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Bobby Eka Gunara

Publications and source records attributed to Bobby Eka Gunara.

45 records · Page 3Linked to original sources
arXiv2019

Fast-forward approach to adiabatic quantum dynamics of regular spin clusters: nature of geometry-dependent driving interactions

The fast forward scheme of adiabatic quantum dynamics is applied to finite regular spin clusters with various geometries and the nature of driving interactions is elucidated. The fast forward is the quasi-adiabatic dynamics guaranteed by regularization terms added to the reference Hamiltonian, followed by a rescaling of time with use of a large scaling factor. With help of the regularization terms consisting of pair-wise and 3-body interactions, we apply the proposed formula (Phys. Rev.A 96, 052106(2017)) to regular triangle and open linear chain for N = 3 spin systems, and to triangular pyramid, square, primary star graph and open linear chain for N = 4 spin systems. The geometry-induced symmetry greatly decreases the rank of coefficient matrix of the linear algebraic equation for regularization terms. Choosing a transverse Ising Hamiltonian as a reference, we find: (1) for N = 3 spin clusters, the driving interaction consists of only the geometry-dependent pairwise interactions and there is no need for the 3-body interaction; (2) for N = 4 spin clusters, the geometry-dependent pair-wise interactions again constitute major part of the driving interaction, whereas the universal 3-body interaction free from the geometry is necessary but plays a subsidiary role. Our scheme predicts the practical driving interaction in accelerating the adiabatic quantum dynamics of structured regular spin clusters.

quant-ph↗
arXiv2018

Self-Gravitating Static Non-Critical Black Holes in 4$D$ Einstein-Klein-Gordon System with Nonminimal Derivative Coupling

We study static non-critical hairy black holes of four dimensional gravitational model with nonminimal derivative coupling and a scalar potential turned on. By taking an ansatz, namely, the first derivative of the scalar field is proportional to square root of a metric function, we reduce the Einstein field equation and the scalar field equation of motions into a single highly nonlinear differential equation. This setup implies that the hair is secondary-like since the scalar charge-like depends on the non-constant mass-like quantity in the asymptotic limit. Then, we show that near boundaries the solution is not the critical point of the scalar potential and the effective geometries become spaces of constant scalar curvature.

hep-th↗
arXiv2018

Fast forward of adiabatic spin dynamics of entangled states

We develop a scheme of fast forward of adiabatic spin dynamics of quantum entangled states. We settle the quasi-adiabatic dynamics by adding the regularization terms to the original Hamiltonian and then accelerate it with use of a large time-scaling factor. Assuming the experimentally-realizable candidate Hamiltonian consisting of the exchange interactions and magnetic field, we solved the regularization terms. These terms multiplied by the velocity function give rise to the state-dependent counter-diabatic terms. The scheme needs neither knowledge of full spectral properties of the system nor solving the initial and boundary value problem. Our fast forward Hamiltonian generates a variety of state-dependent counter-diabatic terms for each of adiabatic states, which can include the state-independent one. We highlight this fact by using minimum (two-spin) models for a simple transverse Ising model, quantum annealing and generation of entanglement.

quant-ph↗
arXiv2015

Existence of Static Dyonic Black Holes in $4d$ $N = 1$ Supergravity With Finite Energy

We prove the existence and the uniqueness of the static dyonic black holes in four dimensional $N=1$ supergravity theory coupled vector and scalar multiplets. We set the near-horizon geometry to be a product of two Einstein surfaces, whereas the asymptotic geometry has to be a space of constant scalar curvature. Using these data, we show that there exist a unique solution for scalar fields which interpolates these regions.

math-ph↗
arXiv2012

Deformation of Dyonic Black Holes and Vacuum Geometries in Four Dimensional N=1 Supergravity

We study some aspects of spherical symmetric dyonic non-supersymmetric black holes in $4d \; N=1$ supergravity coupled to chiral and vector multiplets on Kähler-Ricci solitons. Then, we have a family of dyonic non-supersymmetric black holes deformed with respect to the flow parameter related to the Kähler-Ricci soliton, which possibly controls the nature of black holes, such as their asymptotic and near horizon geometries. Two types of black holes are discussed, namely a family of dyonic Reissner-Nordström-like black holes and Bertotti-Robinson-like black holes where the scalars are freezing all over spacetime and at the horizon, respectively. In addition, the corresponding vacuum structures for such black holes are also studied in the context of Morse-(Bott) theory. Finally, we give some simple $\;{\lC \mathrm{P}}^n$-models whose superpotential and gauge couplings have a linear form.

hep-th↗
arXiv2009

Flat BPS Domain Walls on 2d Kähler-Ricci Soliton

In this paper we address several aspects of flat Bogomolnyi-Prasad-Sommerfeld (BPS) domain walls together with their Lorentz invariant vacua of 4d N=1 supergravity coupled to a chiral multiplet. The scalar field spans a one-parameter family of 2d Kähler manifolds satisfying a Kähler-Ricci flow equation. We find that BPS equations and the scalar potential deform with respect to the real parameter related to the Kähler-Ricci soliton. In addition, the analysis using gradient and renormalization group flows are carried out to ensure the existence of Lorentz invariant vacua related to Anti de Sitter/Conformal Field Theory (AdS/CFT) correspondence.

hep-th↗
arXiv1999

Construction of the Extended Supersymmetry Theory via Semi-Hopf Algebra

We construct the general supersymmetry algebra via the adjoint action on a semi-Hopf algebra which has a more general structure than a Hopf algebra. As a result we have an extended supersymmetry theory with quantum gauge group, i.e., quantised enveloping algebra of a simple Lie algebra. For the example, we construct the N=1 and generalized N=2 supersymmetry theory which leads to the Seiberg-Witten theory.

math-ph↗
arXiv1999

Semi-Hopf Algebra and Supersymmetry

We define a semi-Hopf algebra which is more general than a Hopf algebra. Then we construct the supersymmetry algebra via the adjoint action on this semi-Hopf algebra. As a result we have a supersymmetry theory with quantum gauge group, i.e., quantised enveloping algebra of a simple Lie algebra. For the example, we construct the Lagrangian N=1 and N=2 supersymmetry.

hep-th↗