@article{PattynPerichonDurandetal.2013,
  author    = {Pattyn, Frank and Perichon, Laura and Durand, Gael and Favier, Lionel and Gagliardini, Olivier and Hindmarsh, Richard C. A. and Zwinger, Thomas and Albrecht, Torsten and Cornford, Stephen and Docquier, David and Furst, Johannes J. and Goldberg, Daniel and Gudmundsson, Gudmundur Hilmar and Humbert, Angelika and Huetten, Moritz and Huybrechts, Philippe and Jouvet, Guillaume and Kleiner, Thomas and Larour, Eric and Martin, Daniel and Morlighem, Mathieu and Payne, Anthony J. and Pollard, David and Rueckamp, Martin and Rybak, Oleg and Seroussi, Helene and Thoma, Malte and Wilkens, Nina},
  title     = {Grounding-line migration in plan-view marine ice-sheet models: results of the ice2sea MISMIP3d intercomparison},
  series = {Journal of glaciology},
  volume    = {59},
  journal   = {Journal of glaciology},
  number    = {215},
  publisher = {International Glaciological Society},
  address   = {Cambridge},
  issn      = {0022-1430},
  doi       = {10.3189/2013JoG12J129},
  pages     = {410 -- 422},
  year      = {2013},
  abstract  = {Predictions of marine ice-sheet behaviour require models able to simulate grounding-line migration. We present results of an intercomparison experiment for plan-view marine ice-sheet models. Verification is effected by comparison with approximate analytical solutions for flux across the grounding line using simplified geometrical configurations (no lateral variations, no buttressing effects from lateral drag). Perturbation experiments specifying spatial variation in basal sliding parameters permitted the evolution of curved grounding lines, generating buttressing effects. The experiments showed regions of compression and extensional flow across the grounding line, thereby invalidating the boundary layer theory. Steady-state grounding-line positions were found to be dependent on the level of physical model approximation. Resolving grounding lines requires inclusion of membrane stresses, a sufficiently small grid size (<500 m), or subgrid interpolation of the grounding line. The latter still requires nominal grid sizes of <5 km. For larger grid spacings, appropriate parameterizations for ice flux may be imposed at the grounding line, but the short-time transient behaviour is then incorrect and different from models that do not incorporate grounding-line parameterizations. The numerical error associated with predicting grounding-line motion can be reduced significantly below the errors associated with parameter ignorance and uncertainties in future scenarios.},
  language  = {en}
}
@misc{RaederEisertWilkensetal.2005,
  author    = {R{\"a}der, Andy and Eisert, Jens and Wilkens, Martin and Schmidt, Robert and Micka, Bettina and Ostermeyer, Martin and Zill, R{\"u}diger and Baur, J{\"u}rgen and Schmidt, Renate and Leppin, Karin and Slotowski, Agnes and Resch-Esser, Ursula},
  title     = {Portal = Albert Einsteins Erbe: Uni-Physiker forschen weiter},
  number    = {01-03/2005},
  organization    = {Universit{\"a}t Potsdam, Referat f{\"u}r Presse- und {\"O}ffentlichkeitsarbeit},
  issn      = {1618-6893},
  doi       = {10.25932/publishup-43984},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-439846},
  pages     = {55},
  year      = {2005},
  abstract  = {Aus dem Inhalt: - Albert Einsteins Erbe: Uni-Physiker forschen weiter - Uni-Studiengang im europ{\"a}ischen Exzellenzprogramm - Sternenstaubsammler - Mit Einfallsreichtum gegen den Trend},
  language  = {de}
}
@misc{VolkMarkertRiejoketal.2006,
  author    = {Volk, Benno and Markert, Doreen and Riejok, Henriette and Dittberner, J{\"u}rgen and Wanka, Johanna and Wilkens, Martin and G{\"o}rtemaker, Manfred and Regierer, Babette and Steup, Martin and M{\"u}ller-R{\"o}ber, Bernd and Wernicke, Matthias and Altenberger, Uwe and St{\"o}lting, Erhard and Fer{\´y}, Carolin and Egenter, Peter and Lenz, Claudia and Jakubowski, Zuzanna and Kl{\"o}tzer, Sylvia and Krause, Michael and Dietsch, Ulrich},
  title     = {Portal = Vor der Pr{\"a}sidenten-Wahl: Erwartungen, W{\"u}nsche, Vorschl{\"a}ge},
  number    = {04-05/2006},
  organization    = {Universit{\"a}t Potsdam, Referat f{\"u}r Presse- und {\"O}ffentlichkeitsarbeit},
  issn      = {1618-6893},
  doi       = {10.25932/publishup-44000},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-440005},
  pages     = {50},
  year      = {2006},
  abstract  = {Aus dem Inhalt: - Vor der Pr{\"a}sidenten-Wahl: Erwartungen, W{\"u}nsche, Vorschl{\"a}ge - Der AStA in der Krise? - {\"U}ber Satire und Macht in der DDR - Vom F{\"u}nf-Sterne-Koch zum Mensaleiter},
  language  = {de}
}
@misc{NeumannHorstkemperKruegeretal.2002,
  author    = {Neumann, Bernhard and Horstkemper, Marianne and Kr{\"u}ger, Wolfgang and Wilkens, Martin and Bohlen, Andreas and Fr{\"u}bing, Peter and Wegener, Michael and Scheff, Ullrich and Neher, Dieter and Brehmer, Ludwig and Kleinpeter, Erich and Wolf, Gunter and Koetz, Joachim and Peter, Martin G. and Senkbeil, Sigrid and Meyer, Till},
  title     = {Portal = Im Trend: Physiker und Chemiker erforschen "Soft Matter"},
  volume    = {2002},
  issn      = {1618-6893},
  doi       = {10.25932/publishup-50144},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-501441},
  pages     = {40},
  year      = {2002},
  abstract  = {Aus dem Inhalt: Im Trend: Physiker und Chemiker erforschen „Soft Matter" -Brandenburger Netzwerk f{\"u}r Existenzgr{\"u}nder erh{\"a}lt F{\"o}rderung -Universit{\"a}t leistet Beitrag zum Romantik-Jahr -Musiksender MTV und Bryan Adams auf dem Campus},
  language  = {de}
}
@article{RaetzelWilkensMenzel2017,
  author    = {R{\"a}tzel, Dennis and Wilkens, Martin and Menzel, Ralf},
  title     = {Effect of polarization entanglement in photon-photon scattering},
  series = {Physical review : A, Atomic, molecular, and optical physics},
  volume    = {95},
  journal   = {Physical review : A, Atomic, molecular, and optical physics},
  number    = {1},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {2469-9926},
  doi       = {10.1103/PhysRevA.95.012101},
  pages     = {6},
  year      = {2017},
  abstract  = {It is found that the differential cross section of photon-photon scattering is a function of the degree of polarization entanglement of the two-photon state. A reduced general expression for the differential cross section of photon-photon scattering is derived by applying simple symmetry arguments. An explicit expression is obtained for the example of photon-photon scattering due to virtual electron-positron pairs in quantum electrodynamics. It is shown how the effect in this explicit example can be explained as an effect of quantum interference and that it fits with the idea of distance-dependent forces.},
  language  = {en}
}
@article{LewensteinCirauquiAngelGarciaMarchetal.2022,
  author    = {Lewenstein, Maciej and Cirauqui, David and Angel Garcia-March, Miguel and Corominas, Guillem Guigo and Grzybowski, Przemyslaw and Saavedra, Jose R. M. and Wilkens, Martin and Wehr, Jan},
  title     = {Haake-Lewenstein-Wilkens approach to spin-glasses revisited},
  series = {Journal of physics : A, Mathematical and theoretical},
  volume    = {55},
  journal   = {Journal of physics : A, Mathematical and theoretical},
  number    = {45},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {1751-8113},
  doi       = {10.1088/1751-8121/ac9d10},
  pages     = {20},
  year      = {2022},
  abstract  = {We revisit the Haake-Lewenstein-Wilkens approach to Edwards-Anderson (EA) model of Ising spin glass (SG) (Haake et al 1985 Phys. Rev. Lett. 55 2606). This approach consists in evaluation and analysis of the probability distribution of configurations of two replicas of the system, averaged over quenched disorder. This probability distribution generates squares of thermal copies of spin variables from the two copies of the systems, averaged over disorder, that is the terms that enter the standard definition of the original EA order parameter, qEA 0 0},
  language  = {en}
}
@misc{EnderleinZimmermannPeteretal.2011,
  author    = {Enderlein, Hinrich and Zimmermann, Matthias and Peter, Andreas and Micka, Bettina and Wilkens, Martin and Lohnwasser, Roswitha and Horn-Conrad, Antje},
  title     = {Portal = Gesichter und Geschichten einer jungen Universit{\"a}t},
  number    = {02/2011},
  organization    = {Universit{\"a}t Potsdam, Referat f{\"u}r Presse- und {\"O}ffentlichkeitsarbeit},
  issn      = {1618-6893},
  doi       = {10.25932/publishup-44045},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-440456},
  pages     = {42},
  year      = {2011},
  abstract  = {Aus dem Inhalt: - 20 Jahre Universit{\"a}t Potsdam - Gesichter und Geschichten einer jungen Universit{\"a}t},
  language  = {de}
}
@misc{WilkensSuetterlinWelleretal.2014,
  author    = {Wilkens, Martin and S{\"u}tterlin, Sabine and Weller, Nina and Horn-Conrad, Antje and Kampe, Heike and Eckardt, Barbara and G{\"o}rlich, Petra and J{\"a}ger, Sophie and Zimmermann, Matthias and Mitsch, Wolfgang},
  title     = {Portal Wissen = Zeit},
  number    = {02/2014},
  organization    = {Universit{\"a}t Potsdam, Referat f{\"u}r Presse- und {\"O}ffentlichkeitsarbeit},
  issn      = {2194-4237},
  doi       = {10.25932/publishup-44084},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-440842},
  pages     = {99},
  year      = {2014},
  abstract  = {„Was ist also 'Zeit'?" seufzt Augustinus von Hippo im 11. Buch seiner „Confessiones" melancholisch, und f{\"a}hrt fort „Wenn mich niemand danach fragt, weiß ich es; will ich einem Fragenden es erkl{\"a}ren, weiß ich es nicht." Auch heute, 1584 Jahre nach Augustinus, erscheint 'Zeit' immer noch r{\"a}tselhaft. Abhandlungen {\"u}ber das Wesen der Zeit f{\"u}llen Bibliotheken. Oder eben dieses Heft. Wesensfragen sind den modernen Wissenschaften allerdings fremd. Zeit ist - zumindest in der Physik - unproblematisch. „Time is defined so that Motion looks simple" erk{\"a}rt man kurz und trocken, und verabschiedet sich damit vom Augustinischen R{\"a}tsel oder der Newtonschen Vorstellung einer absoluten Zeit, deren mathematischen Fluss man durch irdische Instrumente eh immer nur n{\"a}herungsweise erfassen kann. In der Alltagssprache, selbst in den Wissenschaften, reden wir zwar weiterhin vom Fluss der Zeit, aber Zeit ist schon lange keine nat{\"u}rliche Gegebenheit mehr. Zeit ist vielmehr ein konventioneller Ordnungsparameter f{\"u}r {\"A}nderung und Bewegung. Geordnet werden Prozesse, indem eine Klasse von Prozessen als Z{\"a}hlsystem dient, um andere Prozesse mit ihnen zu vergleichen und anhand der tempor{\"a}ren Kategorien „vorher", „w{\"a}hrend" und „nachher" anzuordnen. Zu Galileis Zeiten galt der eigene Pulsschlag als Zeitstandard f{\"u}r den Flug von Kanonenkugeln. Mit zunehmender Verfeinerung der Untersuchungsmethoden erschien das zu unpraktisch: Die Weg-Zeit-Diagramme frei fliegender Kanonenkugeln erweisen sich in diesem Standard ziemlich verwackelt, schlecht reproduzierbar, und keineswegs „simpel". Heutzutage greift man zu C{\"a}sium-Atomen. Demnach dauert ein Prozess eine Sekunde, wenn ein 133Cs-Atom genau 9 192 631 770 Schwingungen zwischen zwei sogenannten Hyperfeinzust{\"a}nden des Grundzustands vollf{\"u}hrt hat. Und ein Meter ist die Entfernung, die Licht im Vakuum in exakt 1/299 792 458 Sekunden zur{\"u}cklegt. Gl{\"u}cklicherweise sind diese Daten im General Positioning System GPS hart kodiert, so dass der Nutzer sie nicht jedes Mal aufs Neue eingeben muss, wenn er wissen will, wo er ist. Aber schon morgen muss er sich vielleicht ein Applet runterladen, weil der Zeitstandard durch raffinierte {\"U}berg{\"a}nge in Ytterbium ersetzt wurde. Der konventionelle Charakter des Zeitbegriffs sollte nicht dazu verf{\"u}hren zu glauben, alles sei irgendwie relativ und daher willk{\"u}rlich. Die Beziehung eines Pulsschlags zu einer Atomuhr ist absolut, und genauso real, wie die Beziehung einer Sanduhr zum Lauf der Sonne. Die exakten Wissenschaften sind Beziehungswissenschaften. Sie handeln nicht vom Ding an sich, was Newton und Kant noch getr{\"a}umt haben, sondern von Beziehungen - worauf schon Leibniz und sp{\"a}ter Mach hingewiesen haben. Kein Wunder, dass sich f{\"u}r andere Wissenschaften der physikalische Zeit-Standard als ziemlich unpraktisch erweist. Der Psychologie der Zeitwahrnehmung entnehmen wir - und jeder wird das best{\"a}tigen k{\"o}nnen - dass das gef{\"u}hlte Alter durchaus verschieden ist vom physikalischen Alter. Je {\"a}lter man ist, desto k{\"u}rzer erscheinen einem die Jahre. Unter der einfachen Annahme, dass die gef{\"u}hlte Dauer umgekehrt proportional zum physikalischen Alter ist, und man als Zwanzigj{\"a}hriger ein physikalisches Jahr auch psychologisch als ein Jahr empfindet, ergibt sich der erstaunliche Befund, dass man mit 90 Jahren 90 Jahre ist. Und - bei einer angenommenen Lebenserwartung von 90 Jahren - mit 20 (bzw. 40) physikalischen Jahren bereits 67 (bzw. 82) Prozent seiner gef{\"u}hlten Lebenszeit hinter sich hat. Bevor man angesichts der „Relativit{\"a}t von Zeit" selbst in Melancholie versinkt, vielleicht die Fortsetzung des Eingangszitats von Augustinus: „Aber zuversichtlich behaupte ich zu wissen, dass es vergangene Zeit nicht g{\"a}be, wenn nichts verginge, und nicht k{\"u}nftige Zeit, wenn nichts herank{\"a}me, und nicht gegenw{\"a}rtige Zeit wenn nichts seiend w{\"a}re." Tja - oder mit Bob Dylan „The times they're a changing". Ich w{\"u}nsche Ihnen eine spannende Zeit bei der Lekt{\"u}re dieser Ausgabe. Prof. Dr. Martin Wilkens Professor f{\"u}r Quantenoptik},
  language  = {de}
}
@misc{WilkensSuetterlinKampeetal.2014,
  author    = {Wilkens, Martin and S{\"u}tterlin, Sabine and Kampe, Heike and Eckardt, Barbara and J{\"a}ger, Sophie and Zimmermann, Matthias},
  title     = {Portal Wissen = Time},
  number    = {02/2014},
  organization    = {University of Potsdam, Press and Public Relations Department},
  issn      = {2198-9974},
  doi       = {10.25932/publishup-44149},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-441497},
  pages     = {55},
  year      = {2014},
  abstract  = {"What then is time?", Augustine of Hippo sighs melancholically in Book XI of "Confessions" and continues, "If no one asks me, I know; if I want to explain it to a questioner, I don't know." Even today, 1584 years after Augustine, time still appears mysterious. Treatises about the essence of time fill whole libraries - and this magazine. However, questions of essence are alien to modern sciences. Time is - at least in physics - unproblematic: "Time is defined so that motion looks simple", briefly and prosaically phrased, waves goodbye to Augustine's riddle and to the Newtonian concept of absolute time, whose mathematical flow can only be approximately recorded with earthly instruments anyway. In our everyday language and even in science we still speak of the flow of time but time has not been a natural condition for quite a while now. It is rather a conventional order parameter for change and movement. Processes are arranged by using a class of processes as a counting system in order to compare other processes and to organize them with the help of the temporary categories "before", "during", and "after". During Galileo's time one's own pulse was seen as the time standard for the flight of cannon balls. More sophisticated examination methods later made this seem too impractical. The distance-time diagrams of free-flying cannon balls turned out to be rather imprecise, difficult to replicate, and in no way "simple". Nowadays, we use cesium atoms. A process is said to take one second when a caesium-133 atom completes 9,192,631,770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state. A meter is the length of the path travelled by light in a vacuum in exactly 1/299,792,458 of a second. Fortunately, these data are hard-coded in the Global Positioning System GPS so users do not have to reenter them each time they want to know where they are. In the future, however, they might have to download an app because the time standard has been replaced by sophisticated transitions to ytterbium. The conventional character of the time concept should not tempt us to believe that everything is somehow relative and, as a result, arbitrary. The relation of one's own pulse to an atomic clock is absolute and as real as the relation of an hourglass to the path of the sun. The exact sciences are relational sciences. They are not about the thing-initself as Newton and Kant dreamt, but rather about relations as Leibniz and, later, Mach pointed out. It is not surprising that the physical time standard turned out to be rather impractical for other scientists. The psychology of time perception tells us - and you will all agree - that the perceived age is quite different from the physical age. The older we get the shorter the years seem. If we simply assume that perceived duration is inversely related to physical age and that a 20-year old also perceives a physical year as a psychological one, we come to the surprising discovery that at 90 years we are 90 years old. With an assumed life expectancy of 90 years, 67\% (or 82\%) of your felt lifetime is behind you at the age of 20 (or 40) physical years. Before we start to wallow in melancholy in the face of the "relativity of time", let me again quote Augustine. "But at any rate this much I dare affirm I know: that if nothing passed there would be no past time; if nothing were approaching, there would be no future time; if nothing were, there would be no present time." Well, - or as Bob Dylan sings "The times they are a-changin". I wish you an exciting time reading this issue. Prof. Martin Wilkens Professor of Quantum Optics},
  language  = {en}
}
@article{AlbusGardinerIlluminatietal.2002,
  author    = {Albus, Alexander P. and Gardiner, Simon A. and Illuminati, Fabrizio and Wilkens, Martin},
  title     = {Quantum field theory of dilute homogeneous Bose-Fermi-mixtures at zero temperature : general formalismand beyond mean-field corrections},
  year      = {2002},
  abstract  = {We consider a dilute homogeneous mixture of bosons and spin-polarized fermions at zero temperature. We first construct the formal scheme for carrying out systematic perturbation theory in terms of single particle Green's functions. We introduce a new relevant object, the renormalized boson-fermion T-matrix which we determine to second order in the boson-fermion s-wave scattering length. We also discuss how to incorporate the usual boson-boson T-matrix in mean-field approximation to obtain the total ground state properties of the system. The next order term beyond mean- field stems from the boson-fermion interaction and is proportional to \$a_{scriptsize BF}k_{scriptsize F}\$. The total ground-state energy-density reads \$E/V =epsilon_{scriptsize F} + epsilon_{scriptsize B} + (2pihbar^{2}a_{ m BF}n_{scriptsize B}n_{scriptsize F}/m) [1 + a_{scriptsize BF}k_{scriptsize F}f(delta)/pi]\$. The first term is the kinetic energy of the free fermions, the second term is the boson-boson mean-field interaction, the pre-factor to the additional term is the usual mean-field contribution to the boson-fermion interaction energy, and the second term in the square brackets is the second-order correction, where \$f(delta)\$ is a known function of \$delta= (m_{scriptsize B} - m_{scriptsize F})/(m_{scriptsize B} + m_{scriptsize F})\$. We discuss the relevance of this new term, how it can be incorporated into existing theories of boson-fermion mixtures, and its importance in various parameter regimes, in particular considering mixtures of \$^{6}\$Li and \$^{7}\$Li and of \$^{3}\$He and \$^{4}\$He.},
  language  = {en}
}
@article{WilkensIlluminatiKraemer2000,
  author    = {Wilkens, Martin and Illuminati, Fabrizio and Kr{\"a}mer, Meret},
  title     = {Transition temperature of the weakly interacting Bose gas: perturbative solution of the crossover equations in the canonical ensemble},
  year      = {2000},
  abstract  = {We compute the shift of the critical temperature Tc with respect to the ideal case for a weakly interacting uniform Bose gas. We work in the framework of the canonical ensemble, extending the criterion of condensation provided by the canonical particle counting statistics for the zero-momentum state of the uniform ideal gas. The perturbative solution of the crossover equation to lowest order in power of the scattering length yields (Tc - Tc0)/Tc0=-0,93ap 1/3, where Tc0 is the transition temperature of the corresponding ideal Bose gas , a is the scattering length, and p is the particle number density. This is at vaiance with the standard grand canonical prediction of a null shift of the critical temperature in the lowest perturbative order. The non-equevalence of statistical ensemble for the ideal Bose gas is thus confirm (at the lowestperturbative level) also in the presence of interactions.},
  language  = {en}
}
@article{PuZhangWilkensetal.2002,
  author    = {Pu, Han and Zhang, Weiping and Wilkens, Martin and Meystre, Pierre},
  title     = {Phonon Spectrum and Dynamical Stability of a Dilute Quantum Degenerate Bose-Fermi Mixture},
  year      = {2002},
  abstract  = {We calculate the phonon excistation spectrum in a zero-temperature dilute boson-fermion gaseous mixture. We show how the sound velocity changes due to the boson-fermion interaction, and we determine the dynamical stability regime of a homogeneous mixture. We identify a resonant phonon-exchange interaction between the fermions as the physical mechanism leading to the instability.},
  language  = {en}
}
@article{RzazewskiGoralCironeetal.2001,
  author    = {Rzazewski, Kazimierz and Goral, K. and Cirone, M. A. and Wilkens, Martin},
  title     = {Bose-Einstein Condensation of two interacting particles},
  year      = {2001},
  abstract  = {We investigate the notion of Bose-Einstein condensation of interacting particles. The definition of the condensate is based on the existence of the dominant eigenvalue of the single-particle density matrix. The statistical properies and the characteristics temperature are computed exactly in the soluble models of two interacting atoms.},
  language  = {en}
}
@article{AlbusIlluminatiWilkens2003,
  author    = {Albus, Alexander P. and Illuminati, Fabrizio and Wilkens, Martin},
  title     = {Ground-state properties of trapped Bose-Fermi mixtures: Role of exchange correlation},
  year      = {2003},
  language  = {en}
}
@article{WeissWilkens1997,
  author    = {Weiss, Christoph and Wilkens, Martin},
  title     = {Particle number counting statistics in ideal Bose gases},
  year      = {1997},
  abstract  = {We discuss the exact particle number counting statistics of degenerate ideal Bose gases in the microcanonical, canonical, and grand-canonical ensemble, respectively, for various trapping potentials. We then invoke the Maxwell's Demon ensemble [P. Navez et al., Phys. Rev. Lett.(1997)] and show that for large total number of particles the root-mean-square fluctuation of the condensate occupation scales delta n0 proportional to [T/Tc]r Ns with scaling exponents r=3/2, s=1/2 for the 3D harmonic oscillator trapping potential, and r=1, s=2/3 for the 3D box. We derive an explicit expression for r and s in terms of spatial dimension D and spectral index sigma of the single- particle energy spectrum. Our predictions also apply to systems where Bose-Einstein condensation does not occur. We point out that the condensate fluctuations in the microcanonical and canonical ensemble respect the principle of thermodynamic equivalence.},
  language  = {en}
}
@article{WilkensWeiss1997,
  author    = {Wilkens, Martin and Weiss, Christoph},
  title     = {Particle number fluctuations in an ideal Bose gas},
  year      = {1997},
  abstract  = {We analyse occupation number fluctuations of an ideal Bose gas in a trap which is isolated from theenvironment with respect to particle exchange (canonical ensemble). We show that in contrast to the predictions of thegrand- canonical ensemble, the counting statistics of particles in the trap ground state changes from monotonously decreasing above the condensation temperature to single-peaked below that temperature. For the exactly solvable case of a harmonic oscillator trapping potential in one spatial dimension we extract a Landau-Ginzburg functional which - despite the non- interacting nature of the system - displays the characteristic behaviour of a weakly interacting Bose gas. We also compare our findings with the usual treatment which is base on the grand-canonical ensemble. We show that for an ideal Bose gas neither are the grand-canonical and canonical ensemble thermodynamically equivalent, nor the grand-canonical ensemble can be viewed as a small system in diffusive contact with a particle reservoir.},
  language  = {en}
}
@article{PowerPfauWilkens1997,
  author    = {Power, W. L. and Pfau, T. and Wilkens, Martin},
  title     = {Loading atoms into a surface trap: simulations of an experimental scheme},
  year      = {1997},
  abstract  = {We present simulations of a scheme for the continuous loading of pre-cooled atoms into the lowest energy states of an optical surface trap. The atoms fall under gravity towards the surface of a prism where evanescent waves are used to decelerate the falling atoms and to pump them into a trapped state in an optical standing wave. The simulations are performed using the Monte-Carlo wavefunction technique and are designed to represent the proposed experimental scheme as closely as is practically possible. The probabilities of atoms being pumped into the different trapped states have been calculated as a function of the properties of the braking and pumping fields. The effective temperature of the final distribution of the atoms is calculated in order to find the change in phase-space density.},
  language  = {en}
}
@article{OehbergSurkovTittonenetal.1997,
  author    = {{\"O}hberg, P. and Surkov, E. L. and Tittonen, I. and Stenholm, Stig and Wilkens, Martin and Shlyapnikov, G. V.},
  title     = {Low-energy elementary excitations of a trapped Bose-condensed gas},
  year      = {1997},
  abstract  = {We develop a method of finding analytical sotutions of the Bogolyubov-de Gennes equations for the excitations of a Bose condensate in the Thomas-Fermi regime in harmonic traps of any asymmetry and introduce a classification of eigenstates. In the case of cylindrical symmetry we emphasize the presence of an accidental degeneracy in the excitation spectrum at certain values of the projection of orbital angular momentum on the symmetry axis and discuss possible consequences of the degeneracy in the context of new signatures of Bose- Einstein condensation},
  language  = {en}
}
@article{JavanainenWilkens1997,
  author    = {Javanainen, Juha and Wilkens, Martin},
  title     = {Phase and Phase Diffusion of a Split Bose-Einstein Condensate},
  year      = {1997},
  abstract  = {We analyze theoretically an experiment in which a trapped Bose-Einstein condensate is cut in half, and the parts are subsequently allowed to interfere. If the delay cutting and atom detection is small, the interference pattern of the two halves of the condensate is the same in every experiment. However, for longer delays the spatial phase of the interference shows random fluctuations from one experiment to the other. This phase diffusion is characterized quantitatively.},
  language  = {en}
}
@article{StenholmWilkens1997,
  author    = {Stenholm, Stig and Wilkens, Martin},
  title     = {Jumps in quantum theory},
  year      = {1997},
  abstract  = {In this paper we review the discussion about quantum jumps. We sketch the historical background before we present the recent revival of this problem originating in the field of atomic investigations. We present both the theoretical methods and their motivations, the relevance to experiments and an attempt at a preliminary discussion of the role of these developments in our fundamental understanding of quantum physics.},
  language  = {en}
}
@misc{HasslerWilkensScheererNeumannetal.2002,
  author    = {Hassler, Gerda and Wilkens, Martin and Scheerer-Neumann, Gerheid and Kretschmann, Martina and Resch-Esser, Ursula and Wagner, Karen and Pabst, Markus},
  title     = {Portal = Nach PISA: Reformbedarf auch f{\"u}r die Lehrerbildung},
  organization    = {Universit{\"a}t Potsdam, Referat f{\"u}r Presse- und {\"O}ffentlichkeitsarbeit},
  issn      = {1618-6893},
  doi       = {10.25932/publishup-43958},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-439583},
  pages     = {42},
  year      = {2002},
  abstract  = {Aus dem Inhalt: - Nach PISA: Reformbedarf auch f{\"u}r die Lehrerbildung - Neue Regelungen im Hochschulrahmengesetz - Bunsen-Gesellschaft f{\"u}r Pysikalische Chemie tagt in Potsdam - Abschied: Neue Aufgaben f{\"u}r Barbara Schneider-Kempf},
  language  = {de}
}
@misc{RaetzelWilkensMenzel2016,
  author    = {R{\"a}tzel, Dennis and Wilkens, Martin and Menzel, Ralf},
  title     = {Gravitational properties of light},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-90553},
  year      = {2016},
  abstract  = {The gravitational field of a laser pulse of finite lifetime, is investigated in the framework of linearized gravity. Although the effects are very small, they may be of fundamental physical interest. It is shown that the gravitational field of a linearly polarized light pulse is modulated as the norm of the corresponding electric field strength, while no modulations arise for circular polarization. In general, the gravitational field is independent of the polarization direction. It is shown that all physical effects are confined to spherical shells expanding with the speed of light, and that these shells are imprints of the spacetime events representing emission and absorption of the pulse. Nearby test particles at rest are attracted towards the pulse trajectory by the gravitational field due to the emission of the pulse, and they are repelled from the pulse trajectory by the gravitational field due to its absorption. Examples are given for the size of the attractive effect. It is recovered that massless test particles do not experience any physical effect if they are co-propagating with the pulse, and that the acceleration of massless test particles counter-propagating with respect to the pulse is four times stronger than for massive particles at rest. The similarities between the gravitational effect of a laser pulse and Newtonian gravity in two dimensions are pointed out. The spacetime curvature close to the pulse is compared to that induced by gravitational waves from astronomical sources.},
  language  = {en}
}
@article{RaetzelWilkensMenzel2016,
  author    = {R{\"a}tzel, Dennis and Wilkens, Martin and Menzel, Ralf},
  title     = {Gravitational properties of light},
  series = {New journal of physics : the open-access journal for physics},
  volume    = {18},
  journal   = {New journal of physics : the open-access journal for physics},
  publisher = {IOP Science},
  address   = {London},
  issn      = {1367-2630},
  doi       = {10.1088/1367-2630/18/2/023009},
  pages     = {1 -- 16},
  year      = {2016},
  abstract  = {The gravitational field of a laser pulse of finite lifetime, is investigated in the framework of linearized gravity. Although the effects are very small, they may be of fundamental physical interest. It is shown that the gravitational field of a linearly polarized light pulse is modulated as the norm of the corresponding electric field strength, while no modulations arise for circular polarization. In general, the gravitational field is independent of the polarization direction. It is shown that all physical effects are confined to spherical shells expanding with the speed of light, and that these shells are imprints of the spacetime events representing emission and absorption of the pulse. Nearby test particles at rest are attracted towards the pulse trajectory by the gravitational field due to the emission of the pulse, and they are repelled from the pulse trajectory by the gravitational field due to its absorption. Examples are given for the size of the attractive effect. It is recovered that massless test particles do not experience any physical effect if they are co-propagating with the pulse, and that the acceleration of massless test particles counter-propagating with respect to the pulse is four times stronger than for massive particles at rest. The similarities between the gravitational effect of a laser pulse and Newtonian gravity in two dimensions are pointed out. The spacetime curvature close to the pulse is compared to that induced by gravitational waves from astronomical sources.},
  language  = {en}
}
@article{TinoCacciapuotiBongsetal.2007,
  author    = {Tino, G. M. and Cacciapuoti, L. and Bongs, K. and Bord{\´e}, Ch. J. and Bouyer, P. and Dittus, H. and Ertmer, W. and G{\"o}rlitz, A. and Inguscio, M. and Landragin, A. and Lemonde, P. and L{\"a}mmerzahl, C. and Peters, A. and Rasel, E. and Reichel, J. and Salomon, C. and Schiller, S. and Schleich, W. and Sengstock, K. and Sterr, U. and Wilkens, Martin},
  title     = {Atom interferometers and optical atomic clocks : new quantum sensors for fundamental physics experiments in space},
  year      = {2007},
  abstract  = {We present projects for future space missions using new quantum devices based on ultracold atoms. They will enable fundamental physics experiments testing quantum physics, physics beyond the standard model of fundamental particles and interactions, special relativity, gravitation and general relativity.},
  language  = {en}
}
@article{JanickeWilkens1998,
  author    = {Janicke, U. and Wilkens, Martin},
  title     = {Atomic matter wave amplification by optical pumping},
  year      = {1998},
  abstract  = {The atom laser (or `Boser') is a device that delivers a beam of atomic de Broglie waves with high coherence and monochromaticity. In this review, we concentrate on an all-optical scheme of an atom laser that is based on optical pumping. The model is first presented in terms of kinetic equations, and its relation to the ordinary laser and the Bose-Einstein condensation is discussed. We then derive a master equation for the quantum statistics dynamics of the atom laser. Neglecting photon reabsorption processes, the master equation is solved and the counting statistics is computed. Finally, the effects of the inelastic reabsorption processes are investigated for the particular case of two atoms. It is shown that the onset of atom-lasing is suppressed in large resonators, but may be achieved in small and/or low-dimensional resonators.},
  language  = {en}
}
@article{NavezWilkens1999,
  author    = {Navez, Patrick and Wilkens, Martin},
  title     = {Single molecule in a Bose-Einstein condensate},
  year      = {1999},
  abstract  = {We study a model describing a rotating linear rigid molicule interacting with a Bose-Einstein condensate. A generalization of the Landau criterion is established and gives the limit for which the molecule moves translationally and rotationally into the condensate without any friction. In particular, we show that the rotational energy released by the molecule is large enough to eject one atom out of the condensate. The detection of such an atom provides a direct measurement of the low-energy cross section of the scattering with the rotating molecule. Finally, increases of inertia and of centrifugal distortion of the molecule due to the surrounding condensate are estimated and compared with the experimental data obtained for a He4 droplet.},
  language  = {en}
}
@article{IdziaszekGajdaNavezetal.1999,
  author    = {Idziaszek, Zbigniew and Gajda, M. and Navez, Patrick and Wilkens, Martin and Rzazewski, Kazimierz},
  title     = {Fluctuation of the Weakly Interacting Bose-Einstein Condensate},
  year      = {1999},
  abstract  = {We consider the role of weak interaction on the fluctuations of the number of condensed atoms within canonical and microanonical ensembles. Unlike the correspinding case of the ideal gas this is not a clean, well-defined problem of mathematical physics. Two related reasons are the following: there is no unique way of defining the condensate fraction of the interacting system and no exact energy levels of the interacting system are known.},
  language  = {en}
}
@article{PowerTanWilkens1997,
  author    = {Power, W. L. and Tan, S. M. and Wilkens, Martin},
  title     = {A scheme for the simultaneous measurement of atomic position and momentum},
  year      = {1997},
  abstract  = {We propose an optical scheme for the simultaneous measurement of the position and momentum of a single atom. The scheme involves the coupling of the atom of two light fields with different spatical and polarization characteristics. The proposed technique is closely related to the Arthurs-Kelly measurement scheme; the principal difference is that in the present case the electromagnetic fields rather than from shifts in the position of a pointer.},
  language  = {en}
}
@article{IdziaszekWilkens1999,
  author    = {Idziaszek, Zbigniew and Wilkens, Martin},
  title     = {Scattering of atoms on the Bose-Einstein condensate},
  year      = {1999},
  abstract  = {We investigate the scattering of slowly moving atoms on the Bose-Einstein condensate. The condensate excitations are described by Bogolyubov-de Gennes equatins. We derive the analytic expressions for the differential cross section for both elastic and ineladtic channels. For the elastic channel we obtain analytic results for total cross sections, and discuss their scaling with the number of condensed atoms. For inelastic channels we present numerical results for the total cross section.},
  language  = {en}
}
@article{BuschEnglertRzazewskietal.1998,
  author    = {Busch, Thomas and Englert, Bertold-Georg and Rzazewski, Kazimierz and Wilkens, Martin},
  title     = {Two cold atoms in a harmonic trap},
  year      = {1998},
  abstract  = {Two ultracold atoms moving in a trap interact weakly at a very short distance. This interaction can be modeled by a properly regularized contact potential. We solve the corresponding time-independent Schr{\"o}dinger equation under the assumption of a parabolic, spherically symmetric trapping potential.},
  language  = {en}
}
@article{LeonhardtWilkens1998,
  author    = {Leonhardt, Ulf and Wilkens, Martin},
  title     = {Aharonov-Bohm scattering of neutral atoms},
  year      = {1998},
  abstract  = {We study the scattering of quantum particles in the presence of an Aharonov-Bohm vortex and in an arbitrary cylindrically symmetric potential. In particular we address the scattering of atoms carrying dipole moments induced by an electrically charged wire and a homogeneous magnetic field. We argue that, despite the strong attraction of the wire, an Aharoniv-Bohm effect will be visible.},
  language  = {en}
}
@article{Wilkens1998,
  author    = {Wilkens, Martin},
  title     = {Quantum Phase of a Moving Dipole},
  year      = {1998},
  abstract  = {It is shown that a neutral particle with an electric dipole moment which moves in a magnetic field acquires a topological phase. This phase may be observed in atom or molecular interferometry.},
  language  = {en}
}
@article{JavanainenWilkens1998,
  author    = {Javanainen, Juha and Wilkens, Martin},
  title     = {Phase and phase diffusion of a split Bose-Einstein condensate},
  year      = {1998},
  language  = {en}
}
@article{IlluminatiNavezWilkens1999,
  author    = {Illuminati, Fabrizio and Navez, Patrick and Wilkens, Martin},
  title     = {Thermodynamic identities and paricle number fluctuations in weakly interacting Bose-Einstein condensates},
  year      = {1999},
  abstract  = {We derive exact thermodynamic identities relating the average number of condensed atoms and the root-mean- square fluctuations determined in different statistical ensembles for the weakly interacting Bose gas confined in a box. This is achieved by introducing the concept of auxiliary partition functions for model Hamiltonians that do conserve the total number of particles. Exploiting such thermodynamic identities, we provide the first, completely analytical prediction of the microcanonical particle number fluctuations in the weakly interacting Bose gas. Such fluctuations, as a function of the volume V of the box are found to behave normally, in contrast wiht the anomalous scaling behaviour V3/ 4 of the fluctuations in the ideal Bose gas.},
  language  = {en}
}
@article{EisertWilkens2000,
  author    = {Eisert, Jens and Wilkens, Martin},
  title     = {Catlysis of Entanglement Manipulation for Mixed States},
  year      = {2000},
  abstract  = {We consider entanglement-assisted remote quantum state manipulation of bipartite mixed states. Several aspects are addressed: we present a class of mixed states of rank two that can be transformed into another class of mixed states under entanglement-assisted local operations with classical communication, but for which such a transformation is impossible without assistance. Furthermore, we demonstrate enhancement of the efficiency of purification protocols with the help of entanglement-assisted operations. Finally, transformations from one mixed state to mixed target states which are sufficiently close to the source state are contrasted with similar transformations in the pure-state case.},
  language  = {en}
}
@article{FelbingerSantosWilkensetal.2000,
  author    = {Felbinger, Timo and Santos, L. and Wilkens, Martin and Lewenstein, Maciej},
  title     = {Time Correlations of a laser-induced Bose-Einstein condensate},
  year      = {2000},
  abstract  = {We analyze the multi-time correlations of a laser-induced Bose Einstein condensate. We use quantum stochastic methods to obtain under certain circumstances a Fokker-Planck equation which describes the phase-difussion process, and obtain an analytical expression of the two-time correlations. We perform also quantum Monte Carlo numerical simulations of the correlations, which are in good agreement with the predicted analytical results.},
  language  = {en}
}
@article{EisertWilkens2000,
  author    = {Eisert, Jens and Wilkens, Martin},
  title     = {Quantum games},
  year      = {2000},
  abstract  = {In these lecture notes we investigate the implications of the identification of strategies with quantum operations in game theory beyond the results presented in [J. Eisert, M. Wilkens, and M. Lewenstein, Phys. Rev. Lett. 83, 3077 (1999)]. After introducing a general framework, we study quantum games with a classical analogue in order to flesh out the peculiarities of game theoretical settings in the quantum domain. Special emphasis is given to a detailed investigation of different sets of quantum strategies.},
  language  = {en}
}
@article{EisertFelbingerPapadopolousetal.2000,
  author    = {Eisert, Jens and Felbinger, Timo and Papadopolous, P. and Plenio, M. B. and Wilkens, Martin},
  title     = {Classical information and distillable entanglement},
  year      = {2000},
  abstract  = {We establish a quantitative connection between the amount of lost classical information about a quantum state and the concomitant loss of entanglement. Using menthods that have been developed for the optimal purification of miced states, we find a class of miced states with known distillable entanglement. These results can be used to determine the quantum capacity of a quantum channel which randomizes the order of transmitted signals.},
  language  = {en}
}
@article{EisertWilkensLewenstein1999,
  author    = {Eisert, Jens and Wilkens, Martin and Lewenstein, Maciej},
  title     = {Quantum Games and Quantum Strategies},
  year      = {1999},
  abstract  = {We investigate the quantization of nonzero sum games. For the particular case of the Prisoners' Dilemma we show that this game ceases to pose a dilemma if quantum strategies are allowed for. We also construct a particular quantum strategy which always gives reward if played against any classical strategy.},
  language  = {en}
}
@article{FelbingerWilkens1999,
  author    = {Felbinger, Timo and Wilkens, Martin},
  title     = {Stochastic Wave-function Simulation of Two-time Correlation Functions},
  year      = {1999},
  abstract  = {We propose an algorithm for the numerical simulation of two-time correlation functions by means of stochastic wave function. As a first application, we investigate the two-time correlation function of a nonlinear optical parametric oscillator.},
  language  = {en}
}
@article{RaetzelWilkensMenzel2017,
  author    = {Raetzel, Dennis and Wilkens, Martin and Menzel, Ralf},
  title     = {Gravitational properties of light: The emission of counter-propagating laser pulses from an atom},
  series = {Physical review : D, Particles, fields, gravitation, and cosmology},
  volume    = {95},
  journal   = {Physical review : D, Particles, fields, gravitation, and cosmology},
  publisher = {American Physical Society},
  address   = {College Park},
  issn      = {2470-0010},
  doi       = {10.1103/PhysRevD.95.084008},
  pages     = {11},
  year      = {2017},
  language  = {en}
}
@article{Wilkens2020,
  author    = {Wilkens, Martin},
  title     = {AS TIME GOES BY. Rythmizit{\"a}t Zyklizit{\"a}t - Kategorien zeitlicher Stukturierung},
  series = {Zyklizit{\"a}t \& Rhythmik: eine multidisziplin{\"a}re Vorlesungsreihe},
  journal   = {Zyklizit{\"a}t \& Rhythmik: eine multidisziplin{\"a}re Vorlesungsreihe},
  publisher = {trafo},
  address   = {Berlin},
  isbn      = {978-3-86464-169-5},
  pages     = {71 -- 84},
  year      = {2020},
  language  = {de}
}
@misc{BehrmannKohlmannRupprechtetal.2010,
  author    = {Behrmann, G{\"u}nter C. and Kohlmann, Birgit and Rupprecht, Holger and Voigt, Sylvia and Paulisch, Antje and Piegler, Sandra and Falk, Andr{\´e} and Kozakowski, Melanie and Heike, Sylvester and Eisner, Beate and John, Peter and Wilkens, Martin and Lohwaßer, Roswitha and Schr{\"u}nder-Lenzen, Agi and Lauterbach, Wolfgang and Schubarth, Wilfried},
  title     = {Portal alumni},
  series = {Das Ehemaligen-Magazin der Universit{\"a}t Potsdam},
  journal   = {Das Ehemaligen-Magazin der Universit{\"a}t Potsdam},
  number    = {8},
  organization    = {Stabsstelle Studierendenmarketing/Alumniprogramm Im Auftrag der Pr{\"a}sidentin der Universit{\"a}t Potsdam},
  issn      = {1613-2343},
  doi       = {10.25932/publishup-44458},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-444587},
  pages     = {59},
  year      = {2010},
  abstract  = {Das gerade begonnene Jahr wird f{\"u}r die Universit{\"a}t Potsdam ein besonderes werden, ist es doch das 20. Jahr ihres Bestehens. Auf das Erreichte ist die Hochschule mit Recht stolz. Die Universit{\"a}t Potsdam ist f{\"u}r Studieninteressierte ungebrochen attraktiv, was die steigenden Bewerberzahlen zeigen. Allein im vergangenen Jahr haben Uni-Wissenschaftler knapp 42 Millionen Euro Drittmittel eingeworben und die Liste gemeinsamer Verbundprojekte mit außeruniversit{\"a}ren Forschungseinrichtungen der Region w{\"a}chst weiter. Zu den Erfolgen z{\"a}hlt weiterhin auch die steigende Anzahl von Absolventinnen und Absolventen der Hochschule. In die Gr{\"u}ndung der Universit{\"a}t Potsdam am 15. Juli 1991 flossen zwei Vorg{\"a}ngereinrichtungen ein. Die wichtigste war die Brandenburgische Landeshochschule, vorher P{\"a}dagogische Hochschule, die {\"u}ber vier Jahrzehnte hinweg Lehrerinnen und Lehrer ausgebildet hat. Die Lehrerbildung hat auch f{\"u}r die Universit{\"a}t Potsdam profilbildenden Charakter, denn allein vier der f{\"u}nf Fakult{\"a}ten sind an der Lehrerbildung beteiligt und haben Generationen von jungen Leuten f{\"u}r den Lehrerberuf qualifiziert. Heute ist das Ziel aller an der Lehrerbildung Beteiligten, eine professionsorientierte, qualitativ hochwertige Lehrerbildung zu sichern, die sich an den Kompetenzen Erziehen, Unterrichten, Beraten, Betreuen, Innovieren und Organisieren orientiert. Eine besondere Herausforderung sieht die Universit{\"a}t Potsdam dabei in der Vernetzung von wissenschaftlicher Forschung und Lehrerbildung. Portal alumni stellt in der hier vorliegenden Ausgabe im Jubil{\"a}umsjahr zw{\"o}lf Absolventen der Lehrerbildung vor. Sie berichten aus jeweils individueller Perspektive, wie sie ihr Studium an der Universit{\"a}t Potsdam erlebt haben und wie es sie gepr{\"a}gt hat. Und nat{\"u}rlich stellt das Magazin zugleich aktuelle Entwicklungstrends in der Lehrerbildung vor. Wie in allen Heften zuvor berichten wir von der Alumni-Arbeit des Jahres 2010 und stellen H{\"o}hepunkte des Unialltags vor. Wir w{\"u}nschen Ihnen eine unterhaltsame Lekt{\"u}re und sind gespannt auf Ihr Feedback zu diesem Heft.},
  language  = {de}
}
@article{RaetzelWilkensMenzel2016,
  author    = {R{\"a}tzel, Dennis and Wilkens, Martin and Menzel, Ralf},
  title     = {Gravitational properties of light-the gravitational field of a laser pulse},
  series = {NEW JOURNAL OF PHYSICS},
  volume    = {18},
  journal   = {NEW JOURNAL OF PHYSICS},
  publisher = {IOP Publ. Ltd.},
  address   = {Bristol},
  issn      = {1367-2630},
  doi       = {10.1088/1367-2630/18/2/023009},
  pages     = {16},
  year      = {2016},
  abstract  = {The gravitational field of a laser pulse of finite lifetime, is investigated in the framework of linearized gravity. Although the effects are very small, they may be of fundamental physical interest. It is shown that the gravitational field of a linearly polarized light pulse is modulated as the norm of the corresponding electric field strength, while no modulations arise for circular polarization. In general, the gravitational field is independent of the polarization direction. It is shown that all physical effects are confined to spherical shells expanding with the speed of light, and that these shells are imprints of the spacetime events representing emission and absorption of the pulse. Nearby test particles at rest are attracted towards the pulse trajectory by the gravitational field due to the emission of the pulse, and they are repelled from the pulse trajectory by the gravitational field due to its absorption. Examples are given for the size of the attractive effect. It is recovered that massless test particles do not experience any physical effect if they are co-propagating with the pulse, and that the acceleration of massless test particles counter-propagating with respect to the pulse is four times stronger than for massive particles at rest. The similarities between the gravitational effect of a laser pulse and Newtonian gravity in two dimensions are pointed out. The spacetime curvature close to the pulse is compared to that induced by gravitational waves from astronomical sources.},
  language  = {en}
}
@article{RaetzelWilkensMenzel2016,
  author    = {R{\"a}tzel, Dennis and Wilkens, Martin and Menzel, Ralf},
  title     = {The effect of entanglement in gravitational photon-photon scattering},
  series = {epl : a letters journal exploring the frontiers of physics},
  volume    = {115},
  journal   = {epl : a letters journal exploring the frontiers of physics},
  publisher = {EDP Sciences},
  address   = {Mulhouse},
  issn      = {0295-5075},
  doi       = {10.1209/0295-5075/115/51002},
  pages     = {S12 -- S13},
  year      = {2016},
  abstract  = {The differential cross-section for gravitational photon-photon scattering calculated in perturbative quantum gravity is shown to depend on the degree of polarization entanglement of the two photons. The interaction between photons in the symmetric Bell state is stronger than between not entangled photons. In contrast, the interaction between photons in the anti-symmetric Bell state is weaker than between not entangled photons. The results are interpreted in terms of quantum interference, and it is shown how they fit into the idea of distance-dependent forces. Copyright (C) EPLA, 2016},
  language  = {en}
}
@article{HenkelWilkens1999,
  author    = {Henkel, Carsten and Wilkens, Martin},
  title     = {Heating of trapped atoms near thermal surfaces},
  year      = {1999},
  abstract  = {We study the electromagnetic coupling and concomitant heating of a particle in a miniaturized trap close to a solid surface. Two dominant heating mechanisms are identified: proximity fields generated by thermally exicted currents in the absorbing solid and timedependent image potentials due to elastic surfaces distortions (Rayleigh phonons. Estimates for the lifetime of the trap ground state are given. Ions are paricularly sinsitive to electric proximity fields: for a silver substrate, we find a lifetime below one second at distrances closer than some ten 10^-6m to the surfaces. Neutral atoms may approach the surface more closely: if they have a magnetic moment, a minimum distance of one 10^-6m is estimatied in tight traps, the heat being transferred via magnetic proximity fields. For spinless atoms, heat is transferred by inelastic scattering of virtual photons off sorface phonons. The corresponding lifetime, however, is estimated to be extremely long compared to the timescale of typical experiments.},
  language  = {en}
}
@article{HenkelWilkens2000,
  author    = {Henkel, Carsten and Wilkens, Martin},
  title     = {Heating of trapped particles close to surfaces-blackbody and beyond},
  year      = {2000},
  abstract  = {We discuss heating and decoherencw in traps fpr ions and neutral paricles close to metallic surfaces. We focus on simple trap geometries and compute noise spectra of thermally excited electromagnetic fields. If the trap is located in the near field of the substrate, the field fluctuations are largely increased compared to the level of the blackbody field, leading to much shorter coherence and life times of the trapped atoms. The correspinding time constants are computed for ion traps and magnetic traps. Analytical estimates for the size dependence of the noise spectrum are given. We finally discuss prospects for the coherent transport of matter waves in integrated surface waveguides.},
  language  = {en}
}
@article{HenkelPoettingWilkens1999,
  author    = {Henkel, Carsten and Poetting, Sierk and Wilkens, Martin},
  title     = {Loss and heating of particles in small and noisy traps},
  year      = {1999},
  abstract  = {We derive the time and loss rate for a trapped atom that is coupled to fluctuating fields in the vicinity of a room-temperature metallic and/or dielectric surface. Our results indicate a clear predominance of near-field effects over ordinary blackbody radiation. We develop a theoretical framework for both charged ions and neutral atoms with and without spin. Loss processes that are due to a transition to an untrapped internal state are included.},
  language  = {en}
}
@misc{SzameitatWilkensGoerlichetal.2015,
  author    = {Szameitat, Ulrike and Wilkens, Martin and G{\"o}rlich, Petra and Horn-Conrad, Antje and Zimmermann, Matthias and Reinhardt, Kristin and Kampe, Heike and J{\"a}ger, Heidi and Wenzel, Anna Theresa and Scholz, Jana},
  title     = {Portal = Unter einem Dach: Lehrerbildung und Bildungsforschung},
  number    = {02/2015},
  organization    = {Universit{\"a}t Potsdam, Referat f{\"u}r Presse- und {\"O}ffentlichkeitsarbeit},
  issn      = {1618-6893},
  doi       = {10.25932/publishup-44063},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-440634},
  pages     = {46},
  year      = {2015},
  abstract  = {Aus dem Inhalt: - Unter einem Dach: Lehrerbildung und Bildungsforschung - Waldweit - Nicht ohne Eisen und Schwefel},
  language  = {de}
}