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Quantum Geometry in the Lab  [PDF]
Craig Hogan
Physics , 2013,
Abstract: Standard particle theory is based on quantized matter embedded in a classical geometry. Here, a complementary model is proposed, based on classical matter -- massive bodies, without quantum properties -- embedded in a quantum geometry. It does not describe elementary particles, but may be a better, fully consistent quantum description for position states in laboratory-scale systems. Gravitational theory suggests that the geometrical quantum system has an information density of about one qubit per Planck length squared. If so, the model here predicts that the quantum uncertainty of geometry creates a new form of noise in the position of massive bodies, detectable by interferometers.
Nonequilibrium work performed in quantum annealing  [PDF]
Masayuki Ohzeki,Hidestoshi Nishimori
Physics , 2011, DOI: 10.1088/1742-6596/302/1/012047
Abstract: Quantum annealing is a generic solver of classical optimization problems that makes full use of quantum fluctuations. We consider work statistics given by a repetition of quantum annealing processes by employing the Jarzynski equality proposed in nonequilibrium statistical physics. In particular, we analyze the distribution of the work performed by a transverse field. A special symmetry, gauge symmetry, leads to a non-trivial relationship between quantum annealing toward different targets in the theory of spin glasses. We believe that our results will be a step toward an alternative realization of efficient quantum computation as well as our better understanding of nonequilibrium behavior of systems under quantum control.
Comparison of the INRIM and PTB lattice-spacing standards  [PDF]
E Massa,G Mana,U Kuetgens
Physics , 2009, DOI: 10.1088/0026-1394/46/3/011
Abstract: To base the kilogram definition on the atomic mass of the silicon 28 atom, the present relative uncertainty of the silicon 28 lattice parameter must lowered to 3E-9. To achieve this goal, a new experimental apparatus capable of a centimetre measurement-baseline has been made at the INRIM. The comparison between the determinations of the lattice parameter of crystals MO*4 of INRIM and WASO4.2a of PTB is intended to verify the measurement capabilities and to assess the limits of this experiment.
Review of recent experimental progresses in Foundations of Quantum Mechanics and Quantum Information obtained in Parametric Down Conversion Experiments at IENGF  [PDF]
M. Genovese,G. Brida,E. Cagliero,M. Gramegna,E. Predazzi
Physics , 2004, DOI: 10.1134/1.2034600
Abstract: We review some recent experimental progresses concerning Foundations of Quantum Mechanics and Quantum Information obtained in Quantum Optics Laboratory "Carlo Novero" at IENGF. More in details, after a short presentation of our polarization entangled photons source (based on precise superposition of two Type I PDC emission) and of the results obtained with it, we describe an innovative double slit experiment where two degenerate photons produced by PDC are sent each to a specific slit. Beyond representing an interesting example of relation between visibility of interference and "welcher weg" knowledge, this configuration has been suggested for testing de Broglie-Bohm theory against Standard Quantum Mechanics. Our results perfectly fit SQM results, but disagree with dBB predictions. Then, we discuss a recent experiment addressed to clarify the issue of which wave-particle observables are really to be considered when discussing wave particle duality. This experiments realises the Agarwal et al. theoretical proposal, overcoming limitations of a former experiment. Finally, we hint to the realization of a high-intensity high-spectral-selected PDC source to be used for quantum information studies.
Poincaré invariant quantum theory, J. Lab lectures  [PDF]
W. N. Polyzou
Physics , 2009,
Abstract: Lectures on Poincare invariant quantum theory presented at TJNAF.
Statistics of work performed on a forced quantum oscillator  [PDF]
Peter Talkner,P. Sekhar Burada,Peter H?nggi
Physics , 2008, DOI: 10.1103/PhysRevE.78.011115
Abstract: Various aspects of the statistics of work performed by an external classical force on a quantum mechanical system are elucidated for a driven harmonic oscillator. In this special case two parameters are introduced that are sufficient to completely characterize the force protocol. Explicit results for the characteristic function of work and the respective probability distribution are provided and discussed for three different types of initial states of the oscillator: microcanonical, canonical and coherent states. Depending on the choice of the initial state the probability distributions of the performed work may grossly differ. This result in particular holds also true for identical force protocols. General fluctuation and work theorems holding for microcanonical and canonical initial states are confirmed.
Lab-Tutorials for teaching quantum physics (Lab-Tutorials fuer den Quantenphysik Unterricht)  [PDF]
Michael C. Wittmann
Physics , 2006,
Abstract: English abstract: In the "Intuitive Quantum Physics" course, we use graphical interpretations of mathematical equations and qualitative reasoning to develop and teach a simplified model of quantum physics. Our course contains three units: Wave physics, Development of a conceptual toolbox, and quantum physics. It also contains three key themes: wave-particle duality, the Schroedinger equation, and tunneling of quantum particles. Students learn most new material in lab-tutorials in which students work in small groups (3 to 3 people) on specially designed worksheets. Lecture reinforces the lab-tutorial content and focuses more on issues about the nature of science. Data show that students are able to learn some of the most difficult concepts in the course, and also that students learn to believe that there is a conceptually accessible structure to the physics in the course. German abstract: Im Kurs "Intuitive Quantum Physics" werden graphische Interpretationen mathematischer Gleichungen und qualitatives Denken durch ein vereinfachtes Modell der Quantenphysik gelehrt. Unser Kurs besteht aus drei wichtigen Abschnitten: Wellenphysik, Aufbau eines Werkzeugkastens ("Toolbox") und Quantenphysik, sowie drei Schluesselthemen: Welle-Teilchen-Dualitaet, die Schroedinger-Gleichung und Tunneln von Quantenteilchen. Wir unterrichten vorwiegend mit Lab-Tutorials, in denen StudentInnen in kleinen Gruppen (3 bis 4 Personen) anwendungsspezifische Arbeitsblaetter durcharbeiten. In den Diskussionen werden auch Auseinandersetzungen ueber das "Bild der Physik", bei uns "Nature of Science" genannt, gefuehrt. Ueberpruefungen haben ergeben, dass StudentInnen nicht nur die schwierigsten Konzepte des Kurses lernen koennen sondern auch lernen, dass die Quantenphysik begrifflich verstaendlich ist.
A proposal for testing Quantum Gravity in the lab  [PDF]
Ahmed Farag Ali,Saurya Das,Elias C. Vagenas
Physics , 2011, DOI: 10.1103/PhysRevD.84.044013
Abstract: Attempts to formulate a quantum theory of gravitation are collectively known as {\it quantum gravity}. Various approaches to quantum gravity such as string theory and loop quantum gravity, as well as black hole physics and doubly special relativity theories predict a minimum measurable length, or a maximum observable momentum, and related modifications of the Heisenberg Uncertainty Principle to a so-called generalized uncertainty principle (GUP). We have proposed a GUP consistent with string theory, black hole physics and doubly special relativity theories and have showed that this modifies all quantum mechanical Hamiltonians. When applied to an elementary particle, it suggests that the space that confines it must be quantized, and in fact that all measurable lengths are quantized in units of a fundamental length (which can be the Planck length). On the one hand, this may signal the breakdown of the spacetime continuum picture near that scale, and on the other hand, it can predict an upper bound on the quantum gravity parameter in the GUP, from current observations. Furthermore, such fundamental discreteness of space may have observable consequences at length scales much larger than the Planck scale. Because this influences all the quantum Hamiltonians in an universal way, it predicts quantum gravity corrections to various quantum phenomena. Therefore, in the present work we compute these corrections to the Lamb shift, simple harmonic oscillator, Landau levels, and the tunneling current in a scanning tunneling microscope.
Experimenting with Quantum Fields in Curved Spacetime in the Lab  [PDF]
Isabeau Prémont-Schwarz
Physics , 2011,
Abstract: In this paper we will investigate how one can create emergent curved spacetimes by locally tuning the coupling constants of condensed matter systems. In the continuum limit we thus obtain continuous effective quantum fields living on curved spacetimes. In particular, using Stingnet condensates we can obtain effective electromagnetism. We will show for example how we obtain quantum electrodynamics in a blackhole (Schwarzschild) spacetime.
Quantum Measurements Performed with a Single-Electron Transistor  [PDF]
Alexander Shnirman,Gerd Schoen
Physics , 1998, DOI: 10.1103/PhysRevB.57.15400
Abstract: Low-capacitance Josephson junction systems as well as coupled quantum dots, in a parameter range where single charges can be controlled, provide physical realizations of quantum bits, discussed in connection with quantum computing. The necessary manipulation of the quantum states can be controlled by applied gate voltages. In addition, the state of the system has to be read out. Here we suggest to measure the quantum state by coupling a single-electron transistor to the q-bit. As long as no transport voltage is applied, the transistor influences the quantum dynamics of the q-bit only weakly. We have analyzed the time evolution of the density matrix of the transistor and q-bit when a voltage is turned on. For values of the capacitances and temperatures which can be realized by modern nano-techniques the process constitutes a quantum measurement process.
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