Kvantna kriptografija putem optičkog vlakna

master's thesis

• Title (english): Quantum cryptography over an optic fibre
• Author: Antonio Cerović
• Mentor: Mario Stipčević (mentor)
• Mentor: Hrvoje Buljan (komentor)
• Committee member: Hrvoje Buljan (predsjednik povjerenstva)
• Committee member: Mario Stipčević (član povjerenstva)
• Committee member: Miroslav Požek (član povjerenstva)
• Committee member: Marinko Jablan (član povjerenstva)
• Committee member: Mihael Srđan Grbić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2024-04-04, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract

U današnjem svijetu tehnologije, razvoj kvantnih računala predstavlja prijetnju sadašnjim kriptografskim sustavima. Naime, pomoću Shorovog algoritma, koji bi se u budućnosti mogao izvoditi na kvantnim računalima, moguće je razbiti kriptografske algoritme koji su trenutačno u upotrebi. Kao moguće rješenje problema nameće se kvantna distribucija ključa. Kvantna distribucija ključa služi za dijeljenje tajnog ključa u simetričnoj kriptografiji, a sigurnost iste temelji se na zakonima kvantne fizike. U ovom radu predstavljena je eksperimentalna kvantna distribucija ključa putem konvencionalnog G.652.D telekomunikacijskog optičkog vlakna. Implementacija se temelji na BB84 protokolu i koristi polarizacijska stanja fotona valne duljine 810nm za prijenos informacije. Za razliku od uobičajenih skupih rješenja, u ovom radu korištene su relativno jeftine optičke komponente za spomenutu valnu duljinu te detektori bazirani na SPAD ćelijama. Dodatno, u našem pristupu pošiljatelj i primatelj ne trebaju imati sinkronizirane satove niti sinkronizirajući signal, već se poravnavanje vrši minimiziranjem udjela pogrešaka. Protokol je uspješno proveden za gubitke do 8.3 dB, što odgovara duljini od 2.7 km G.652.D optičkog vlakna. Također, napravljena je analiza eksperimentalnog postava te ustanovljena učinkovitost provedene kvantne distribucije ključa.

Abstract (english)

In today’s world of technology, the development of quantum computers poses a threat to current cryptographic systems. Specifically, with Shor’s algorithm, which could be executed on future quantum computers, it becomes possible to break cryptographic algorithms currently in use. As a possible solution to this problem, quantum key distribution emerges. Quantum key distribution is used for sharing a secret key in symmetric cryptography, and its security is based on the laws of quantum physics.This paper presents experimental quantum key distribution via conventional G.652.D telecommunications optical fiber. The implementation is based on the BB84 protocol and utilizes polarization states of photons with a wavelength of 810 nm for information transmission. Unlike conventional, expensive solutions, this setup uses relatively inexpensive optical components for this wavelength and detectors based on SPAD cells. In our approach, the sender and receiver do not need synchronized clocks or a synchronizing signal; alignment is achieved by minimizing error rates. The protocol was successfully implemented for losses up to 8.3 dB, corresponding to a length of2.7 km of G.652.D optical fiber. Furthermore, an analysis of the experimental setup was conducted, and the effectiveness of the implemented quantum key distribution was established.

• Keywords: kvantna distribucija ključa; kvantna kriptografija; BB84 protokol
• Keywords (english): quantum key distribution; quantum cryptography; BB84 protocol
• Language: croatian
• URN:NBN: urn:nbn:hr:217:343785
• Project: Number: KK.01.1.1.01.0001; Title: Potpora vrhunskim istraživanjima Centra izvrstnosti za napredne materijale i senzore (CEMS); Title: Support for Center of Excellence for Advanced Materials and Sensing Devices cutting-edge research; Acronym: CEMS; Leader: Marko Kralj; Jurisdiction: eu; Funder: Europska komisija; Funding stream: European Regional Development Fund
• Study programme: Title: The University Integrated Undergraduate and Graduate Programme in Physics; Research Physics; specializations in: Research Physics; Course: Research Physics; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: sveučilišni magistar fizike (sveučilišni magistar fizike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-06-03 10:18:44