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Continuous Quantum Correlations for Secure Information Processing

Carlsberg Foundation Young Researcher Fellowships


The behaviour of light and matter is ultimately governed by quantum physics which often runs counter to everyday experience and can defy classical notions of cause and effect. This represents a striking departure from classical physics and is central to the foundations of modern physics. At the same time, the lack of any classical causal explanation means that quantum events can be truly random, which enables novel information processing with security based directly on laws of nature. This project will explore quantum correlations in continuous degrees of freedom, which are not yet well understood. The goal is to advance our fundamental understanding of quantum physics as well as to develop ultra-secure information processing and communication.


Understanding continuous quantum correlations will both provide new insight into fundamental physics and enable new protocols for cryptography in the so-called device-independent setting, where strong security guarantees can be made under minimal assumptions. Quantum correlations have been extensively studied in discrete settings with separate, distinct states, like the 0s and 1s of a digital computer. Much less is known about continuous quantum correlations, even though continuous systems play a vital role throughout physics. At the same time, many quantum states and measurements available in the lab are of a continuous nature. Device-independent protocols tailored to continuous degrees of freedom may therefore offer significant advantages in terms of speed and ease of implementation.


We will pursue three complementary lines of research: We will explore the fundamental structure of continuous quantum correlations, building on existing methods for discrete correlations to develop new mathematical tools and pinpoint what makes a continuous correlation genuinely quantum. We will explore generation of random numbers, as randomness is central to information security. And, using our new insight, we will develop cryptography protocols exploiting continuous quantum correlations to achieve device-independent security. The Young Researcher Fellowship will allow assembling a team of researchers to address the challenging theoretical questions under each research line. In addition, we aim to collaborate with experimental colleagues to realise our ideas in practice.


Secure communication and information processing is vital in modern and future society, both to protect individual freedom and privacy and to transmit and store confidential records in the public and private sectors. Information security is essential for infrastructure and services and unpins good economy, prosperity, and political stability. Technological advances, such as the development of a quantum computer, make commonly used cryptography vulnerable to new types of attacks and pose a threat to long-term security. Novel cryptographic protocols that are themselves based on quantum physics will play an important part in maintaining information security into the future.