A5037497635- Quantum many-body systems
- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Topological Materials and Phenomena
- Cold Atom Physics and Bose-Einstein Condensates
- Graphene research and applications
- Quantum Computing Algorithms and Architecture
- Quantum, superfluid, helium dynamics
- Algebraic structures and combinatorial models
- Theoretical and Computational Physics
- Software System Performance and Reliability
- Quantum Information and Cryptography
- Parallel Computing and Optimization Techniques
- Model Reduction and Neural Networks
- Research Data Management Practices
- Radiomics and Machine Learning in Medical Imaging
- Computational Physics and Python Applications
- Manufacturing Process and Optimization
- Industrial Vision Systems and Defect Detection
- Strong Light-Matter Interactions
- Functional Brain Connectivity Studies
- Advanced Thermodynamics and Statistical Mechanics
- Software Engineering Research
- Flexible and Reconfigurable Manufacturing Systems
- Magnetic Field Sensors Techniques
Technical University of Munich
2018-2024
Munich Center for Quantum Science and Technology
2023-2024
University of California, Berkeley
2020-2023
Max Planck Institute for the Physics of Complex Systems
2015-2016
Max Planck Society
2015
Ludwig-Maximilians-Universität München
2013
Tensor product state (TPS) based methods are powerful tools to efficiently simulate quantum many-body systems in and out of equilibrium. In particular, the one-dimensional matrix-product (MPS) formalism is by now an established tool condensed matter theory chemistry. these lecture notes, we combine a compact review basic TPS concepts with introduction versatile tensor library for Python (TeNPy) [https://github.com/tenpy/tenpy]. As concrete examples, consider MPS time-evolving block...
We investigate the effect of uniaxial heterostrain on interacting phase diagram magic-angle twisted bilayer graphene. Using both self-consistent Hartree-Fock and density-matrix renormalization group calculations, we find that small strain values ($\epsilon \sim 0.1 - 0.2 \%$) drive a zero-temperature transition between symmetry-broken Kramers intervalley-coherent insulator nematic semi-metal. The critical lies within range experimentally observed values, therefore predict is at least partly...
We present an infinite density-matrix renormalization group (DMRG) study of interacting continuum model twisted bilayer graphene (tBLG) near the magic angle. Because long-range Coulomb interaction and large number orbital degrees freedom, tBLG is difficult to with standard DMRG techniques -- even constructing storing Hamiltonian already poses a major challenge. To overcome these difficulties, we use recently developed compression procedure obtain matrix product operator representation which...
Analog quantum simulation has the potential to be an indispensable technique in investigation of complex systems. In this work, we numerically investigate a one-dimensional, faithful, analog, electronic circuit simulator built out Josephson junctions for one paradigmatic models integrable field theory: sine-Gordon (qSG) model 1+1 space-time dimensions. We analyze lattice using density matrix renormalization group and benchmark our numerical results with existing Bethe ansatz computations....
This work investigates the zero-temperature physics of generalized Bose-Hubbard models, which conserve finite Fourier momenta particle number. Analytical and numerical calculations predict a novel quasi-long-range order phase, in addition to more conventional Mott insulators. The former is characterized by two-species Luttinger liquid infrared, with microscopic expectation values dressed oscillatory contributions. authors also conjecture that this phase destroyed unbinding topological...
Purification is a tool that allows to represent mixed quantum states as pure on enlarged Hilbert spaces. A purification of given state not unique and its entanglement strongly depends the particular choice made. Moreover, in one-dimensional systems, amount linked how efficiently purified can be represented using matrix-product (MPS). We introduce an MPS based method find minimally entangled representation by iteratively minimizing second Renyi entropy. First, we consider thermofield double...
We revisit the problem of spin Drude weight $D$ integrable spin-$1/2$ XXZ chain using two complementary approaches, exact diagonalization (ED) and time-dependent density-matrix renormalization group (tDMRG). pursue main goals. First, we present extensive results for temperature dependence $D$. By exploiting time translation invariance within tDMRG, one can extract significantly lower temperatures than in previous tDMRG studies. Second, discuss numerical quality data elaborate on details...
Motivated by a recent optical-lattice experiment Choi et al. [Science 352, 1547 (2016)], we discuss how domain-wall melting can be used to investigate many-body localization. First, considering noninteracting fermion models, demonstrate that experimentally accessible measures are sensitive localization and thus detect the delocalization-localization transition, including divergences of characteristic length scales. Second, using extensive time-dependent density matrix renormalization group...
While standard approaches to quantum simulation require a number of qubits proportional the simulated particles, current noisy computers are limited tens qubits. With technique holographic simulation, D-dimensional system can be with (D−1)-dimensional subset qubits, enabling study systems significantly larger than computers. Using circuits derived from multiscale entanglement renormalization ansatz (MERA), we accurately prepare ground state an L=32 critical, nonintegrable perturbed Ising...
We investigate twisted bilayer graphene (TBG) at filling $\ensuremath{\nu}=\ensuremath{-}3$ in the presence of realistic heterostrain. Strain amplifies band dispersion and drives system beyond strong-coupling regime previous theoretical studies. use DMRG to conduct an unbiased, large-scale numerical calculations that include all spin valley degrees freedom, up bond dimension $\ensuremath{\chi}=24\phantom{\rule{0.16em}{0ex}}576$. establish a global phase diagram unifies number experimental...
TeNPy (short for ‘Tensor Network Python’) is a python library the simulation of strongly correlated quantum systems with tensor networks. The philosophy this to achieve balance readability and usability new-comers, while at same time providing powerful algorithms experts. focus on MPS 1D 2D lattices, such as DMRG ground state search, well dynamics using TEBD, TDVP, or MPO evolution. This article companion recent version 1.0 release gives brief overview package.
In contrast to the fractional quantum Hall (FQH) effect, where electron density fixes applied magnetic field, Chern insulators (FCIs) can realize FQH states in comparatively weak or even zero fields. Previous theoretical work highlighted magic angle graphene as a promising FCI platform, satisfying twin requirements of flat bands and lowest-Landau-level-like geometry. Indeed, recent experiments have demonstrated FCIs with Here we conduct detailed study most prominent state observed, clarify...
We numerically investigate the expansion of clouds hard-core bosons in two-dimensional square lattice using a matrix-product-state based method. This nonequilibrium set-up is induced by quenching trapping potential to zero and our work specifically motivated recent experiment with interacting an optical [Ronzheimer et al., Phys. Rev. Lett. 110, 205301 (2013)]. As anisotropy amplitudes $J_x$ $J_y$ for hopping different spatial directions varied from one- case, we observe crossover fast...
We propose and benchmark a modified time-evolving block decimation algorithm that uses truncation scheme based on the QR decomposition instead of singular value (SVD). The modification reduces scaling with dimension physical Hilbert space $d$ from ${d}^{3}$ down to ${d}^{2}$. Moreover, has lower computational complexity than SVD allows for highly efficient implementations GPU hardware. In simulation global quench in quantum clock model, we observe speedup up three orders magnitude comparing...
TeNPy (short for ‘Tensor Network Python’) is a python library the simulation of strongly correlated quantum systems with tensor networks. The philosophy this to achieve balance readability and usability new-comers, while at same time providing powerful algorithms experts. focus on MPS 1D 2D lattices, such as DMRG ground state search, well dynamics using TEBD, TDVP, or MPO evolution. This article companion recent version 1.0 release gives brief overview package.
When the two layers of a twisted moiré system are subject to different degrees strain, effect is amplified by inverse twist angle, e.g., factor 50 in magic angle bilayer graphene (TBG). Samples TBG typically have heterostrains 0.1-0.7%, increasing bandwidth "flat'' bands as much tenfold, placing an intermediate coupling regime. Here we study phase diagram presence heterostrain with unbiased, large-scale density matrix renormalization group calculations (bond dimension $χ=24576$), including...
Majorana zero modes (MZM-s) occurring at the edges of a 1D, p-wave, spinless superconductor, in absence fluctuations phase superconducting order parameter, are quintessential examples topologically-protected zero-energy 1D symmetry-protected topological phases. In this work, we numerically investigate fate presence phase-fluctuations using density matrix renormalization group (DMRG) technique. To that end, consider one-dimensional array MZM-s on mesoscopic islands temperature. Cooper-pair...
The highly tunable nature of synthetic quantum materials -- both in the solid-state and cold atom contexts invites examining which microscopic ingredients aid realization correlated phases matter such as superconductors. Recent experimental advances moir\'e suggest that unifying features Fermi-Hubbard model Hall systems creates a fertile ground for emergence phases. Here, we introduce minimal 2D lattice incorporates exactly these features: time-reversal symmetry, band topology, strong...
Spontaneous symmetry breaking underlies much of our classification phases matter and their associated transitions. The nature the underlying being broken determines many qualitative properties phase; this is illustrated by case discrete versus continuous breaking. Indeed, in contrast to case, a leads emergence gapless Goldstone modes controlling, for instance, thermodynamic stability ordered phase. Here, we realize two-dimensional dipolar XY model -- which exhibits spin-rotational utilizing...
We predict that the gapless $U(1)$ Dirac spin liquid naturally emerges in a two-dimensional array of quantum dipoles. In particular, we demonstrate dipolar XY model$\unicode{x2014}$realized both Rydberg atom arrays and ultracold polar molecules$\unicode{x2014}$hosts ground state on kagome lattice. Large-scale density matrix renormalization group calculations indicate this exhibits signatures gapless, linearly-dispersing spinons, consistent with liquid. identify route to adiabatic preparation...
Can superconductivity arise from strong repulsive interactions between electrons in a lattice model with topological bands? Here, the authors answer this question affirmative via DMRG numerical simulations of an interacting spinful bilayer Hofstadter featuring low-lying bands opposite Chern number. Furthermore, by developing new technique to probe pairing symmetry number-conserving DMRG, demonstrate that is $p$-wave, tantalizingly reminiscent nodal recently observed twisted graphene, which...
While standard approaches to quantum simulation require a number of qubits proportional the simulated particles, current noisy computers are limited tens qubits. With technique holographic simulation, $D$-dimensional system can be with $D{\rm -}1$-dimensional subset qubits, enabling study systems significantly larger than computers. Using circuits derived from multiscale entanglement renormalization ansatz (MERA), we accurately prepare ground state an $L=32$ critical, non-integrable...
We investigate the effect that spatially modulated continuous conserved quantities can have on quantum ground states. do so by introducing a family of one-dimensional local rotor and bosonic models which conserve finite Fourier momenta particle number, but not number itself. These correspond to generalizations standard Bose-Hubbard model (BHM), relate physics Bose surfaces. First, we show while having an infinite-dimensional Hilbert space, such systems feature non-trivial space fragmentation...