Gerhard C. Hegerfeldt

Work Address:

Phone:   ++49 551 39-7676
Fax:       ++49 551 39-9263
E-Mail: Gerhard.Hegerfeldt@physik.uni-goettingen.de

__________________________________________________________________________________________________________________
 

Biographical Sketch:

G. C. Hegerfeldt studied Physics and Mathematics at the universities of Kiel, Cambridge (UK) and Marburg, where he obtained his diploma doctorate and Habilitation at the institute of G. Ludwig. He has worked on quantum field theory, on causality questions on statistical physics of spectral line broadening, and more recently on quantum optics ("quantum jump approach") and on atom optics (diffraction of "matter waves" and of extended molecules).  He was visiting fellow at Princeton University in the year 1979/80, at the California Institute of Technology in Pasadena in the year 1984/85 and a member of the Institute for Advanced study in Princeton in the year 1989/90.
 

Research Interests:
 
 

Publications:
 
 

• Symmetries and time operators, J. Phys. A: Math. Theor. 43 (2010), 505303.
• Manufacturing time operators: Covariance, selection criteria, and examples, Phys. Rev. A 82 (2009), 012113.
• The quantum jump approach and some of its applications, Lect. Notes Phys. 789 (2009), 127 - 174.
• Detector models for the quantum time of arrival (with A. Ruschhaupt and J. G. Muga), Lect. Notes Phys. 789 (2009), 65 - 96.
• The Aharonov-Bohm effect: the role of tunneling and associated forces (with J. T. Neumann), J. Phys. A: Math. Theor. 41 (2008), 155305.
• How to measure the wave function absolute squared of a moving particle by using mirrors (with V. Hannstein) , Europhys. Letters 77 (2007), 60003
• Passage-time distributions from a spin-boson detector model (with J. T. Neumann, L. S. Schulman), Phys. Rev. A 75 (2007), 012108
• Comment on Evolution in Time of Moving Unstable Systems, Concepts of Physics III (2006), 207 - 210
• Investigation of a quantum mechanical detector model for moving, spread-out particles (with J. T. Neumann und L. S. Schulman), J. of Physics A39 (2006), 14447 - 14463
• Scattering of two-level atoms by delta lasers: Exactly solvable models in atom optics (with D. Seidel und J. G. Muga), J. Phys. B: At. Mol. Opt. Phys. 39 (2006), 4673 - 4682
• Simplified approach to double jumps for fluorescing dipole-dipole interacting atoms (with V. Hannstein), Eur. Phys. J. D. 38 , (2006), 415 (Highlight Paper)
• Time development of single quantum systems In: Group Theoretical Methods in Physics, Inst. of Physics Conference Series Number 185, Ed. by George S. Pogosyan, Luis Edgar Vicent and Kurt Bernardo Wolf, Institute of Physics Publishing(IOP), Bristol and Philadelphia (2005), 299 - 304
• Quantum optical time-of-arrival model in three dimensions (with V. Hannstein, J. G. Muga), J. Phys. B: At. Mol. Opt. Phys 38 , (2005), 409-420
• Matter Wave Diffraction from an Inclined Transmission Grating: Searching for the Elusive 4He Trimer Efimov State (with R. Brühl, A. Kalinin, O. Kornilov, J. P. Toennies, M. Stoll) Phys. Rev. Letters 95 (2005) 063002-1 - 063002-4
• Exact and approximate complex potentials for modelling time observables (with A. Ruschhaupt, J. A. Damborenea, B. Navarro, J. G. Muga) Europhys. Letters 67 1-7 (2004)
  
• Cooperative quantum jumps for three dipole-interacting atoms (with V. Hannstein), Phys. Rev. A 70, 023820
  
• Operator-normalized quantum arrival times in the presence of interactions (with D. Seidel, J. G. Muga, B. Navarro), Phys. Rev. A 70, 012110 (2004)
  
•  Cooperative fluorescence effects for dipole-dipole interacting systems with experimentally relevant level configurations (with V. Hannstein), Phys. Rev. A 68, 043826 (2003)
  
• Blinking Molecules: Determination of photophysical parameters from the intensity correlation function (with Seidel), J. of Chem. Phys. 118,  7741 (2003)
  
• The  Quantum Jump Approach and Quantum Trajectories, Springer LNP 622: Irreversible Quantum Dynamics, F. Benatti, R. Floreanini Eds., p. 233 - 242 (2003)
  
• On atomic time-of-arrival measurements with a laser of finite beam width (with J. A. Damborenea, I. L. Egusquiza, J. G. Muga), J. Phys. B: At. Mol. Opt. Phys., 36, 2657 - 2669 (2003)
  
• Optimal atomic detection of ultracold atoms by control of detuning and spatial dependence of laser intensity (with I. L. Egusquiza, J. G. Muga, B. Navarro), J. Phys., B: At. Mol. Opt. Phys. 36, 3899 - 3907 (2003)
  
• Suppression of Rabi oscillations for moving atoms (with I. L. Egusquiza, J. G. Muga, B. Navarro), Phys. Ref. A 67, 063819 (2003)
  
• Quantum arrival times and operator normalization (with J. G. Muga, D. Seidel), Phys. Rev. A 68, 022111 (2003)
  
• A measurement-based approach to quantum arrical times (with   J. A. Damborenea, I. L. Egusaquiza, J. G. Muga), Phys. Rev. A 66, 502104 (2002)
• The intensity correlation function of "blinking" quantum systems (with D. Seidel), Quantum Semicl. Opt. 4, 245-251 (2002)
• Matter-Wave-Diffraction off Nano Gratings: Quantum Effects, Proceeding of th XXII Solvy Conference, to appear.
• The van der Waals Potential between Metastable Atoms and Solid Surfaces: Novel Diffraction Experiments versus Theory, Eur. Phys. Lett. 59 (3), 357-363 (2002) (with R. Brühl, P. Fouquet, R. E. Grisenti, J. P. Toennies, T. Köhler, M. Stoll, C. Walter)
• Particle localization and the notion of Einstein causality, in: Extensions of Quantum Theory 3, Eds. A. Horzela and E. Kapuscik, Apeiron, Montreal (2001), p. 9 - 16
• Double jumps and transition rates for two dipole-interacting atoms (with S. U. Addicks, A. Beige, M. Dakna), Eur. Phys. J. D15, 393-404 (2001)
• Quantentheorie der Materiewellenbeugung, Physikalisches Blätter 56, Heft 11, p. 53 - 55(2000) (with R. E. Grisenti, T. Köhler, J. P. Toennies)
• Determination of the Bond Length and Binding Energy of the  Helium Dimer by Diffraction from a Transmission Grating,  Phys. Rev. Lett. 85, 2284-2287 (2000) (with R. E. Grisenti, W. Schöllkopf, J. P. Toennies, T. Köhler, M. Stoll)
• How to study the Elusive Efimov State of the 4He3 Molecule through a New Atom-Optical State-Selection Technique, Phys. Rev. Lett. 84, 15-3219 (2000) (with T. Köhler)
• Deviations from classical optics in matter diffraction and determination of the size of weakly bound molecules, Phys. Rev. 61,236061-2360610 (1999)(with T. Köhler)
• Determination of Atom-Surface van der Waals Potentials from Transmission-Grating Diffraction Intensities, Phys. Rev. Lett. 83, 1755-1759 (with R.E. Grisenti, W. Schöllkopf, J.P. Toennies, T. Köhler)
• Cooperative effects in the light and dark periods of two dipole-interacting atoms. Phys. Rev. A59, 2385-2391 (1999) (with A. Beige)
• Few-Body Approach to Diffraction of Small Helium Clusters by Nanostructures. Few-Body Systems Suppl. 10, 263-272 (1999) (with T. Köhler)
• Instantaneous spreading and Einstein causality in quantum theory. Ann. d. Phys. 7, 716-725 (1998)
• Ensemble versus individual system in quantum optics. Fortschr. Phys. 46, 595-604 (1998)
• Transition from antibunching to bunching for two dipole-interacting atoms. Phys. Rev. A58, 4133-4139 (1998) (with A. Beige)
• Causality, Particle Localization and Positivity of the Energy in quantum theory, in: Irreversibility and Causality edited by A. Bohm, H.-D. Doebner, and P. Kielanowski. Lecture Notes in Physics 504, p. 238-245 (1998)
• Atomic versus molecular diffraction: Influence of break-ups and finite size, Phys. Rev. A 57, 2021-2029 (1998) (with T. Köhler)
• Unusual light spectra from a two-level atom in squeezed vacuum, Quantum Semiclass. Opt. 9, 1-13 (1997) (with T.I. Sachse und D.G. Sondermann)
• Atomic Quantum Zeno Effect for Ensembles and Single Systems, Found. Phys. 27, 1671-1688 (1997) (with A. Beige, D.G. Sondermann)
• Quantum Zeno Effect and Light-Dark Periods, J. Phys. A: Math. Gen. 30, 1323-1334 (1997)  (with A. Beige)
• State Measurements with Short Laser Pulses and Lower-Efficiency Photon Detectors, J. Mod. Opt. 44, 345-357 (1997) (with  A. Beige)
• Laser Pulses as Measurements: Applications to the Quantum Zeno Effect, Quantum Semiclass Opt. 8, 999-1015 (1996)(with A. Beige and D.G. Sondermann)
• Conditional Hamiltonian and Reset Operator in the Quantum Jump Approach, Quantum Semiclass. Opt. 8, 121-132 (1996) (with D.G.  Sondermann)
• Conditional resonance-fluorescence spectra of single atoms, Phys. Rev. A 53, 1164-1178 (1996) (with M.B. Plenio)
• Projection Postulate and Atomic Quantum Zeno Effect, Phys. Rev. A 53, 53-65 (1996) (with A. Beige)
• Spectral structures induced by electron shelving, Phys. Rev. A 52, 3333-3343 (1995)  (with M.B. Plenio)
• Dark periods in a single radiating Lambda-System, Z. Phys. B 96, 533-539 (1995) (with M.B. Plenio)
• Quantum beats revisited: a quantum jump approach, Quantum Opt. 6, 15-25 (1994) (with M.B. Plenio)
• Level statistics for continuous energy spectra with application to hydrogen atom in crossed electric and magnetic fields, Phys. Rev. A 49, 3531-3540 (1994) (with R. Henneberg)
• Problems about Causality in Fermi's Two-Atom Model and Possible Resolutions, in: Nonlinear, Deformed and Irreversible Quantum Systems, ed. by H.-D. Doebner, World Scientific, Singapore (1995), p. 253-264 (with V.K. Dobrev, P. Nattermann)
• Causality Problems for Fermi's Two-Atom System. Phys. Rev. Lett 72, 596-599 (1994)
• Coherence with incoherent light: A new type of quantum beats for a single atom. Phys. Rev. A 47 (1993), p. 2186-2189 (with M.B. Plenio)
• How to reset an atom after a photon detection. Applications to photon counting processes. Phys. Rev. A 47 (1993), 449
• Macroscopic dark periods without metastable state. Phys. Rev. A 46, 373 (1992) (with M.B. Plenio)
• Ensemble or Individual System, Collapse or no Collapse: A Description of a Single Radiating Atom, in:  Classical and Quantum Systems, Proc. II. International Wigner Symposium, Goslar 1991, H.D. Doebner, W. Scherer, and F. Schroeck, Eds., World Scientific 1992; p. 104-115 (with T.S. Wilser)
• A Quantum Characterization of Gaussianness. In: Quantum Probability and Related Topics, Vol. VII, L. Accardi Ed., World Scientific, 1992, pp. 165-173
• Novel Quantization Phenomenon for Relativistic Wave Equations. Phys. Rev. D 45 (1992), 713-716 (with M.K. Hinders, B.A. Rhodes, and G. v. H. Sandri)
• An Alternative Approach to the Quantization of Linear Relativistic Field Equations. Lecture Notes in Physics 379, J.D. Hennig, W. Lücke, J. Tolar, Eds., Springer 1991, p. 75-83
• Quantum Chaos in Hydrogen, Phys. Rev. A 41 (1990), 1161-1164 (Rapid Communication, with R. Henneberg)
• Laser Cooling in Ion Traps: Noncooling of a Transverse Component. Phys. Rev. A 41 (1990), 2610-2613 (with A. Vogt)
• Über ein Problem der Relativitätstheorie: Wann sind Punktbildungen des $R^n$ linear? Nachr. Akad. Wiss. Göttingen, Jahrgang 1972, 205-229 (with H.J. Borchers)
• The structure of space-time transformations, Commun. math. Phys. 28,(1972) 259 - 266 (with H. J. Borchers)