11,112 research outputs found

### The Static Quantum Multiverse

We consider the multiverse in the intrinsically quantum mechanical framework
recently proposed in Refs. [1,2]. By requiring that the principles of quantum
mechanics are universally valid and that physical predictions do not depend on
the reference frame one chooses to describe the multiverse, we find that the
multiverse state must be static---in particular, the multiverse does not have a
beginning or end. We argue that, despite its naive appearance, this does not
contradict observation, including the fact that we observe that time flows in a
definite direction. Selecting the multiverse state is ultimately boiled down to
finding normalizable solutions to certain zero-eigenvalue equations, analogous
to the case of the hydrogen atom. Unambiguous physical predictions would then
follow, according to the rules of quantum mechanics.Comment: 27 pages, 2 figures; a typo in the abstract correcte

### The q-harmonic oscillators, q-coherent states and the q-symplecton

The recently introduced notion of a quantum group is discussed conceptually and then related to deformed harmonic oscillators ('q-harmonic oscillators'). Two developments in applying q-harmonic oscillators are reviewed: q-coherent states and the q-symplecton

### Covariant - tensor method for quantum groups and applications I: $SU(2)_{q}$

A covariant - tensor method for $SU(2)_{q}$ is described. This tensor method
is used to calculate q - deformed Clebsch - Gordan coefficients. The connection
with covariant oscillators and irreducible tensor operators is established.
This approach can be extended to other quantum groups.Comment: 18 page

### Airport management in Japan: any lessons learnt from the UK?

The aim of this paper is to examine the possible involvement of private sector airport management in Japan, particularly at Kansai Airport. A comparison is undertaken with the UK airport industry, as some parallels can be drawn with this country around the 1990s when it went through a period of aviation liberalisation and privatisation of its airports. The findings suggest that private sector involvement in Japan has the potential to be successful, arguably as in the UK, and may help overcome certain problems facing Japanese airports, especially those associated with the funding system and lack of integrated airport management models. Financial problems at the airports, however, and especially the huge debt at Kansai, are likely to make it challenging to attract the private sector investors that are needed

### $SU(2)/Z_2$ symmetry of the BKT transition and twisted boundary conditio n

Berezinskii-Kosterlitz-Thouless (BKT) transition, the transition of the 2D
sine-Gordon model, plays an important role in the low dimensional physics. We
relate the operator content of the BKT transition to that of the SU(2)
Wess-Zumino-Witten model, using twisted boundary conditions. With this method,
in order to determine the BKT critical point, we can use the level crossing of
the lower excitations than the periodic boundary case, thus the convergence to
the transition point is highly improved. Then we verify the efficiency of this
method by applying to the S=1,2 spin chains.Comment: LaTex2e,, 33 pages, 14 figures in eps file

### On the spectroscopy of quantum dots in microcavities

At the occasion of the OECS conference in Madrid, we give a succinct account
of some recent predictions in the spectroscopy of a quantum dot in a
microcavity that remain to be observed experimentally, sometimes within the
reach of the current state of the art.Comment: OECS11 Conference proceedings, in editor style. 4 pages, 1 figure.
Animations provided separatel

### How to distinguish the Haldane/Large-D state and the intermediate-D state in an S=2 quantum spin chain with the XXZ and on-site anisotropies

We numerically investigate the ground-state phase diagram of an S=2 quantum
spin chain with the $XXZ$ and on-site anisotropies described by ${\mathcal
H}=\sum_j (S_j^x S_{j+1}^x+S_j^y S_{j+1}^y+\Delta S_j^z S_{j+1}^z) + D \sum_j
(S_j^z)^2$, where $\Delta$ denotes the XXZ anisotropy parameter of the
nearest-neighbor interactions and $D$ the on-site anisotropy parameter. We
restrict ourselves to the $\Delta>0$ and $D>0$ case for simplicity. Our main
purpose is to obtain the definite conclusion whether there exists or not the
intermediate-$D$ (ID) phase, which was proposed by Oshikawa in 1992 and has
been believed to be absent since the DMRG studies in the latter half of 1990's.
In the phase diagram with $\Delta>0$ and $D>0$ there appear the XY state, the
Haldane state, the ID state, the large-$D$ (LD) state and the N\'eel state. In
the analysis of the numerical data it is important to distinguish three gapped
states; the Haldane state, the ID state and the LD state. We give a physical
and intuitive explanation for our level spectroscopy method how to distinguish
these three phases.Comment: Proceedings of "International Conference on Frustration in Condensed
Matter (ICFCM)" (Jan. 11-14, 2011, Sendai, Japan

### Incommensurability and edge states in the one-dimensional S=1 bilinear-biquadratic model

Commensurate-incommensurate change on the one-dimensional S=1
bilinear-biquadratic model (${\cal H}(\alpha)=\sum_i \{{\bf S}_i\cdot {\bf
S}_{i+1} +\alpha ({\bf S}_i\cdot{\bf S}_{i+1})^2\}$) is examined. The gapped
Haldane phase has two subphases (the commensurate Haldane subphase and the
incommensurate Haldane subphase) and the commensurate-incommensurate change
point (the Affleck-Kennedy-Lieb-Tasaki point, $\alpha=1/3$). There have been
two different analytical predictions about the static structure factor in the
neighborhood of this point. By using the S{\o}rensen-Affleck prescription,
these static structure factors are related to the Green functions, and also to
the energy gap behaviors. Numerical calculations support one of the
predictions. Accordingly, the commensurate-incommensurate change is recognized
as a motion of a pair of poles in the complex plane.Comment: 29 pages, 15 figure

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