Publications
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Quantum Birthmarks: Ergodicity Breaking Beyond Scarring
A. M. Graf, S. Atwood, M. Xiao, R. Ketzmerick, E. J. Heller, and J. Keski-Rahkonen
Phys. Rev. X 16, 031063 (2026), arXiv:2412.02982 [quant-ph]Featured in Physics 19, 125 (2026)
Featured in Philosophical Magazine 25 September 2026
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Left-Right Husimi Representation of Chaotic Resonance States: Invariance and Factorization
F. Lorenz, J.-R. Schmidt, and R. Ketzmerick
New J. Phys. 27, 114517 (2025), arXiv:2507.10431 [nlin.CD] -
Eigenstate Correlations in Dual-Unitary Quantum Circuits: Partial Spectral Form Factor
F. Fritzsch, M. F. I. Kieler, and A. Bäcker
Quantum 9, 1709 (2025), arXiv:2407.19929v4 [quant-ph] -
Semiclassical limit of resonance states in chaotic scattering
R. Ketzmerick, F. Lorenz, and J.-R. Schmidt
Phys. Rev. Lett. 134, 020404 (2025), arXiv:2408.17088 [nlin.CD] - Quantum transport through partial barriers in higher-dimensional systems
F. Fritzsch, M. F. I. Kieler
Phys. Rev. E109, 014202 (2024), arXiv:2308.01162 [nlin.CD] - Universal spectral correlations in interacting chaotic few-body quantum systems
J. R. Schmidt and R. Ketzmerick
Phys. Rev. E 109, 014202 (2024), arXiv:2302.09955 [quant-ph] - Resonance states of the three-disk scattering system
J. R. Schmidt and R. Ketzmerick
New J. Phys. 25, 123034 (2023), arXiv:2308.12783 [nlin.CD] - Classical drift in the Arnold web induces quantum delocalization transition
J. R. Schmidt, A. Bäcker, and R. Ketzmerick
Phys. Rev. Lett. 131, 187201 (2023), 7 pages, arXiv:2307.06717 [nlin.CD] - Characterizing quantum chaoticity of kicked spin chains
T. Herrmann, M. F. I. Kieler, and A. Bäcker
Phys. Rev. E 108, 044213 (2023), 9 pages, arXiv:2306.09034 [quant-ph] - Fast bit flipping based on stability transition of coupled spins
M. F. I. Kieler and A. Bäcker
Phys. Rev. E 108, L022203 (2023), 6 pages, arXiv:2303.16171 [quant-ph] -
Partial barriers to chaotic transport in 4D symplectic maps
M. Firmbach, A. Bäcker, and R. Ketzmerick
Chaos 33, 013125 (2023), arXiv:2210.09863v1 [nlin.CD] - Quantum coherence controls the nature of equilibration in coupled chaotic systems
J. J. Pulikkottil, A. Lakshminarayan, S. C. L. Srivastava, M. F. I. Kieler, A. Bäcker, and S. Tomsovic
Phys. Rev. E 107, 024124 (2023), arXiv:2204.07561 [quant-ph] - Chaotic resonance modes in dielectric cavities: Product of conditionally invariant measure and universal fluctuations
Roland Ketzmerick, Konstantin Clauß, Felix Fritzsch, and Arnd BäckerPhys. Rev. Lett. 129, 193901 (2022), arXiv:2203.09752v1 [physics.optics]
- Creating triple-NOON states with ultracold atoms via chaos-assisted tunnelling
G. Vanhaele, A. Bäcker, R. Ketzmerick, and P. Schlagheck
Phys. Rev. A 106, L011301 (2022), arXiv:2202.05589v1 [cond-mat.quant-gas] -
Local random vector model for semiclassical fractal structure of chaotic resonance states
K. Clauß and R. Ketzmerick
J. Phys. A: Math. Theor. 55, 204006 (2022), arXiv:2112.12626v2 [nlin.CD] -
Universal intensity statistics of multifractal resonance states
K. Clauß, F. Kunzmann, A. Bäcker, and R. Ketzmerick
Phys. Rev. E 103, 042204 (2021), arXiv:2012.02541v2 [nlin.CD] -
Geometry of complex instability and escape in four-dimensional symplectic maps
J. Stöber and A. Bäcker
Phys. Rev. E 103, 042208 (2021), arXiv:2009.00970 [nlin.CD], Videos -
Linear and logarithmic entanglement production in an interacting chaotic system
S. Paul and A. Bäcker
Phys. Rev. E 102, 050102(R) (2020), arXiv:2007.13604 [quant-ph] -
Entanglement production by interaction quenches of quantum chaotic subsystems
J. J. Pulikkottil, A. Lakshminarayan, S. C. L. Srivastava, A. Bäcker, and S. Tomsovic
Phys. Rev. E 101, 032212 (2020), arXiv:1909.04733 [quant-ph] -
Power-law trapping in the volume-preserving Arnold-Beltrami-Childress map
S. Das and A. Bäcker
Phys. Rev. E 101, 032201 (2020), arXiv 1911.08207 [nlin.CD] -
Entanglement in coupled kicked tops with chaotic dynamics
T. Herrmann, M. F. I. Kieler, F. Fritzsch, and A. Bäcker
Phys. Rev. E 101, 022221 (2020), arXiv 1910.13447 [quant-ph] -
Structure of resonance eigenfunctions for chaotic systems with partial escape
K. Clauß, E. G. Altmann A. Bäcker, and R. Ketzmerick -
Resonance-assisted tunneling in deformed optical microdisks with a mixed phase space
F. Fritzsch, R. Ketzmerick, and A. Bäcker
Phys. Rev. E 100, 042219 (2019), arXiv:1907.06900 [physics.optics] -
Multifractal dimensions for random matrices, chaotic quantum maps, and many-body systems
A. Bäcker, M. Haque, and I. M. Khaymovich
Phys. Rev. E 100, 032117 (2019), arXiv:1905.03099 [cond-mat.stat-mech] -
Elliptic Bubbles in Moser's 4D Quadratic Map: the Quadfurcation
A. Bäcker and J. D. Meiss
SIAM J. Appl. Dyn. Syst. 19, 442-479 (2020), arXiv:1807.06074 [nlin.CD], Videos -
Resonance-Assisted Tunneling in 4D Normal-Form Hamiltonians
M. Firmbach, F. Fritzsch, R. Ketzmerick, and A. Bäcker -
Ordered level spacing probability densities
S. C. L. Srivastava, A. Lakshminarayan, S. Tomsovic, and A. Bäcker
J. Phys. A 52, 025101 (2019), arXiv:1810.01569 [nlin.CD] -
Unified theory for excited-state, fragmented, and equilibriumlike Bose
condensation in pumped photonic many-body systems
D. Vorberg, R. Ketzmerick, and A. Eckardt
Phys. Rev. A 97, 063621 (2018), arXiv:1803.08866 [cond-mat.str-el] -
Moser's quadratic, symplectic map
A. Bäcker and J. D. Meiss
Regul. Chaotic Dyn. 23, 654-664 (2018), arXiv:1808.07229 [nlin.CD] Videos -
Eigenstate entanglement between quantum chaotic subsystems: Universal transitions and power laws in the entanglement spectrum
S. Tomsovic, A. Lakshminarayan, S. C. L. Srivastava, and A. Bäcker -
Three-dimensional billiards: Visualization of regular structures and trapping of chaotic trajectories
M. Firmbach, S. Lange, R. Ketzmerick, and A. Bäcker
Phys. Rev. E 98, 022214 (2018), arXiv:1805.06823 [nlin.CD], Videos
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Resonance eigenfunction hypothesis for chaotic systems
K. Clauß, M. J. Körber, A. Bäcker, and R. Ketzmerick
Phys. Rev. Lett. 121, 074101 (2018), arXiv:1803.02631 [nlin.CD] -
On the number of Bose-selected modes in driven-dissipative ideal Bose gases
A. Schnell, R. Ketzmerick, and A. EckardtPhys. Rev. E 97, 032136 (2018), arXiv:1802.04088 [cond-mat.quant-gas]
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Statistical Properties of Eigenstate Amplitudes in Complex Quantum Systems
W. Beugeling, A. Bäcker, R. Moessner, and M. HaquePhys. Rev. E 98, 022204 (2018), [arXiv:1710.11433 [cond-mat.stat-mech]]
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High-temperature nonequilibrium Bose condensation induced by a hot needle
A. Schnell, D. Vorberg, R. Ketzmerick, and A. Eckardt
Phys. Rev. Lett. 119, 140602 (2017), arXiv:1705.06692 [cond-mat.quant-gas] -
Pump-power-driven mode switching in a microcavity device and its relation to Bose-Einstein condensation
H. A. M. Leymann, D. Vorberg, T. Lettau, C. Hopfmann, C. Schneider, M. Kamp, S. Höfling, R. Ketzmerick, J. Wiersig, S. Reitzenstein, and A. Eckardt
Phys. Rev. X 7, 021045 (2017), arXiv:1612.04312 [physics.optics] -
Homoclinic points of 2D and 4D maps via the parametrization method
S. Anastassiou, T. Bountis, and A. Bäcker
Nonlinearity 30, 3799-3820 (2017), arXiv:1605.05521 [nlin.DS] Videos - Complex-path prediction of resonance-assisted tunneling in mixed systems
F. Fritzsch, A. Bäcker, R. Ketzmerick, and N. MertigPhys. Rev. E 95, 020202(R) (2017), arXiv:1609.09276 [nlin.CD]
- Experimental observation of the Poincaré-Birkhoff scenario in a driven many-body quantum system
J. Tomkovič, W. Muessel, H. Strobel, S. Löck, P. Schlagheck, R. Ketzmerick, and M. K. Oberthaler
Phys. Rev. A 95, 011602(R) (2017), arXiv:1509.01809 [quant-ph]
Editors' Suggestion and featured in Physics (APS), Synopsis, January 12, 2017 - Perturbation-free prediction of resonance-assisted tunneling in mixed regular--chaotic systems
N. Mertig, J. Kullig, C. Löbner, A. Bäcker, and R. Ketzmerick
Phys. Rev. E 94, 062220 (2016), arXiv:1607.06477 [nlin.CD] - What is the mechanism of power-law distributed Poincaré recurrences in higher-dimensional systems?
S. Lange, A. Bäcker, and R. Ketzmerick
EPL 116, 30002 (2016), arXiv:1609.07977 [nlin.CD] Videos - Bifurcations of families of 1D-tori in 4D symplectic maps
F. Onken, S. Lange, R. Ketzmerick, and A. Bäcker
Chaos 26, 063124 (2016), arXiv:1602.04658 [nlin.CD] Videos - Entanglement and localization transitions in eigenstates of interacting chaotic systems
A. Lakshminarayan, S. C. L. Srivastava, R. Ketzmerick, A. Bäcker, and S. Tomsovic
Phys. Rev. E 94, 010205(R) (2016), arXiv:1601.07061 [quant-ph] - Universal scaling of spectral fluctuation transitions for interacting chaotic systems
S. C. L. Srivastava, S. Tomsovic, A. Lakshminarayan, R. Ketzmerick, and A. Bäcker
Phys. Rev. Lett. 116, 054101 (2016), arXiv:1509.02329 [nlin.CD] - Localization of Chaotic Resonance States due to a Partial Transport Barrier
M. J. Körber, A. Bäcker, and R. Ketzmerick
Phys. Rev. Lett. 115, 254101 (2015), arXiv:1509.00665 [nlin.CD] - Experimental Observation of Resonance-Assisted Tunneling
S. Gehler, S. Löck, S. Shinohara, A. Bäcker, R. Ketzmerick , U. Kuhl, and H.-J. Stöckmann
Phys. Rev. Lett. 115, 104101 (2015), arXiv:1502.04263 [cond-mat] - Nonequilibrium steady states of ideal bosonic and fermionic quantum gases
D. Vorberg, W. Wustmann, H. Schomerus, R. Ketzmerick, and A. Eckardt
Phys. Rev. E 92, 062119 (2015), arXiv:1508.02898 [cond-mat.quant-gas] - Integrable approximation of regular regions with a nonlinear resonance chain
J. Kullig, C. Löbner, N. Mertig, A. Bäcker, and R. Ketzmerick
Phys. Rev. E 90, 052906 (2014), arXiv:1407.2513 [nlin.CD] - Temporal flooding of regular islands by chaotic wave packets
L. Bittrich, A. Bäcker, and R. Ketzmerick
Phys. Rev. E 89, 032922 (2014), arXiv:1401.5923 [nlin.CD] - Quantum Goos-Hänchen shift and tunneling transmission at a curved step potential
S.-Y. Lee, J. Le Deunff, M. Choi, and R. Ketzmerick
Phys. Rev. A 89, 022120 (2014), arXiv:1402.2752 [quant-ph] - Global structure of regular tori in a generic 4D symplectic map
S. Lange, M. Richter, F. Onken, A. Bäcker, and R. Ketzmerick
Chaos 24, 024409 (2014), arXiv:1311.7632 [nlin.CD], Videos
Editors' pick, Featured article, and Cover image (pdf) (Chaos, June 2014, volume 24, number 2) - Visualization and comparison of classical structures and quantum states of 4D maps
M. Richter, S. Lange, A. Bäcker, and R. Ketzmerick
Phys. Rev. E 89, 022902 (2014), arXiv:1307.6109 [nlin.CD], Videos - Integrable approximation of regular islands: The iterative canonical transformation method
C. Löbner, S. Löck, A. Bäcker, and R. Ketzmerick
Phys. Rev. E 88, 062901 (2013), arXiv:1308.1561 [nlin.CD] - Generalized Bose-Einstein condensation into multiple states in driven-dissipative systems
D. Vorberg, W. Wustmann, R. Ketzmerick, and A. Eckardt
Phys. Rev. Lett. 111, 240405 (2013), arXiv:1308.2776 [cond-mat.stat-mech]
Editors' suggestion and highlighted in Physics (APS) ,Focus, December 20, 2013 - Hierarchical Fractal Weyl Laws for Chaotic Resonance States in Open Mixed Systems
M. J. Körber, M. Michler, A. Bäcker, and R. Ketzmerick
Phys. Rev. Lett. 111, 114102 (2013), arXiv:1304.2662 [nlin.CD] - Complex paths for regular-to-chaotic tunnelling rates
N. Mertig, S. Löck, A. Bäcker, R. Ketzmerick, and A. Shudo
Europhys. Lett. 102, 10005 (2013), arXiv:1207.0985 [nlin.CD] - Universal Quantum Localizing Transition of a Partial Barrier in a Chaotic Sea
M. Michler, A. Bäcker, R. Ketzmerick, H.-J. Stöckmann, and S. Tomsovic
Phys. Rev. Lett. 109, 234101 (2012), arXiv:1206.3118 [nlin.CD] - Biased diffusion inside regular islands under random symplectic perturbations
A. Kruscha, R. Ketzmerick, and H. Kantz
Phys. Rev. E 85, 066210 (2012) - Consequences of Flooding on Spectral Statistics
T. Rudolf, N. Mertig, S. Löck, and A. Bäcker
Phys. Rev. E 85, 036213 (2012), arXiv:1201.4288 [nlin.CD] - Coupling of bouncing-ball modes to the chaotic sea and their counting function
S. Löck, A. Bäcker, and R. Ketzmerick
Phys. Rev. E 85, 016210 (2012), arXiv:1110.6307v1 [nlin.CD] - Partial Weyl Law for Billiards
A. Bäcker, R. Ketzmerick, S. Löck, and H. Schanz
Europhys. Lett. 94, 30004 (2011), arXiv:1010.5093v2 [nlin.CD] - Fractional Power-Law Level-Statistics due to Dynamical Tunneling
A. Bäcker, R. Ketzmerick, S. Löck, and N. Mertig
Phys. Rev. Lett. 106, 024101 (2011), arXiv:1007.4130v1 [nlin.CD] - Direct regular-to-chaotic tunneling rates using the fictitious integrable system approach
A. Bäcker, R. Ketzmerick, and S. Löck
Phys. Rev. E 82, 056208 (2010), arXiv:1009.0418v1 [nlin.CD] - Statistical Mechanics of Floquet Systems with Regular and Chaotic States
R. Ketzmerick and W. Wustmann
Phys. Rev. E 82, 021114 (2010), arXiv:1005.0757 [cond-mat.stat-mech] - Regular-to-Chaotic Tunneling Rates: From the Quantum to the Semiclassical Regime
S. Löck, A. Bäcker, R. Ketzmerick, and P. Schlagheck
Phys. Rev. Lett. 104, 114101 (2010), arXiv:0906.4893 [nlin.CD] - The Hubbard model extended by nearest-neighbor Coulomb and exchange interaction on a cubic cluster - rigorous and exact results
R. Schumann and D. Zwicker
Ann. Phys. (Berlin) 522, 419-439 (2010), arXiv:0906.3589 [cond-mat.str-el] - Friedel oscillations in microwave billiards
A. Bäcker, B. Dietz, T. Friedrich, M. Miski-Oglu, A. Richter, F. Schäfer, and S. Tomsovic
Phys. Rev. E 80, 066210 (2009), arXiv:0910.2855 [nlin.CD] - Switching mechanism in periodically driven quantum systems with dissipation
R. Ketzmerick and W. Wustmann
Phys. Rev. E 80, 021117 (2009), arXiv:0901.1236 [cond-mat.stat-mech] - Quality factors and dynamical tunneling in annular microcavities
A. Bäcker, R. Ketzmerick, S. Löck, J. Wiersig, and M. Hentschel
Phys. Rev. A 79, 063804 (2009), arXiv:0903.0974 [nlin.CD] - Statistical mechanics of Floquet systems: The pervasive problem of near degeneracies
D. W. Hone, R. Ketzmerick, and W. Kohn
Phys. Rev. E 79, 051129 (2009), arXiv:0811.3243 [cond-mat.stat-mech] - Nano-wires with surface disorder: Giant localization lengths and dynamical tunneling in the presence of directed chaos
J. Feist, A. Bäcker, R. Ketzmerick, J. Burgdörfer, and S. Rotter
Phys. Rev. B 80, 245322 (2009), arXiv:0908.3278 [cond-mat.mes-hall] - Semiclassical theory of nonlocal statistical measures: Residual Coulomb interactions
D. Ullmo, S. Tomsovic, and A. Bäcker
Phys. Rev. E 79, 056217 (2009), arXiv:0812.5110 [cond-mat.mes-hall] - Dynamic Light Scattering for the Characterization of Polydisperse Fractal Systems: I. Simulation of the Diffusional Behavior
U. Kätzel, R. Bedrich, M. Stintz, R. Ketzmerick, T. Gottschalk-Gaudig, and H. Barthel
Part. Part. Syst. Charact. 25, 9-18 (2008) - Suppression of Photoionization by a Static Field
I. Gilary, Y. Sajeev, M.F. Ciappina, A. Croy, C.M. Goletz, S. Klaiman, M. Sindelka, M. Winter, W. Wustmann, and N. Moiseyev
Phys. Rev. Lett. 101, 163002 (2008) - Dynamical tunneling in mushroom billiards
A. Bäcker, R. Ketzmerick, S. Löck, M. Robnik, G. Vidmar, R. Höhmann, U. Kuhl, and H.-J. Stöckmann
Phys. Rev. Lett. 100, 174103 (2008), arXiv:0801.2833 [nlin.CD] - Residual Coulomb interaction fluctuations in chaotic systems: the boundary, random plane waves, and semiclassical theory
S. Tomsovic, D. Ullmo, and A. Bäcker
Phys. Rev. Lett. 100, 164101 (2008), arXiv:0712.0225 [cond-mat.mes-hall] - On universality of algebraic decays in Hamiltonian systems
G. Cristadoro and R. Ketzmerick,
Phys. Rev. Lett. 100, 184101 (2008), arXiv:0801.2756 [nlin.CD] - Regular-to-chaotic tunneling rates using a fictitious integrable system
A. Bäcker, R. Ketzmerick, S. Löck, and L. Schilling
Phys. Rev. Lett. 100, 104101 (2008), arXiv:0707.0217v1 [nlin.CD] - Rigorous solution of a Hubbard model extended by nearest neighbour Coulomb and exchange interaction on a triangle and tetrahedron
R. Schumann
Ann. Phys. (Berlin) 17, 1-39 (2008), arXiv:0902.0900 [cond-mat.str-el] - Criticality condition of the fully anisotropic Ising model with next-nearest neighbour interaction
R. Schumann and S. Kobe
Physica A, Volume 386, Issue 1, 1 December 2007, Pages 187-193 - Universality in the flooding of regular islands by chaotic states
A. Bäcker, R. Ketzmerick, and A. Monastra
Phys. Rev. E 75, 066204 (2007), arXiv:nlin/0701032 [nlin.CD] - Analytical solution of extended Hubbard models on three- and four-site clusters
R. Schumann
Physica C 460-462 (2007) 1015-1017 - Nano-wires with surface disorder: Giant localization lengths and quantum-to-classical crossover
J. Feist, A. Bäcker, R. Ketzmerick, S. Rotter, B. Huckestein, and J. Burgdörfer
Phys. Rev. Lett. 97, 116804 (2006), arXiv:cond-mat/0606586 [cond-mat.mes-hall] - Average ground-state energy of finite Fermi systems
M. Centelles, P. Leboeuf, A. G. Monastra, J. Roccia, P. Schuck, and X. Viñas
Phys. Rev. Rev. C 74, 034332 (2006), arXiv:cond-mat/0607735 [cond-mat.other] - On the spacing distribution of the Riemann zeros: corrections to the asymptotic result
E. Bogomolny, O. Bohigas, P. Leboeuf, and A. G. Monastra
J. Phys. A 39, 10743-10754 (2006), arXiv:math/0602270 [math.NT] - Fluctuations in the level density of a Fermi gas
P. Leboeuf, A. G. Monastra, and A. Relaño
Phys. Rev. Lett. 94, 102502 (2005), arXiv:nucl-th/0411068 - Flooding of Chaotic Eigenstates into Regular Phase Space Islands
A. Bäcker, R. Ketzmerick, and A. Monastra
Phys. Rev. Lett. 94, 054102 (2005), arXiv:nlin.CD/0409029 - Directed chaotic transport in Hamiltonian ratchets
H. Schanz, T. Dittrich, and R. Ketzmerick
Phys. Rev. E 71, 026228 (2005), arXiv:nlin.CD/0408021 - Poincaré Husimi representation of eigenstates in quantum billiards
A. Bäcker, S. Fürstberger, and R. Schubert
Phys. Rev. E 70, 036204 (2004), arXiv:nlin.CD/0307035 - Detection of Landau band coupling induced rearrangement of the Hofstadter butterfly
M. C. Geisler, J. H. Smet, V. Umansky, K. von Klitzing, B. Naundorf, R. Ketzmerick, and H. Schweizer
Phys. Rev. Lett. 92, 256801 (2004) - Thermal remagnetization in polycrystalline permanent magnets
R. Schumann and L. Jahn
in Recent Research Developments in Magnetism & Magnetic Materials Vol. 1 (2003) Part I, Transworld Research Network 2003, arXiv:cond-mat/0305292 - Influence of the initial temperature on the thermal remagnetization of SmCo5 sintered magnets
L. Jahn, V. Ivanov, R. Schumann, and M. Loewenhaupt
J. of Magnetism and Magnetic Materials 256 (2003) 41-45, https://www.physik.tu-dresden.de/itp/members/schumann/Literatur/jmmm2001a.pdf - Can simple renormalization theories describe the trapping of chaotic trajectories in mixed systems?
M. Weiss, L. Hufnagel, and R. Ketzmerick
Phys. Rev. E 67, 046209 (2003), arXiv:nlin.CD/0106021 - Field dependence of the thermal remagnetization in sintered hard magnets
L. Jahn and R. Schumann
J. of Magnetism and Magnetic Materials 251 (2002) 93-99, https://wwwpub.zih.tu-dresden.de/~schumann/schumann/Literatur/magma22121.pdf - Thermodynamics of a 4-site Hubbard model by analytical diagonalization
R. Schumann
Ann. Phys. (Leipzig) 11 (2002) 49-87, arXiv:cond-mat/0101476 [cond-mat.str-el]