Sep 4, 2013 ... optical nanofibers and nanofiber - cavities on an atom chip. ...... Foundation (FWF
) under projects SFB F4008 and CoQuS, the Austrian ...
Atomic Physics and Quantum Optics Wednesday, 04.09.2013, HS 4 Time
ID
Atomic Physics and Quantum Optics I Chair: NN
13:30
501
Measuring higher-order interferences with a five-path interferometer Thomas Kauten, Benjamin Gschösser, Patrick Mai, Zoltán Vörös, Gregor Weihs Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, AT-6020 Innsbruck In this work we will present results of a five-path interferometer experiment with the goal of putting a bound on the potential magnitude of higher order interference ter This experiment was first proposed for three paths by Sorkin in 1994, and was experimentally implemented for the first time in 2010 by Sinha et al. Our experiment expands this to five paths, which not only allows us to measure third and fourth order interference terms but also allows testing for the possibility of quantum mechanical wavefunctions based on quaternions or octonions rather than complex numbers.
13:45
502
Extraction of Ionic Cores From Charged Helium Nanodroplets Michael Renzler, Paul Scheier Ionphysics and Applied Physics, University of Innsbruck, Technikerstraße 25, AT-6020 Innsbruck Size distributions of charged helium nanodroplets (HND) determined by mass spectrometry always differed considerably from distributions obtained by electrostatic deflection voltages or retarding field analysis. We propose that this difference is due to the electric fields in mass spectrometers which extract small ions from HND. In our setup we were able to detect charged HND, containing more than 106 atoms. By passing such mass selected HND through retarding fields we were able to extract the ionic cores which can be analyzed in the field-dependent loss of the signal. This work is supported by the FWF project P23657, L633 and I978
14:00
503
Probing Non-Equilibrium Dynamics of Isolated Quantum Many-Body Systems Bernhard Rauer, Tim Langen, Maximilian Kuhnert, Thomas Schweigler, Remi Geiger, Jörg Schmiedmayer, Atominstitut / TU Wien, Stadionallee 2, AT-1020 Wien One of the challenges in probing quantum many-body systems is that there is no general approach to characterize their quantum states. In the last years we developed techniques to characterize relaxed states and the dynamics leading to them. Our model system is a quantum degenerate 1d Bose gas which we coherently split into two parts. Interfering two such 1d systems results in a fluctuating interference pattern. The noise and correlations in these interference patterns open a probe into the manybody states of the 1d Bose gas, its fluctuations and relaxation. In our experiment we study how the coherence created between the two many-body systems by the splitting process is slowly lost. Two distinct regimes are clearly visible: for short length scales the system is characterized by spin diffusion, for long length scales by spin decay. After a rapid evolution a steady state is approached, which can be characterized by the establishment of a generalized Gibbs ensemble and pre-thermalization. A detailed look at the phase correlation functions reveals that this relaxed thermal like state is established locally and spreads throughout the system in a light-cone-like evolution.
14:15
504
Buffer gas cooling of atoms and molecules Sarah Skoff, Nick E. Bulleid, Didier M. M. Nohlmans, Richard J. Hendricks, Jony J. Hudson, Daniel M. Segal, Ben E. Sauer, Edward A. Hinds, Michael R. Tarbutt Imperial College London, Prince Consort Road, SW7 2BW London, UK Increasing the sensitivity of the measurement of the electron's electric dipole moment requires intense sources of cold and slow molecules [Hudson et al., Nature, 2011, 473, 493]. Using a cryogenic buffer gas source [Skoff et al., Phys. Rev. A, 2011, 83, 023418 ], we have produced a slow YbF beam (130 m/s-200 m/s) at 4 K with a flux exceeding 1011 s-1 sr-1 ground state molecules. The design of a source with higher extraction efficiency was achieved by comparing simulations and experimental results of the flow dynamics of an ytterbium buffer gas beam. We are also pursuing buffer gas cooling of molecules and atoms directly in a permanent magnetic trap. First results using dysprosium atoms will be presented. 97
14:30
505
Spectroscopic and Theoretical Studies of Chromium Doped Helium Nanodroplets Andreas Kautsch, Martin Ratschek, Friedrich Lindebner, Markus Koch, Wolfgang E. Ernst Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, AT-8010 Graz Helium nanodroplets (HeN) are doped with chromium atoms and the influence of the cold chemically inert environment on Cr spectra is investigated. Shifted and broadened excitation lines as well as electronic relaxation phenomena have been measured with various experimental techniques such as laser excitation, ionization, laser induced fluorescence, and beam depletion. Diatomic Cr-He potentials were calculated by quantum chemical methods and applied to droplet based DFT calculations to support our conclusions from the experiments.
14:45
506
A graph state formalism for mutually unbiased bases Christoph Spengler, Barbara Kraus, Institute for Theoretical Physics, University of Innsbruck Complementarity is one of the key features of quantum theory. In simple terms, it states that there exist observables which cannot be simultaneously specified with arbitrary precision. Best-known examples of complementary observables are position and momentum, or the spin in different directions. In the discrete case, i.e. for finite-dimensional Hilbert spaces, complementarity manifests itself through the relation between the associated eigenbases: Namely, all (normalized) eigenvectors of one observable have the same overlap with all eigenvectors of the other observable. That is, if a measurement outcome is predictable with certainty in one basis, it is totally random with respect to the other, and vice versa. These bases are therefore commonly called 'mutually unbiased bases' (MUBs). Existing applications of MUBs include quantum state tomography, cryptography, entanglement detection, and the so-called mean king's problem. In this talk, the focus is on the construction of such bases. Existing methods generally rely on abstract mathematical concepts such as character sums over Galois fields and rings, or the generalized Pauli group. Here, we show that MUBs may alternatively be described in terms of graph states. These states have found widespread applications in quantum information, and have an illustrative representation in terms of graphs. Based on them, we introduce a complete framework for the construction of MUBs in all prime-power dimensions (PPD). In comparison to other approaches, this formalism is particularly well-suited to investigate entanglement structures arising in MUBs for complex manybody systems. Furthermore, it shows that for all PPD, there always exist MUBs which can be decomposed into local operations and two-body interactions. Therefore, giving rise to an experimentallyfriendly general construction.
15:00
507
Strong coupling between single atoms and non-transversal photons Christian Junge, Michael Scheucher, Danny O’Shea, Jürgen Volz, Arno Rauschenbeutel Vienna Center for Quantum Science and Technology, TU Wien, Atominstitut, Stadionallee 2, AT-1020 Wien We investigate the interaction between single quantum emitters and non-transversally polarized photons for which the electric field vector amplitude has a significant component in the direction of propagation. Even though this situation seems to be at odds with the description of light as a transverse wave, it regularly occurs when inter-facing or manipulating emitters with non-paraxial, guided, or evanescent light. Here, we quantitatively investigate this phenomenon for the case of single 85Rb atoms that strongly interact with a bottle-microresonator - a novel type of whispering-gallery-mode (WGM) microresonator. Our experimental results show that the non-transversal polarization decisively alters the physics of light–matter interaction [1]. In addition they demonstrate that WGM resonators constitute a novel class of microresonators that can, e.g., simultaneously sustain three orthogonally polarized eigenmodes. Building on our improved understanding, we investigate pathways to future WGM resonator based photonic devices. As a first example, we simultaneously interface the resonator with two coupling fibers, and use a single atom to route the incoming light between the optical fibers [2]. [1] C. Junge et al., Phys. Rev. Lett. 110, 213604 (2013) [2] D. O'Shea et al., arXiv:1306.1357 (2013)
98
15:15
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Interactions of He– in doped He droplets Michael Neustetter 1, Matthias Daxner 1, Johannes Postler 1, Nikolaus Weinberger 1, Andreas Mauracher 1, Stephan Denifl 1, Andrew M. Ellis 2, Jan Peter Toennies 3, Paul Scheier 1 1 Inst. für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25/3, AT-6020 Innsbruck 2 Department of Chemistry, University of Leicester , University Rd, Leicester LE1 7RH, UK 3 Max Planck Institut für Dynamik und Selbstorganisation, Universität Göttingen, Willhelmsplatz 1, DE-37073 Göttingen Mass spectra of anions formed via electron bombardment of large pristine He nanodroplets (>105 atoms) reveal the formation of large quantities of He– and less He2–. Both anions have been observed previously via sequential electron capture of fast cations from alkali vapor. However, in He nanodroplets they are formed via resonances at electron energies >20 eV. He– interacts with dopant molecules or clusters via several novel reaction mechanisms. This work is supported by the FWF project P23657, L633 and I978.
15:30
Coffee Break
Time
ID
Atomic Physics and Quantum Optics II Chair: NN
16:00
511
Decoration of anionic and cationic fullerenes with polar and apolar molecules. Nikolaus Weinberger 1, Paul Scheier 1, Matthias Daxner 1, Johannes Postler 1, Samuel Zöttl 1, Olof Echt 2, Diethard Kurt Bohme 3 1 Inst. für Ionen- und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, AT-6020 Innsbruck 2 Materials Science & Physics, University of New Hampshire, Library Way 9, 03824 Durham, USA 3 Department of Physical Chemistry, York University, 4700 Keele Street, Toronto, Canada Clusters of (C60)n fullerenes were decorated with H2, CO2, O2, H2O and S via sequential pickup of the C60 and other dopant into helium nanodroplets (HND) containing more than 105 He atoms. The doped HND were ionized via electron irradiation and the resulting ions were analyzed by a time of flight mass spectrometer. Apolar molecules or atoms physisorbed to C60 exhibit a pronounced shell closure or magic number for 32 adducts. This shell closure can be explained by the occupation of each hexagonal and pentagonal ring of the fullerene with one adduct. In contrast, polar molecules, such as H2O, do not exhibit this commensurate decoration motive and form via non-wetting of the fullerene surface droplets, weakly attached to the charged C60. This work is supported by the FWF project P23657, L633 and I978
16:15
512
Nonequilibrium dynamics, Optimal Control and Nanofibers on an Atom Chip Dominik Fischer, Wolfgang Rohringer, Florian Steiner, Igor E. Mazets, Michael Trupke, Hannes-Jörg Schmiedmayer, VCQ, Atominstitut, TU Wien, Stadionallee 2, 1020 Vienna, Austria We present experiments on dynamical scaling of many-particle states, performed on degenerate 87Rb Bose gases in a time dependent trapping potential. A stochastic optimal control scheme has been implemented to manipulate the motional dynamics of such clouds, with prospects to engineer specific nonequilibrium states. Further, we present a novel atom - photon interface based on integrating optical nanofibers and nanofiber - cavities on an atom chip. Applications encompass light storage and nonlinear interactions between photons within the device, facilitated by the high optical densities and low temperatures of ultracold atom clouds in a chip trap, as well as the high transmission of an optical nanofiber.
16:30
513
A Spin Polarised Temperature Controlled Atomic Hydrogen Beamline Peter Caradonna, Martin Diermaier, Michael Wolf, Oswald Massiczek, Nazli Dilaver, Bernadette Kolbinger, Chloè Malbrunot, Clemens Sauerzopf, Barbara Wuenschek, Johann Zmeskal, Eberhard Widmann, Stefan-Meyer-Institut für subatomare Physik, Boltzmanngasse, 3, AT-1090 Wien The purpose of this instrument is to test the performance on sections of the ASACUSA experimental setup which are used for the microwave spectroscopy of anti-hydrogen. A discussion will be given on how this instrument will produce spin polarised H beam that can be used to characterize the microwave cavity (which flips the spin of anti-hydrogen) and the superconducting sextupole magnet (which acts as a anti-hydrogen spin analyser). 99
16:45
514
Theoretical Investigation of Excited States of the Diatomic Molecule LiCa Johann Pototschnig 1, Günter Krois 1, Florian Lackner 1, Andreas Hauser 2, Wolfgang Ernst 1 1 Institute of Experimental Physics, TU Graz, Petersgasse 16, AT-8010 Graz 2 Dep. of Chemical and Biomolecular Engineering, University of California, 45 Gilman Hall, Berkeley, CA 94720-1462, USA The excited states of the diatomic molecule LiCa were investigated theoretically by means of CASSCF/MRCI-calculations. The results of these calculations will be presented alongside experimental results. Li and Ca have been investigated recently on superfluid helium nanodroplets (HeN). It was shown that the atoms are located on the surface of HeN. An investigation of the diatomic molecule LiCa on HeN was realized by two-photon photoionization spectroscopy. Since LiCa is expected to be located on the surface the perturbation of the diatomic transitions should be weak and these results can be compared with theoretical predictions.
17:00
515
Coherent manipulation of cold cesium atoms in a nanofiber-based two-color dipole trap Daniel Reitz, Rudolf Mitsch, Clement Sayrin, Philipp Schneeweiss, Arno Rauschenbeutel Vienna Center for Quantum Science and Technology, TU Wien, Atominstitut, Stadionallee 2, AT-1020 Wien We have recently demonstrated a new experimental platform for trapping and optically interfacing laser-cooled cesium atoms. The scheme uses a two-color evanescent field surrounding an optical nanofiber to localize the atoms in a one-dimensional optical lattice 200 nm above the nanofiber surface. In order to use this fiber-coupled ensemble of trapped atoms for applications in the context of quantum communication and quantum information processing, non-classical states of the atomic spins have to be prepared and should live long enough to allow one to apply successive quantum gates. The close proximity of the trapped atoms to the nanofiber surface and the strong polarization gradients of nanofiber-guided light fields are potentially important sources of decoherence. Here, we present our latest experimental results on the coherence properties of atomic spins in our nanofiberbased trap [1]. Using a microwave field to drive the clock transition, we determine inhomogeneous and homogeneous dephasing times by Ramsey and spin echo techniques, respectively. Our results constitute the first measurement of the coherence properties of atoms trapped in the vicinity of a nanofiber and represent a fundamental step towards establishing nanofiber-based traps for cold atoms as a building block in a quantum network. [1] D. Reitz et al., Phys. Rev. Lett. 110, 243603 (2013)
17:15
516
Mapping Magnetic Nanostructures Using Radical Pair Reactions Jofre Espigule Pons, Thomas Juffmann, Markus Arndt University of Vienna, Faculty of Physics & QuNaBioS, Boltzmanngasse 5, AT-1090 Vienna Radical pair reactions in chemistry are based on spin-correlated electrons in binary molecular systems. Depending on their joint spin state, singlet or triplet, the two reacting molecules can recombine and form different products. Since an external magnetic field can modulate the spin dynamics through the Zeeman interaction, radical pair reactions can be used as magnetometers. Here we use this effect to study the distribution of magnetite particles along the antenna of a honeybee and the magnetic field induced by the current through a gold nanowire. The local magnetic fields produced by the magnetite particles and the induced magnetic field from the current-carrying wire alter the spin dynamics of the radical pair and yield an increase in singlet fluorescence near these nanostructures. We discuss the present state of the art as well as the perspectives for nanomagnet imaging.
17:30
517
Merging two immiscible BECs of Rb and Cs for optimized production of RbCs ground-state molecules Lukas Reichsöllner 1, Tetsu Takekoshi 1,2, Michael D. Kugler 1, Verena Pramhaas 1, Carl Hippler 1, Francesca Ferlaino 1, Rudolf Grimm 1,2, Hanns-Christoph Nägerl 1 1 Institut für Experimentalphysik, Universität Innsbruck 2 Institut für Quantenoptik und Quanteninformation IQOQI, Innsbruck Ultracold dipolar particles are a unique tool for addressing fundamental questions in condensed matter physics, quantum simulation, precision spectroscopy or ultracold chemistry [1,2]. The goal of our work is the optimized production and perfect control of all degrees of freedom of ultracold rovibronic ground-state RbCs molecules. 100
Adapting the scheme proposed in Ref [3] we are starting with two immiscible BECs of Rb and Cs that are spatially separated [4]. With the aid of an optical lattice we prevent three-body loss by first ramping up the lattice to achieve a Mott insulator (MI) state of Cs with exactly one Cs atom per site while the spatially separated Rb ensemble is still in the superfluid regime. We adiabatically change the experimental parameters so that we can move the superfluid Rb cloud on top of the Cs atoms and attach exactly one Rb atom to a Cs atom by tuning the interspecies scattering properties [5]. Following the approach that has been successfully demonstrated in our group [6] we plan to finally create weakly bound molecules by exploiting a Feshbach resonance and subsequently transfer the molecules into the rovibronic ground state with the STIRAP technique [7]. In this work report on the optimized technique of merging and show data of coexisting SF and MI states of different atomic species in the same lattice. [1] L. D. Carr, D. DeMille, R. V. Krems, J. Ye, New J. Phys. 11, 055049 (2009) [2] M. A. Baranov, Physics Reports 464, 71 (2008) [3] D. Jaksch et al., Phys. Rev. Lett. 89, 040402 (2002) [4] A. D. Lercher et al., Eur. Phys. J. D 65, 3 (2011) [5] J. Freericks and coworkers, priv. comm. [6] J. G. Danzl et al., Nature Physics 6, 265 (2010) [7] M. Debatin et al., Phys. Chem. Chem. Phys. 13, 18926 (2011)
17:45
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Cavity cooling of free silicon nanoparticles in high vacuum Peter Asenbaum, Stefan Kuhn, Stefan Nimmrichter, Ugur Sezer, Markus Arndt Quantum Optics, Quantum Nanophysics, Quantum Information Universität Wien We create and launch silicon nanoparticles beneath a high finesse cavity in high vacuum environment. While a particle transits through the intense cavity field the transverse kinetic energy is cooled by a factor of over 30. By detecting the scattered light from the particle we can trace the particles movement in real time. This is a vital step towards quantum coherence experiments with nanoparticles.
18:00
519
Integrated Mach-Zehnder interferometer for Bose-Einstein condensates J.-F. Schaff, T. Berrada, S. van Frank, R. Bücker, T. Schumm, J. Schmiedmayer Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, Stadionallee 2, AT-1020 Wien Quantum mechanical particle-wave duality enables the construction of interferometers for matter waves, which may complement lasers in precision measurement devices such as gravimeters or gyroscopes. This requires the development of atom-optics analogs to beam splitters, phase shifters, and recombiners. Implementing and integrating these elements into a single device has been a long-standing goal. Here we demonstrate a full Mach-Zehnder sequence with trapped Bose-Einstein condensates (BEC) confined on an atom chip (Berrada et al., arXiv:1303.1030). Particle interactions in our BEC matter waves lead to a non-linearity, absent in photon optics. We exploit this interaction to generate a non-classical state with reduced number fluctuations inside the interferometer. Making use of spatially separated wave packets, a controlled phase shift is applied and read out by a nonadiabatic matter-wave recombiner. We demonstrate coherence times a factor of three beyond what is expected for coherent states, highlighting the potential of entanglement as a resource for metrology. Our results pave the way towards integrated quantum-enhanced matter-wave sensors.
18:15
520
Entanglement Swapping over a 143 km free-space link Thomas Herbst 1,2, Thomas Scheidl 1, Matthias Fink 1, Johannes Handsteiner 1, Bernhard Wittmann 1,2, Rupert Ursin 1,2, Anton Zeilinger 1,2 1 Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, AT-1090 Vienna 2 Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, AT-1090 Vienna Quantum teleportation is a quintessential prerequisite of many quantum information-processing protocols. By using quantum teleportation, one can circumvent the no-cloning theorem and faithfully transfer unknown quantum states to a party whose location is even unknown over arbitrary distances. Quantum teleportation can also be used to create entanglement between formally completely independent particles via the process of entanglement swapping. Quantum entanglement swapping will be of utmost importance in a future quantum communication network since it enables the global interconnection of quantum computers. Furthermore, the subsequent application of entanglement swapping might be utilized in a future quantum repeater, where in addition to entanglement swapping, local operations are performed to purify the teleported entanglement. 101
In order to prove the feasibility of quantum entanglement swapping under optical link attenuations that will arise in a future application scenario, we extended the communication distance to 143 km, employing an optical free-space link between the two Canary Islands of La Palma and Tenerife. The real-life long-distance environment implied a number of challenges for the present experiment. They resulted most significantly in the necessity to cope with an extremely low signal-to-noise ratio when using standard techniques, indeed too low for performing a successful experiment. To enhance it to a level making the experiment possible at all, we employed a combination of various cutting-edge techniques. Furthermore, the severe environmental conditions imposed demanding requirements onto the whole long-distance teleportation setup. Our work proofs the feasibility of ground-based free-space quantum entanglement swapping. Our setup was able to achieve coincidence production rates and fidelities to cope with the optical link attenuation, resulting from various experimental and technical challenges, which will arise in a quantum transmission between a ground-based transmitter to a low-earth-orbiting (LEO) satellite receiver. This experiment represents a crucial step towards future quantum networks in space, which require space to ground quantum communication. The technology implemented in our experiment thus certainly reached the required maturity both for satellite and for long-distance ground communication. We expect that many of the features implemented here will be key blocks for a new area of fascinating experiments. This experiment was supported by the European Space Agency (ESA) under the project QTPS and by the Federal Ministry of Science and Research (BMWF).
18:30
Postersession and Apéro
20:00
Public Lecture Thursday, 05.09.2013, HS 4
Time
ID
Atomic Physics and Quantum Optics III Chair: NN
13:30
521
Tenfold reduction of Brownian noise in high-reflectivity optical coatings 1
Garrett D. Cole 1,2, Wei Zhang 3, Michael J. Martin 3, Jun Ye 3, Markus Aspelmeyer 1 Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, AT-1090 Vienna 2 Crystalline Mirror Solutions GmbH, AT-1090 Vienna 3 JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309-0440, USA
Thermally induced fluctuations impose a fundamental limit on precision measurement. In optical interferometry, the current bounds of stability and sensitivity are dictated by the excess mechanical damping of the high-reflectivity coatings that comprise the cavity end mirrors. Over the preceding decade, the loss of these amorphous multilayer reflectors has at best been reduced by a factor of two. Here we demonstrate a new paradigm in optical coating technology based on direct-bonded monocrystalline multilayers, which exhibit both intrinsically low mechanical loss and high optical quality. Employing these "crystalline coatings" as end mirrors in a Fabry-Pérot cavity, we obtain a finesse of 150,000. More importantly, at room temperature, we observe a thermally-limited noise floor consistent with a tenfold reduction in mechanical damping when compared with the best dielectric multilayers. These results pave the way for the next generation of ultra-sensitive interferometers, as well as for new levels of laser stability.
13:45
522
Doublon stability and decay mechanisms M. J. Mark, F. Meinert, E. Kirilov, K. Lauber, P. Weinmann, M. Gröbner, H.-C. Nägerl Institut für Experimentalphysik, Universität Innsbruck We present experiments in the context of Bose-Hubbard physics, combining optical lattice potentials with the capability to tune the strength of the particle interaction U. We prepare and study doublons formed by two bosons in an optical lattice at attractive or repulsive interactions. Around zero interactions we observe a rapid decay of doublons as the binding energy vanishes. For large repulsive interactions a decay of doublons is observed, whereas such a decay is absent for attractively bound doublons. Analysing the loss of doublons and the total atom number reveals off-resonant three-body loss as one decay mechanism for large repulsive interactions.
102
14:00
523
Cavity cooling of an optically levitated nanoparticle Florian Blaser, Nikolai Kiesel, Uros Deli, David Grass, Rainer Kaltenbaek, Markus Aspelmeyer Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, AT-1090 Vienna Cavity cooling of a single nanoparticle in high vacuum allows for the generation of quantum states of motion in a room-temperature environment as well as for unprecedented force sensitivity. This opens up new avenues both for the study of fundamental quantum phenomena in the context of matter wave interference, and for new sensing and transduction applications in the context of quantum optomechanics. Here, we take the first steps into this regime. We demonstrate cavity cooling of an optically levitated nanoparticle consisting of approximately 109 atoms. The particle is trapped at modest vacuum levels of a few millibar in the standing-wave field of an optical cavity and is cooled through coherent scattering into the modes of the same cavity. We estimate that our cooling rates are sufficient for ground-state cooling, provided that optical trapping at a vacuum level of 10-7 millibar can be realized in the future, e.g., by employing additional active-feedback schemes to stabilize the optical trap in three dimensions.
14:15
524
Entanglement properties of locally maximally entangleable states Martí Cuquet, Tatjana Carle, Barbara Kraus, Institute for Theoretical Physics, University of Innsbruck Locally maximally entangleable states (LMES) are a class of multipartite quantum states characterized by 2n-1 real phases, where n is the number of qubits. Prominent examples of LMES are graph states and stabilizer states. They can be prepared by applying general phase gates to a product state. One can associate any LMES to a weighted hypergraph, identifying each of these phase gates acting non-trivially on a subset of qubits to a weighted hyperedge connecting a subset of vertices. In this regard, they can be understood as a generalization of (weighted) graph states. The hypergraph, or equivalently the 2n-1 phases, determine the entanglement. We investigated the entanglement of LME states, ie their usefulness as a resource when the parties are separated and their manipulation is restricted to local operations and classical communication (LOCC). We discuss local unitary (LU) and stochastic LOCC equivalence of these states. In some cases, LU equivalence can be reduced to the much simpler case of equivalence under the action of local Pauli gates, which simplifies the characterization of LU-equivalent classes. We also present the convertibility of LMESs under local operations and classical communication (LOCC) to characterize the set of states that can be deterministically obtained from them.
14:30
525
Decrease in query complexity for quantum computers with superposition of circuits M. Araujo, C. Bruckner Quantum Optics, Quantum Nanophysics, Quantum Information, Boltzmanngasse 5, 1090 Wien A new model of quantum computation was introduced by Chiribella et al. in arXiv:0912.0195, in which the structure of the quantum circuits is entangled with a control quantum system. The new model is proven to allow the realization of tasks impossible in standard quantum computation, but the question whether it is more powerful in the complexity sense was left open. Here we answer this question in the affirmative, by showing a promise problem that has query complexity O(n) on a quantum computer with superposition of circuits, whereas the best known quantum algorithm has query complexity O(n2).
14:45
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Optimal state reconstruction for cavity-optomechanical systems via Kalman filtering Ralf Riedinger 1, Jason Hoelscher-Obermaier 1, Sebastian G. Hofer 1,2, Witlef Wieczorek 1, Karoline Siquans 1, Garrett D. Cole 1, Klemens Hammerer 2, Markus Aspelmeyer 1 1 Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, AT-1090 Vienna 2 Institute for Theoretical Physics, Institute for Gravitational Physics (Albert Einstein Institute), Leibniz University Hannover, DE-30167 Hannover We employ Kalman filtering to reconstruct both the bipartite Wigner function of an optomechanical system, i.e. the joint state of an optical cavity mode and a mechanical mode, and the conditional state of the mechanics from measurements on the light field alone. We demonstrate optimal state reconstruction both in the weak and in the strong coupling regime, where direct reconstruction methods typically fail. 103
15:00
527
Quantum Entanglement of High Angular Momenta Robert Fickler, Radek Lapkiewicz, William N. Plick, Mario Krenn, Sven Ramelow, Anton Zeilinger IQOQI Vienna, Austrian Academy of Sciences, Austria, and Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna Orbital angular momentum (OAM) of single photons represents a relatively novel optical degree of freedom for the entanglement of photons. One physical realization of OAM carrying light beams are the so called Laguerre-Gaussian modes which have the required helical phase structure. One big advantage over the well-known polarization degree of freedom is the possibility of realizing entanglement between two photons with very high quantum numbers and momenta respectively. However, the creation of photonic OAM entanglement by the widely used spontaneous parametric down conversion (SPDC) process is limited by the strongly reduced efficiency for higher momenta. We have realized a novel method to create entanglement between two photons which is not constrained by the SPDC efficiency or conservation law for the OAM degree of freedom. We created and measured the entanglement of two photons with up to 600ħ difference in their angular momentum by transferring the polarization entanglement to the orbital angular momentum degree of freedom within an interferometric scheme. Additionally, we used hybrid entangled biphoton states between polarization and OAM to show the angular resolution enhancement in possible remote sensing applications. Supported by ERC (Advanced Grant QIT4QAD) and the Austrian Science Fund FWF (FoQuS Nr. F4006-N16 and CoQuS Nr.W1210-24007).
15:15
528
Cooling-by-measurement and mechanical state tomography via pulsed optomechanics Ralf Riedinger, M. R. Vanner, J. Hofer, G. D. Cole, M. Aspelmeyer Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, AT-1090 Vienna Quantum-non-demolition measurements have become an indispensable tool in quantum science for preparing, manipulating, and detecting quantum states of light, atoms, and other quantum systems. Here we exploit ultra-short optical pulses, i.e. of duration much shorter than a period of mechanical motion, to realize a quantum non-demolition interaction for the position readout of a mechanical oscillator. We demonstrate both state preparation via `cooling-by-measurement' and full state tomography of the mechanical motional state. The obtained position uncertainty of 19 pm is limited only by the quantum fluctuations of the optical pulse. We discuss future improvements to this technique, specifically a route towards quantum squeezing of mechanical motion even from room temperature.
15:30
Coffee Break
Time
ID
Atomic Physics and Quantum Optics IV Chair: NN
16:00
531
Einstein-Podolsky-Rosen correlations from colliding Bose-Einstein condensates M. Ebner, Austrian Academy of Sciences, Institute for Quantum Optics and Quantum Information (IQOQI). Boltzmanngasse 3, AT-1090 Vienna We propose an experiment which can demonstrate quantum correlations in a physical scenario as discussed in the seminal work of Einstein, Podolsky, and Rosen. Momentum-entangled massive particles are produced via the four-wave mixing process of two colliding Bose-Einstein condensates. Central to establishing the correlations is the coherence length of the colliding BECs and we define the necessary conditions to observe quantum correlations. The particles’ quantum correlations can then be shown in a double–double-slit experiment or via ghost interference, which can be realized on a metastable Helium platform that has recently been developed in our group.
16:15
532
Real-Time Imaging of Quantum Entanglement Robert Fickler, Mario Krenn, Radek Lapkiewicz, Sven Ramelow, Anton Zeilinger University of Vienna, Faculty of Physics, IQOQI Vienna, Austrian Academy of Sciences, and Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna Photonic entanglement of spatial modes is routinely studied in many experiments and offers interesting features for quantum optical and quantum information experiments. To investigate the properties of these complex modes, it is crucial to gain information about the transversal structure with high precision and in an efficient way. We show that modern technology, namely triggered intensified 104
charge coupled device (ICCD) cameras are fast and sensitive enough to image in real-time the effect of the measurement of one photon on the spatial mode of its entangled partner photon. We determine from imaged intensity pattern the number of photons within a certain region, evaluate its error margin and thereby quantitatively verify the non-classicality of the measurements. In addition, the use of the ICCD camera allows us to demonstrate visually the enhanced remote angular sensing and the high flexibility of our setup in creating any desired spatial-mode entanglement. Supported by ERC (Advanced Grant QIT4QAD) and the Austrian Science Fund FWF (FoQuS Nr. F4006-N16 and CoQuS Nr.W1210-24007).
16:30
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Creation of nitrogen-vacancy centres for cavity QED Kathrin Buczak, Tobias Nöbauer, Jörg Schmiedmayer, Michael Trupke Technische Universität Wien - Atominstitut, Stadionallee 2, AT-1020 Wien Nitrogen-vacancy or NV centres in diamond are among the most promising solid-state systems for quantum information processing as they possess convenient properties such as optical initialisation and read-out, a ZPL at 637 nm with transform-limited emission at low temperatures. Most importantly, the NV centre possesses a long room-temperature electron coherence lifetime. It is on the order of 100 µs in natural diamond, and reaches values approaching 2 ms in artificial isotope-purified (spinless) carbon-12 diamonds. We present the creation of NV centre ensembles for quantum applications, using a variety of irradiation and implantation techniques. We have irradiated nitrogen-rich artificial diamond samples for applications including magnetometry, electric field sensing and coupling of NV ensembles to microwave resonators. Here we compare the effects of neutron irradiation, electron irradiation and electron irradiation at high temperature, showing that the latter leads to high conversion efficiency and low damage in the crystal lattice. We furthermore present measurements which display the charge-state dynamics (population transfer between NV0 and NV-) in dependence of the density of nitrogen and NVs. Finally, we present our efforts towards the creation of arrays of NV centres by nitrogen implantation with a spatial resolution on the order of 25 nm. This will enable the precise positioning of NV centres in optical microcavity arrays, with the aim of enhancing their weak zero-phonon transition.
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Studies of Quantum Entanglement in 100 Dimensions Mario Krenn 1,2, Marcus Huber 3,4,5, Robert Fickler 1,2, Radek Lapkiewicz 1,2, Sven Ramelow 1,2, Anton Zeilinger 1,2 1 Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, AT-1090 Vienna 2 Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, AT-1090 Vienna 3 University of Bristol, Department of Mathematics, Bristol BS8 1TW, U.K. 4 ICFO-Institut de Ciencies Fotoniques, ES-08860 Castelldefels (Barcelona) 5 Fisica Teorica: Informacio i Fenomens Quantics, Departament de Fisica, Universitat Autonoma de Barcelona, ES-08193 Bellaterra (Barcelona) Entangled quantum systems have properties that have fundamentally overthrown a classical worldview. Increasing the complexity of entangled states by expanding their dimensionality not only allows the implementation of novel fundamental tests of nature, but also enables genuinely new protocols for quantum information. Spatial modes of photons are a vivid field of research, as they provide a source for high-dimensional entanglement readily available from down-conversion. We present an experiment that determines the dimensionality of two-photon entangled state. The photons are created in spontaneous parametric down-conversion, and we use the "full-field" Laguerre-Gauss basis to analyze the photons. To examine high-dimensional entanglement, we develop a novel state-independent entanglement witness. The non-linear witness is capable of unambiguously revealing high dimensional entanglement through sub-space correlations. In the experiment, we analyze a (186*186)-dimensional Hilbert space. With only ~210.000 projective measurements, we were able to demonstrate 100-dimensional entanglement. This result indicates the great potential of high-dimensional entangled systems for various quantum information tasks.
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Entanglement spectra in one dimension Lars Bonnes, Chia-Min Chung, Andreas Läuchli Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 25, AT-6020 Innsbruck Entanglement spectra can encode information about topological phases or the conformal structure underlying a wave function. First, we discuss the particular structure of the entanglement spectrum of systems at one-dimensional conformal critical points that reveal the operator content of the describing CFT and show the effects of boundary conditions on the spectrum that can be understood in the context of boundary CFT. A peculiar structure is revealed in the thermodynamic limit using iMPS directly related to the question how symmetry breaking occurs in the regime of finite-entanglement scaling compared to the (usual) finite-size scaling. New algorithmic developments in the area of quantum Monte-Carlo allow an efficient calculation of Renyi entropies within this framework so the question arises whether the entanglement spectrum can be reconstructed from these methods. Studying a Haldane insulating phase we demonstrate that it is in fact possible and discuss the possibilities but also the limitations of our reconstruction protocol.
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18:30
Postersession and Apéro
20:00
Conference Dinner
ID
Atomic Physics and Quantum Optics Poster
541
Coupling Spins and Diamond Color Centers to Superconducting Cavities Stefan Putz 1, Robert Amsüss 1, Christian Koller 2, Tobias Nöbauer 1, Roman Voglauer 1, Andreas Maier 1, Stefan Rotter 3, Katrin Sandner 4, Helmut Ritsch 4, Jörg Schmiedmayer 1, Johannes Majer 1 1 Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, Stadionallee 2, AT-1020 Wien 2 School of Physics and Astronomy, The University of Nottingham, University Park, Nottingham NG7 2RD, UK 3 Institute for Theoretical Physics, TU Wien, Wiedner Hauptstrasse 8-10/136, AT-1040 Wien 4 Institute for Theoretical Physics, Universität Innsbruck, Technikerstr. 25 , AT-6020 Innsbruck Reversible transfer of quantum information between long-lived memories and quantum processors is a favorable building block of scalable quantum information devices. We present recent experimental results of strong coupling between an ensemble of nitrogen-vacancy center electron spins in diamond and a superconducting microwave coplanar waveguide resonator. Additionally, we measure hyperfine coupling to 13C nuclear spins, which is a first step towards a nuclear ensemble quantum memory. Using the dispersive shift of the cavity resonance frequency, we measure the relaxation time T1 of the NV center at millikelvin temperatures in a nondestructive way.
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Dipole-dipole influenced Ramsey interferometry Laurin Ostermann, Claudiu Genes, Helmut Ritsch Institute for Theoretical Physics, University of Innsbruck, Technikerstraße 25/2, AT-6020 Innsbruck The presence of dipole-dipole interaction and collective dissipation can substantially alter the Ramsey signal obtained from an optical lattice atomic clock system. We investigate these effects in a treatment of the full system dynamics, both analytically and numerically. Further, we suggest different mechanisms geared towards particular geometries, which leverage these effects yielding an improvement in the overall signal quality and precision.
543
Ultracold atoms on a superconducting Atomchip Stefan Minniberger, Fritz Diorico, Johannes Majer, Stephan Schneider, Jörg Schmiedmayer Atominstitut, Technische Universität Wien, Stadionallee 2, AT-1020 Wien Hybrid quantum systems are a promising approach to quantum information processing. The combination of superconducting microwave circuits with ultracold atoms could make use of both the fast processing in solidstate systems and very long coherence times in atomic ensembles. Our experiment features a novel magnetic transport system, which allows us to efficiently transfer 87Rb atoms from a room temperature MOT-chamber into a cryostat. We reload more than 5*106 atoms on a superconducting Z-trap, where evaporative cooling is employed to reach degeneracy. The integration of a superconducting resonator on the same atomchip will allow us to couple the two quantum systems. 106
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Single atom cavity quantum electrodynamics with non-transversally polarized light fields Michael Scheucher, Christian Junge, Danny O’Shea, Jürgen Volz, Arno Rauschenbeutel Vienna Center for Quantum Science and Technology, TU Wien, Atominstitut, Stadionallee 2, AT-1020 Wien Whispering-gallery-mode (WGM) microresonators are versatile devices for enhancing light–matter interaction. They combine ultra-high quality factors and small mode volumes with near lossless in- and out-coupling of light via tapered fiber couplers. Here, we report on a cavity quantum electrodynamics (CQED) experiment in which single 85Rb atoms interact in the strong coupling regime with a WGM in an ultra-high-Q bottle microresonator. We present optical transmission spectra of our system that fundamentally deviate from the predictions of the established theoretical model for CQED in ring resonators. We identify the non-transversal character of the field of WGMs as the origin of this discrepancy [1]. Excellent agreement is found between our data and the predictions of an extended theoretical model that accounts for the full vectorial description of the WGMs. Our studies demonstrate that the non-transversal character of WGMs allows one to realize a paradigmatic quantum system that is ideally suited for basic studies as well as for technological applications [2]. [1] C. Junge et al., Phys. Rev. Lett. 110, 213604 (2013) [2] D. O'Shea et a., arXiv:1306.1357 (2013)
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Coherence properties of cold cesium atomic spins in a nanofiber-based dipole trap Rudolf Mitsch, Daniel Reitz, Clément Sayrin, Philipp Schneeweiss, Arno Rauschenbeutel Vienna Center for Quantum Science and Technology, TU Wien, Atominstitut, Stadionallee 2, AT-1020 Wien The possibility to efficiently store quantum information over extended periods of time is a prerequisite for quantum protocols. Here, we present the first experimental characterization of the coherence properties of nanofibertrapped atoms [1]. In our system, neutral Cs atoms are trapped in a two-color evanescent field surrounding a subwavelength-diameter optical fiber. The atoms are localized in an one-dimensional optical lattice only 200 nm above the dielectric surface [2]. This close proximity and the strong polarization gradients of nanofiber-guided light fields are prone to cause decoherence. In order to investigate these effects, a resonant microwave field is used to drive the mF = 0 " 0 clock-transition between the two hyperfine ground states. Ramsey interferometry on this transition yields inhomogeneous dephasing times of about T2* = 500 µs, whereas spin echo measurements result in homogeneous dephasing times of up to T2' = 2 ms. These long coherence times are compatible with the implementation of more complex quantum operations, thereby paving the road towards establishing nanofiberbased traps for cold atoms as a building block in a quantum network. [1] D. Reitz et al., Phys. Rev. Lett. 110, 243603 (2013) [2] E. Vetsch et al., Phys. Rev. Lett. 104, 203603 (2010).
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Photonic platform for experiments in higher dimensional quantum systems Christoph Schaeff, Robert Polster, Radek Lapkiewicz, Robert Fickler, Sven Ramelow, Anton Zeilinger Institute for Quantum Optics and Quantum Information, Boltzmanngasse 3, AT-1090 Vienna The aim of our work is to access and explore higher dimensional photonic quantum systems. In terms of stability and complexity normal bulk-optic setups greatly limit the capabilities of reaching higher dimensional systems. However, the rapid development in integrated photonic circuits in recent years opens new possibilities. Our approach is to use integrated photonic circuits on-chip as well as in fiber to reach photonic states of higher dimension. We are working on a fully integrated realization of a device called a Multiport [1] capable of applying any unitary transformation depending on its internal (tunable) parameters. The basic unit of the Multiport is a QuBit operation consisting of one phase shifter and one (integrated) beam splitter. Combining a certain number of QuBit operations at different settings results in a specific unitary transformation on the full Hilbert Space in any dimension. Furthermore, we have built an integrated source using purely in-fiber components for creating higher dimensional path-entangled photons. Due to its special design it allows good scalability in terms of complexity with increasing dimension of the photonic system. Combining the source and the Multiport results in a very general platform for experiments in higher dimensional Hilbert spaces. By externally setting the device to a variety of different incoming entangled states followed by applying any desired unitary transformation, different experimental setups can be realized. Possible experiments range from fundamental questions of quantum information [2] to interesting applicational possibilities due to the compatibility to telecom technology and fiber networks. [1] M.Reck and A.Zeilinger, PRL Vol.73, No.1 (1994) [2] M.Zukowski, A.Zeilinger and M.A.Horne, PRA Vol.55, No.1 (1997) This work is supported by the ERC (Advanced Grant QIT4QAD), the Vienna Doctoral Program on Complex Quantum Systems, SFB and the Austrian Science Fund (FWF): W1210.
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Loophole-free Einstein Podolsky Rosen Experiment via Quantum Steering Bernhard Wittmann 1,2, Sven Ramelow 1,2, Fabian Steinlechner 2, Nathan K Langford 2, Nicolas Brunner 3, Howard M Wiseman 4, Rupert Ursin 2, Anton Zeilinger 1,2,5 1 Quantum Optics, Quantum Nanophysics, Quantum Information, University of Vienna, Boltzmanngasse 5, AT-1090 Vienna 2 Institute for Quantum Optics and Quantum Information, Boltzmanngasse 3, AT-1090 Vienna 3 HH Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, UK 4 Centre for Quantum Computation and Communication Technology (Australian Research Council), Centre for Quantum Dynamics, Griffith University, Brisbane, QLD 4111, Australia 5 Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, AT-1090 Vienna Experiments testing quantum mechanics have provided increasing evidence against local realistic theories. However, a conclusive test that simultaneously closes all major loopholes (the locality, freedom-of-choice, and detection loopholes) remains an open challenge. An important class of local realistic theories incorporates the assumption of quantum mechanic and can be tested with the concept of EPR-steering. The term steering was introduced by Schrödinger in 1935 [1] for the fact that entanglement would seem to allow an experimenter to remotely steer or pilot the state of a distant system as used in the original Einstein–Podolsky–Rosen (EPR) paradox [2]. EPR-Steering can be described in theory by the test of local hidden states [3]. Here, we present the first loophole-free steering experiment. We use entangled photons shared between two distant laboratories and close all loopholes by a large separation, ultra-fast switching and quantum random number generation, and high, overall detection efficiency. Beside its foundational importance loop-hole-free steering is relevant for the secure distribution of quantum entanglement. [1] E. Schrödinger, Proc. Camb. , Phil. Soc. 31, 553 (1935) [2] A. Einstein, B. Podolsky, N. Rosen, Phys. Rev. 47 777 (1935) [3] H.M. Wiseman, S.J. Jones, A.C. Doherty, PRL 98, 140402 (2007)
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Quantum communication with satellites, its preparatory terrestrial free-space demonstrations and future missions 1
Thomas Scheidl 1, Rupert Ursin 1,2, Anton Zeilinger 1,2 Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, AT-1090 Vienna 2 Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, AT-1090 Vienna
In order to experimentally test the limits of quantum theory, study the interplay between gravitation and entanglement and to eventually establish a worldwide quantum communication network, it is important to significantly expand the distances for distributing quantum systems beyond the capabilities of terrestrial experiments. Entangled photon pairs as well as faint laser pulses would enable both, fundamental quantum tests and the applications of quantum sciences such as quantum key distribution, and are therefore expected to be a key resource for implementing such experiments. One approach for bridging distances on a global scale is the implementation of quantum repeaters, which, however, are in the early stages of development. Another approach is using freespace links involving satellites. We will present the existing terrestrial free-space demonstrations, investigating the feasibility of satellite based quantum communication, and outline the technical scenarios for using the International Space Station (as has been investigated in theoretical studies funded by the European Space Agency) or dedicated satellites in a potential future space-to-ground or ground-to-space experiment. Furthermore, we will present the basic points of a project our institute is currently pursuing in collaboration with the Chinese Academy of Sciences. The goal of this project is to actually perform quantum communication experiments in a down-link scenario from a lowearth-orbit satellite. Optical ground stations in China and Europe have to be adapted for receiving the quantum signal. In the course of this project, an optical ground station has been installed at the roof-top of the IQOQI institute in Vienna, which serves as a test-bed for the final space-to-ground link. The projects described in this work have been and are supported by the European Space Agency (ESA), the Austrian Science Foundation (FWF) under projects SFB F4008 and CoQuS, the Austrian Research Promotion Agency (FFG) and by the Federal Ministry of Science and Research (BMWF).
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Laser desorption/vaporization/ionization techniques for matter-wave interferometry Ugur Sezer 1, Philipp Schmid 1, Lukas Felix 2, Marcel Mayor 2,3, Markus Arndt 1 1 University of Vienna, Faculty of Physics, QuNaBioS, VCQ Vienna, Austria 2 Department of Chemistry, University of Basel, Switzerland 3 Karlsruhe Institute of Technology (KIT), Institute of Nanotechnology, Karlsruhe, Germany Testing the delocalization of individual massive objects is an exciting experimental challenge of modern quantum physics and substantial progress in matter-wave interferometry with complex particles has led to the establishment of quantum-assisted molecule metrology [1,2] and advanced investigations at the boundary between the classical and quantum mechanical evolution of very massive objects [3]. New interferometers [4] have led to demonstrations of the quantum wave nature of organic molecules beyond 10 000 amu [1] and even of clusters of molecules [2]. One of the major challenges for future interference experiments with large particles is the production of a neutral and slow molecular beam. We aim at particles with a mass beyond 104 u that should travel with sufficient intensity, low internal temperature and low transverse velocity [5]. Here we present a series of experiments characterizing different laser desorption sources for future quantum interference experiments, the Quantum LIMES (Laser Induced Molecule Evaporation Sources). We describe the matrix-free laser desorption and laser-induced acoustic desorption (LIAD) with subsequent UV/VUV photoionization in combination with time-of-flight mass spectrometry [6]. We present mass spectra and velocity distributions of large tailor-made perfluoroalkyl-functionalized molecules as well as more thermolabile biomolecules and we discuss the suitability of LIAD for matter wave interferometry. The project is supported by the EU project NANOQUESTFIT (304886), ERC PROBIOTIQUS (320694) and ESA (4000105799/127NL/ Cbi). [1] Eibenberger, S. et al. "Molecular libraries for testing quantum macroscopicity beyond 10 kDa", Phys. Chem. Chem. Phys. (2013). [2] Haslinger, P. et al. "A universal matter-wave interferometer with optical ionization gratings in time domain", Nature Physics 9, 144–148 (2013). [3] Hornberger et al., "Colloquium: Quantum interference of clusters and molecules", Rev. Mod. Phys. Vol. 84, 157-173 (2012) [4] Gerlich et al., "Quantum Interference of large organic molecules", Nat. Comm. 2: 263 (2011) [5] Schmid et al., "Single-Photon Ionization of Organic Molecules beyond 10 kDa", J. Am. Soc.Mass Spectrom. 24, 602-608 (2013) [6] Zinovev et al., "Laser-Driven Acoustic Desorption of Organic Molecules from Back-Irradiated Solid Foils", Anal. Chem. 79 (21), 8232-8241 (2007)
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