Talks

Particle physics underpins our understanding of the world at a fundamental level by describing the interplay of matter and forces through gauge theories. Yet, despite their unmatched success, the intrinsic quantum mechanical nature of gauge theories makes important problem classes notoriously difficult to address with classical computational techniques. A promising way to overcome these roadblocks is offered by quantum computers, which are based on the same laws that make the classical computations so difficult. Here, we present a quantum computation of the properties of the basic building block of two-dimensional lattice quantum electrodynamics, involving both gauge fields and matter. This computation is made possible by the use of a trapped-ion qudit quantum processor, where quantum information is encoded in different states per ion, rather than in two states as in qubits. Qudits are ideally suited for describing gauge fields, which are naturally high-dimensional, leading to a dramatic reduction in the quantum register size and circuit complexity. Using a variational quantum eigensolver, we find the ground state of the model and observe the interplay between virtual pair creation and quantized magnetic field effects. The qudit approach further allows us to seamlessly observe the effect of different gauge field truncations by controlling the qudit dimension. Our results open the door for hardware-efficient quantum simulations with qudits in near-term quantum devices.

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The genome is organized within a nucleus where chromosomes fold into an ensemble of conformations. This spatial arrangement within the nucleus is critical for regulating gene expression and other DNA-templated processes. Chromosome conformation capture techniques such as Hi-C provide information about the genome architecture by creating 2D contact maps. Recently, measuring efforts were expanded to several organisms, cell lines, tissues, and cell cycle phases, in which obtaining high-quality maps is still challenging. These contact maps serve as an essential input for top-down theoretical models. Aided by the under-development chromatin folding and structure theory, we create a framework using polymer theory enriched with the Maximum Entropy Approach to learn and understand the chromosome spatial organization. To enhance the training of the energy functions, we included a combined machine learning minimization method that allows us to speed up the modeling, even for large systems. We use our developed platform, Open-MiChroM, to perform fast simulations and training. The models generated are precise compared to the experimental Hi-Cs, and the 3D structures ensemble is consistent with the crystal liquid theory for chromosomes. Additionally, we are able to predict important features of chromosome organization, such as the phase separation between chromatin types and the formation of chromosome territories. This novel modeling allows the exploration of a broad spectrum of 3D genome organizations on different organisms, cell lines, and cell phases.

Topological strings are well understood in perturbation theory, but their non-perturbative structure has been the subject of much work and speculation. A useful approach to this problem is to unveil the non-perturbative sectors of the theory by looking at the large order behavior of the perturbative series. This approach can be formulated in a mathematically rigorous way by using the theory of resurgence. In this talk I review the basic ideas behind this approach and I show that it can be successfully applied to topological string theory on arbitrary Calabi-Yau threefolds. Thsee methods lead, not only to explicit non-perturbative topological string amplitudes, but also to a conjecture relating the “invariants” of the theory of resurgence (also known as Stokes constants) to BPS invariants. Physically, this conjecture implies that the large order behavior of the topological string perturbative series contains information about the spectrum of stable D-brane sectors.

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Besides providing a possible explanation to the strong CP problem and dark matter, the QCD axion possesses a rich cosmology. For example, if PQ breaking occurs after inflation, then axion cosmic strings form. Near the QCD phase transition, every axion string become attached to a domain wall which pull on the strings and cause the string-wall network to decay. While every string becomes attached to a domain wall, it is possible, though rare, to form an enclosed domain wall that is not attached to any axion string. These enclosed domain walls collapse under their own self tension, compressing a large amount of energy into a small volume and thereby potentially forming a primordial black hole. In this talk, I will discuss the abundance of enclosed domain walls, their dynamics of collapse, the efficiency of black hole formation, and their relic abundance. For sufficiently large axion decay constants, there may be an observable gravitational lensing signal at future lensing telescopes, especially in models with axion-like-particles.

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Stochastic thermodynamics consists of a family of formalisms able to describe non-equilibrium processes in a general way and from a thermodynamic standpoint. It allows to obtain powerful results of universal nature, and has been employed in recent years to a wide variety of problems in different areas. I will introduce the basic concepts of the field and review recent developments. In particular, I will discuss a recent extension of the Second Law of thermodynamics to non-equilibrium steady states (Freitas and Esposito, Nat. Commun. 13, 5084 (2022)). I will also discuss the application of stochastic thermodynamics to non-linear electronic circuits (Freitas et. al. Phys. Rev. X 11, 031064 (2021)), and population dynamics models