Seminar: Quantum Internet in the Sky (Vision, Challenges, Solutions)

Fri, 15 May 2026 00:00:00 +0000

This is a seminar I prepared for a graduate course at SoICT, Hanoi University of Science and Technology, class CH2025A, analyzing the paper “Quantum Internet in the Sky: Vision, Challenges, Solutions & Future Directions” by Phuc V. Trinh and Shinya Sugiura, published in IEEE Communications Magazine in 2024.

The paper envisions a layered Quantum Internet built on satellites and airborne platforms, HAPS and LAPS, combining Free-Space Optics with Quantum Key Distribution. The topic sits exactly at the intersection of two directions I already work in: satellite QKD and FSO at PTIT, and satellite technology through the Master in Space program at USTH.

Foundational concepts

The paper opens with a set of core concepts. A qubit is the unit of quantum information, existing in superposition until measured. Superposition is a linear combination of basis states, allowing parallel computation across 2ⁿ states at once. Entanglement is a non-local correlation between two qubits, where measuring one instantly determines the other’s state regardless of distance. The No-Cloning Theorem states that an unknown qubit cannot be copied without destroying the original.

These four ideas lead directly to QKD, key distribution using quantum states with unconditional security. Two metrics come with it: QBER, the quantum bit error rate that rises abnormally whenever an eavesdropper is present, and Secret Key Rate, the rate at which a usable secret key is produced after error correction and privacy amplification. I explain each of these in more depth in .

The paper’s infrastructure section introduces a second set of concepts around Free-Space Optics and non-terrestrial networks. FSO transmits an optical signal through air or vacuum and requires line-of-sight. Pointing error is the angular misalignment of the laser beam, measured in microradians. Atmospheric turbulence is the refractive-index fluctuation that causes beam wander and scintillation. Three platform layers, LEO, HAPS, and LAPS, span from 500 kilometers down to below 5 kilometers, and every one of them is bound by SWaP-C: size, weight, power, and cost. Entanglement swapping connects two nodes with no direct physical link through a Bell-state measurement at an intermediate node, while finite-key effects remind us that a short overpass yields only a limited number of photons, pushing statistical error above the asymptotic theoretical limit. I cover this full set of concepts in .

Background and motivation

The paper’s second part asks why this topic is urgent now, rather than a purely academic interest. The timeline runs from Feynman and Deutsch in the 1980s, through Shor’s algorithm in 1994 proving RSA could be broken in polynomial time, to Google’s Sycamore in 2019 demonstrating quantum supremacy. Current roadmaps place 2030 to 2035 as the point where quantum computers may become powerful enough to exploit this in practice. The most pressing motivation, though, is the harvest-now-decrypt-later strategy: an attacker can collect encrypted data today, store it, and decrypt it once the technology matures. I go through this timeline in detail in .

Facing that threat, two lines of defense are being developed in parallel. PQC, post-quantum cryptography, operates at the software layer, relies on computational hardness, and can already be deployed using NIST’s 2024 standards, CRYSTALS-Kyber and Dilithium. QKD sits at the hardware layer, relies on physical law, and reaches information-theoretic security at the cost of needing new infrastructure. The paper focuses on QKD while explicitly stating that PQC and QKD complement rather than replace each other. I compare the two in more detail in .

Finally, the paper explains why FSO is the natural platform for QKD. Compared to RF and terrestrial fiber, FSO carries almost no thermal noise, handles single-photon counting well, and, most importantly, needs no trusted relay, which is fiber-based QKD’s central weakness: a single compromised node can collapse the security of an entire link. A single LEO satellite link can span thousands of kilometers with no intermediate station at all, making true end-to-end quantum security achievable. I lay out this argument fully in .

Why this matters for my research

The paper reinforces the theoretical framework behind what I am actually doing at PTIT: modeling atmospheric loss and turbulence for tropical satellite FSO channels, working toward a SIKD system described in . The paper’s three-layer LEO, HAPS, LAPS framework also suggests a natural extension for the three-state weather model I am developing, particularly the LEO-to-HAPS link, where HAPS flies above the cloud layer and avoids cloud-induced loss entirely, facing only the effects of the lower atmosphere.

Source: Phuc V. Trinh, Shinya Sugiura, “Quantum Internet in the Sky: Vision, Challenges, Solutions & Future Directions,” IEEE Communications Magazine, 2024.

Moov'Hanoi: Multimodal Urban Mobility Simulation in Hanoi

Mon, 01 Apr 2024 00:00:00 +0000

Overview

Moov’Hanoi is an international research project involving IRD/UMMISCO (France), Thuy Loi University, and multiple partners, aimed at making public transportation in Hanoi more accessible and attractive.

I participated as a research intern at ACROSS LAB, Thuy Loi University (04/2024 – 06/2025).

My Contributions

Collected and analyzed survey data on mobility patterns in Hanoi
Performed exploratory data analysis (EDA) to extract insights
Developed an agent-based traffic simulation model on the GAMA platform
Built deployment scenarios for proposed solutions
Calibrated and validated the simulation model

Tech Stack

GAMA Platform — agent-based modeling and simulation
Python — data analysis, survey processing
QGIS — spatial data processing

Results

Presented and published a paper at the international Gama Days 2024 conference:

“Moov’Hanoi: A Data-Driven Agent-Based Model for Simulating Multimodal Urban Mobility in Hanoi”

Nghia Truong Tuan, Patrick Taillandier, Ines Langlet, Maxime Bisbau, Alexis Drogoul, Arnaud Grignard

Rapid Deforestation Detection Using ALOS-2 and Sentinel-1 SAR Imagery

Mon, 01 May 2023 00:00:00 +0000

Overview

Research project at the Vietnam National Space Center (VNSC), Earth Observation Application Department. Goal: use satellite radar imagery (SAR) to rapidly detect deforested areas in Vietnam.

I participated as an intern (05/2023 – 11/2023).

My Contributions

Studied fundamentals of Earth Science and Geophysics
Practiced SAR (Synthetic Aperture Radar) image processing
Combined data from two satellites: ALOS-2 (JAXA) and Sentinel-1 (ESA)
Analyzed forest cover changes over time

Tech Stack

SNAP (ESA) — SAR image processing
QGIS — spatial analysis, visualization
Python — data processing

Results

Co-authored a paper at the international GIS-IDEAS 2023 conference:

“A Combination of ALOS-2, Sentinel-1 Imagery for Rapid Deforestation Detection in Vietnam”

Ngo Duc Anh, Vu Anh Tuan, Truong Tuan Nghia

Projects | Truong Tuan Nghia

Seminar: Quantum Internet in the Sky (Vision, Challenges, Solutions)

Foundational concepts

Background and motivation

Why this matters for my research

Moov'Hanoi: Multimodal Urban Mobility Simulation in Hanoi

Overview

My Contributions

Tech Stack

Results

Rapid Deforestation Detection Using ALOS-2 and Sentinel-1 SAR Imagery

Overview

My Contributions

Tech Stack

Results