Need a secure means of communication? Like, really secure? Quantum communication is used in protecting secure channels against eavesdropping—i.e. keeping top secret communications safe from hackers (we hope).
For example, you need a quantum key to decrypt messages. However, if you are using quantum communication and that key is tampered with, all parties concerned will know immediately and the message is instantly switched out for a new (safe) one. Yes, we’re in Mission Impossible territory, but this is real.
Dr. Marina Mondin, Associate Professor at the Electrical and Computer Engineering Department at California State University, Los Angeles, is an expert in quantum communication and leads research for NATO. PCMag spoke with her, via phone and email. Here are edited and condensed excerpts of our conversation.
Dr. Mondin, could you tell us first how you became interested in telecommunications engineering, which lead to your PhD at Italy’s Politecnico di Torino?
It happened a little bit by chance. I liked science, math, and technology, so I enrolled in the MSEE program at Politecnico di Torino. At the time—when I started my MSEE program in 1980—you had to choose among specializing in electronics, computer science, or telecommunications. The encounter with a collection of excellent professors in telecommunications steered me towards that field.
It’s always about the people, isn’t it?
Oh yes, and those were golden years for telecommunications. As you know, 1G was introduced in 1979; 2G in 1991, and it was booming—the digital wireless infrastructure was being implemented, and I fell in love with the field. At the end of the MS program, my mentor “informed me” that in his opinion my destiny was to enroll in a PhD program and pursue a career focused on research and teaching, and I followed his advice. And here I am.
When did you observe telecommunications and quantum communication moving into the field of cybersecurity?
The first protocol using the laws of quantum mechanics to transmit a quantum key in a secure way dates back to 1984. Quantum Key Distribution (QKD) remained only at the research level until the 2000s. As far as I know, the first commercial implementations started in 2004, with the first bank transfer based on QKD in Vienna and the first DARPA Quantum Network. I started to be interested in QKD in 2005, thanks to a collaboration with the quantum optics group at INRIM [Italian National Metrology Institute, the Italian equivalent of National Institute of Standards and Technology, NIST].
What problem were you all trying to solve in those days?
Since when you transmit a cryptographic key using photons you may have errors, they were looking for an expert in error correction. That was one of my specialties, so we started collaborating. When you correct errors in quantum key distribution, it is called Information Reconciliation, and I started working on that. This is how it all started. The people at INRIM and at University of Milano I started collaborating with were in physics—QKD was mainly a physics research topic back then—and I was coming from engineering, and had a different background. It was a challenge to find a common language, but it was also extremely interesting.
This is a tall order but could you sum up your life’s work and give us a brief explanation of how quantum communications works?
Sure [Laughs]. So, when performing encryption you need to transmit a sequence of bits—called keys— guaranteed to be secret; you will later mix these bits with your actual information so that those who do not know the key cannot decipher your message, that is why we call it a key.
In the classical schemes, the secrecy of the key is guaranteed by complex functions that would require a long time to be “inverted.” A possible future very fast quantum computer could however reverse these functions, making the schemes not secure. In quantum key distribution, the bits composing the key are transmitted using photons, [or] light at very low intensity. If somebody eavesdrops the photons, it modifies the photons themselves since they have an extremely small energy. Heisenberg Uncertainty Principle tells us if you perturb the system, you change its quantum state.
So the hacker’s act of tampering with the message ensures everyone knows it’s been compromised?
Yes. The act of measurement by the eavesdropper perturbs the system, and is therefore detectable. It is possible to understand that the photons have been modified, and that therefore the key has been eavesdropped. That key therefore will not be used because it is not secure anymore. So the security is based on the physical properties of the system and the laws of quantum mechanics, and not on complex functions that could eventually be inverted by an extremely fast computer. It is a completely different concept.
Before coming to the US, you studied the feasibility of a Earth-satellite quantum optical communication channel. Can you briefly outline the outcome of that work?
You can also perform quantum communication—i.e. the transmission of bits using photons—in an optical fiber, or in free space, through the atmosphere. That projectwas focused on studying and simulating the effects of the atmosphere on quantum communications towards or from a satellite, and to study information reconciliation schemes optimized for that channel. It was a feasibility study, so in a sense it was preliminary to what we are doing today.
What was crucial about using satellites as a delivery system?
The key distribution from satellites is extremely important since it gives you global reach at relatively low infrastructure costs. Besides, satellites can beam the signal anywhere in the world, you can imagine its potential advantage in military and commercial applications.
As Principal Investigator of a NATO Science for Peace and Security grant on secure communication using quantum information systems, what was the main thrust of your research?
That was a project on fundamental research, not so much on implementation, and different groups tackled different problems. At the Moscow Lomonosov University, they studied the possible use of bi-photons (two entangled photons) in quantum communications. INRIM, in Italy, studied quantum imaging, [which is] a branch of quantum optics that exploits quantum-mechanical properties to image objects with a resolution beyond what is possible in classical optics). Here at The California State University of Los Angeles and Politecnico di Torino, we modeled the transmission channel in QKD and studied the possibility of using powerful code for correcting transmission errors. The Ukrainian partner studied continuous variable QKD, an alternative method of performing QKD.
Wow. You had all those countries working in harmony on a single research project?
Yes, science crosses national boundaries. NATO Science for Peace and Security is an excellent program because it encourages, and finances, international collaborations between nations that generally do not collaborate with each other, and all for the purpose of increasing peace and security.
We had some exceptional partnerships. In the first NATO project I coordinated, the partners were Italy, the US, Russia, and Ukraine—and this was during the conflict between Russia and Ukraine! This proves that science is above conflict and that scientists like to collaborate with each other, and are driven by pursuit of knowledge regardless of national or other boundaries. In the second NATO project, we currently have, as partners, the US, Italy, Israel, and Pakistan.
Yet Pakistan and Israel do not even have formal diplomatic relations with each other.
Nonetheless, we are working together very well. Although the generation of subcontracts and the money transfer is not easy.
You hold four patents including a receiver for wireless communications networks and method and system for information processing. Could you tell us how they are being used in academia and industry today?
These patents are the results of collaborations and consulting with various companies in Europe including: Siemens Telecommunications, the German company producing radio relay links and satellite transceivers; Euroconcepts, a small company producing software for software-defined radio applications that I co-founded during the dotcom period; and Telecom Italia, the largest Italian telecom operator. The patents are all on algorithms for the reception of digital signals. The Siemens patent was probably implemented in a satellite receiver, while I do not know the status of the others today.
Finally, what are you working on now, that you’re able to tell us about, and its significance to your field of research?
Now I am coordinating a new NATO project more focused on practical implementation. We wish to study the effects of device imperfections, model these imperfections and use them to improve the performance of our QKD schemes. We intend to use the implementation of a QKD link in north Italy as testbed for our measurements.
I am currently analyzing how we can efficiently correct possible transmission errors when the transmission is very noisy or the signal is very weak. I am [also] working on wireless communications and on receiver schemes for the future 5Gstandard, and exploring new research avenues, like applying my knowledge of signal processing to other physics problems, and the study of mirrors imperfections for the detection of gravitational waves.
Science is so much fun and I will never run out of interesting problems to look at. The challenge and privilege of working in perhaps one of the most diverse universities in the world at Cal State LA, gives me a great satisfaction and sense of purpose. There, you really transform lives through education.