Bulletin of the American Physical Society
2009 APS March Meeting
Volume 54, Number 1
Monday–Friday, March 16–20, 2009; Pittsburgh, Pennsylvania
Session D17: Focus Session: Foundations of Quantum Theory |
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Sponsoring Units: GQI Chair: Ian Durham, Saint Anselm College Room: 318 |
Monday, March 16, 2009 2:30PM - 3:06PM |
D17.00001: LeRoy Apker Award Talk: Factoring Quantum Logic Gates with Cartan Involutions Invited Speaker: This abstract not available. [Preview Abstract] |
Monday, March 16, 2009 3:06PM - 3:18PM |
D17.00002: Types and location of information Looi Shiang Yong, Vlad Gheorghiu, Robert B. Griffiths Imagine having some quantum information encoded in $n$ carrier qubits. We are interested in the question of how much information is present in a subset of the carrier qubits. In the case where the encoding is done using a stabilizer code, we have a precise and complete answer. The two extreme cases of having too small a subset whereby no information is present versus having a large subset of almost $n$ qubits from which all the information can be extracted are already well understood. In this talk we focus on the intermediate situation where only partial information is present. For this purpose we define different ``types'' of information, where the presence of a type of information on a subset of carrier qubits implies the ability to distinguish a particular set of encoded states associated to that type. With this we can determine how much and what types of information are present in any given subset of carrier qubits. With the help of some simple examples, we will show how sometimes only ``classical'' information is present and sometimes more can be present. Finally our results can be generalized to higher dimensional qudit stabilizer codes. [Preview Abstract] |
Monday, March 16, 2009 3:18PM - 3:30PM |
D17.00003: Testing Born's rule in Quantum Mechanics using a Triple slit experiment Urbasi Sinha, Christophe Couteau, Zachari Medendorp, Immo Soellner, Raymond Laflamme, Rafael Sorkin, Gregor Weihs In Mod. Phys. Lett.A \textbf{9} 3119 (1994), one of us (R.D.S) investigated a formulation of quantum mechanics as a generalized measure theory. Quantum mechanics computes probabilities from the absolute squares of complex amplitudes, and the resulting interference violates the (Kolmogorov) sum rule expressing the additivity of probabilities of mutually exclusive events. However, there is a higher order sum rule that quantum mechanics does obey, involving the probabilities of three mutually exclusive possibilities. We could imagine a yet more general theory by assuming that it violates the next higher sum rule. In this presentation, we report results from an ongoing experiment that sets out to test the validity of this second sum rule by measuring the interference patterns produced by three slits and all the possible combinations of those slits being open or closed. We use either attenuated laser light or a heralded single photon source (using parametric down conversion) combined with single photon counting to confirm the single photon character of the measured light. [Preview Abstract] |
Monday, March 16, 2009 3:30PM - 3:42PM |
D17.00004: Cartan Involutions in Quantum Information Peter Love We discuss some applications of Cartan decompositions and the corresponding involutions of the unitary group in quantum information theory. Recently, such involutions were used to obtain a constructive quantum Shannon decomposition with an application to quantum circuits. We will discuss some practical aspects of the use of this decomposition to obtain circuits for arbitrary unitary matrices. We discuss further applications of these techniques to the computation of mixed state entanglement and the parameterization of quantum operations on open systems. [Preview Abstract] |
Monday, March 16, 2009 3:42PM - 4:18PM |
D17.00005: Quantum Foundations of Quantum Information Invited Speaker: The main foundational issue for quantum information is: What is quantum information about? What does it refer to? Classical information typically refers to physical properties, and since classical is a subset of quantum information (assuming the world is quantum mechanical), quantum information should--and, it will be argued, does--refer to quantum physical properties represented by projectors on appropriate subspaces of a quantum Hilbert space. All sorts of microscopic and macroscopic properties, not just measurement outcomes, can be represented in this way, and are thus a proper subject of quantum information. The Stern-Gerlach experiment illustrates this. When properties are compatible, which is to say their projectors commute, Shannon's classical information theory based on statistical correlations extends without difficulty or change to the quantum case. When projectors do not commute, giving rise to characteristic quantum effects, a foundation for the subject can still be constructed by replacing the ``measurement and wave-function collapse'' found in textbooks--an efficient calculational tool, but one giving rise to numerous conceptual difficulties--with a fully consistent and paradox free stochastic formulation of standard quantum mechanics. This formulation is particularly helpful in that it contains no nonlocal superluminal influences; the reason the latter carry no information is that they do not exist. [Preview Abstract] |
Monday, March 16, 2009 4:18PM - 4:30PM |
D17.00006: Measuring the distance between unitary propagators of quantum systems of differing dimensions Matthew Grace, Jason Dominy, Robert Kosut, Constantin Brif, Herschel Rabitz In this work, we develop a general distance measure that evaluates the distance between unitary quantum operations of differing dimensions which is (i) independent of the initial state of the system, (ii) straightforward to numerically calculate, and, most importantly, (iii) designed to directly evaluate quantum operations resulting from open-system dynamics. This measure is a natural extension of distance and corresponding fidelity measures employed in previous works that construct closed-system unitary operations. The properties of this measure are desirable for the calculation of distance, e.g., optimal control applied to open systems for quantum information processing, and enable a consistent comparison of quantum operations resulting from both closed- and open-system dynamics. As a numerical example, this distance measure is used to evaluate the fidelity of quantum operations resulting from the optimal control of one- and two-qubit unitary operations in the presence of a decohering environment. This example illustrates the utility of this measure for use in designing unitary quantum operations from open-system dynamics. [Preview Abstract] |
Monday, March 16, 2009 4:30PM - 4:42PM |
D17.00007: Riemannian Curvature in Quantum Computational Geometry Howard Brandt In the Riemannian geometry of quantum computation [1]-[3], the quantum evolution is described in terms of the special unitary group of n-qubit unitary operators with unit determinant. To elaborate on one aspect of the methodology, the Riemannian curvature on the group manifold is explicitly derived using the associated Lie algebra. This is important for investigations of the global characteristics of geodesic paths in the group manifold. [1] M. R. Dowling and M. A. Nielsen, ``The Geometry of Quantum Computation,'' \textit{Quantum Information and Computation} \textbf{8}, 0861-0899 (2008). [2] H. E. Brandt, ``Riemannian Geometry of Quantum Computation,'' to appear in \textit{Nonlinear Analysis} (2008). [3] H. E. Brandt, ``Riemannian Geometry of Quantum Computation,'' AMS Short Course Lecture, to appear in Proc. Symposia in Applied Mathematics., American Mathematical Society (2009). [Preview Abstract] |
Monday, March 16, 2009 4:42PM - 4:54PM |
D17.00008: Closed timelike curves enable perfect state distinguishability Todd A. Brun, Jim Harrington, Mark M. Wilde The causal self-consistency condition for closed timelike curves can give rise to nonlinear interactions on chronology-respecting qubits. We demonstrate that particular unitary interactions between closed timelike curve qubits and chronology-respecting qubits allow perfect distinguishability of nonorthogonal states, and provide a constructive proof for an arbitrary number of nonorthogonal states. This has a number of highly significant consequences. For example, an adversary with access to closed timelike curves can break the B92, BB84, and SARG04 quantum key distribution protocols, or any prepare-and-measure quantum key distribution scheme. Our result also implies that a party with access to closed timelike curves can violate the Holevo bound by accessing more than $\log(N)$ bits of information from an $N$-dimensional quantum state. In principle, he can transmit an arbitrarily large amount of classical information with a quantum system of fixed size. We discuss the implications of this for quantum cloning. [Preview Abstract] |
Monday, March 16, 2009 4:54PM - 5:06PM |
D17.00009: Experimental Basis for IED Particle Model J. Zheng-Johansson The internally electrodynamic (IED) particle model is built on three experimental facts: a) electric charges present in all matter particles, b) an accelerated charge generates electromagnetic (EM) waves by Maxwell's equations and Planck energy equation, and c) source motion gives Doppler effect. A set of well-kwon basic particle equations have been predicted based on first-principles solutions for IED particle (e.g. J Phys CS{\bf 128}, 012019, 2008); the equations are long experimentally validated. A critical review of the key experiments suggests that the IED process underlies these equations not just sufficiently but also necessarily. E.g.: 1) A free IED electron solution is a plane wave $\psi \dot{=} Ce^{i(k_d X-\omega T)}$ requisite for producing the diffraction fringe in a Davisson-Germer experiment, and of also all basic point-like attributes facilitated by a linear momentum $\hbar k_d $ and the model structure. It needs not further be a wave packet which produces not a diffraction fringe. 2)The radial partial EM waves, hence the total $\psi$, of an IED electron will, on both EM theory and experiment basis -not by assumption, enter two slits at the {\it same} time, as is requisite for an electron to interfere with itself as shown in double slit experiments. 3) On annihilation, an electron converts (from mass $m$) to a radiation energy $\hbar \omega$ without an acceleration which is externally observable and yet requisite by EM theory. So a charge oscillation of frequency $\omega$ and its EM waves must regularly present internal of a normal electron, whence the IED model. [Preview Abstract] |
Monday, March 16, 2009 5:06PM - 5:18PM |
D17.00010: ABSTRACT WITHDRAWN |
Monday, March 16, 2009 5:18PM - 5:30PM |
D17.00011: Quantum entanglement and informational activities of biomolecules Hanan Al-Shargi, Simon Berkovich Our model of holographic Universe [1] explains the surprising property of quantum entanglement and reveals its biological implications. The suggested holographic mechanism handles 2D slices of the physical world as a whole. Fitting this simple holistic process in the Procrustean bed of individual particles interactions leads to intricacies of quantum theory with an unintelligible protrusion of distant correlations. Holographic medium imposes dependence of quantum effects on absolute positioning. Testing this prediction for a non-exponential radioactive decay could resolutely point to outside ``memory.'' The essence of Life is in the sophistication of macromolecules. Distinctions in biological information processing of nucleotides in DNA and amino acids in proteins are related to entropies of their structures. Randomness of genetic configurations as exposed by their maximal entropy is characteristic of passive identification rather than active storage functionality. Structural redundancy of proteins shows their operability, of which different foldings of prions is most indicative. Folding of one prion can reshape another prion without a direct contact appearing like ``quantum entanglement,'' or ``teleportation.'' Testing the surmised influence of absolute orientation on the prion reshaping can uncover the latency effects in the ``mad cow'' disease. 1. Simon Berkovich, TR-GWU-CS-07-006, http://www.cs.gwu.edu/research/reports.php [Preview Abstract] |
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