2,569 research outputs found
Development of a PJVS System for Quantum-Based Sampled Power Measurements
The paper deals with recent progresses at INRiM towards the development and characterization of a programmable Josephson voltage standard (PJVS) operating in a small liquid helium dewar as well as with its integration for the realization of a practical quantum sampling electrical power standard. The
PJVS is based on a 1V superconductor-normal metal-superconductor (SNS) binary-divided array of 8192 Josephson junctions. To ensure proper operating conditions of the PJVS chip, a custom short cryoprobe was designed, built and successfully tested. The overall system is being developed in the framework of EMPIR project 19RPT01-QuantumPower. The goal is to establish a new quantum power standard (QPS) based on a single Josephson voltage standard for sampled power measurements and to gain confidence
in running PJVS for precise calibration of digital sampling multimeters and arbitrary waveform digitizers used in the ac-voltage and power metrology community
Muon and Cosmogenic Neutron Detection in Borexino
Borexino, a liquid scintillator detector at LNGS, is designed for the
detection of neutrinos and antineutrinos from the Sun, supernovae, nuclear
reactors, and the Earth. The feeble nature of these signals requires a strong
suppression of backgrounds below a few MeV. Very low intrinsic radiogenic
contamination of all detector components needs to be accompanied by the
efficient identification of muons and of muon-induced backgrounds. Muons
produce unstable nuclei by spallation processes along their trajectory through
the detector whose decays can mimic the expected signals; for isotopes with
half-lives longer than a few seconds, the dead time induced by a muon-related
veto becomes unacceptably long, unless its application can be restricted to a
sub-volume along the muon track. Consequently, not only the identification of
muons with very high efficiency but also a precise reconstruction of their
tracks is of primary importance for the physics program of the experiment. The
Borexino inner detector is surrounded by an outer water-Cherenkov detector that
plays a fundamental role in accomplishing this task. The detector design
principles and their implementation are described. The strategies adopted to
identify muons are reviewed and their efficiency is evaluated. The overall muon
veto efficiency is found to be 99.992% or better. Ad-hoc track reconstruction
algorithms developed are presented. Their performance is tested against muon
events of known direction such as those from the CNGS neutrino beam, test
tracks available from a dedicated External Muon Tracker and cosmic muons whose
angular distribution reflects the local overburden profile. The achieved
angular resolution is 3-5 deg and the lateral resolution is 35-50 cm, depending
on the impact parameter of the crossing muon. The methods implemented to
efficiently tag cosmogenic neutrons are also presented.Comment: 42 pages. 32 figures on 37 files. Uses JINST.cls. 1 auxiliary file
(defines.tex) with TEX macros. submitted to Journal of Instrumentatio
Muon and Cosmogenic Neutron Detection in Borexino
Borexino, a liquid scintillator detector at LNGS, is designed for the
detection of neutrinos and antineutrinos from the Sun, supernovae, nuclear
reactors, and the Earth. The feeble nature of these signals requires a strong
suppression of backgrounds below a few MeV. Very low intrinsic radiogenic
contamination of all detector components needs to be accompanied by the
efficient identification of muons and of muon-induced backgrounds. Muons
produce unstable nuclei by spallation processes along their trajectory through
the detector whose decays can mimic the expected signals; for isotopes with
half-lives longer than a few seconds, the dead time induced by a muon-related
veto becomes unacceptably long, unless its application can be restricted to a
sub-volume along the muon track. Consequently, not only the identification of
muons with very high efficiency but also a precise reconstruction of their
tracks is of primary importance for the physics program of the experiment. The
Borexino inner detector is surrounded by an outer water-Cherenkov detector that
plays a fundamental role in accomplishing this task. The detector design
principles and their implementation are described. The strategies adopted to
identify muons are reviewed and their efficiency is evaluated. The overall muon
veto efficiency is found to be 99.992% or better. Ad-hoc track reconstruction
algorithms developed are presented. Their performance is tested against muon
events of known direction such as those from the CNGS neutrino beam, test
tracks available from a dedicated External Muon Tracker and cosmic muons whose
angular distribution reflects the local overburden profile. The achieved
angular resolution is 3-5 deg and the lateral resolution is 35-50 cm, depending
on the impact parameter of the crossing muon. The methods implemented to
efficiently tag cosmogenic neutrons are also presented.Comment: 42 pages. 32 figures on 37 files. Uses JINST.cls. 1 auxiliary file
(defines.tex) with TEX macros. submitted to Journal of Instrumentatio
Muon and Cosmogenic Neutron Detection in Borexino
Borexino, a liquid scintillator detector at LNGS, is designed for the
detection of neutrinos and antineutrinos from the Sun, supernovae, nuclear
reactors, and the Earth. The feeble nature of these signals requires a strong
suppression of backgrounds below a few MeV. Very low intrinsic radiogenic
contamination of all detector components needs to be accompanied by the
efficient identification of muons and of muon-induced backgrounds. Muons
produce unstable nuclei by spallation processes along their trajectory through
the detector whose decays can mimic the expected signals; for isotopes with
half-lives longer than a few seconds, the dead time induced by a muon-related
veto becomes unacceptably long, unless its application can be restricted to a
sub-volume along the muon track. Consequently, not only the identification of
muons with very high efficiency but also a precise reconstruction of their
tracks is of primary importance for the physics program of the experiment. The
Borexino inner detector is surrounded by an outer water-Cherenkov detector that
plays a fundamental role in accomplishing this task. The detector design
principles and their implementation are described. The strategies adopted to
identify muons are reviewed and their efficiency is evaluated. The overall muon
veto efficiency is found to be 99.992% or better. Ad-hoc track reconstruction
algorithms developed are presented. Their performance is tested against muon
events of known direction such as those from the CNGS neutrino beam, test
tracks available from a dedicated External Muon Tracker and cosmic muons whose
angular distribution reflects the local overburden profile. The achieved
angular resolution is 3-5 deg and the lateral resolution is 35-50 cm, depending
on the impact parameter of the crossing muon. The methods implemented to
efficiently tag cosmogenic neutrons are also presented.Comment: 42 pages. 32 figures on 37 files. Uses JINST.cls. 1 auxiliary file
(defines.tex) with TEX macros. submitted to Journal of Instrumentatio
Integrated photonic transmitters for secure space quantum communication
An important issue in today's information society is the security of data transmission against potential intruders, which always put at risk the confidentiality. Current methods to increase security require that the two parties wishing to transmit information, exchange or share one or more security keys. Once the key has been identified, the information can be transferred in a provable secure way using a one-time pad, i. e. the key length is as long as the plaintext. Therefore, the security of the information transmission is based exclusively on the security of the key exchange. Quantum cryptography, or more precisely quantum key distribution (QKD), guarantees absolutely secure key distribution based on the principles of quantum physics, according to which it is not possible to measure or reproduce a state (e.g. polarization or phase of a photon) without being detected. The key is generated out from the measurement of the information encoded into specific quantum states of a photon, named qubits. For example, a qubit can be created using properties such as the polarization or the phase of a photon.
Achieved goals of this thesis are the development of a new class of high speed integrated photonic sources for applications in quantum key distribution systems, capable of producing unprecedented qubit rates (100 Mbps - 1 Gbps) and transmitting those over larger distances than those achieved so far (>200 km). More specifically the work has been focused on developing faint pulse sources which can be used in very demanding environmental conditions, such as those in Space. For the development of these sources, apart from the optical design, essential is the opto-mechanical engineering as well as the integration with the electronics. One of the objectives was to achieve very high level of integration and power efficiency, e.g. volumes and power consumption between 10 and 100 times smaller than those typical of a laboratory experiment. Moreover, work in related parts of a whole QKD transmission system has been carried out. In particular, a new scheme for a compact, fast and simple random number generator has been demonstrated successfully achieving a random number generation rate of 1.1 Gbps. Also, during the course of this thesis, the development and engineering of a free-space QKD optical link has been initiated.
This thesis makes use of novel ideas to alternatively demonstrate proof-of-concept experiments, which could then further develop into commercial products. To this end, close collaborations with world-wide leading companies in the field have been established. The Optoelectronics Group at ICFO has been involved in current European Space Agency (ESA) projects to develop a small footprint and low power consumption quantum transceiver and a high-flux entangled photon source.En lâactual societat del coneixement Ă©s important la seguretat en la transmissiĂł de dades contra potencial intrusos, els quals sempre posen en risc la confidencialitat. MĂštodes actuals per incrementar la seguretat requereixen que les dos parts que volen transmetre informaciĂł, intercanviĂŻn o comparteixin una o mĂ©s claus. Una vegada la clau ha estat identificada, la informaciĂł pot ser transferida de forma provadament segura utilitzant ââone-time padââ. Per tant, la seguretat en la transmissiĂł de la informaciĂł es basa exclusivament en la seguretat en lâintercanvi de la clau. La criptografia quĂ ntica, o mĂ©s precisament distribuciĂł de clau quĂ ntica (QKD), garanteix absolutament la seguretat de la distribuciĂł de la clau basant-se en els principis de la fĂsica quĂ ntica, segons la qual no Ă©s possible mesurar o reproduir un estat (p. e. la polaritzaciĂł o fase dâun fotĂł) sense ser detectat.
La clau es genera a partir de les mesures de la informaciĂł codificada en estat quĂ ntics del fotĂł, anomenats qubits. Per exemple, un qubit pot ser creat utilitzant propietats com la polaritzaciĂł o fase dâun fotĂł.
Els objectius aconseguits dâaquesta tesis sĂłn el desenvolupament dâuna nova classe dâemissors fotĂČnics dâalta velocitat per a aplicacions en sistemes
de distribuciĂł de clau quĂ ntica, capaçžos de produir velocitats de qubit sense precedents (100 Mbps - 1 Gbps) i transmetreâls a travĂ©s de distĂ ncies mĂ©s llunyanes que les aconseguides fins ara (> 200 Km). MĂ©s en concret el treball sâha centrat en el desenvolupament de fonts de pulsos
atenuats que poden ser usades en condicions ambientals molt extremes, com les presents a lâEspai. Per al desenvolupament dâaquestes fonts, apart del disseny ĂČptic, importantĂssim es lâenginyeria optomecĂ nica com tambĂ© la integraciĂł amb la electrĂČnica. Un dels objectius ha estat aconseguir un molt alt nivell de integraciĂł i eficiĂšncia de potĂšncia, p. e. volums i consums de potĂšncia entre 10 i 100 vegades mĂ©s petits que els tĂpics en experiments de laboratori. AdemĂ©s, sâha realitzat treball en altres parts relacionades amb un sistema de transmissiĂł QKD. En particular, un nou esquema per a un generador de nĂșmeros aleatori compacte, rĂ pid i simple ha estat positivament demostrat aconseguint velocitats de generaciĂł de nĂșmeros aleatoris de 1:1 Gbps. TambĂ©, el desenvolupament i enginyeria dâun enllaç ĂČptic per a QKD en espai lliure ha estat iniciat durant aquesta tesis.
Aquesta tesis utilitza idees novedoses per a demostrar experiments de prova de concepte, els quals poden esdevenir en productes comercials. Per a aquest fi, sâhan establert colâąlaboracions amb empreses internacionals lĂders del sector. A mĂ©s a mĂ©s, el Grup dâOptoelectrĂČnica de ICFO ha estat involucrat en projectes de la AgĂšncia Espacial Europea (ESA) per a desenvolupar un transceptor quĂ ntic de tamany reduĂŻt i baix consum de potĂšncia, el qual tambĂ© contĂ© una font de fotons entrellaçts dâalt flux
Entanglement-based quantum digital signatures over deployed campus network
The quantum digital signature protocol offers a replacement for most aspects
of public-key digital signatures ubiquitous in today's digital world. A major
advantage of a quantum digital signatures protocol is that it can have
information-theoretic security, whereas public-key cryptography cannot. Here we
demonstrate and characterize hardware to implement entanglement-based quantum
digital signatures over our campus network. Over 25 hours, we collect
measurements on our campus network, where we measure sufficiently low quantum
bit error rates (<5\% in most cases) which in principle enable quantum digital
signatures over up to 50 km as shown in rigorous simulation accompanied by a
noise model developed specifically for our implementation. These results show
quantum digital signatures can be successfully employed over deployed fiber.
While the current implementation of our entanglement-based approach has a low
signature rate, feasible upgrades would significantly increase the signature
rate. In addition, our reported method provides great flexibility in the number
of users.Comment: 16 pages, 5 figures, 1 tabl
Quantum Key Distribution With an Integrated Photonic Receiver
Photonic integrated circuits (PICs) are key in advancing quantum technologies
for secure communications. They offer inherent stability, low losses and
compactness compared to standard fiber-based and free-space systems.
Our reasearch demonstrates PIC's effectivness in enhancing quantum
communications, implementing a three-state BB84 protocol with decoy-state
method. We employ an integrated receiver and superconducting nanowire single
photon detectors (SNSPDs) to achieve technological advancements.
One of the most notable results is the extraction of a secret key over a
record-breaking 45 dB channel attenuation. Our results demonstrate a remarkable
220% boost in key rate compared to our prototype fiber-based receiver over a 10
dB channel attenuation. This improvement in the secret key rate (SKR) signifies
the potential of integrated photonics to advance the field of quantum
communication
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