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Physics

Mathematics, Physics, and Computer Science Faculty Articles and Research

2006

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Slow Light With Large Fractional Delays By Spectral Hole-Burning In Rubidium Vapor, Ryan M. Camacho, Michael V. Pack, John C. Howell Sep 2006

Slow Light With Large Fractional Delays By Spectral Hole-Burning In Rubidium Vapor, Ryan M. Camacho, Michael V. Pack, John C. Howell

Mathematics, Physics, and Computer Science Faculty Articles and Research

We report on the experimental realization of large fractional pulse delays in a hot, Doppler-broadened rubidium vapor. A pump laser burns a deep spectral hole in the inhomogeneously broadened vapor. The delay is shown to be widely tunable by both power broadening the resonance and frequency modulating the pump laser. The simplicity of the scheme opens up the possibility for practical optical delays and buffers.


Transients Of The Electromagnetically-Induced-Transparency-Enhanced Refractive Kerr Nonlinearity: Theory, M. V. Pack, R. M. Camacho, John C. Howell Jul 2006

Transients Of The Electromagnetically-Induced-Transparency-Enhanced Refractive Kerr Nonlinearity: Theory, M. V. Pack, R. M. Camacho, John C. Howell

Mathematics, Physics, and Computer Science Faculty Articles and Research

We present a theory describing the transients and rise times of the refractive Kerr nonlinearity which is enhanced using electromagnetically induced transparency (EIT). We restrict our analysis to the case of a pulsed signal field with continuous-wave EIT fields, and all fields are well below saturation. These restrictions enable the reduction of an EIT Kerr, four-level, density-matrix equation to a two-level Bloch-vector equation which has a simple and physically intuitive algebraic solution. The physically intuitive picture of a two-level Bloch vector provides insights that are easily generalized to more complex and experimentally realistic models. We consider generalization to the cases …


Low-Distortion Slow Light Using Two Absorption Resonances, Ryan M. Camacho, Michael V. Pack, John C. Howell Jun 2006

Low-Distortion Slow Light Using Two Absorption Resonances, Ryan M. Camacho, Michael V. Pack, John C. Howell

Mathematics, Physics, and Computer Science Faculty Articles and Research

We consider group delay and broadening using two strongly absorbing and widely spaced resonances. We derive relations which show that very large pulse bandwidths coupled with large group delays and small broadening can be achieved. Unlike single resonance systems, the dispersive broadening dominates the absorptive broadening which leads to a dramatic increase in the possible group delay. We show that the double resonance systems are excellent candidates for realizing all-optical delay lines. We report on an experiment which achieved up to 50 pulse delays with 40% broadening.


Erratum: Exploring The Optimal Sensitivity Of Sum-Variance Nonseparability Critera For Spin-1/2 Systems, Irfan Ali Khan, John C. Howell Apr 2006

Erratum: Exploring The Optimal Sensitivity Of Sum-Variance Nonseparability Critera For Spin-1/2 Systems, Irfan Ali Khan, John C. Howell

Mathematics, Physics, and Computer Science Faculty Articles and Research

No abstract provided.


Experimental Demonstration Of High Two-Photon Time-Energy Entanglement, Irfan Ali Khan, John C. Howell Mar 2006

Experimental Demonstration Of High Two-Photon Time-Energy Entanglement, Irfan Ali Khan, John C. Howell

Mathematics, Physics, and Computer Science Faculty Articles and Research

We report on the experimental demonstration of high energy-time entanglement in two-photon states created in the process of spontaneous parametric down-conversion. We show that the classical variance product, which we violate by three orders of magnitude, actually represents a lower bound estimate of the number of information eigenmodes K. Explicit measurements estimate K to be greater than 100, with theoretical estimates predicting a value of as high as 1×106. These results provide incentive for the practical feasibility of large bandwidth quantum information processing, particularly in cryptography over large distances.


Quantum Dynamics As An Analog Of Conditional Probability, Matthew S. Leifer Jan 2006

Quantum Dynamics As An Analog Of Conditional Probability, Matthew S. Leifer

Mathematics, Physics, and Computer Science Faculty Articles and Research

Quantum theory can be regarded as a noncommutative generalization of classical probability. From this point of view, one expects quantum dynamics to be analogous to classical conditional probabilities. In this paper, a variant of the well-known isomorphism between completely positive maps and bipartite density operators is derived, which makes this connection much more explicit. This isomorphism is given an operational interpretation in terms of statistical correlations between ensemble preparation procedures and outcomes of measurements. Finally, the isomorphism is applied to elucidate the connection between no-cloning and no-broadcasting theorems and the monogamy of entanglement, and a simplified proof of the no-broadcasting …


Conditional Density Operators And The Subjectivity Of Quantum Operations, Matthew S. Leifer Jan 2006

Conditional Density Operators And The Subjectivity Of Quantum Operations, Matthew S. Leifer

Mathematics, Physics, and Computer Science Faculty Articles and Research

Assuming that quantum states, including pure states, represent subjective degrees of belief rather than objective properties of systems, the question of what other elements of the quantum formalism must also be taken as subjective is addressed. In particular, we ask this of the dynamical aspects of the formalism, such as Hamiltonians and unitary operators. Whilst some operations, such as the update maps corresponding to a complete projective measurement, must be subjective, the situation is not so clear in other cases. Here, it is argued that all trace preserving completely positive maps, including unitary operators, should be regarded as subjective, in …