Noise as a Computational Resource

In systems far from equilibrium, such as cellular biomolecular assemblies, energetic input is converted into systematic execution of function. The functional machinery comprises transport and interconversion of matter, as well as signalling systems and the regulation of other functional components. Within the microscopic dimensions of the cell, these processes are carried out by discrete co-ordinated interactions among molecules in a noisy environment. We take the position that given the pronounced effects noise can have in such small volumes having low copy numbers of molecular species, cells have harnessed evolutionary pressures into making productive use of noise. Correspondingly, given the drive towards miniaturisation in future computational hardware, we can view the attendant concerns about “taming” the noise inherent to this regime as an opportunity to learn from the way cells fulfil their transport and information processing needs. In particular, we shall look at how molecular ratchets exploit thermal noise, how signalling processes may exploit fluctuations in the number of enzymes, and how the ability to read out from conformational substates of enzymes can enable targeted low-pass filtering to guide computational steps through a suitably mapped state space

The Cultural Contradictions of Cryptography

This dissertation examines the origins of political and scientific commitments that currently frame cryptography, the study of secret codes, arguing that these commitments took shape over the course of the twentieth century. Looking back to the nineteenth century, cryptography was rarely practiced systematically, let alone scientifically, nor was it the contentious political subject it has become in the digital age. Beginning with the rise of computational cryptography in the first half of the twentieth century, this history identifies a quarter-century gap beginning in the late 1940s, when cryptography research was classified and tightly controlled in the US. Observing the reemergence of open research in cryptography in the early 1970s, a course of events that was directly opposed by many members of the US intelligence community, a wave of political scandals unrelated to cryptography during the Nixon years also made the secrecy surrounding cryptography appear untenable, weakening the official capacity to enforce this classification. Today, the subject of cryptography remains highly political and adversarial, with many proponents gripped by the conviction that widespread access to strong cryptography is necessary for a free society in the digital age, while opponents contend that strong cryptography in fact presents a danger to society and the rule of law. I argue that cryptography would not have become invested with these deep political commitments if it had not been suppressed in research and the media during the postwar years. The greater the force exerted to dissuade writers and scientists from studying cryptography, the more the subject became wrapped in an aura of civil disobedience and public need. These positive political investments in cryptography have since become widely accepted among many civil libertarians, transparency activists, journalists, and computer scientists who treat cryptography as an essential instrument for maintaining a free and open society in the digital age. Likewise, even as opponents of widespread access to strong cryptography have conceded considerable ground in recent decades, their opposition is grounded in many of the same principles that defined their stance during cryptography’s public reemergence in the 1970s. Studying this critical historical moment reveals not only the origins of cryptography’s current politics, but also the political origins of modern cryptography

Quantum noise as a computational resource for materials science simulations

Quantum computing could eventually bring forth the possibility to simulate novel materials in physics and chemistry beyond the reach of classical computers. Nonetheless, current quantum hardware is inherently noisy, restricting the scope to minimal working examples that do not represent any computational advantage. Although noise is typically considered undesirable, recent works propose to exploit the intrinsic noise in NISQ-devices as an integral part of the algorithm. In this work, we aim to construct a toolbox that is tailored to the simulation of non-equilibrium dynamics in electronic networks. Given the ubiquity and generality of this formalism in materials science, possible applications range from ultrafast process in photovoltaics, cavity-enhanced catalysis in electrochemistry or the characterization of the noise present in quantum hardware