Publications

Order by: publication date number of citations

• Codebase release 1.0 for BlockGen

  Enrico Bothmann, Walter Giele, Stefan Hoeche, Joshua Isaacson, Max Knobbe

  SciPost Phys. Codebases 3-r1.0 (2022) · published 23 August 2022 | Toggle abstract · src

  The compute efficiency of Monte-Carlo event generators for the Large Hadron Collider is expected to become a major bottleneck for simulations in the high-luminosity phase. Aiming at the development of a full-fledged generator for modern GPUs, we study the performance of various recursive strategies to compute multi-gluon tree-level amplitudes. We investigate the scaling of the algorithms on both CPU and GPU hardware. Finally, we provide practical recommendations as well as baseline implementations for the development of future simulation programs. The GPU implementations can be found at: https://www.gitlab.com/ebothmann/blockgen-archive.

  3 citations

• Low-energy excitations and transport functions of the one-dimensional Kondo insulator

  Robert Peters, Roman Rausch

  SciPost Phys. 14, 166 (2023) · published 21 June 2023 | Toggle abstract · pdf

  Using variational matrix product states, we analyze the finite temperature behavior of a half-filled periodic Anderson model in one dimension, a prototypical model of a Kondo insulator. We present an extensive analysis of single-particle Green's functions, two-particle Green's functions, and transport functions creating a broad picture of the low-temperature properties. We confirm the existence of energetically low-lying spin excitations in this model and study their energy-momentum dispersion and temperature dependence. We demonstrate that charge-charge correlations at the Fermi energy exhibit a different temperature dependence than spin-spin correlations. While energetically low-lying spin excitations emerge approximately at the Kondo temperature, which exponentially depends on the interaction strength, charge correlations vanish already at high temperatures. Furthermore, we analyze the charge and thermal conductivity at finite temperatures by calculating the time-dependent current-current correlation functions. While both charge and thermal conductivity can be fitted for all interaction strengths by gapped systems with a renormalized band gap, the gap in the system describing the thermal conductivity is generally smaller than the system describing the charge conductivity. Thus, two-particle correlations affect the charge and heat conductivities in a different way resulting in a temperature region where the charge conductivity of this one-dimensional Kondo insulator is already decreasing while the heat conductivity is still increasing.

  3 citations

• The DAMIC-M experiment: Status and first results

  Isaac J. Arnquist, Nicolas Avalos, Philippe Bailly, David Baxter, Xavier Bertou, Mircea Bogdan, Christian Bourgeois, J. Brandt, Arnaud Cadiou, Nuria Castelló-Mor, Alvaro E. Chavarria, Marcel Conde, Nicholas J. Corso, J. C. Gutiérrez, Julian Cuevas-Zepeda, Ali Dastgheibi-Fard, Claudia De Dominicis, Olivier Deligny, R. Desani, Marc Dhellot, Jean-Jacques Dormard, Jordi Duarte-Campderros, E. Estrada, D. Florin, N. Gadola, R. Gaïor, J. González Sánchez, Todd W. Hossbach, Michael Huehn, Latifa Khalil, Ben Kilminster, Agustin Lantero-Barreda, Ian Lawson, Hervé Lebbolo, Steven Lee, Pascal Leray, Antoine Letessier-Selvon, Pia Loaiza, Amparo Lopez-Virto, David Martin, Ariel Matalon, Kellie McGuire, T. Milleto, Pitam Mitra, David M. Martin, S. Munagavalasa, Danielle Norcini, Cory T. Overman, Giorgos Papadopoulos, S. Paul, David Peterson, Alexander Piers, Olivier Pochon, Paolo Privitera, Karthik Ramanathan, Denis Reynet, Peter Robmann, Ryan Roehnelt, Mariangela Settimo, Radomir Smida, Ben Stillwell, Ryan Thomas, Michelangelo Traina, Philippe Vallerand, Tim Van Wechel, Ivan Vila, Rocio V. Cortabitarte, Achim Vollhardt, Guillaume Warot, D. Wolf, Rachana Yajur, J-P. Zopounidis

  SciPost Phys. Proc. 12, 014 (2023) · published 3 July 2023 | Toggle abstract · pdf

  The DAMIC-M (DArk Matter In CCDs at Modane) experiment employs thick, fully depleted silicon charged-coupled devices (CCDs) to search for dark matter particles with a target exposure of 1 kg-year. A novel skipper readout implemented in the CCDs provides single electron resolution through multiple non-destructive measurements of the individual pixel charge, pushing the detection threshold to the eV-scale. DAMIC-M will advance by several orders of magnitude the exploration of the dark matter particle hypothesis, in particular of candidates pertaining to the so-called "hidden sector." A prototype, the Low Background Chamber (LBC), with 20g of low background Skipper CCDs, has been recently installed at Laboratoire Souterrain de Modane and is currently taking data. We will report the status of the DAMIC-M experiment and first results obtained with LBC commissioning data.

  3 citations

• A systematic interpolatory method for an impurity in a one-dimensional fermionic background

  Erik J. Lindgren, Rafael E. Barfknecht, Nikolaj T. Zinner

  SciPost Phys. 9, 005 (2020) · published 13 July 2020 | Toggle abstract · pdf

  We explore a new numerical method for studying one-dimensional quantum systems in a trapping potential. We focus on the setup of an impurity in a fermionic background, where a single distinguishable particle interacts through a contact potential with a number of identical fermions. We can accurately describe this system, for various particle numbers, different trapping potentials and arbitrary finite repulsion, by constructing a truncated basis containing states at both zero and infinite repulsion. The results are compared with matrix product states methods and with the analytical result for two particles in a harmonic well.

  3 citations

• Quantum walks on graphs of the ordered Hamming scheme and spin networks

  Hiroshi Miki, Satoshi Tsujimoto, Luc Vinet

  SciPost Phys. 7, 001 (2019) · published 2 July 2019 | Toggle abstract · pdf

  It is shown that the hopping of a single excitation on certain triangular spin lattices with non-uniform couplings and local magnetic fields can be described as the projections of quantum walks on graphs of the ordered Hamming scheme of depth 2. For some values of the parameters the models exhibit perfect state transfer between two summits of the lattice. Fractional revival is also observed in some instances. The bivariate Krawtchouk polynomials of the Tratnik type that form the eigenvalue matrices of the ordered Hamming scheme of depth 2 give the overlaps between the energy eigenstates and the occupational basis vectors.

  3 citations

• The search for the neutron electric dipole moment at PSI

  Guillaume Pignol, Philipp Schmidt-Wellenburg

  SciPost Phys. Proc. 5, 027 (2021) · published 6 September 2021 | Toggle abstract · pdf

  The existence of a nonzero permanent electric dipole moment (EDM) of the neutron would reveal a new source of CP violation and shed light on the origin of the matter--antimatter asymmetry of the Universe. The sensitivity of current experiments using stored ultracold neutrons (UCN) probes new physics beyond the TeV scale. Using the UCN source at the Paul Scherrer Institut, the nEDM collaboration has performed the most sensitive measurement of the neutron EDM to date, still compatible with zero ($|d_n|<1.8\times 10^{-26} \, e {\rm cm}$, C.L.90%). A new experiment designed to improve the sensitivity by an order of magnitude, n2EDM, is currently in construction.

  3 citations

• Collective Monte Carlo updates through tensor network renormalization

  Miguel Frías-Pérez, Michael Mariën, David Pérez García, Mari Carmen Bañuls, Sofyan Iblisdir

  SciPost Phys. 14, 123 (2023) · published 22 May 2023 | Toggle abstract · pdf

  We introduce a Metropolis-Hastings Markov chain for Boltzmann distributions of classical spin systems. It relies on approximate tensor network contractions to propose correlated collective updates at each step of the evolution. We present benchmark computations for a wide variety of instances of the two-dimensional Ising model, including ferromagnetic, antiferromagnetic, (fully) frustrated and Edwards-Anderson spin glass instances, and we show that, with modest computational effort, our Markov chain achieves sizeable acceptance rates, even in the vicinity of critical points. In each of the situations we have considered, the Markov chain compares well with other Monte Carlo schemes such as the Metropolis or Wolff's algorithm: equilibration times appear to be reduced by a factor that varies between $40$ and $2000$, depending on the model and the observable being monitored. We also present an extension to three spatial dimensions, and demonstrate that it exhibits fast equilibration for finite ferro- and antiferromagnetic instances. Additionally, and although it is originally designed for a square lattice of finite degrees of freedom with open boundary conditions, the proposed scheme can be used as such, or with slight modifications, to study triangular lattices, systems with continuous degrees of freedom, matrix models, a confined gas of hard spheres, or to deal with arbitrary boundary conditions.

  3 citations

• On the spin content of the classical massless Rarita-Schwinger system

  Mauricio Valenzuela, Jorge Zanelli

  SciPost Phys. Proc. 14, 047 (2023) · published 24 November 2023 | Toggle abstract · pdf

  We analyze the Rarita-Schwinger massless theory in the Lagrangian and Hamiltonian approaches. At the Lagrangian level, the standard gamma-trace gauge fixing constraint leaves a 1/2 and a 3/2 propagating Poincaré group helicities. At the Hamiltonian level, the result depends on whether the Dirac conjecture is assumed or not. In the affirmative case, a secondary first class constraint is added to the total Hamiltonian and a corresponding gauge fixing condition must be imposed, completely removing the 1/2 sector. In the opposite case, the 1/2 field propagates and the Hamilton field equations match the Euler-Lagrange equations.

  3 citations

• Emergence of generalized hydrodynamics in the non-local Luttinger model

  Per Moosavi

  SciPost Phys. 9, 037 (2020) · published 11 September 2020 | Toggle abstract · pdf

  We propose the Luttinger model with finite-range interactions as a simple tractable example in 1+1 dimensions to analytically study the emergence of Euler-scale hydrodynamics in a quantum many-body system. This non-local Luttinger model is an exactly solvable quantum field theory somewhere between conformal and Bethe-ansatz integrable models. Applying the recent proposal of generalized hydrodynamics, we show that the model allows for fully explicit yet non-trivial solutions of the resulting Euler-scale hydrodynamic equations. Comparing with exact analytical non-equilibrium results valid at all time and length scales, we show perfect agreement at the Euler scale when the interactions are short range. A formal proof of the emergence of generalized hydrodynamics in the non-local Luttinger model is also given, and effects of long-range interactions are briefly discussed.

  3 citations

• An association sequence suitable for producing ground-state RbCs molecules in optical lattices

  Arpita Das, Philip D. Gregory, Tetsu Takekoshi, Luke Fernley, Manuele Landini, Jeremy M. Hutson, Simon L. Cornish, Hanns-Christoph Nägerl

  SciPost Phys. 15, 220 (2023) · published 1 December 2023 | Toggle abstract · pdf

  We identify a route for the production of $^{87}$Rb$^{133}$Cs molecules in the $X^1\Sigma^+$ rovibronic ground state that is compatible with efficient mixing of the atoms in optical lattices. We first construct a model for the excited-state structure using constants found by fitting to spectroscopy of the relevant $a\,^3 \Sigma^+ → b\, ^3\Pi_1$ transitions at 181.5 G and 217.1 G. We then compare the predicted transition dipole moments from this model to those found for the transitions that have been successfully used for STIRAP at 181.5 G. We form molecules by magnetoassociation on a broad interspecies Feshbach resonance at 352.7 G and explore the pattern of Feshbach states near 305 G. This allows us to navigate to a suitable initial state for STIRAP by jumping across an avoided crossing with radiofrequency radiation. We identify suitable transitions for STIRAP at 305 G. We characterize these transitions experimentally and demonstrate STIRAP to a single hyperfine level of the ground state with a one-way efficiency of 85(4)%.

  3 citations