Imperial College London

DrJohannesKnolle

Faculty of Natural SciencesDepartment of Physics

Lecturer in Quantum Simulation and Computation of Materials
 
 
 
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Contact

 

j.knolle

 
 
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Location

 

812Blackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

94 results found

Zhao H, Knolle J, Moessner R, Mintert Fet al., 2022, Suppression of Interband Heating for Random Driving, Physical Review Letters, Vol: 129, ISSN: 0031-9007

Journal article

Willsher J, Liu S-W, Moessner R, Knolle Jet al., 2022, Measurement-induced phase transition in a chaotic classical many-body system, PHYSICAL REVIEW B, Vol: 106, ISSN: 2469-9950

Journal article

Jin H-K, Natori WMH, Pollmann F, Knolle Jet al., 2022, Unveiling the S=3/2 Kitaev honeycomb spin liquids, NATURE COMMUNICATIONS, Vol: 13

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Zhao H, Rudner MS, Moessner R, Knolle Jet al., 2022, Anomalous random multipolar driven insulators, PHYSICAL REVIEW B, Vol: 105, ISSN: 2469-9950

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Powalla L, Kiemle J, Koenig EJ, Schnyder AP, Knolle J, Kern K, Holleitner A, Kastl C, Burghard Met al., 2022, Berry curvature-induced local spin polarisation in gated graphene/WTe2 heterostructures, NATURE COMMUNICATIONS, Vol: 13

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Halimeh JC, Homeier L, Zhao H, Bohrdt A, Grusdt F, Hauke P, Knolle Jet al., 2022, Enhancing Disorder-Free Localization through Dynamically Emergent Local Symmetries, PRX QUANTUM, Vol: 3

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Metavitsiadis A, Natori W, Knolle J, Brenig Wet al., 2022, Optical phonons coupled to a Kitaev spin liquid, PHYSICAL REVIEW B, Vol: 105, ISSN: 2469-9950

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Vovrosh J, Zhao H, Knolle J, Bastianello Aet al., 2022, Confinement-induced impurity states in spin chains, PHYSICAL REVIEW B, Vol: 105, ISSN: 2469-9950

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Zhao H, Smith A, Mintert F, Knolle Jet al., 2021, Orthogonal Quantum Many-Body Scars, PHYSICAL REVIEW LETTERS, Vol: 127, ISSN: 0031-9007

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Vovrosh J, Khosla KE, Greenaway S, Self C, Kim MS, Knolle Jet al., 2021, Simple mitigation of global depolarizing errors in quantum simulations., Physical Review E: Statistical, Nonlinear, and Soft Matter Physics, Vol: 104, Pages: 1-8, ISSN: 1539-3755

To get the best possible results from current quantum devices error mitigation is essential. In this work we present a simple but effective error mitigation technique based on the assumption that noise in a deep quantum circuit is well described by global depolarizing error channels. By measuring the errors directly on the device, we use an error model ansatz to infer error-free results from noisy data. We highlight the effectiveness of our mitigation via two examples of recent interest in quantum many-body physics: entanglement measurements and real-time dynamics of confinement in quantum spin chains. Our technique enables us to get quantitative results from the IBM quantum computers showing signatures of confinement, i.e., we are able to extract the meson masses of the confined excitations which were previously out of reach. Additionally, we show the applicability of this mitigation protocol in a wider setting with numerical simulations of more general tasks using a realistic error model. Our protocol is device-independent, simply implementable, and leads to large improvements in results if the global errors are well described by depolarization.

Journal article

Pizzi A, Nunnenkamp A, Knolle J, 2021, Classical Prethermal Phases of Matter, PHYSICAL REVIEW LETTERS, Vol: 127, ISSN: 0031-9007

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Pizzi A, Nunnenkamp A, Knolle J, 2021, Classical approaches to prethermal discrete time crystals in one, two, and three dimensions, PHYSICAL REVIEW B, Vol: 104, ISSN: 2469-9950

Journal article

Mori T, Zhao H, Mintert F, Knolle J, Moessner Ret al., 2021, Rigorous Bounds on the Heating Rate in Thue-Morse Quasiperiodically and Randomly Driven Quantum Many-Body Systems, PHYSICAL REVIEW LETTERS, Vol: 127, ISSN: 0031-9007

Journal article

Jin H-K, Knolle J, 2021, Flat and correlated plasmon bands in graphenek/alpha-RuCl3 heterostructures, PHYSICAL REVIEW B, Vol: 104, ISSN: 2469-9950

Journal article

Self CN, Khosla KE, Smith AWR, Sauvage F, Haynes PD, Knolle J, Mintert F, Kim MSet al., 2021, Variational quantum algorithm with information sharing, npj Quantum Information, Vol: 7, ISSN: 2056-6387

We introduce an optimisation method for variational quantum algorithms and experimentally demonstrate a 100-fold improvement in efficiency compared to naive implementations. The effectiveness of our approach is shown by obtaining multi-dimensional energy surfaces for small molecules and a spin model. Our method solves related variational problems in parallel by exploiting the global nature of Bayesian optimisation and sharing information between different optimisers. Parallelisation makes our method ideally suited to the next generation of variational problems with many physical degrees of freedom. This addresses a key challenge in scaling-up quantum algorithms towards demonstrating quantum advantage for problems of real-world interest.

Journal article

Hodson T, Willsher J, Knolle J, 2021, One-dimensional long-range Falikov-Kimball model: Thermal phase transition and disorder-free localization, PHYSICAL REVIEW B, Vol: 104, ISSN: 2469-9950

Journal article

Vovrosh J, Knolle J, 2021, Confinement and entanglement dynamics on a digital quantum computer, Scientific Reports, Vol: 11, Pages: 1-8, ISSN: 2045-2322

Confinement describes the phenomenon when the attraction between two particles grows with their distance, most prominently found in quantum chromodynamics (QCD) between quarks. In condensed matter physics, confinement can appear in quantum spin chains, for example, in the one dimensional transverse field Ising model (TFIM) with an additional longitudinal field, famously observed in the quantum material cobalt niobate or in optical lattices. Here, we establish that state-of-the-art quantum computers have reached capabilities to simulate confinement physics in spin chains. We report quantitative confinement signatures of the TFIM on an IBM quantum computer observed via two distinct velocities for information propagation from domain walls and their mesonic bound states. We also find the confinement induced slow down of entanglement spreading by implementing randomized measurement protocols for the second order Rényi entanglement entropy. Our results are a crucial step for probing non-perturbative interacting quantum phenomena on digital quantum computers beyond the capabilities of classical hardware.

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Pizzi A, Knolle J, Nunnenkamp A, 2021, Higher-order and fractional discrete time crystals in clean long-range interacting systems, NATURE COMMUNICATIONS, Vol: 12, ISSN: 2041-1723

Journal article

Agarwala A, Bhattacharjee S, Knolle J, Moessner Ret al., 2021, Gapless state of interacting Majorana fermions in a strain-induced Landau level, PHYSICAL REVIEW B, Vol: 103, ISSN: 2469-9950

Journal article

Liu S-W, Willsher J, Bilitewski T, Li J-J, Smith A, Christensen K, Moessner R, Knolle Jet al., 2021, Butterfly effect and spatial structure of information spreading in a chaotic cellular automaton, Physical Review B, Vol: 103, Pages: 1-6, ISSN: 2469-9950

Inspired by recent developments in the study of chaos in many-body systems, we construct a measure of local information spreading for a stochastic cellular automaton in the form of a spatiotemporally resolved Hamming distance. This decorrelator is a classical version of an out-of-time-order correlator studied in the context of quantum many-body systems. Focusing on the one-dimensional Kauffman cellular automaton, we extract the scaling form of our decorrelator with an associated butterfly velocity vb and a velocity-dependent Lyapunov exponent λ(v). The existence of the latter is not a given in a discrete classical system. Second, we account for the behavior of the decorrelator in a framework based solely on the boundary of the information spreading, including an effective boundary random walk model yielding the full functional form of the decorrelator. In particular, we obtain analytic results for vb and the exponent β in the scaling ansatz λ(v)∼μ(v−vb)β, which is usually only obtained numerically. Finally, a full scaling collapse establishes the decorrelator as a unifying diagnostic of information spreading.

Journal article

Leeb V, Polyudov K, Mashhadi S, Biswas S, Valenti R, Burghard M, Knolle Jet al., 2021, Anomalous Quantum Oscillations in a Heterostructure of Graphene on a Proximate Quantum Spin Liquid, PHYSICAL REVIEW LETTERS, Vol: 126, ISSN: 0031-9007

Journal article

Kao W-H, Knolle J, Halasz GB, Moessner R, Perkins NBet al., 2021, Vacancy-Induced Low-Energy Density of States in the Kitaev Spin Liquid, PHYSICAL REVIEW X, Vol: 11, ISSN: 2160-3308

Journal article

Pizzi A, Nunnenkamp A, Knolle J, 2021, Bistability and time crystals in long-ranged directed percolation, NATURE COMMUNICATIONS, Vol: 12

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Malz D, Pizzi A, Nunnenkamp A, Knolle Jet al., 2021, Seasonal epidemic spreading on small-world networks: Biennial outbreaks and classical discrete time crystals, PHYSICAL REVIEW RESEARCH, Vol: 3

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Zhao H, Mintert F, Moessner R, Knolle Jet al., 2021, Random Multipolar Driving: Tunably Slow Heating through Spectral Engineering, PHYSICAL REVIEW LETTERS, Vol: 126, ISSN: 0031-9007

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Pizzi A, Malz D, De Tomasi G, Knolle J, Nunnenkamp Aet al., 2020, Time crystallinity and finite-size effects in clean Floquet systems, PHYSICAL REVIEW B, Vol: 102, ISSN: 2469-9950

Journal article

Stalhammar M, Larana-Aragon J, Knolle J, Bergholtz EJet al., 2020, Magneto-optical conductivity in generic Weyl semimetals, PHYSICAL REVIEW B, Vol: 102, ISSN: 2469-9950

Journal article

Feldmeier J, Natori W, Knap M, Knolle Jet al., 2020, Local probes for charge-neutral edge states in two-dimensional quantum magnets, PHYSICAL REVIEW B, Vol: 102, ISSN: 2469-9950

Journal article

Papaefstathiou I, Smith A, Knolle J, 2020, Disorder-free localization in a simple U (1) lattice gauge theory, PHYSICAL REVIEW B, Vol: 102, ISSN: 2469-9950

Journal article

Natori WMH, Knolle J, 2020, Dynamics of a two-dimensional quantum spin-orbital liquid: spectroscopic signatures of fermionic magnons, Physical Review Letters, Vol: 125, Pages: 067201 – 1-067201 – 6, ISSN: 0031-9007

We provide an exact study of dynamical correlations for the quantum spin-orbital liquid phases of an SU(2)-symmetric Kitaev honeycomb lattice model. We show that the spin dynamics in this Kugel-Khomskii type model is exactly the density-density correlation function of S=1 fermionic magnons, which could be probed in resonant inelastic x-ray scattering experiments. We predict the characteristic signatures of spin-orbital fractionalization in inelastic scattering experiments and compare them to the ones of the spin-anisotropic Kitaev honeycomb spin liquid. In particular, the resonant inelastic x-ray scattering response shows a characteristic momentum dependence directly related to the dispersion of fermionic excitations. The neutron scattering cross section displays a mixed response of fermionic magnons as well as spin-orbital excitations. The latter has a bandwidth of broad excitations and a vison gap that is three times larger than that of the spin-1=2 Kitaev model.

Journal article

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