摘要:

We review the formulation of quantum mechanics for identical spinning particles with wavefunctions that are singlevalued when permuted configurations are identified. The identification requires the spins to be smoothly permuted along with position variables, so spin is represented in a position-dependent ‘transported basis’, rather than the usual fixed basis. The simplest transported basis, constructed in terms of spins represented as pairs of commuting harmonic oscillators, gives the correct connection between spin and statistics. More complicated constructions can give the wrong exchange sign. The theory is generalized to incorporate additional properties such as isospin, color and strangeness. Some remarks about the relation between this approach and those based on relatitivity and/or field theory are given. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1337708

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We review the main aspects of entanglement and we prove some general theorems concerning entangled states. In order to satisfy the symmetry requirements for systems containing identical constituents one is unavoidably led to consider entangled states. One could then naively conclude that the identity gives rise, by itself, to peculiar and problematic aspects of physical systems. This is by no means the case: the symmetrization or antisymmetrization of factorized states is an absolutely benign procedure and does not pose any specific conceptual problem apart from the one of the impossibility of attributing their elemetary constituents to one or another of two far-away systems. We briefly reconsider the same problem within the context of recently proposed models of dynamical reduction based on nonlinear and stochastic modifications of the standard evolution. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1337709

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

In the frame of a general scheme aimed to relate dynamical algebras with quantum statistics, the possibility is discussed that interacting fermions may be described by the dynamical algebraosp(2|2)instead ofh(1|1).This is exemplified by the application to superconductivity, for which the analogue in the new scheme of the BCS theory is constructed. The results are quite similar, showing that the proposed description of fermions is consistent also with such a complex phenomenology. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1337710

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Quantum Field Theory formulated in terms of hermitian fields automatically leads to a spin-statistics connection when invariance under rotations is required. In three (or more) dimensions of space this implies Bose statistics for integer spin fields and Fermi statistics for half-integer spin fields. One should recall that spin-1/2 fields in three dimensions have two nonhermitian or four hermitian components. This automatic doubling of the number of components enables one to define a pseudoscalar matrix, and this in turn allows one to prove the TCP theorem for rotationally invariant field theories. In two space dimensions one obtains anyon statistics independent of the “spin”. For the quantum mechanics of identical particles we obtain only the possibility of either statistics for either spin as long as the spatial dimension is three (or higher). For two space dimensions we get anyon statistics. This difference is due to the contractibility of closed loops in three or more dimensions. The relation to the arguments of Broyles, of Bacry, and of Berry and Robbins is discussed. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1337711

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

In this paper I first survey some of the peculiar features of quantum statistics in quantum field theory. I then discuss the possibility of building known particles from bosons bound to monopoles. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1337712

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The role of the background in bosonic quantum statistics is discussed in the frame of a new approach in terms of coherent states. Bose gas is not the only physical situation where bosons are detected. In particle physics bosons are dealt with in a context where the number of observed particles is finite: here the relevant feature are the canonical commutation relations, which we shall show to be related to a Boltzmann-like distribution. A further case is Bose condensate in harmonic traps, where discrete spectrum leads us to predict a new critical temperature. All these cases are analyzed in the unified approach proposed, showing that all differences can be ascribed to the role of the background. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1337713

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We give a group-theoretical generalization of Berry and Robbins’ treatment of identical particles with spin. The original construction, which leads to the correct spin-statistics relation, is seen to arise from particular irreducible representations—the totally symmetric representations—of the group SU(4). Here we calculate the exchange signs and corresponding statistics for all irreducible representations of SU(4). ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1337714

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The connection between the Pauli spin-statistics theorem, parastatistics, and quasiparticles is discussed. Although all elementary particles known at present are bosons or fermions, the parastatistics can be realized for quasiparticles. As was shown by author [13], the quasiparticles in a periodical lattice (the Frenkel excitons and magnons) obey the modified parafermi statistics. This result was extended recently to delocalized hole [17] and hole pairs in highTcsuperconducting ceramics [18]. The properties of quasiparticle system obeying the modified parafermi statistics are analyzed. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1337715

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Explicit expressions are derived for the action of all conjugacy classsums of the symmetric group within the space spanned bynidentical spin-1/2 particles, in terms of the total spin operator. For identical particles with elementary spin &sgr; all conjugacy class-sums are presented in terms of the lowest 2&sgr; single cycle conjugacy class-sums. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1337716

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

In the talk, I briefly demonstrate the quantum theory for mesoscopic electric circuits and its applications. In the theory, the importance of the charge discreteness in a mesoscopic electric circuit is addressed. As a result, a new kind of commutation relation for electric charge and current occurred inevitably. The charge representation, canonical current representation and pseudo-current representation are discussed extensively. It not only provides a concrete realization of mathematical models which discuss the space quantization in high energy physics and quantum gravity but also presents a sequence of applications in condensed matter physics from a different point of view. A possible generalization to coupled circuits is also proposed. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1337717

出版商:AIP    

年代:1900

数据来源: AIP