Defect CFT techniques in the 6d $$ \mathcal{N} $$ = (2, 0) theory

Surface operators are among the most important observables of the 6d $$ \mathcal{N} $$ N = (2, 0) theory. Here we apply the tools of defect CFT to study local operator insertions into the 1/2-BPS plane. We first relate the 2-point function of the displacement operator to the expectation value of the bulk stress tensor and translate this relation into a constraint on the anomaly coefficients associated with the defect. Secondly, we study the defect operator expansion of the stress tensor multiplet and identify several new operators of the defect CFT. Technical results derived along the way include the explicit supersymmetry tranformations of the stress tensor multiplet and the classification of unitary representations of the superconformal algebra preserved by the defect.

The multi-faceted inverted harmonic oscillator: Chaos and complexity

The harmonic oscillator is the paragon of physical models; conceptually and computationally simple, yet rich enough to teach us about physics on scales that span classical mechanics to quantum field theory. This multifaceted nature extends also to its inverted counterpart, in which the oscillator frequency is analytically continued to pure imaginary values. In this article we probe the inverted harmonic oscillator (IHO) with recently developed quantum chaos diagnostics such as the out-of-time-order correlator (OTOC) and the circuit complexity. In particular, we study the OTOC for the displacement operator of the IHO with and without a non-Gaussian cubic perturbation to explore genuine and quasi scrambling respectively. In addition, we compute the full quantum Lyapunov spectrum for the inverted oscillator, finding a paired structure among the Lyapunov exponents. We also use the Heisenberg group to compute the complexity for the time evolved displacement operator, which displays chaotic behaviour. Finally, we extended our analysis to N-inverted harmonic oscillators to study the behaviour of complexity at the different timescales encoded in dissipation, scrambling and asymptotic regimes.

Introduction, generation and entanglement of entangled displaced even and odd squeezed states

In this paper, first, we introduce special types of entangled quantum states named “entangled displaced even and odd squeezed states” by using displaced even and odd squeezed states which are constructed via the action of displacement operator on the even and odd squeezed states, respectively. Next, we present a theoretical scheme to generate the introduced entangled states. This scheme is based on the interaction between a [Formula: see text]-type three-level atom and a two-mode quantized field in the presence of two strong classical fields. In the continuation, we consider the entanglement feature of the introduced entangled states by evaluating concurrence. Moreover, we study the influence of the displacement parameter on the entanglement degree of the introduced entangled states and compare the results. It will be observed that the concurrence of the “entangled displaced odd squeezed states” has less decrement with respect to the “entangled displaced even squeezed states” by increasing the displacement parameter.

Generation of various classes of entangled states in a two-mode Bose–Einstein condensate under the influence of interatom collisions

In this paper, we generate some new classes of entangled states of a bimodal Bose–Einstein condensate (BEC), a pair of tunnel-coupled BEC, in the presence of two- and three-body elastic as well as mode-exchange collisions. The Hamiltonian of the considered system is very complicated, moreover, it can be fortunately transformed into a simple form using a two-mode displacement operator. After introducing the general form of the time evolved state, various classes of entangled states are generated. Indeed, the influence of different orders of tunneling strengths on the generated entangled states has been studied. Depending on the tunneling strength constants, two-, three- and four-partite entangled states are generated, all of which are superposition states of macroscopic number of BEC atoms. Considering three-particle collision dramatically changes the generated entangled states. Moreover, in particular cases, the resulted states are non-entangled. Also, we show that tunneling and collisional interactions can be manipulated to generate a pair of atomic entangled coherent states (quasi-Bell states). In addition, it is observed that the degree of entanglement for two-partite entangled states can be tuned via the number of BEC atoms, i.e. the corresponding concurrences tend to their maximum value by increasing the atoms in both modes of system.

Displacement and visualization of point symbols based on spatial distribution characteristics

<p><strong>Abstract.</strong> In WEB2.0 environment, the number of map-based mashups which display user-led POI data keeps increasing. When the cartographic processing of these map mashups is lacking, the display of the POI data showed on the maps are quite unsatisfactory because of the overlapping of symbols.</p><p>At present, some widely used methods commonly use selection and simplification operations based on a quadtree data structure, which can get a good result in the small and medium scales in which users mainly focus on the distribution characteristics and the density difference of POI, but will lose a lot of information in the large scales in which users mainly focus on the specific location and detailed information of the data. For example, two hotels with the same size will retain only one symbol after using selection or simplification operation although in the large scale if they are adjacent to each other, which will bring trouble to users when using maps. Displacement is a suitable operation to deal with this situation, however, current displacement methods face the problems of symbol position drift and nevertheless the loss of information in high-density areas.</p><p>In order to address these problems, this paper proposes a real-time POI visualization algorithm combining the characteristics of traditional quadtree data structure and the advantages of an improved displacement operator.</p>

Geometric momentum and angular momentum for charge-monopole system

For a charge-monopole pair, we have another definition of the orbital angular momentum, and the transverse part of the momentum including the vector potential turns out to be the so-called geometric momentum that is under intensive study recently. For the charge on the spherical surface with the monopole at the origin, the commutation relations between all components of both the geometric momentum and the orbital angular momentum satisfy the so(3,[Formula: see text]1) algebra. With construction of the geometrically infinitesimal displacement operator based on the geometric momentum, the so(3,[Formula: see text]1) algebra implies the Aharonov–Bohm phase shift. The related problems such as charge and flux quantization are also addressed.