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Projecte llegit

Títol: Assembly and Characterization of Single-Photon Detectors for Quantum Networks

Estudiants que han llegit aquest projecte:

Director/a: JOFRE CRUANYES, MARC

Departament: ENTEL

Títol: Assembly and Characterization of Single-Photon Detectors for Quantum Networks

Data inici oferta: 01-02-2026     Data finalització oferta: 31-07-2026


Estudis d'assignació del projecte:
    GR ENG SIS TELECOMUN
Tipus: Individual
 
Lloc de realització: EETAC
 
Segon director/a (UPC): AGUSTÍ TORRA, ANNA
 
Paraules clau:
Quantum Communications, Single-Photon Detector, Single-Photon Avalanche Diode (SPAD)
 
Descripció del contingut i pla d'activitats:
Description
Quantum single-photon detectors (SPADs) are highly sensitive devices designed to detect and measure individual qubits/photons, playing a crucial role in quantum networks [1]. These detectors operate based on avalanche photodiodes (APDs). The ability to detect single photons with high temporal resolution is essential for quantum communications. Nevertheless, current SPADs are complex systems that need to be well assembled and characterized in order to have them operating in optimal conditions.
To address these challenges, this project proposes to assemble a hardware transceiver to generate and detect single photons at optical frequencies, hereby utilizing measurement instruments to effectively model and evaluate its performance and scalability.

In this direction, single-photon avalanche detectors will be employed due to their affordability, versatility, and flexibility, which serve as an ideal platform for implementing and modelling quantum transceivers.

Methodology and Objectives to achieve
The approach of the project follows the implementable methods for characterizing single photon avalanche diode detectors [2], [3]. Accordingly, the main objective of this research project is to model, assemble and characterize the emission and detection of attenuated laser pulses as single-photons.
The specific objectives of this research project are:
- Model attenuated laser pulses for Quantum communications.
- Experimentally assemble and characterize the detector modules.
- Characterize and discuss results, future work and limitations.

Workplan
First, at the modelling phase, the student will model single-photon detectors with the direction of the directors of the thesis. At the experimental stage the candidate will have access to hardware equipment to configure and evaluate the detector system.
 
Overview (resum en anglès):
The use of quantum technologies has risen drastically in the last decades, offering an enhancement in terms of the technological capabilities available nowadays. Found in this field of research, quantum communications based on the transmission of single photons offer new approaches to redefine the use of protocols and devices for specialised applications. As a final result, this leads to the accomplishment of long-range quantum networks with terrestrial and satellite-based communications set to establish a new scale of Telecommunication applications.

Within these kinds of applications, this project focuses on the assembly of a single-photon detector using a photodiode of type Single-Photon Avalanche Diode (SPAD), essential device to define the level of performance of any quantum communication system. To carry this out, the system is assembled around its centre piece, an Excelitas APD operated in Geiger mode above its breakdown voltage. The electronic circuit that drives the photodiode is characterised to work with its adjusted bias voltage, its dedicated temperature management system and its active quenching circuit to detect pulses with certainty and precision. The final version of the project is adjusted to work in the 1300nm and 1500nm operating wavelengths as the photodiode used is formed by an InGaAs/InP semiconductor structure.

Working on top of the original circuit provided initially, the experimental measurements obtained in the course of the project prove that the design modifications implemented have improved the functioning of the whole system. The main achievements accomplished encompass the generation of pulses for photon detection at 20kHz, the reduction of electromagnetic interferences by a factor 40, the enhancement of the manipulated signals in the circuit by a factor of tens, and the correct management of the SPAD temperature to maintain a fixed value of dark counts for a long time.

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