, is the use of quantum theory
imperative to explain this high efficiency? Making use of the quantum-classical
correspondence of electronic energy transfer recently introduced by Eisfeld and
Briggs [Phys. Rev. E 85, 046118 (2012)], we show here that the highly-efficient
noise-assisted energy transport described by Rebentrost et al. [New J. Phys.
11, 033003 (2009)], and Plenio and Huelga [New J. Phys. 10, 113019 (2008)], as
the result of the interplay between the quantum coherent evolution of the
photosynthetic system and noise introduced by its surrounding environment, it
can be found as well in purely classical systems. The wider scope of
applicability of the enhancement of energy transfer assisted by noise might
open new ways for developing new technologies aimed at enhancing the efficiency
of a myriad of energy transfer systems, from information channels in
micro-electronic circuits to long-distance high-voltage electrical lines.Comment: 4 pages, 3 figure
Measurement-based tailoring of Anderson localization of partially coherent light
We put forward an experimental configuration to observe transverse Anderson
localization of partially coherent light beams with a tunable degree of
first-order coherence. The scheme makes use of entangled photons propagating in
disordered waveguide arrays, and is based on the unique relationship between
the degree of entanglement of a pair of photons and the coherence properties of
the individual photons constituting the pair. The scheme can be readily
implemented with current waveguide-on-a-chip technology, and surprisingly, the
tunability of the coherence properties of the individual photons is done at the
measurement stage, without resorting changes of the light source itself.Comment: 7 pages, 5 figures, additional correction
Frequency conversion of structured light
We demonstrate the coherent frequency conversion of structured light, optical
beams in which the phase varies in each point of the transverse plane, from the
near infrared (803nm) to the visible (527nm). The frequency conversion process
makes use of sum-frequency generation in a periodically poled lithium niobate
(ppLN) crystal with the help of a 1540-nm Gaussian pump beam. We perform
far-field intensity measurements of the frequency-converted field, and verify
the sought-after transformation of the characteristic intensity and phase
profiles for various input modes. The coherence of the frequency-conversion
process is confirmed using a mode-projection technique with a phase mask and a
single-mode fiber. The presented results could be of great relevance to novel
applications in high-resolution microscopy and quantum information processing
How to automate a kinematic mount using a 3D printed Arduino-based system
We demonstrate a simple, flexible and cost-effective system to automatize
most of the kinematic mounts available nowadays on the market. It combines 3D
printed components, an Arduino board, stepper motors, and simple electronics.
The system developed can control independently and simultaneously up to ten
stepper motors using commands sent through the serial port, and it is suitable
for applications where optical realignment using flat mirrors is required on a
periodic basis.Comment: 9 pages, 8 figure
Generation of indistinguishable and pure heralded single photons with tunable bandwidth
We describe a new scheme to fully control the joint spectrum of paired
photons generated in spontaneous parametric down-conversion. We show the
capability of this method to generate frequency-uncorrelated photon pairs that
are pure and indistinguishable, and whose bandwidth can be readily tuned.
Importantly, the scheme we propose here can be implemented in any nonlinear
crystal and frequency band of interest.Comment: 3 pages, 3 figure
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