Manne Siegbahn Memorial Lecture

Abstracts

1993

Gerald Gabrielse

Physics Dept., Harvard University, U.S.A.

One Antiproton Radio: Precision Comparisons of a Single Trapped Antiproton and Proton

17 November 1993

Abstract: During the last several years, our TRAP collaboration at LEAR, CERN, has pioneered techniques for slowing, trapping, cooling and indefinitely storing antiprotons to energies more than 1010 times lower than previously possible. The initial comparison of the cyclotron frequencies of antiprotons and protons resulted in a 1000-fold improvement over previous relative mass comparisons. The radio signal from a single trapped antiproton is now being used for precision measurements. An additional 50-fold improvement in the antiproton to proton mass ratio is expected soon. Many cold antiprotons are "stacked" as another important step toward the eventual production of antihydrogen. Sufficient amounts of positrons have been trapped in vacuum in pursuit of the same goal. The proton-antiproton mass ratio and studies of antihydrogen offer checks of CPT for strongly and electromagnetically interacting particles, respectively.


1994

Till Kirsten

Max-Planck-Institute, Heidelberg, Germany

GALLEX Solar Neutrino Results and their Implications

16 May 1994

Abstract: Solar neutrino detection can probe the state of the solar interior. The flux of pp-neutrinos (from hydrogen fusion: p+p->d+e++ve) is firmly predicted from the solar luminosity, any shortage would indicate restmass-mediated ve-disappearance during transit between the solar core and the detector. The expected fluxes of the less abundant but higher energy neutrinos from 8B and 7Be are more sensitive to the details of the solar model. For them the observation of a deficit may indicate either incomplete understanding of the stellar interior or new physics through massive neutrinos. The low-threshold gallium detector operated by the GALLEX collaboration1 in the Gran Sasso undergound laboratory (Italy) is sensitive to pp-neutrinos. It succeeded in their detection. For this, techniques were developed to routinely extract and detect a few radioactive 71Ge atoms from a 100 ton target. This first observation of hydrogen fusion inside a start transfers solar models since Eddington from the realm of theory into the sphere of observational facts. The GALLEX result can accommodate the expected pp-neutrinos at full strength. Hence, massive neutrinos are not enforced. At the same time, GALLEX confirms a shortage of the higher energy neutrinos, consistent with the results of the Homestake and Kamiokande experiments.
1MPI Heidelberg; KFK Karlsruhe; LNGS L'Aquila (Gran Sasso); Università di Milano; TUM München; Observatoire de Nice; WIS Rehovot; Università di Roma; CE Saclay; BNL, Upton, N.Y.


1995

Hiroyuki Sasaki

Research Center for Advanced Science and Technology, University of Tokyo, Japan

Quantum Engineering of Nanostructures. Novel Physics and New Concepts for Electronic Devices

11 October 1995

Abstract: The remarkable progress in semiconductor technology has allowed us to form various ultrathin layered structures with feature sizes of 10-30 nm. In such systems, electrons are quantum mechanically confined to form a series of standing wave states fi(z) with discrete energies Ez(i), while their in-plane motion remains free. Indeed, such a two dimensional (2-D) electron gas plays now very important roles both in solid-state physics and electronics. Although the 2-D electron system is still a fertile field, there are vast fields of nanostructures, where new classes of phenomena are being disclosed and exploited. In this lecture, we review and discuss such studies. First we describe various attempts, by which the tunnel escape process of electrons through the barrier layer is quantum mechanically controlled; we examine how they can be used in realizing such devices as intersubband infrared detectors, ultrafast resonant tunnelling diodes, and quantum-beat oscillators. Second, we review a series of work to confine electrons in quantum-wire and/or quantum dot strucutres and discuss what kind of unique properties or functions have been and will be found in such 1-D and 0-D systems. We examin the current status of nanotechnology by which 10-nm scale wires and dots are formed.


1996

Eric Cornell

J.I.L.A., University of Colorado and the National Institute for Standards and Technology, Boulder, Colorado, U.S.A.

Bose-Einstein Condensation in a Dilute Atomic Vapor

19 March 1996

Abstract: Advances in optical and magnetic cooling and trapping of atoms have made possible the creation of a Bose-Einstein condensate in dilute atomic vapors at temperatures around 100 nK. The range of experimental techniques available for making sensitive measurements in atomic gases is quite distinct from (and complementary to) those currently used in superfluid liquid helium. From a theoretical point of view, the interactions between the atoms are weak enough that calculations can be performed in the framework of perturbation theory. Thus Bose condensed atomic vapors are an ideal environment for studying many novel aspects of quantum degeneracy. The lecture will review previous efforts to reach Bose condensation, describe the techniques which have recently been successful, and discuss some of the possible directions for future scientific exploration in this area.


1996

Geoffrey W. Marcy

San Francisco State University and University of California, Berkeley, California, U.S.A.

Discovery of Planets Orbiting Sun-Like Stars

3 October 1996

Abstract: During the past 12 months, astronomers have finally discovered planets orbiting Sun-like stars. All were discovered by precise Doppler measurements of the host stars. Some of these planets have properties similar to the nine planets in our own Solar System. But many of the planets have properties that are totally unexpected. Several of the planets are more massive than even Jupiter and some orbit their host star in very small orbits, smaller than Mercury's orbit. Equally unexpected is that two of these "planets" have non-circular orbits. Current theory of the formation of planetary systems is suddenly challenged to account for these new planetary properties. The character of the new worlds spawns many questions about the uniqueness of our Solar System and the prevalence of Earth-like planets. These questions are now being addressed with the Keck 10-meter telescope, which will hunt for Saturn-like and Neptune-like planets.


1997

Alain Blondel

LPNHE, Ecole Polytechnique, Paris, France

Elementary Particles from the Z to the Higgs. Loops, tides and trains

8 October 1997

Abstract: During 8 years of operation of the LEP accelerator in Geneva, the properties of the Z boson have been measured with extreme precision. The structure of the Standard Model of elementary particles and their interactions has been verified. Furthermore, quantum tunnel effects make these precise measurements sensitive to the existence and mass of yet unknown particles - in particular the mysterious Higgs boson. Real perturbations, induced on the 27-km long accelerator by the moon, the trains and the sun make sure that physicists remain on planet earth.


1998

Rainer Weiss

Massachusetts Institute of Technology, Cambridge, U.S.A.

The Prospects for the Detection of Gravitational Waves

14 October 1998

Abstract: The talk describes the world wide effort to detect gravitational waves from astrophysical sources by long baseline laser interferometry. Projects in Europe, the United States of America, Japan and Australia hope to be operating within the coming decade. The talk includes:

1999

Yuri Oganessian

Joint Institute for Nuclear Research (JINR), Dubna, Russia

The Long Way to the Island of Stability of Superheavy Elements Close to Z=114

12 October 1999

Abstract: The talk will present and discuss the results of experiments aimed at testing the fundamental predictions of the modern theory on the existence of "islands of stability" of super heavy elements. The talk will include:

2000

Serge Haroche

Ecole Normale Supérieure, Paris, France

Seeing a Single Photon without Destroying it and Manipulating Entanglement in Atom-Cavity Experiments

10 October 2000

Abstract: Light detection is usually a destructive process, in that detectors annihilate photons and convert them into electrical signals, making it impossible to see a single photon twice. But this limitation is not fundamental — quantum non-demolition strategies permit repeated measurements of physically observable quantities, yielding identical results. The non-destructive measurement of a single photon requires an extremely strong matter-radiation coupling. This can be realized in cavity quantum electrodynamics, where the strength of the interaction between an atom and a photon can overwhelm all dissipative couplings to the environment. In the experiments reported, an atomic interferometer has been used to measure the phase shift in an atomic wavefunction, caused by a cycle of photon absorption and emission. The method amounts to a restricted quantum non-demolition measurement, which can be applied only to states containing one or zero photons. It may lead to quantum logic gates based on cavity quantum electrodynamics, and multi-atom entanglement.


2001

Andrew E. Lange

Department of Astronomy, California Institute of Technology (Caltech), Pasadena, California, U.S.A.

Imaging the Embryonic Universe: First Resolved Images of the Cosmic Microwave Background

14 February 2002

Abstract: The primeval fireball that accompanied the Big Bang is still visible today as a faint microwave glow that fills the sky. This Cosmic Microwave Background (CMB) provides a snapshot of the universe at an age of ~ 0.5 Myr, equivalent to imaging a human being a few hours after conception. The details of the faint structures visible in the nearly isotropic CMB reveal much about the structure and evolution of the universe. The first resolved images of the CMB were obtained by BOOMERANG, a balloon-borne microwave telescope that circumnavigated the Antarctic. The BOOMERANG images reveal a universe that is composed of 5% baryonic matter, 30 % non-relativistic dark matter of unknown form, and 65% "dark energy" that is currently causing the expansion of the universe to accelerate.


2002

Lene Vestergaard Hau

Lyman Laboratory, Harvard University, Cambridge, U.S.A.

Light at Bicycle Speed ... and Slower Yet!

7 November 2002

Abstract: Light pulses have been slowed in a Bose-Einstein condensate to only 17 m/s, more than seven orders of magnitude lower than the light speed in vacuum. Associated with the dramatic reduction factor for the light speed is a spatial compression of the pulses by the same large factor. A light pulse, which is 1-2 miles long in vacuum, is compressed to a size of ~50 um, and at that point it is completely contained within the atom cloud. This further allows the light pulse to be completely stopped and stored in the atomic medium for up to several milliseconds, and subsequently regenerated with no loss. With the most recent extension of the method, the light roadblock, light pulses have been compressed from 2 miles to only 1-2 um. This system has been used to generate the superfluid analogue of shock waves, Quantum Shock Waves, in Bose-Einstein condensates. These dramatic excitations result in the formation of solitons that in turn decay into quantized vortices - created far out of equilibrium, in pairs of opposite circulation - revealing directly the process of superfluid breakdown in Bose-Einstein condensates.


2003

Andreas Eckart

Physikalisches Institut, Universität zu Köln, Köln, Germany

A Massive Accreting Black Hole at the Center of the Milky Way!

12 February 2004

Abstract: At a distance of only ~26400 light years the Galactic center is the closest 'quiescent' galaxy nucleus that we can now study in unprecedented detail. Over more than 10 years proper motions and orbits of individual stars in the central stellar cluster have been observed using speckle and adaptive optics techniques at the ESO NTT and the VLT. Recently the unique equipment in combination with the advantages of the ESO Paranal site (excellent seeing, GC passes close to Zenith), make the VLT the ideal instrument for studying the extremely dense GC stellar cluster and the immediate environment of the compact radio source SagittariusA* (SgrA*) at ist center. Observations of the orbit of star S2 have provided new, highly significant evidence that the central non-thermal radio source SgrA* is indeed a super-massive black hole with a mass of 3-4 million solar masses. The recent detection of quiescent emission and powerful flare activity of SgrA* in the X-ray and near-infrared domain have strengthened the case for an accreting massive black hole even further.


2004

Michel H. Devoret

Department of Applied Physics, Yale University, New Haven, U.S.A.

Towards a Solid State Quantum Information Processor: Manipulation and Control of the Quantum State of an Electrical Circuit

14 April 2005

Abstract: Could the bits of a computer be atom-like entities behaving quantum-mechanically? The miniaturization of transistors and Boolean gates down to single atoms or electrons has been explored as early as the 1980's, but it is only in the last decade that the superiority, for certain class of problems, of the quantum computer over its conventional classical counterpart has been fully understood theoretically. This discovery has spurred a flurry of activity aimed at implementing practically a "quantum machine" which would compute. In our own laboratory, we have followed the lead of superconducting integrated circuits, whose fabrication directly benefits from a whole body of knowledge in micro- and nano-technology developed for semiconducting devices. The problem with solid-state implementations of "qubits" is their potentially strong coupling to unwanted degrees of freedom in the various materials of the circuit. Yet, we have shown experimentally that for a particular superconducting tunnel junction circuit ? the so-called "quantronium"? electrical symmetries could be exploited to suppress, to a large extent, this undesirable coupling [1]. In the last few years, recent advances in Europe, Japan and the US have propelled the quantum mechanical coherence of superconducting circuits at a stage where genuine quantum information processing involving a register of several qubits can be engineered.
[1] D. Vion et al., Science 296 (2002) 286


2005

Arthur B. McDonald

Queen's University, Kingston, Ontario, Canada

Neutrino and Astro-Physics Measurements with the Sudbury Neutrino Observatory

8 September 2005

Abstract: The Sudbury Neutrino Observatory (SNO) is a 1,000 tonne heavy-water-based neutrino detector in an ultra-clean environment created 2 km underground in a mine near Sudbury, Canada. Past measurements of solar neutrino fluxes have been smaller than predicted by solar model calculations, implying that the calculations are incomplete or that some of the electron neutrinos produced in the Sun change to another flavor en route to earth. SNO has used neutrinos from 8B decay in the Sun to observe one neutrino reaction sensitive only to solar electron neutrinos and others sensitive to all active neutrino flavors and has found clear evidence for neutrino flavor change. This requires modification of the Standard Model for elementary particles and confirms solar model calculations with great accuracy. Results from the multi-year SNO observation program will be presented, including details of the broad calibration program, extensive control and measurement of radioactive backgrounds and use of salt in the heavy water to enhance sensitivity to all active neutrino flavors. The implications of the SNO results and other recent neutrino results for particle physics and solar physics will be discussed. The expansion of the underground facility to create a long-term international laboratory (SNOLAB) with a broad future experimental capability will also be described.


2006

Ferenc Krausz

Max-Planck-Institut für Quantenoptik, Garching, Germany; Ludwig-Maximilians-Universität, München, Germany; Technische Universität Wien, Austria

Attosecond Physics

14 September 2006

Abstract: Fundamental processes in atoms, molecules, as well as condensed matter are triggered or mediated by the motion of electrons inside or between atoms. Electronic dynamics on atomic length scales tends to unfold within tens to thousands of attoseconds (1 attosecond [as] = 10-18 s). Recent breakthroughs in laser science are now opening the door to watching and controlling these hitherto inaccessible microscopic dynamics. The key to accessing the attosecond time domain is the control of the electric field of (visible) light, which varies its strength and direction within less than a femtosecond (1 femtosecond = 1000 attoseconds). Atoms exposed to a few oscillations cycles of intense laser light are able to emit a single extreme ultraviolet (xuv) burst lasting less than one femtosecond [1,2]. Full control of the evolution of the electromagnetic field in laser pulses comprising a few wave cycles [3] have recently allowed the reproducible generation and measurement of isolated 250-attosecond xuv pulses [4], constituting the shortest reproducible events and fastest measurement to date. These tools have enabled us to visualize the oscillating electric field of visible light with an attosecond “oscilloscope” [5] as well as steering and real-time observation of the motion of electrons in atoms [6] and molecules [7]. Recent experiments [8] hold promise for the development of an attosecond x-ray source, which may pave the way towards 4D electron imaging with sub-atomic resolution in space and time.
[1] M. Hentschel et al., Nature 414, 509 (2001); [2] R. Kienberger et al., Science 291, 1923 (2002); [3] A. Baltuska et al., Nature 421, 611 (2003); [4] R. Kienberger et al., Nature 427, 817 (2004); [5] E. Goulielmakis et al., Science 305, 1267 (2004); [6] M. Drescher et al., Nature 419, 803 (2002). [7] J. Seres et al, Nature 433, 596 (2005)¸ [8] M. Kling et al., Science 312, 246 (2006).


2007

Sidney R. Nagel

University of Chicago, U.S.A.

Topological Transitions and Singularities in Fluids: The Life and Death of a Drop

18 October 2007

Abstract: The exhilarating spray from waves crashing into the shore, the distressing sound of a faucet leaking in the night, and the indispensable role of bubbles dissolving gas into the oceans are but a few examples of the ubiquitous presence and profound importance of drop formation and splashing in our lives. They are also examples of a liquid changing its topology. Although part of our common everyday experience, these transitions are far from understood and reveal delightful and profound surprises upon careful investigation. For example in droplet fission, the fluid forms a neck that becomes vanishingly thin at the point of breakup. This topological transition is thus accompanied by a dynamic singularity in which physical properties such as pressure diverge. Singularities of this sort often organize the overall dynamical evolution of nonlinear systems. I will first discuss the role of singularities in the breakup of drops. I will then discuss the fate of the drop when it falls and eventually splashes against a solid surface.


2008

Alan Watson

University of Leeds, United Kingdom

Is the Search for the Origin of the Highest-Energy Cosmic Rays Over?

2 October 2008

Abstract: The reasons for studying the highest energy cosmic rays will be outlined together with a description of the Pierre Auger Observatory, now in full operation. The question posed in the title can now be asked only because of two results obtained using data recorded at the Observatory. Firstly, it has been established that the flux of the highest energy cosmic rays is suppressed at energies beyond 5 x 1019 eV. Secondly, above this energy anisotropy in the arrival directions of the particles has been discovered that appears to be associated with sources lying within 75 Mpc. From these two observations it seems probable that we have observed the long-sought Greisen-Zatsepin-Kuz’min effect, demonstrating that ultra-high energy cosmic rays are of extragalactic origin. It is also probable that these particles are protons, thus offering the possibility of insights into features of particle physics at centre-of-mass energies 30 times greater than will be reached at the LHC. Preliminary conclusions from studies of detailed features of extensive air showers suggest that extrapolations from Tevatron energies may not be what have been anticipated hitherto. Much further work remains to be done and the next steps will be outlined.


2009

Fritz Bosch

GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany

Experiments on the beta decay of highly-ionized atoms with challenging and puzzling results

29 September 2009

Abstract: Beta decay of highly-ionized atoms plays a significant role in stellar nucleosynthesis at temperatures of about 30 keV (s-process) where most nuclei are in a high atomic charge state. The facility at GSI, Darmstadt, providing both unstable highly-charged nuclides and an ion storage-cooler ring (ESR) to preserve their high charge state over a long time (hours) was and still is the only place addressing this field which is interesting for nuclear physics as well as for astrophysics. During the last decade, the focus was on the investigation of two-body beta decays, i.e. bound-state beta decay and orbital electron capture (EC), where monochromatic (anti)neutrinos in the electron-flavour eigenstate are created. In course of the first measurements of the EC decay probability of few-electron ions it turned out that hydrogen-like 140Pr58+ and 142Pm60+ nuclides decay by about 50% faster than the helium-like ions, and even faster than the corresponding neutral atoms. This result, although somewhat surprising, can be fully understood in the framework of standard nuclear physics. A few years ago, a new technique, single-ion decay spectroscopy has been developed at the ESR. Here, the number of stored ions is reduced to less than four and the "fate" of each single stored ion is observed continuously and time-resolved. On top of the expected exponentially decreasing EC decay probability, for both hydrogen-like 140Pr and 142Pm ions, periodic modulations were found with a period of about 7s and relative amplitude of 0.2. Tentatively, we argued that these oscillations could be due - as a special kind of "quantum beats"- to the coherent superposition of (at least) two mass eigenstates of the generated electron-neutrino which is a flavour eigenstate, but neither an energy- nor momentum eigenstate. This very controversially discussed hypothesis predicts that similar modulations should also appear in other two-body beta decays with a period being proportional to the mass of the parent ion. To corroborate or disprove this hypothesis, some months ago an experiment with hydrogen-like 122I ions has been conducted, where a modulation period of about 6s is expected, supposed this "neutrino hypothesis" holds true. First results will be reported.

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