Publications

Order by: publication date number of citations

• Chiral symmetry restoration with three chiral partners

  Juan M. Torres-Rincon

  SciPost Phys. Proc. 6, 015 (2022) · published 31 May 2022 | Toggle abstract · pdf

  I discuss the masses of chiral partners in the context of chiral symmetry restoration at finite temperature. Using the Nambu–Jona-Lasinio model I first remind the usual situation where two mesons of opposed parity become degenerate above the chiral transition temperature. Then I consider an effective theory for D mesons where the positive parity companion presents a “double pole structure”. In this case three different masses need to be analyzed as functions of the temperature. I suggest a possible restoration pattern at high temperatures when the back-reaction of the quark condensate is incorporated.

  1 citation

• Applying machine learning methods to prediction problems of lattice observables

  N. V. Gerasimeniuk, M. N. Chernodub, V. A. Goy, D. L. Boyda, S. D. Liubimov, A. V. Molochkov

  SciPost Phys. Proc. 6, 020 (2022) · published 31 May 2022 | Toggle abstract · pdf

  We discuss the prediction of critical behavior of lattice observables in SU(2) and SU(3) gauge theories. We show that feed-forward neural network, trained on the lattice configurations of gauge fields as input data, finds correlations with the target observable, which is also true in the critical region where the neural network has not been trained. We have verified that the neural network constructs a gauge-invariant function and this property does not change over the entire range of the parameter space.

  1 citation

• Tapered amplifier laser with frequency-shifted feedback

  A. Bayerle, S. Tzanova, P. Vlaar, B. Pasquiou, F. Schreck

  SciPost Phys. 1, 002 (2016) · published 22 October 2016 | Toggle abstract · pdf

  We present a frequency-shifted feedback (FSF) laser based on a tapered amplifier. The laser operates as a coherent broadband source with up to 370GHz spectral width and 2.3us coherence time. If the FSF laser is seeded by a continuous-wave laser a frequency comb spanning the output spectrum appears in addition to the broadband emission. The laser has an output power of 280mW and a center wavelength of 780nm. The ease and flexibility of use of tapered amplifiers makes our FSF laser attractive for a wide range of applications, especially in metrology.

  1 citation

• Mutual multilinearity of nonequilibrium network currents

  Sara Dal Cengio, Pedro E. Harunari, Vivien Lecomte, Matteo Polettini

  SciPost Phys. 19, 111 (2025) · published 27 October 2025 | Toggle abstract · pdf

  Continuous-time Markov chains have been successful in modelling systems across numerous fields, with currents being fundamental entities that describe the flows of energy, particles, individuals, chemical species, information, or other quantities. They apply to systems described by agents transitioning between vertices along the edges of a network (at some rate in each direction). It has recently been shown by the authors that, at stationarity, a hidden linearity exists between currents that flow along edges: if one controls the current of a specific "input" edge (by tuning transition rates along it), any other current is a linear-affine function of the input current [Phys. Rev. Lett. 133, 047401 (2024)]. In this paper, we extend this result to the situation where one controls the currents of several edges, and prove that other currents are in linear-affine relation with the input ones. Two proofs with distinct insights are provided: the first relies on Kirchhoff's current law and reduces the input set inductively through graph analysis, while the second utilizes the resolvent approach via a Laplace transform in time. We obtain explicit expressions for the current-to-current susceptibilities, which allow one to map current dependencies through the network. We also verify from our expression that Kirchhoff's current law is recovered as a limiting case of our mutual linearity. Last, we uncover that susceptibilities can be obtained from fluctuations when the reference system is originally at equilibrium.

  1 citation

• The high-temperature expansion of the thermal sunset

  Andreas Ekstedt, Johan Löfgren

  SciPost Phys. Core 3, 008 (2020) · published 22 October 2020 | Toggle abstract · pdf

  We give a prescription for calculating the high-temperature expansion of the thermal sunset integral to arbitrary order. We derive all terms odd in $T$, and rederive previous results up to $\mathcal{O}(T^0) $ for both bosonic and fermionic thermal sunsets in dimensional regularisation. We perform analytical and numerical cross-checks. Intermediate steps involve integrals over three Bessel functions.

  1 citation

• Importance of the X-ray edge singularity for the detection of relic neutrinos in the PTOLEMY project

  Zhiyang Tan, Vadim Cheianov

  SciPost Phys. 17, 022 (2024) · published 26 July 2024 | Toggle abstract · pdf

  Direct detection of relic neutrinos in a beta-decay experiment is an ambitious goal that has long been beyond the reach of available technology. One of the most challenging practical difficulties for such an experiment is managing a large amount of radioactive material without compromising the energy resolution required to distinguish useful events from the substantial beta-decay background. The PTOLEMY project offers an innovative solution to this problem by depositing radioactive material on graphene. While this approach is expected to address the main challenge, it introduces new issues due to the proximity of the beta decayers to a solid-state system. In this work, we focus on the effect of the shakeup of the graphene electron system caused by a beta-decay event. We calculate the distortion of the relic neutrino peaks resulting from this shakeup, analyze the impact of the distortion on the visibility of neutrino capture events, and discuss potential technological solutions to enhance the visibility of these events.

  1 citation

• Nodal-antinodal dichotomy from anisotropic quantum critical continua in holographic models

  Ronnie Rodgers, Jewel Kumar Ghosh, Alexander Krikun

  SciPost Phys. 14, 161 (2023) · published 19 June 2023 | Toggle abstract · pdf

  We demonstrate that the absence of stable quasiparticle excitations on parts of the Fermi surface, similar to the "nodal-antinodal dichotomy" in underdoped cuprate superconductors, can be reproduced in models of strongly correlated electrons defined via a holographic dual. We show analytically that the anisotropy of the quantum critical continuum, which is a feature of these models, may lead to washing out the quasiparticle peak in one direction while leaving it intact in the perpendicular one. The effect relies on the qualitatively different scaling of the self-energy in different directions. Using the explicit example of the anisotropic Q-lattice model, we demonstrate how this effect emerges due to specific features of the near horizon geometry of the black hole in the dual description.

  1 citation

• QDarts: A quantum dot array transition simulator for finding charge transitions in the presence of finite tunnel couplings, non-constant charging energies and sensor dots

  Jan A. Krzywda, Weikun Liu, Evert van Nieuwenburg, Oswin Krause

  SciPost Phys. Codebases 43 (2025) · published 9 January 2025 | Toggle abstract · pdf

  We present QDarts, an efficient simulator for realistic charge stability diagrams of quantum dot array (QDA) devices in equilibrium states. It allows for pinpointing the location of concrete charge states and their transitions in a high-dimensional voltage space (via arbitrary two-dimensional cuts through it), and includes effects of finite tunnel coupling, non-constant charging energy and a simulation of noisy sensor dots. These features enable close matching of various experimental results in the literature, and the package hence provides a flexible tool for testing QDA experiments, as well as opening the avenue for developing new methods of device tuning.

  1 citation

• Fermionic defects of topological phases and logical gates

  Ryohei Kobayashi

  SciPost Phys. 15, 028 (2023) · published 25 July 2023 | Toggle abstract · pdf

  We discuss the codimension-1 defects of (2+1)D bosonic topological phases, where the defects can support fermionic degrees of freedom. We refer to such defects as fermionic defects, and introduce a certain subclass of invertible fermionic defects called "gauged Gu-Wen SPT defects" that can shift self-statistics of anyons. We derive a canonical form of a general fermionic invertible defect, in terms of the fusion of a gauged Gu-Wen SPT defect and a bosonic invertible defect decoupled from fermions on the defect. We then derive the fusion rule of generic invertible fermionic defects. The gauged Gu-Wen SPT defects give rise to interesting logical gates of stabilizer codes in the presence of additional ancilla fermions. For example, we find a realization of the CZ logical gate on the (2+1)D $\mathbb{Z}_2$ toric code stacked with a (2+1)D ancilla trivial atomic insulator. We also investigate a gapped fermionic interface between (2+1)D bosonic topological phases realized on the boundary of the (3+1)D Walker-Wang model. In that case, the gapped interface can shift the chiral central charge of the (2+1)D phase. Among these fermionic interfaces, we study an interesting example where the (3+1)D phase has a spatial reflection symmetry, and the fermionic interface is supported on a reflection plane that interpolates a (2+1)D surface topological order and its orientation-reversal. We construct a (3+1)D exactly solvable Hamiltonian realizing this setup, and find that the model generates the $\mathbb{Z}_8$ classification of the (3+1)D invertible phase with spatial reflection symmetry and fermion parity on the reflection plane. We make contact with an effective field theory, known in literature as the exotic invertible phase with spacetime higher-group symmetry.

  1 citation

• Quantum rotor in a two-dimensional mesoscopic Bose gas

  Michał Suchorowski, Alina Badamshina, Mikhail Lemeshko, Michał Tomza, Artem G. Volosniev

  SciPost Phys. 18, 059 (2025) · published 19 February 2025 | Toggle abstract · pdf

  We investigate a molecular quantum rotor in a two-dimensional Bose-Einstein condensate. The focus is on studying the angulon quasiparticle concept in the crossover from few- to many-body physics. To this end, we formulate the problem in real space and solve it with a mean-field approach in the frame co-rotating with the impurity. We show that the system starts to feature angulon characteristics when the size of the bosonic cloud is large enough to screen the rotor. More importantly, we demonstrate the departure from the angulon picture for large system sizes or large angular momenta where the properties of the system are determined by collective excitations of the Bose gas.

  1 citation