99 research outputs found
Review on qudits production and their application to Quantum Communication and Studies on Local Realism
The codification in higher dimensional Hilbert Spaces (whose logical basis
states are dubbed qudits in analogy with bidimensional qubits) presents various
advantages both for Quantum Information applications and for studies on
Foundations of Quantum Mechanics.
Purpose of this review is to introduce qudits, to summarize their application
to Quantum Communication and researches on Local Realism and, finally, to
describe some recent experiment for realizing them.
A Little more in details: after a short introduction, we will consider the
advantages of testing local realism with qudits, discussing both the 3-4
dimensional case (both for maximally and non-maximally entanglement) and then
the extension to an arbitrary dimension. Afterwards, we will discuss the
theoretical results on using qudits for quantum communication, epitomizing the
outcomes on a larger security in Quantum Key Distribution protocols (again
considering separately qutrits, ququats and generalization to arbitrary
dimension). Finally, we will present the experiments performed up to now for
producing quantum optical qudits and their applications. In particular, we will
mention schemes based on interferometric set-ups, orbital angular momentum
entanglement and biphoton polarization. Finally, we will summarize what
hyperentanglement is and its applications
Experimental Test of an Event-Based Corpuscular Model Modification as an Alternative to Quantum Mechanics
We present the first experimental test that distinguishes between an
event-based corpuscular model (EBCM) [H. De Raedt et al.: J. Comput. Theor.
Nanosci. 8 (2011) 1052] of the interaction of photons with matter and quantum
mechanics. The test looks at the interference that results as a single photon
passes through a Mach-Zehnder interferometer [H. De Raedt et al.: J. Phys. Soc.
Jpn. 74 (2005) 16]. The experimental results, obtained with a low-noise
single-photon source [G. Brida et al.: Opt. Expr. 19 (2011) 1484], agree with
the predictions of standard quantum mechanics with a reduced of 0.98
and falsify the EBCM with a reduced of greater than 20
Experimental quantum cryptography scheme based on orthogonal states
Since, in general, non-orthogonal states cannot be cloned, any eavesdropping
attempt in a Quantum Communication scheme using non-orthogonal states as
carriers of information introduces some errors in the transmission, leading to
the possibility of detecting the spy. Usually, orthogonal states are not used
in Quantum Cryptography schemes since they can be faithfully cloned without
altering the transmitted data. Nevertheless, L. Goldberg and L. Vaidman [\prl
75 (1995) 1239] proposed a protocol in which, even if the data exchange is
realized using two orthogonal states, any attempt to eavesdrop is detectable by
the legal users. In this scheme the orthogonal states are superpositions of two
localized wave packets travelling along separate channels. Here we present an
experiment realizing this scheme
Experimental realization of Counterfactual Quantum Cryptography
In counterfactual QKD information is transfered, in a secure way, between
Alice and Bob even when no particle carrying the information is in fact
transmitted between them. In this letter we fully implement the scheme for
counterfactual QKD proposed in [T. Noh, \PRL \textbf{103}, 230501 (2009)],
demonstrating for the first time that information can be transmitted between
two parties without the transmission of a carrier
Creation and characterization of He-related color centers in diamond
Diamond is a promising material for the development of emerging applications
in quantum optics, quantum information and quantum sensing. The fabrication and
characterization of novel luminescent defects with suitable opto-physical
properties is therefore of primary importance for further advances in these
research fields. In this work we report on the investigation in the formation
of photoluminescent (PL) defects upon MeV He implantation in diamond. Such
color centers, previously reported only in electroluminescence and
cathodoluminescence regime, exhibited two sharp emission lines at 536.5 nm and
560.5 nm, without significant phonon sidebands. A strong correlation between
the PL intensities of the above-mentioned emission lines and the He
implantation fluence was found in the 10^15-10^17 cm^{-2} fluence range. The PL
emission features were not detected in control samples, i.e. samples that were
either unirradiated or irradiated with different ion species (H, C). Moreover,
the PL emission lines disappeared in samples that were He-implanted above the
graphitization threshold. Therefore, the PL features are attributed to
optically active defects in the diamond matrix associated with He impurities.
The intensity of the 536.5 nm and 560.5 nm emission lines was investigated as a
function of the annealing temperature of the diamond substrate. The emission
was observed upon annealing at temperatures higher than 500{\deg}C, at the
expenses of the concurrently decreasing neutral-vacancy-related GR1 emission
intensity. Therefore, our findings indicate that the luminescence originates
from the formation of a stable lattice defect. Finally, the emission was
investigated under different laser excitations wavelengths (i.e. 532 nm and 405
nm) with the purpose of gaining a preliminary insight about the position of the
related levels in the energy gap of diamond
Improving interferometers by quantum light: toward testing quantum gravity on an optical bench
We analyze in detail a system of two interferometers aimed at the detection of extremely faint phase
uctuations.
The idea behind is that a correlated phase-signal like the one predicted by some phenomenological theory of
Quantum Gravity (QG) could emerge by correlating the output ports of the interferometers, even when in the
single interferometer it confounds with the background. We demonstrated that injecting quantum light in the
free ports of the interferometers can reduce the photon noise of the system beyond the shot-noise, enhancing the
resolution in the phase-correlation estimation. Our results conrms the benet of using squeezed beams together
with strong coherent beams in interferometry, even in this correlated case. On the other hand, our results
concerning the possible use of photon number entanglement in twin beam state pave the way to interesting
and probably unexplored areas of application of bipartite entanglement and, in particular, the possibility of
reaching surprising uncertainty reduction exploiting new interferometric congurations, as in the case of the
system described here
Biocompatible technique for nanoscale magnetic field sensing with Nitrogen-Vacancy centers
The possibility of using Nitrogen-vacancy centers in diamonds to measure
nanoscale magnetic fields with unprecedented sensitivity is one of the most
significant achievements of quantum sensing. Here we present an innovative
experimental set-up, showing an achieved sensitivity comparable to the state of
the art ODMR protocols if the sensing volume is taken into account. The
apparatus allows magnetic sensing in biological samples such as individual
cells, as it is characterized by a small sensing volume and full
bio-compatibility. The sensitivity at different optical powers is studied to
extend this technique to the intercellular scale.Comment: 6 pages, 5 figure
Is a Quantum Biosensing Revolution Approaching? Perspectives in NV‐Assisted Current and Thermal Biosensing in Living Cells
none8openPetrini, Giulia; Moreva, Ekaterina; Bernardi, Ettore; Traina, Paolo; Tomagra, Giulia; Carabelli, Valentina; Degiovanni, Ivo Pietro; Genovese, MarcoPetrini, Giulia; Moreva, Ekaterina; Bernardi, Ettore; Traina, Paolo; Tomagra, Giulia; Carabelli, Valentina; Degiovanni, Ivo Pietro; Genovese, Marc
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