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Ioannis Raptis

Publications and source records attributed to Ioannis Raptis.

28 records · Page 2Linked to original sources
arXiv2001

`Mixed' Jordan-Lie Superalgebra

An algebra A not encountered in either the usual algebraic varieties or supervarieties is introduced. A is a graded and deformed version of the quaternions, with structure similar to that of a Jordan-Lie superalgebra as defined by Okubo and Kamiya, but it is shown to be neither that of a purely associative Lie superalgebra, nor that of a purely antiassociative Jordan-Lie superalgebra. Rather, it exhibits a novel kind of associativity, here called `ordered graded associativity', that is somewhat `in between' pure associativity and pure antiassociativity. In addition to graded associativity, the generators of A obey graded commutation relations encountered in both the usual Lie superalgebras and in graded Jordan-Lie algebras. They also satisfy new graded Jacobi identities that combine characteristics of the Jacobis obeyed by the generators of ungraded Lie, graded Lie and graded Jordan-Lie algebras. Mainly due to these three features, A is called a `mixed' Jordan-Lie superalgebra. The present paper defines A and compares it with the Jordan-Lie superalgebra defined by Okubo and Kamiya.

math-ph↗
arXiv2001

Algebraic description of spacetime foam

A mathematical formalism for treating spacetime topology as a quantum observable is provided. We describe spacetime foam entirely in algebraic terms. To implement the correspondence principle we express the classical spacetime manifold of general relativity and the commutative coordinates of its events by means of appropriate limit constructions.

gr-qc↗
arXiv2001

Sheafifying Consistent Histories

Isham's topos-theoretic perspective on the logic of the consistent-histories theory is extended in two ways. First, the presheaves of consistent sets of history propositions in the topos proposed by Isham are endowed with a Vietoris-type of topology and subsequently they are sheafified with respect to it. The category resulting from this sheafification procedure is the topos of sheaves of sets varying continuously over the Vietoris-topologized base poset category of Boolean subalgebras of the universal orthoalgebra of quantum history propositions. The second extension of Isham's topos consists in endowing the stalks of the aforementioned sheaves, which were originally inhabited by structureless sets, with further algebraic structure, that also enjoys a quantum causal interpretation, so as to arrive at the topos of consistent-histories of quantum causal sets. The resulting quantum causal histories topos is compared with Markopoulou's quantum causal histories, with Mallios and this author's finitary spacetime sheaves of quantum causal sets, as well as with Butterfield and Isham's topos perspective on the Kochen-Specker theorem of quantum logic.

quant-ph↗
arXiv2001

Finitary Spacetime Sheaves

The notion of finitary spacetime sheaves is introduced based on locally finite approximations of the continuous topology of a bounded region of a spacetime manifold. Finitary spacetime sheaves are seen to be sound mathematical models of approximations of continuous spacetime observables.

gr-qc↗
arXiv2001

Non-Commutative Topology for Curved Quantum Causality

A quantum causal topology is presented. This is modeled after a non-commutative scheme type of theory for the curved finitary spacetime sheaves of the non-abelian incidence Rota algebras that represent `gravitational quantum causal sets'. The finitary spacetime primitive algebra scheme structures for quantum causal sets proposed here are interpreted as the kinematics of a curved and reticular local quantum causality. Dynamics for quantum causal sets is then represented by appropriate scheme morphisms, thus it has a purely categorical description that is manifestly `gauge-independent'. Hence, a schematic version of the Principle of General Covariance of General Relativity is formulated for the dynamically variable quantum causal sets. We compare our non-commutative scheme-theoretic curved quantum causal topology with some recent $C^{*}$-quantale models for non-abelian generalizations of classical commutative topological spaces or locales, as well as with some relevant recent results obtained from applying sheaf and topos-theoretic ideas to quantum logic proper. Motivated by the latter, we organize our finitary spacetime primitive algebra schemes of curved quantum causal sets into a topos-like structure, coined `quantum topos', and argue that it is a sound model of a structure that Selesnick has anticipated to underlie Finkelstein's reticular and curved quantum causal net. At the end we conjecture that the fundamental quantum time-asymmetry that Penrose has expected to be the main characteristic of the elusive `true quantum gravity' is possibly of a kinematical or structural rather than of a dynamical character, and we also discuss the possibility of a unified description of quantum logic and quantum gravity in quantum topos-theoretic terms.

gr-qc↗
arXiv2000

Decomposition of pure states of a quantum register

Using the leading vector method, we show that any vector $h\in(C^2)^{\otimes l}$ can be decomposed as a sum of at most (and at least in the generic case) $2^l-l$ product vectors using local bitwise unitary transformations. The method is based on representing the vectors by chains of appropriate simplicial complex. This generalizes the Scmidt decomposition of pure states of a 2-bit register to registers of arbitrary length $l$.

quant-ph↗
arXiv1999

A Non-Classical Linear Xenomorph as a Model for Quantum Causal Space

A quantum picture of the causal structure of Minkowski space M is presented. The mathematical model employed to this end is a non-classical version of the classical topos {H} of real quaternion algebras used elsewhere to organize the perceptions of spacetime events of a Boolean observer into M. Certain key properties of this new quantum topos are highlighted by contrast against the corresponding ones of its classical counterpart {H} modelling M and are seen to accord with some key features of the algebraically quantized causal set structure.

gr-qc↗
arXiv1999

An Algebraic Quantization of Causal Sets

A scheme for an algebraic quantization of the causal sets of Sorkin et al. is presented. The suggested scenario is along the lines of a similar algebraization and quantum interpretation of finitary topological spaces due to Zapatrin and this author. To be able to apply the latter procedure to causal sets Sorkin's `semantic switch' from `partially ordered sets as finitary topological spaces' to `partially ordered sets as locally finite causal sets' is employed. The result is the definition of `quantum causal sets'. Such a procedure and its resulting definition is physically justified by a property of quantum causal sets that meets Finkelstein's requirement from `quantum causality' to be an immediate, as well as an algebraically represented, relation between events for discrete locality's sake. The quantum causal sets introduced here are shown to have this property by direct use of a result from the algebraization of finitary topological spaces due to Breslav, Parfionov and Zapatrin.

gr-qc↗
arXiv1999

Quantization of discretized spacetimes and the correspondence principle

An algebraic quantization procedure for discretized spacetime models is suggested based on the duality between finitary substitutes and their incidence algebras. The provided limiting procedure that yields conventional manifold characteristics of spacetime structures is interpreted in the algebraic quantum framework as a correspondence principle.

gr-qc↗