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The Trilinear Hamiltonian: A Zero-Dimensional Mmodel Of Hawking Radiation From A Quantized Source, Paul D. Nation, Miles P. Blencowe 2010 Dartmouth College

The Trilinear Hamiltonian: A Zero-Dimensional Mmodel Of Hawking Radiation From A Quantized Source, Paul D. Nation, Miles P. Blencowe

Open Dartmouth: Faculty Open Access Articles

We investigate a quantum parametric amplifier with dynamical pump mode, viewed as a zero-dimensional model of Hawking radiation from an evaporating black hole. We derive the conditions under which the spectrum of particles generated from vacuum fluctuations deviates from the thermal spectrum predicted for the conventional parametric amplifier. We find that significant deviations arise when the pump mode (black hole) has emitted nearly half of its initial energy into the signal (Hawking radiation) and idler (in-falling particle) modes. As a model of black hole dynamics, this finding lends support to the view that late-time Hawking radiation contains information about the ...


History Of Communication And Its Application In Multicultaral,Multilingual Social System In India Across Ages, Ratnesh Dwivedi Mr 2010 India Today Group

History Of Communication And Its Application In Multicultaral,Multilingual Social System In India Across Ages, Ratnesh Dwivedi Mr

Ratnesh Dwivedi

The history of communication dates back to the earliest signs of cavemen.Communication can range from very subtle processes of exchange, to full conversations and mass communication. Human communication was revolutionized with speech perhaps 200,000 years ago, Symbols were developed about 30,000 years ago and writing about 7,000. On a much shorter scale, there have been major developments in the field of telecommunication in the past few centuries.


Magnetic Structure And Magnetoelectric Coupling In Bulk And Thin Film Fevo4, Ambesh V. Dixit, Gavin J. Lawes, A. Brooks Harris 2010 University of Pennsylvania

Magnetic Structure And Magnetoelectric Coupling In Bulk And Thin Film Fevo4, Ambesh V. Dixit, Gavin J. Lawes, A. Brooks Harris

Department of Physics Papers

We have investigated the magnetoelectric and magnetodielectric response in FeVO4, which exhibits a change in magnetic structure coincident with ferroelectric ordering at TN2≈15 K. Using symmetry considerations, we construct a model for the possible magnetoelectric coupling in this system and present a discussion of the allowed spin structures in FeVO4. Based on this model, in which the spontaneous polarization is caused by a trilinear spin-phonon interaction, we experimentally explore the magnetoelectric coupling in FeVO4 thin films through measurements of the electric field-induced shift of the multiferroic phase transition temperature, which exhibits an increase of 0 ...


Exotic Smoothness In Four Dimensions And Euclidean Quantum Gravity, Christopher L. Duston 2010 Merrimack

Exotic Smoothness In Four Dimensions And Euclidean Quantum Gravity, Christopher L. Duston

Physics Faculty Publications

In this paper we calculate the effect of the inclusion of exotic smooth structures on typical observables in Euclidean quantum gravity. We do this in the semiclassical regime for several gravitational free-field actions and find that the results are similar, independent of the particular action that is chosen. These are the first results of their kind in dimension four, which we extend to include one-loop contributions as well. We find these topological features can have physically significant results without the need for additional exotic physics.


Intermode Dephasing In A Superconducting Stripline Resonator, Oren Suchoi, Baleegh Abdo, Eran Segev, Oleg Shtempluck, M. P. Blencowe, Eyal Buks 2010 Technion-Israel Institute of Technology

Intermode Dephasing In A Superconducting Stripline Resonator, Oren Suchoi, Baleegh Abdo, Eran Segev, Oleg Shtempluck, M. P. Blencowe, Eyal Buks

Open Dartmouth: Faculty Open Access Articles

We study a superconducting stripline resonator (SSR) made of niobium, which is integrated with a superconducting interference device (SQUID). The large nonlinear inductance of the SQUID gives rise to a strong Kerr nonlinearity in the response of the SSR, which in turn results in strong coupling between different modes of the SSR. We experimentally demonstrate that such intermode coupling gives rise to dephasing of microwave photons. The dephasing rate depends periodically on the external magnetic flux applied to the SQUID, where the largest rate is obtained at half integer values (in units of the flux quantum). To account for our ...


Results From Electrostatic Calibrations For Measuring The Casimir Force In The Cylinder-Plane Geometry, Q. Wei, D. A. R. Dalvit, F. C. Lombardo, F. D. Mazzitelli, R. Onofrio 2010 Dartmouth College

Results From Electrostatic Calibrations For Measuring The Casimir Force In The Cylinder-Plane Geometry, Q. Wei, D. A. R. Dalvit, F. C. Lombardo, F. D. Mazzitelli, R. Onofrio

Open Dartmouth: Faculty Open Access Articles

We report on measurements performed on an apparatus aimed to study the Casimir force in the cylinder-plane configuration. The electrostatic calibrations evidence anomalous behaviors in the dependence of the electrostatic force and the minimizing potential upon distance. We discuss analogies and differences of these anomalies with respect to those already observed in the sphere-plane configuration. At the smallest explored distances we observe frequency shifts of non-Coulombian nature preventing the measurement of the Casimir force in the same range. We also report on measurements performed in the parallel-plane configuration, showing that the dependence on distance of the minimizing potential, if present ...


Modeling Bound States In The Continuum For Multiple Electrons In A Quantum Dot Pair, Thomas Ian Tuegel 2010 Butler University

Modeling Bound States In The Continuum For Multiple Electrons In A Quantum Dot Pair, Thomas Ian Tuegel

Undergraduate Honors Thesis Collection

The bound eigenstates of an electron inside a pair of quantum dots embedded on an infinite quantum wire are examined using the method of particular solutions. The eigenstates of a two-electron system in the same structure are examined perturbatively using wavefunction expansions for the one-electron eigenstates. The stability of the two-electron eigenstates is evaluated and compared with other theoretical results. It is found that stable bound states in the continuum exist for two electrons confined to this geometry.


Charge And Spin Ordering In The Mixed-Valence Compound Lufe2O4, A. Brooks Harris, Taner Yildirim 2010 University of Pennsylvania

Charge And Spin Ordering In The Mixed-Valence Compound Lufe2O4, A. Brooks Harris, Taner Yildirim

Department of Physics Papers

Landau theory and symmetry considerations lead us to propose an explanation for several seemingly paradoxical behaviors of charge ordering (CO) and spin ordering (SO) in the mixed valence compound LuFe2O4. Both SO and CO are highly frustrated. We analyze a lattice gas model of CO within mean-field theory and determine the magnitude of several of the phenomenological interactions. We show that the assumption of a continuous phase transitions at which CO or SO develops implies that both CO and SO are incommensurate. To explain how ferroelectric fluctuations in the charge-disordered phase can be consistent with an antiferroelectric ...


Theoretical And Computational Study Of Time Dependent Scattering On A 2d Surface, Michael Sohn 2010 University of Nevada Las Vegas

Theoretical And Computational Study Of Time Dependent Scattering On A 2d Surface, Michael Sohn

UNLV Theses, Dissertations, Professional Papers, and Capstones

The quantum mechanical treatment of the elastic scattring of atoms from a crystal surface provides valuable information, such as surface properties and gas-surface interaction potentials. However, since it is based on the stationary state solution, it does not provide the details of the scattering process in the neighborhood of the surface, especially when atoms are physically adsorbed. In this thesis, the time evolution of the scattering process is treated in 2D with a model potential, V(x, z) = -|g|δ(z) + λδ(z)cos(2πx/a), using the Gaussian wave packet approach. The focus is on the case where the ...


Photoemission Spectroscopy Of A Strongly Interacting Fermi Gas, John Pagnucci Gaebler 2010 University of Colorado, Boulder

Photoemission Spectroscopy Of A Strongly Interacting Fermi Gas, John Pagnucci Gaebler

Physics Graduate Theses & Dissertations

The ability to study ultracold atomic Fermi gases holds the promise of significant advances in testing fundamental theories of many-body quantum physics. Of particular interest are strongly interacting Fermi gases in the BCS to BEC crossover that exhibit a transition to a superfluid state at temperatures near 0.2TF , where TF is the Fermi temperature. This transition, as a fraction of TF, is extremely high compared to any known superfluid or superconductor. These gases are also in a universal regime where the physics is independent of the details of the atomic interactions and is therefore relevant ...


Equilibrium States Of A Test Particle Coupled To Finite-Size Heat Baths, Qun Wei, S. Taylor Smith, Roberto Onofrio 2010 Dartmouth College

Equilibrium States Of A Test Particle Coupled To Finite-Size Heat Baths, Qun Wei, S. Taylor Smith, Roberto Onofrio

Open Dartmouth: Faculty Open Access Articles

We report on numerical simulations of the dynamics of a test particle coupled to competing Boltzmann heat baths of finite size. After discussing some features of the single bath case, we show that the presence of two heat baths further constrains the conditions necessary for the test particle to thermalize with the heat baths. We find that thermalization is a spectral property in which the oscillators of the bath with frequencies in the range of the test particle characteristic frequency determine its degree of thermalization. We also find an unexpected frequency shift of the test particle response with respect to ...


Casimir Interactions Of An Object Inside A Spherical Metal Shell, Saad Zaheer, Sahand Jamal Rahi, Thorsten Emig, Robert L. Jaffe 2010 University of Pennsylvania

Casimir Interactions Of An Object Inside A Spherical Metal Shell, Saad Zaheer, Sahand Jamal Rahi, Thorsten Emig, Robert L. Jaffe

Department of Physics Papers

We investigate the electromagnetic Casimir interactions of an object contained within an otherwise empty, perfectly conducting spherical shell. For a small object we present analytical calculations of the force, which is directed away from the center of the cavity, and the torque, which tends to align the object opposite to the preferred alignment outside the cavity. For a perfectly conducting sphere as the interior object, we compute the corrections to the proximity force approximation (PFA) numerically. In both cases the results for the interior configuration match smoothly onto those for the corresponding exterior configuration.


Arbitrarily Accurate Dynamical Control In Open Quantum Systems, Kaveh Khodjasteh, Daniel A. Lidar, Lorenza Viola 2010 Dartmouth College

Arbitrarily Accurate Dynamical Control In Open Quantum Systems, Kaveh Khodjasteh, Daniel A. Lidar, Lorenza Viola

Open Dartmouth: Faculty Open Access Articles

We show that open-loop dynamical control techniques may be used to synthesize unitary transformations in open quantum systems in such a way that decoherence is perturbatively compensated for to a desired (in principle arbitrarily high) level of accuracy, which depends only on the strength of the relevant errors and the achievable rate of control modulation. Our constructive and fully analytical solution employs concatenated dynamically corrected gates, and is applicable independently of detailed knowledge of the system-environment interactions and environment dynamics. Explicit implications for boosting quantum gate fidelities in realistic scenarios are addressed.


Efficient Modeling Techniques For Time-Dependent Quantum System With Applications To Carbon Nanotubes, Zuojing Chen 2010 University of Massachusetts Amherst

Efficient Modeling Techniques For Time-Dependent Quantum System With Applications To Carbon Nanotubes, Zuojing Chen

Masters Theses 1911 - February 2014

The famous Moore's law states: Since the invention of the integrated circuit, the number of transistors that can be placed on an integrated circuit has increased exponentially, doubling approximately every two years. As a result of the downscaling of the size of the transistor, quantum effects have become increasingly important while affecting significantly the device performances. Nowadays, at the nanometer scale, inter-atomic interactions and quantum mechanical properties need to be studied extensively. Device and material simulations are important to achieve these goals because they are flexible and less expensive than experiments. They are also important for designing and characterizing ...


Two-Species Ion Arrays For Quantum Logic Spectroscopy And Entanglement Generation, David Brian Hume 2010 University of Colorado, Boulder

Two-Species Ion Arrays For Quantum Logic Spectroscopy And Entanglement Generation, David Brian Hume

Physics Graduate Theses & Dissertations

The quantum states of trapped atomic ions can be highly isolated from external perturbation, and precisely manipulated with applied laser fields. This makes them an excellent medium for quantum-limited experiments such as quantum information processing and precision spectroscopy. A relatively small number of ion species have been used for these types of experiments because most species are difficult to laser cool and detect directly. This thesis demonstrates a way to overcome this limitation by use of sympathetic cooling and state detection based on quantum logic. We apply these techniques to mixed-species arrays of Al+ and Be+ ions. A mathematical model ...


Quantum Information Dynamics, Jeffrey Yepez 2010 College of William & Mary - Arts & Sciences

Quantum Information Dynamics, Jeffrey Yepez

Dissertations, Theses, and Masters Projects

Presented is a study of quantum entanglement from the perspective of the theory of quantum information dynamics. We consider pairwise entanglement and present an analytical development using joint ladder operators, the sum of two single-particle fermionic ladder operators. This approach allows us to write down analytical representations of quantum algorithms and to explore quantum entanglement as it is manifested in a system of qubits.;We present a topological representation of quantum logic that views entangled qubit spacetime histories (or qubit world lines) as a generalized braid, referred to as a super-braid. The crossing of world lines may be either classical ...


Upper Limits On A Possible Gluon Mass, Shmuel Nussinov, Robert Shrock 2010 Chapman University

Upper Limits On A Possible Gluon Mass, Shmuel Nussinov, Robert Shrock

Mathematics, Physics, and Computer Science Faculty Articles and Research

We analyze upper limits on a possible gluon mass, mg. We first discuss various ways to modify quantum chromodynamics to include m(g) not equal 0, including a bare mass, a Higgs mechanism, and dynamical breaking of color SU(3)(c). From an examination of experimental data, we infer an upper limit m(g) < O(1) MeV. As part of our analysis, we show that a claim, hitherto unrefuted in the literature, of a much stronger upper limit on m(g), is invalid. We discuss subtleties in interpreting gluon mass limits in view of the fact that at scales below Lambda(QCD), quantum chromodynamics is strongly coupled, perturbation theory is not reliable, and the physics is not accurately described in terms of the Lagrangian degrees of freedom, including gluons. We also point out a fundamental difference in the behavior of quantum chromodynamics with a nonzero gluon mass and a weakly coupled gauge theory with a gauge boson mass.


Entropy And Information Causality In General Probabilistic Theories, Howard Barnum, Jonathan Barrett, Lisa Orloff Clark, Matthew S. Leifer, Robert Spekkens, Nicholas Stepanik, Alex Wilce, Robin Wilke 2010 Perimeter Institute for Theoretical Physics

Entropy And Information Causality In General Probabilistic Theories, Howard Barnum, Jonathan Barrett, Lisa Orloff Clark, Matthew S. Leifer, Robert Spekkens, Nicholas Stepanik, Alex Wilce, Robin Wilke

Mathematics, Physics, and Computer Science Faculty Articles and Research

We investigate the concept of entropy in probabilistic theories more general than quantum mechanics, with particular reference to the notion of information causality (IC) recently proposed by Pawlowski et al (2009 arXiv:0905.2292). We consider two entropic quantities, which we term measurement and mixing entropy. In the context of classical and quantum theory, these coincide, being given by the Shannon and von Neumann entropies, respectively; in general, however, they are very different. In particular, while measurement entropy is easily seen to be concave, mixing entropy need not be. In fact, as we show, mixing entropy is not concave whenever ...


A Time-Symmetric Formulation Of Quantum Mechanics, Yakir Aharonov, Sandu Popescu, Jeff Tollaksen 2010 Chapman University

A Time-Symmetric Formulation Of Quantum Mechanics, Yakir Aharonov, Sandu Popescu, Jeff Tollaksen

Mathematics, Physics, and Computer Science Faculty Articles and Research

Quantum mechanics allows one to independently select both the initial and final states of a single system. Such pre- and postselection reveals novel effects that challenge our ideas about what time is and how it flows.


Quantum Interference Experiments, Modular Variables And Weak Measurements, Jeff Tollaksen, Yakir Aharonov, Aharon Casher, Tirzah Kaufherr, Shmuel Nussinov 2010 Chapman University

Quantum Interference Experiments, Modular Variables And Weak Measurements, Jeff Tollaksen, Yakir Aharonov, Aharon Casher, Tirzah Kaufherr, Shmuel Nussinov

Mathematics, Physics, and Computer Science Faculty Articles and Research

We address the problem of interference using the Heisenberg picture and highlight some new aspects through the use of pre-selection, post-selection, weak measurements and modular variables. We present a physical explanation for the different behaviors of a single particle when the distant slit is open or closed; instead of having a quantum wave that passes through all slits, we have a localized particle with non-local interactions with the other slit(s). We introduce a Gedanken experiment to measure this non-local exchange. While the Heisenberg and Schrodinger pictures are equivalent formulations of quantum mechanics, nevertheless, the results discussed here support a ...


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