In June 1925, a young Werner Heisenberg sought refuge from his relentless hay fever on a German island, a short ferry ride from the shores of Hamburg. Exactly a hundred years later, several hundred quantum scientists gathered on those same sands and cliffs to discuss the latest advances in the field. Why would an island, known for little else than being virtually pollen-free, become a destination for such a varied and far-flung community of physicists?
A century ago, Heisenberg’s frustrations stemmed from more than a mere physical affliction. Though he was battling a severe fever, resistant even to the best treatments of the time—Aspirin and cocaine—it was a fever of thought that truly consumed him. He was tormented by foundational problems in atomic theory, particularly by questions of a deeply epistemic nature.
At the heart of the problem lay the observation of discrete emission and absorption frequencies, spectral lines that appeared in fixed patterns with varying intensity. Bohr’s model described electrons as orbiting the nucleus at fixed radii, and changes in energy were explained through transitions between these orbits. It was a mechanical picture, neat and intelligible, yet somehow inadequate.
It was on the island of Helgoland that Heisenberg experienced the insight that changed everything. To extend the atomic model, one had to relinquish the mechanical framework entirely, and with it, the very quantities that enabled it but were fundamentally unobservable.
This moment marked the beginning of modern quantum mechanics. For the first time, the absence of a mechanical explanation was not viewed as a failure of the theory. On the contrary, it signified a deliberate act of intellectual defiance against the classical worldview that had long constrained our understanding of physical phenomena.
The path from that insight to the quantum mechanics we use today was anything but straightforward. While the mathematical formalism is widely accepted, its interpretation and use still vary greatly. This is especially significant in quantum cryptography. When using quantum systems to enhance the security of a protocol, particularly in the absence of device-independent guarantees, one must present compelling arguments that the quantum description is fundamental enough to preclude the possibility of malicious interference.
The conference on Helgoland was a rare occasion where theory and experiment met in harmony, echoing the spirit of twentieth-century physics. The first day took place in Hamburg and featured historical and philosophical discussions about the origins of the theory and the intellectual climate in which it emerged. These conversations unfolded during a gala dinner, an evening for reflection and reunion, an opportunity to speak with colleagues and old friends, and to ponder a strange question: why are we celebrating a theory on an isolated island in the North Sea?
The following day, with impressive punctuality and organization, we sailed to the island under grey skies and a biting wind. The crossing stirred spirited divisions, greater even than those provoked by debates on quantum gravity. Some among us stood on deck, exhilarated by the salt and spray; others sat below, pale with nausea, hoping the sea would be merciful. There was even a division of opinion on the consequences of sinking. Given the number of Nobel laureates and leading theorists aboard, some feared the end of quantum physics itself. Others, more optimistic, imagined a surge in available faculty positions and our entry into the mythos of the discipline.
Helgoland, though a natural wonder, was not fully prepared to host such a vibrant academic exchange. There were only two pubs. One was too small and too smoky to contain us all. In the other, the host received us warmly, though the neighbours did not share his hospitality. The island’s strict tradition of silence after 11pm, combined with talks that stretched nearly to 10pm, may well have delayed progress in the field by decades.
The presentations balanced foundational questions in quantum theory, state-of-the-art experimental achievements, and novel approaches in quantum computing. One clear takeaway from the rapid pace of experimental development was that, very soon, we may find ourselves able to create quantum states in systems of increasing mass. This will test the theory in unprecedented ways.
To this challenge, the theoretical community offers two main responses. One group holds that the increasing scale of quantum systems will eventually force a resolution of the so-called measurement problem, requiring a sharp distinction between the classical and the quantum. The other group, to which I and many followers of Bohr belong, believes that the classical framework is already woven into the language of the theory. In this view, any meaningful application of quantum mechanics must begin by identifying a priori, in the way the experiment itself is described, which degrees of freedom are to be treated classically and which are left to quantum dynamics.
Despite recent strides in quantum computing, many talks made it clear that much remains to be done in building robust quantum networks and the supporting infrastructure for distributed quantum experiments. These developments not only offer unmatched levels of security, well beyond anything achievable through classical means, but also open new ways to probe the interaction between quantum systems, space, time, and gravitation. On the final day, we learned of remarkable progress by a team of Chinese researchers who are working to overcome the limitations of current cryptographic protocols by building networks spanning hundreds of kilometres.
On a more controversial note, it was a week of rich dialogue, and it was an honour to represent NeverLocal at a milestone event in the evolution of quantum technologies. Yet it is clear that the community remains divided in its vision. A large portion still concentrates, perhaps in contradiction to Heisenberg’s own philosophical stance, on domains fundamentally inaccessible to experiment. Much philosophical energy is spent on questions of ontology, while the interface between theory and experiment, where quantum mechanics is actually applied, often rests on fragile foundations.
The structure of quantum theory not only represents a new frontier for physics, but also demands a redefinition of the scientific method: one in which observations are not merely structures that guide the formulation of theories, or acts that inform theory, but a method in which the experiment itself provides the very substance of a formal account of phenomena. In this way, academic discourse interlaces with technology in ways that exude hope in their mutual development, standing apart from the stagnation found in certain directions taken by fundamental physics. The efficacy of quantum information in quantum mechanics has gained such prominence that, as became clear at our meeting on Helgoland, the marriage between academia and industry has become a seamless and beautiful union.
A rigorous grammar of what it means to conduct a quantum experiment is needed. This is no trivial matter; it conceals a host of subtle yet vital foundational issues. At NeverLocal, we are constructing the very foundation upon which the study of quantum protocols must rest. To do so, we must dwell in this liminal space where classical information is encoded into quantum systems—not merely a technological feat, but a conceptual study that pushes the boundaries of fundamental research through new technological breakthroughs, all in the name of cryptographic security.