580 research outputs found
A Test of CPT Symmetry in K^0 vs \bar{K}^0 to \pi^+\pi^-\pi^0 Decays
I show that the CP-violating asymmetry in K^0 vs \bar{K}^0 \to
\pi^+\pi^-\pi^0 decays differs from that in K_L \to \pi^+\pi^-, K_L \to
\pi^0\pi^0 or the semileptonic K_L transitions, if there exists CPT violation
in K^0-\bar{K}^0 mixing. A delicate measurement of this difference at a super
flavor factory (e.g., the \phi factory) will provide us with a robust test of
CPT symmetry in the neutral kaon system.Comment: 4 pages, 1 figure. To appear in the Proceedings of the International
PHIPSI09 Workshop, October 2009, Beijing, Chin
The EPR experiment in the energy-based stochastic reduction framework
We consider the EPR experiment in the energy-based stochastic reduction
framework. A gedanken set up is constructed to model the interaction of the
particles with the measurement devices. The evolution of particles' density
matrix is analytically derived. We compute the dependence of the
disentanglement rate on the parameters of the model, and study the dependence
of the outcome probabilities on the noise trajectories. Finally, we argue that
these trajectories can be regarded as non-local hidden variables.Comment: 11 pages, 5 figure
Coherence of a Josephson phase qubit under partial-collapse measurement
We discuss quantum evolution of a decaying state in relation to a recent
experiment of Katz et al. Based on exact analytical and numerical solutions of
a simple model, we identify a regime where qubit retains coherence over a
finite time interval independently of the rates of three competing decoherence
processes. In this regime, the quantum decay process can be continuously
monitored via a ``weak'' measurement without affecting the qubit coherence.Comment: 4p., 2eps figure
State Measurements with Short Laser Pulses and Lower-Efficiency Photon Detectors
It has been proposed by Cook (Phys. Scr. T 21, 49 (1988)) to use a short
probe laser pulse for state measurements of two-level systems. In previous work
we have investigated to what extent this proposal fulfills the projection
postulate if ideal photon detectors are considered. For detectors with overall
efficiency less than 1 complications arise for single systems, and for this
case we present a simple criterion for a laser pulse to act as a state
measurement and to cause an almost complete state reduction.Comment: 13 pages, LaTeX; submitted to J. mod. Op
Supersymmetry and Lorentz Violation
Supersymmetric field theories can be constructed that violate Lorentz and CPT
symmetry. We illustrate this with some simple examples related to the original
Wess-Zumino model.Comment: 4 page
Towards an Axiomatic Formulation of Noncommutative Quantum Field Theory
We propose new Wightman functions as vacuum expectation values of products of
field operators in the noncommutative space-time. These Wightman functions
involve the -product among the fields, compatible with the twisted
Poincar\'e symmetry of the noncommutative quantum field theory (NC QFT). In the
case of only space-space noncommutativity (), we prove the CPT
theorem using the noncommutative form of the Wightman functions. We also show
that the spin-statistics theorem, demonstrated for the simplest case of a
scalar field, holds in NC QFT within this formalism.Comment: 16 pages, version to appear in J. Math. Phy
Quantum Nondemolition Monitoring of Universal Quantum Computers
The halt scheme for quantum Turing machines, originally proposed by Deutsch,
is reformulated precisely and is proved to work without spoiling the
computation. The ``conflict'' pointed out recently by Myers in the definition
of a universal quantum computer is shown to be only apparent. In the context of
quantum nondemolition (QND) measurement, it is also shown that the output
observable, an observable representing the output of the computation, is a QND
observable and that the halt scheme is equivalent to the QND monitoring of the
output observable.Comment: 5 pages, RevTeX, no figures, revised, to appear in Phys. Rev. Let
CPT Violation, Strings, and Neutral-Meson Systems
This talk provides a short overview of recent results on possible CPT
violation and some associated experimental signatures.Comment: Presented at Orbis Scientiae, January 199
Structural transition in LaVO3/SrVO3 superlattices and its influence on transport properties
Measurements of the resistive properties and the lattice parameters of a
(LaVO3)[6 unit cells]/(SrVO3)[1 unit cell] superlattice between 10K and room
temperature are presented. A low temperature metallic phase compatible with a
Fermi liquid behavior is evidenced. It disappears in the vicinity of a
structural transition from a monoclinic to tetragonal phase, in which disorder
seems to strongly influence the transport. Our results will enrich the
understanding of the electronic properties of complex heterostructures.Comment: accepted in APL 201
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