16 research outputs found
A Molecule‐Based Single‐Photon Source Applied in Quantum Radiometry
Single photon sources (SPSs) based on quantum emitters hold promise in
quantum radiometry as metrology standard for photon fluxes at the low light
level. Ideally this requires control over the photon flux in a wide dynamic
range, sub-Poissonian photon statistics and narrow-band emission spectrum. In
this work, a monochromatic single-photon source based on an organic dye
molecule is presented, whose photon flux is traceably measured to be adjustable
between 144 000 and 1320 000 photons per second at a wavelength of (785.6 +/-
0.1) nm, corresponding to an optical radiant flux between 36.5 fW and 334 fW.
The high purity of the single-photon stream is verified, with a second-order
autocorrelation function at zero time delay below 0.1 throughout the whole
range. Featuring an appropriate combination of emission properties, the
molecular SPS shows here application in the calibration of a silicon
Single-Photon Avalanche Detector (SPAD) against a low-noise analog silicon
photodiode traceable to the primary standard for optical radiant flux (i.e. the
cryogenic radiometer). Due to the narrow bandwidth of the source, corrections
to the SPAD detection efficiency arising from the spectral power distribution
are negligible. With this major advantage, the developed device may finally
realize a low-photon-flux standard source for quantum radiometry
A 3D Polymeric Platform for Photonic Quantum Technologies
open10The successful development of future photonic quantum technologies will much depend on the possibility of realizing robust and scalable nanophotonic devices. These should include quantum emitters like on-demand single-photon sources and non-linear elements, provided their transition linewidth is broadened only by spontaneous emission. However, conventional strategies to on-chip integration, based on lithographic processes in semiconductors, are typically detrimental to the coherence properties of the emitter. Moreover, such approaches are difficult to scale and bear limitations in terms of geometries. Here an alternative platform is discussed, based on molecules that preserve near-Fourier-limited fluorescence even when embedded in polymeric photonic structures. 3D patterns are achieved via direct laser writing around selected molecular emitters, with a fast, inexpensive, and scalable fabrication process. By using an integrated polymeric design, detected photon counts of about 2.4 Mcps from a single cold molecule are reported. The proposed technology will allow for competitive organic quantum devices, including integrated multi-photon interferometers, arrays of indistinguishable single-photon sources, and hybrid electro-optical nanophotonic chips.openColautti, Maja; Lombardi, Pietro; Trapuzzano, Marco; Piccioli, Francesco S.; Pazzagli, Sofia; Tiribilli, Bruno; Nocentini, Sara; Cataliotti, Francesco S.; Wiersma, Diederik S.; Toninelli, CostanzaColautti, Maja; Lombardi, Pietro; Trapuzzano, Marco; Piccioli, Francesco S.; Pazzagli, Sofia; Tiribilli, Bruno; Nocentini, Sara; Cataliotti, Francesco S.; Wiersma, Diederik S.; Toninelli, Costanz
Singular Spectrum Analysis of Two Photon Interference from Distinct Quantum Emitters
Two-photon interference underlies the functioning of many quantum photonics
devices. It also serves as the prominent tool for testing the
indistinguishability of distinct photons. However, as their time-spectral
profile becomes more involved, extracting relevant parameters, foremost the
central frequency difference, may start suffering difficulties. In a parametric
approach, these arise from the need for an exhaustive model combined with
limited count statistics. Here we discuss a solution to curtail these effects
on the evaluation of frequency separation relying on a semiparametric method.
The time trace of the quantum interference pattern of two photons from two
independent solid-state emitters is preprocessed by means of singular spectral
analysis before inspecting its spectral content. This approach allows to single
out the relevant oscillations from both the envelope and the noise, without
resorting to fitting. This opens the way for robust and efficient on-line
monitoring of quantum emitters
Single photon sources for quantum radiometry: a brief review about the current state-of-the-art
Single-photon sources have a variety of applications. One of these is quantum radiometry, which is reported on in this paper in the form of an overview, specifically of the current state of the art in the application of deterministic single photon sources to the calibration of single photon detectors. To optimize single-photon sources for this purpose, extensive research is currently carried out at the European National Metrology Institutes (NMIs), in collaboration with partners from universities. Single-photon sources of different types are currently under investigation, including sources based on defect centres in (nano-)diamonds, on molecules and on semiconductor quantum dots. We will present, summarise, and compare the current results obtained at European NMIs for single-photon sources in terms of photon flux, single-photon purity, and spectral power distribution as well as the results of single-photon detector calibrations carried out with this type of light sources.DFG, 390837967, EXC 2123: QuantumFrontiers - Licht und Materie an der Quantengrenz
Sviluppo di una Membrana Submicrometrica di Germanio per Esperimenti di Channeling
In seguito alla recente dimostrazione sperimentale del fenomeno di mirroring con cristalli piatti di Silicio, si è ritenuto interessante ottenere dei dati di confronto con cristalli sottili di Germanio. Il lavoro di tesi si occupa della ricerca ottimale di sviluppo di una membrana submicrometrica di Germanio attraverso metodi allo stato dell'arte di caratterizzazione di diffrattometria, spettrometria e interferometria, metodi di etching chimico e di drogaggio
Entanglement Assisted Transport of Two Walkers in Noisy Quantum Networks
Understanding the transport mechanisms and properties of complex networks is fundamental for the comprehension of a vast class of phenomena, from state transfer on a spin network to light-harvesting in photosynthetic complexes. It has been theoretically and experimentally demonstrated that noise can enhance transport when the system parameters are properly tuned, an effect known as noise-assisted transport (NAT). In this work we investigate the role of initial entanglement in the transfer efficiency of two walkers in a noisy network. By using the formalism of quantum walks, we define a range of small dephasing noise where initial site-entanglement provides transport enhancement and outperforms the NAT effect. Furthermore, we show two specific scenarios where entanglement-assisted transport can open faster channels for slow walkers and avoid a broken link in a communication line. These findings may be of potential interest for quantum technologies
Laser-induced frequency tuning of Fourier-limited single-molecule emitters
The local interaction of charges and light in organic solids is the basis of
distinct and fundamental effects. We here observe, at the single molecule
scale, how a focused laser beam can locally shift by hundreds-time their
natural linewidth and in a persistent way the transition frequency of organic
chromophores, cooled at liquid helium temperatures in different host matrices.
Supported by quantum chemistry calculations, the results are interpreted as
effects of a photo-ionization cascade, leading to a stable electric field,
which Stark-shifts the molecular electronic levels. The experimental method is
then applied to a common challenge in quantum photonics, i.e. the independent
tuning and synchronization of close-by quantum emitters, which is desirable for
multi-photon experiments. Five molecules that are spatially separated by about
50 microns and originally 20 GHz apart are brought into resonance within twice
their linewidth. Combining this ability with an emission linewidth that is only
limited by the spontaneous decay, the system enables fabrication-free,
independent tuning of multiple molecules integrated on the same photonic chip.Comment: 15 pages, 5 figures. Supplementary Informations 23 pages, 13 figure