Publications

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Asymmetric transport in long-range interacting chiral spin chains

Javad Vahedi

SciPost Phys. Core 5, 021 (2022) · published 13 April 2022 | · pdf

Harnessing power-law interactions ($1/r^\alpha$) in a large variety of physical systems are increasing. We study the dynamics of chiral spin chains as a possible multi-directional quantum channel. This arises from the nonlinear character of the dispersion with complex quantum interference effects. Using complementary numerical and analytical techniques, we propose a model to guide quantum states to a desired direction. We illustrate our approach using the long-range XXZ model modulated by Dzyaloshinskii-Moriya (DM) interaction. By exploring non-equilibrium dynamics after a local quantum quench, we identify the interplay of interaction range $\alpha$ and Dzyaloshinskii-Moriya coupling giving rise to an appreciable asymmetric spin excitations transport. This could be interesting for quantum information protocols to transfer quantum states, and it may be testable with current trapped-ion experiments. We further explore the growth of block entanglement entropy in these systems, and an order of magnitude reduction is distinguished.

2 citations
Di-$\pi^0$ correlations in p+p, p+Al and p+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV at STAR

Xiaoxuan Chu

SciPost Phys. Proc. 8, 043 (2022) · published 12 July 2022 | · pdf

The STAR Collaboration reports measurements of back-to-back azimuthal correlations of di-$\pi^0$ produced at forward pseudorapidity ($2.6<\eta<4.0$) in $p+$$p$, $p+$$\mathrm{Al}$ and $p+$$\mathrm{Au}$ collisions at a center-of-mass energy per nucleon-nucleon pair of 200 GeV. A clear suppression of the correlated away-side yields is observed in $p+$$\mathrm{Au}$ and for the first time in $p+$$\mathrm{Al}$ collisions, compared with the $p$$+$$p$ data. The enhanced suppression found in $p+$$\mathrm{Au}$ with respect to $p+$$\mathrm{Al}$ collisions exhibits the saturation scale ($Q_s^2$) dependence on the mass number~~$A$. The observed suppression of back-to-back pairs as a function of event activity and transverse momentum points to non-linear gluon dynamics arising at high parton densities.

2 citations
Codebase release r1.0 for disorder

Alexander Karlberg

SciPost Phys. Codebases 32-r1.0 (2024) · published 9 July 2024 | · src

We present a Fortran 77/95 code capable of computing QCD corrections in deep inelastic scattering (DIS). The code uses the Projection-to-Born method to augment an existing $\mathcal{O}(\alpha_{\mathrm{s}}^2)$ dijet DIS code, thereby obtaining predictions for photon-mediated neutral-current single-jet DIS production in the laboratory frame. The code is lightweight and fast, and yet includes the most common functionalities found in typical perturbative QCD programs, like automatic renormalisation and factorisation scale uncertainties, options to run and combine multiple seeds, and interfaces to fastjet and LHAPDF. Due to the underlying disent and HOPPET codes, the program also provides stable results in the infrared, relevant for extracting logarithmic coefficients for analytic resummations, and access to the massless DIS structure functions and (reduced) cross sections up to $\mathcal{O}(\alpha_{\mathrm{s}}^3)$.

2 citations
Equilibration of quantum cat states

Tony Jin

SciPost Phys. 9, 004 (2020) · published 8 July 2020 | · pdf

We study the equilibration properties of isolated ergodic quantum systems initially prepared in a cat state, i.e a macroscopic quantum superposition of states. Our main result consists in showing that, even though decoherence is at work in the mean, there exists a remnant of the initial quantum coherences visible in the strength of the fluctuations of the steady state. We back-up our analysis with numerical results obtained on the XXX spin chain with a random field along the z-axis in the ergodic regime and find good qualitative and quantitative agreement with the theory. We also present and discuss a framework where equilibrium quantities can be computed from general statistical ensembles without relying on microscopic details about the initial state, akin to the eigenstate thermalization hypothesis.

2 citations
On old relations of Lie theory, classical geometry and gauge theory

Rolf Dahm

SciPost Phys. Proc. 14, 025 (2023) · published 24 November 2023 | · pdf

Having been led by hadron interactions and low-energy photoproduction to SU(4) and non-compact SU*(4) symmetry, the general background turned out to be projective geometry (PG) of $P^3$, or when considering line and Complex geometry to include gauge theory, aspects of $P^5$. Point calculus and its dual completion by planes introduced quaternary (quadratic) "invariants" $x_{\mu}x^{\mu}=0$ and $p_{\mu}p^{\mu}=0$, and put focus on the intermediary form $(xu)$ and its treatment. Here, the major result is the identification of the symmetric 20 of SU(4) comprising nucleon and Delta states as related to the quaternary cubic forms discussed by Hilbert in his work on full invariant systems. So PG determines geometrically the scene by representations (reps) and invariant theory without having to force affine restrictions and additional (spinorial or gauge) rep theory.

2 citations
Introducing the Journal of Robustness Reports

František Bartoš, Alexandra Sarafoglou, Balazs Aczel, Suzanne Hoogeveen, Christopher D. Chambers, Eric-Jan Wagenmakers

J. Robust. Rep. 0-Editorial (2025) · published 16 April 2025 | · pdf

The vast majority of empirical research articles report a single primary analysis outcome that is the result of a single analysis plan, executed by a single analysis team (usually the team that also designed the experiment and collected the data). However, recent many-analyst projects have demonstrated that different analysis teams generally adopt a unique approach and that there exists considerable variability in the associated conclusions. There appears to be no single optimal statistical analysis plan, and different plausible plans need not lead to the same conclusion. A high variability in outcomes signals that the conclusions are relatively fragile and dependent on the specifics of the analysis plan. Crucially, without multiple teams analyzing the data, it is difficult to gauge the extent to which the conclusions are robust. We have recently proposed that empirical articles of particular scientific interest or societal importance are accompanied by two or three short reports that summarize the results of alternative analyses conducted by independent experts [F. Bartoš et al., Nat. Hum. Behav. (2025)]. In order to showcase the practical feasibility and epistemic benefits of this approach we have founded the Journal of Robustness Reports, which is dedicated to publishing short reanalyses of empirical findings. This editorial describes the scope and the workflow of the Journal of Robustness Reports including the type and format of the published articles. We hope that the Journal of Robustness Reports will help make reanalyses of published findings the norm across the empirical sciences.

2 citations
Intermittency Analysis of Toy Monte Carlo Events

Sheetal Sharma, Ramni Gupta

SciPost Phys. Proc. 10, 024 (2022) · published 11 August 2022 | · pdf

Event-by-event intermittency analysis of Toy Monte Carlo events is performed in the scenario of high multiplicity events as is the case at recent colliders RHIC and LHC for AA collisions. A power law behaviour of Normalized Factorial Moments (NFM), $F_{q}$ as function of number of bins ($M$) known as intermittency, is a signature of self-similar fluctuations. Dependence of NFM on the detector efficiencies and on the presence of fluctuations have been studied. Results presented here provide a baseline to the experimental results and clarity on the application of efficiency corrections to the experimental data.

2 citations
Engineering Gaussian states of light from a planar microcavity

Mathias Van Regemortel, Sylvain Ravets, Atac Imamoglu, Iacopo Carusotto, Michiel Wouters

SciPost Phys. 5, 013 (2018) · published 30 July 2018 | · pdf

Quantum fluids of light in a nonlinear planar microcavity can exhibit antibunched photon statistics at short distances due to repulsive polariton interactions. We show that, despite the weakness of the nonlinearity, the antibunching signal can be amplified orders of magnitude with an appropriate free-space optics scheme to select and interfere output modes. Our results are understood from the unconventional photon blockade perspective by analyzing the approximate Gaussian output state of the microcavity. In a second part, we illustrate how the temporal and spatial profile of the density-density correlation function of a fluid of light can be reconstructed with free-space optics. Also here the nontrivial (anti)bunching signal can be amplified significantly by shaping the light emitted by the microcavity.

2 citations
Constraints on physical computers in holographic spacetimes

Aleksander M. Kubicki, Alex May, David Pérez-Garcia

SciPost Phys. 16, 024 (2024) · published 23 January 2024 | · pdf

Within the setting of the AdS/CFT correspondence, we ask about the power of computers in the presence of gravity. We show that there are computations on $n$ qubits which cannot be implemented inside of black holes with entropy less than $O(2^n)$. To establish our claim, we argue computations happening inside the black hole must be implementable in a programmable quantum processor, so long as the inputs and description of the unitary to be run are not too large. We then prove a bound on quantum processors which shows many unitaries cannot be implemented inside the black hole, and further show some of these have short descriptions and act on small systems. These unitaries with short descriptions must be computationally forbidden from happening inside the black hole.

2 citations
Nonequilibrium probability currents in optically-driven colloidal suspensions

Samudrajit Thapa, Daniel Zaretzky, Ron Vatash, Grzegorz Gradziuk, Chase Broedersz, Yair Shokef, Yael Roichman

SciPost Phys. 17, 096 (2024) · published 1 October 2024 | · pdf

In the absence of directional motion it is often hard to recognize athermal fluctuations. Probability currents provide such a measure in terms of the rate at which they enclose area in the reduced phase space. We measure this area enclosing rate for trapped colloidal particles, where only one particle is driven. By combining experiment, theory, and simulation, we single out the effect of the different time scales in the system on the measured probability currents. In this controlled experimental setup, particles interact hydrodynamically. These interactions lead to a strong spatial dependence of the probability currents and to a local influence of athermal agitation. In a multiple-particle system, we show that even when the driving acts only on one particle, probability currents occur between other, non-driven particles. This may have significant implications for the interpretation of fluctuations in biological systems containing elastic networks in addition to a suspending fluid.

2 citations

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