Equilibrium States Of A Test Particle Coupled To Finite-Size Heat Baths, 2010 Dartmouth College

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

*Dartmouth Scholarship*

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 …

Interferometric Weak Value Deflections: Quantum And Classical Treatments, 2010 Chapman University

#### Interferometric Weak Value Deflections: Quantum And Classical Treatments, John C. Howell, David J. Starling, P. Ben Dixon, Praveen K. Vudyasetu, Andrew N. Jordan

*Mathematics, Physics, and Computer Science Faculty Articles and Research*

We derive the weak value deflection given in an article by Dixon et al. [P. B. Dixon et al. Phys. Rev. Lett. 102 173601 (2009)] both quantum mechanically and classically, including diffraction effects. This article is meant to cover some of the mathematical details omitted in that article owing to space constraints.

Arbitrarily Accurate Dynamical Control In Open Quantum Systems, 2010 Dartmouth College

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

*Dartmouth Scholarship*

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.

On Relational Quantum Mechanics, 2010 University of Texas at El Paso

#### On Relational Quantum Mechanics, Oscar Acosta

*Open Access Theses & Dissertations*

A problem facing quantum mechanics is that there are a number of views or interpretations available that purport to 'explain' quantum mechanics. In this paper I discuss and analyze the view of relational quantum mechanics by Carlo Rovelli in the context of theoretical underdetermination. I will show that even though Rovelli offers a view that consolidates some of the aspects of competing theories it still falls short of breaking out of the theoretical underdetermination. The criteria that I have used to consider a theory successful in this context is one that increases the predictive output of quantum theory. Lacking an …

A Time-Symmetric Formulation Of Quantum Mechanics, 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, 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 new …

Upper Limits On A Possible Gluon Mass, 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, 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 the state …

Quantum Information Dynamics, 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 or …

Influence Of Coulomb Interactions On Emission Dynamics In Semiconductor Quantum Dot Systems, 2010 Department of Applied Physics and Instrumentation, Cork Institute of Technology, Cork, Ireland.

#### Influence Of Coulomb Interactions On Emission Dynamics In Semiconductor Quantum Dot Systems, Kamil Gradkowski

*Theses*

In this thesis the novel self-assembled quantum dots based on GaSb/GaAs technology are investigated for the possible application in the near- and mid-infrared, i.e. telecommunication networks, solar cells, gas sensors and imaging systems. These heterostructures exhibit a type-Il band alignment, which means that one species of carriers is confined to the dot, while the other is outside in the surrounding matrix. This physical separation of carriers leads to profound Coulomb interactions, which makes the optical properties of these structures dependent on the injected charge density. The relationship between two of those properties, the emission energy and transition probability, leads to …