Physics World Weekly Podcast

Artur Ekert explains how Albert Einstein and John Bell inspired quantum cryptography

Mar 20, 2025

Artur Ekert, a theoretical crypto-physicist from Oxford and Singapore, dives into the world of quantum cryptography inspired by giants like Einstein and Bell. He explains the historical significance of the EPR paradox and how Bell’s theorem revolutionized secure communication methods. The conversation highlights the transformative experiments that validated these theories, the challenges in quantum communication security, and the promising advancements in quantum computation. Ekert’s insights illuminate the philosophical implications of quantum mechanics and the pursuit of randomness.

55:00

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Artur Ekert

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Quick takeaways

Einstein's EPR paradox challenged the completeness of quantum theory by promoting a deterministic framework over inherent randomness.

Bell's theorem transformed quantum mechanics by enabling experimental tests of the EPR paradox, highlighting the non-locality of quantum particles and its cryptographic applications.

Deep dives

Einstein's EPR Paradox and Quantum Mechanics

Einstein expressed concerns about quantum mechanics through the EPR paradox, which questioned the completeness of quantum theory. He believed that inherent randomness suggested by quantum mechanics undermined the predictability of physical laws, advocating for a deterministic framework instead. This perspective led him to propose a local hidden variable model, asserting that an ideal physical theory should predict outcomes based on predetermined conditions rather than probabilities. As the conversation reveals, Einstein's dissatisfaction with quantum mechanics set the stage for further exploration into the foundational principles of the field.

Intro

5min

Unraveling Quantum Paradoxes: From EPR to Cryptography

26min

Collaborative Innovations in Quantum Cryptography

14min

Exploring Bell Tests and Their Impact on Quantum Cryptography

5min

Exploring Quantum Computation and the Nature of Randomness

2min

Exploring Quantum Interpretations and Their Philosophical Implications

3min

When physicists got their first insights into the quantum world more than a century ago, they found it puzzling to say the least. But gradually, and through clever theoretical and experimental work, a consistent quantum theory emerged.

Two physicists that who played crucial roles in this evolution were Albert Einstein and John Bell. In this episode of the Physics World Weekly podcast the theoretical crypto-physicist Artur Ekert explains how a quantum paradox identified by Einstein and colleagues in 1935 inspired a profound theoretical breakthrough by Bell three decades later.

Ekert, who splits his time between the University of Oxford and the National University of Singapore, describes how he used Bell’s theorem to create a pioneering quantum cryptography protocol and he also chats about current research in quantum physics and beyond.

You can read more about this topic here: “Bohr, Einstein and Bell: what the 2022 Nobel Prize for Physics tells us about quantum mechanics”

This article forms part of Physics World‘s contribution to the 2025 International Year of Quantum Science and Technology (IYQ), which aims to raise global awareness of quantum physics and its applications.

Stayed tuned to Physics World and our international partners throughout the next 12 months for more coverage of the IYQ.

Find out more on our quantum channel.