5,203 research outputs found
Classical and quantum behavior of dynamical systems defined by functions of solvable Hamiltonians
We discuss the classical and quantum mechanical evolution of systems
described by a Hamiltonian that is a function of a solvable one, both
classically and quantum mechanically. The case in which the solvable
Hamiltonian corresponds to the harmonic oscillator is emphasized. We show that,
in spite of the similarities at the classical level, the quantum evolution is
very different. In particular, this difference is important in constructing
coherent states, which is impossible in most cases. The class of Hamiltonians
we consider is interesting due to its pedagogical value and its applicability
to some open research problems in quantum optics and quantum gravity.Comment: Accepted for publication in American Journal of Physic
Mobile Solar Energy Environmental Control System with Remote Accessibility
The proposed system, Mobile Solar Energy Environmental Control System with Remote Accessibility (mSEECS w/ RA), is based on the utilization of an already available Energy Storage Unit (ESU) in a Transport Unit System (TUS) to harness solar energy to provide a system to enhance the environment, safety and security of a TUS in a stationary or a mobile state by monitoring and controlling the operation of its onboard systems, and provide remote accessibility to know the state of affairs at any time. To relate to a real world application, the battery (ESU) of a vehicle (TUS) is underutilized most of the time while being stationary in a parking lot. Adding a solar panel to the vehicle with a charge controller provides a charging mechanism for the already installed battery. This allows for the operation of onboard systems, such as air circulation and surveillance, which are normally shutdown to avoid draining the battery. However, this calls for a sophisticated control and monitoring system which needs to monitor the battery to avoid draining it beyond a certain percent depending on the type of battery, control onboard systems to keep them operational at a specified level, and at the same time send alerts and provide remote access to users. Using a Raspberry Pi (RPi), a small hardened computer system, with add-on sensors to gauge key environmental variables, data can be retrieved from customized inputs and thresholds to generate signals to trigger other subsystems
Elasticae in Killing submersions
Classical elastic curves (elastica) are variational objects with many applications in physics and engineering. Elastica in real space forms are well understood, but in other ambient spaces there are few known explicit examples, except geodesics. In this work, we study elastica living in the total space of a Killing submersion focusing on those curves whose osculating plane forms a constant angle with the vertical foliation (slant elastica). First, we compute the Euler–Lagrange equations for elastica and construct new examples of slant elastica in Killing submersions. Then, we completely classify the two main families of slant elastica in Bianchi–Cartan–Vranceanu ambient spaces (giving also explicit parametrizations)
Wormholes as Basis for the Hilbert Space in Lorentzian Gravity
We carry out to completion the quantization of a Friedmann-Robertson-Walker
model provided with a conformal scalar field, and of a Kantowski-Sachs
spacetime minimally coupled to a massless scalar field. We prove that the
Hilbert space determined by the reality conditions that correspond to
Lorentzian gravity admits a basis of wormhole wave functions. This result
implies that the vector space spanned by the quantum wormholes can be equipped
with an unique inner product by demanding an adequate set of Lorentzian reality
conditions, and that the Hilbert space of wormholes obtained in this way can be
identified with the whole Hilbert space of physical states for Lorentzian
gravity. In particular, all the normalizable quantum states can then be
interpreted as superpositions of wormholes. For each of the models considered
here, we finally show that the physical Hilbert space is separable by
constructing a discrete orthonormal basis of wormhole solutions.Comment: 23 pages (Latex), Preprint IMAFF-RC-04-94, CGPG-94/5-
Updatable Blockchains
Software updates for blockchain systems become a real challenge when they impact the underlying consensus mechanism.
The activation of such changes might jeopardize the integrity of the blockchain by resulting in chain splits. Moreover, the software update process should be handed over to the community and this means that the blockchain should support updates without relying on a trusted party.
In this paper, we introduce the notion of updatable blockchains and show how to construct blockchains that satisfy this definition. Informally, an updatable blockchain is a secure blockchain and in addition it allows to update its protocol preserving the history of the chain.
In this work, we focus only on the processes that allow securely switching from one blockchain protocol to another assuming that the blockchain protocols are correct. That is, we do not aim at providing a mechanism that allows reaching consensus on what is the code of the new blockchain protocol. We just assume that such a mechanism exists (like the one proposed in NDSS 2019 by Zhang et. al), and show how to securely go from the old protocol to the new one.
The contribution of this paper can be summarized as follows. We provide the first formal definition of updatable ledgers and propose the description of two compilers. These compilers take a blockchain and turn it into an updatable blockchain.
The first compiler requires the structure of the current and the updated blockchain to be very similar (only the structure of the blocks can be different) but it allows for an update process more simple, efficient.
The second compiler that we propose is very generic (i.e., makes few assumptions on the similarities between the structure of the current blockchain and the update blockchain). The drawback of this compiler is that it requires the new blockchain to be resilient against a specific adversarial behaviour and requires all the honest parties to be online during the update process.
However, we show how to get rid of the latest requirement (the honest parties being online during the update) in the case of proof-of-work and proof-of-stake ledgers
Probing Quantized Einstein-Rosen Waves with Massless Scalar Matter
The purpose of this paper is to discuss in detail the use of scalar matter
coupled to linearly polarized Einstein-Rosen waves as a probe to study quantum
gravity in the restricted setting provided by this symmetry reduction of
general relativity. We will obtain the relevant Hamiltonian and quantize it
with the techniques already used for the purely gravitational case. Finally we
will discuss the use of particle-like modes of the quantized fields to
operationally explore some of the features of quantum gravity within this
framework. Specifically we will study two-point functions, the Newton-Wigner
propagator, and radial wave functions for one-particle states.Comment: Accepted for publication in Physical Review
Quantum Electromagnetic Wormholes and Geometrical Description of the Electric Charge
I present and discuss a class of solutions of the Wheeler-de Witt equation
describing wormholes generated by coupling of gravity to the electromagnetic
field for Kantowski-Sachs and Bianchi I spacetimes. Since the electric charge
can be viewed as electric lines of force trapped in a finite region of
spacetime, these solutions can be interpreted as the quantum corresponding of
the Ein\-stein\--Ro\-sen\--Mis\-ner\--Whee\-ler electromagnetic geon.Comment: 13 pages, PLAIN TEX, Report No: SISSA 92/94/A (to appear in Phys.
Rev. D15
Pure States, Mixed States and Hawking Problem in Generalized Quantum Mechanics
This paper is the continuation of a study into the information paradox
problem started by the author in his earlier works. As previously, the key
instrument is a deformed density matrix in quantum mechanics of the early
universe. It is assumed that the latter represents quantum mechanics with
fundamental length. It is demonstrated that the obtained results agree well
with the canonical viewpoint that in the processes involving black holes pure
states go to the mixed ones in the assumption that all measurements are
performed by the observer in a well-known quantum mechanics. Also it is shown
that high entropy for Planck remnants of black holes appearing in the
assumption of the Generalized Uncertainty Relations may be explained within the
scope of the density matrix entropy introduced by the author previously. It is
noted that the suggested paradigm is consistent with the Holographic Principle.
Because of this, a conjecture is made about the possibility for obtaining the
Generalized Uncertainty Relations from the covariant entropy bound at high
energies in the same way as R. Bousso has derived Heisenberg uncertainty
principle for the flat space.Comment: 12 pages,no figures,some corrections,new reference
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En torno a la economÃa polÃtica de la exclusión social en Colombia
Colombia is a society with grave problems of social exclusion. However it is possible to work toward social inclusion if the political and economic forces of the country restructured democratically. It is necessary to create a comprehensive system of social protection and social security, adjust public finances, establish justice and defense as the two pillars of a state based on law enforcement, work toward economic and political democratization, without interrupting the development of the market regime with appropriate regulation of the State. It is only possible to construct a political, economical and social democracy with a profound social transformation.social exclusion, economic development, democracy, social transformation
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