arXiv subjects

Christian Rupp

Publications and source records attributed to Christian Rupp.

9 recordsLinked to original sources

arXiv2023

Triggered telecom C-band single-photon source with high brightness, high indistinguishability and sub-GHz spectral linewidth

Long-range, terrestrial quantum networks will require high brightness single-photon sources emitting in the telecom C-band for maximum transmission rate. Many applications additionally demand triggered operation with high indistinguishability and narrow spectral linewidth. This would enable the efficient implementation of photonic gate operations and photon storage in quantum memories, as for instance required for a quantum repeater. Especially, semiconductor quantum dots (QDs) have shown these properties in the near-infrared regime. However, the simultaneous demonstration of all these properties in the telecom C-band has been elusive. Here, we present a coherently (incoherently) optically-pumped narrow-band (0.8 GHz) triggered single-photon source in the telecom C-band. The source shows simultaneously high single-photon purity with $g^{(2)}(0) = 0.026$ ($g^{(2)}(0) = 0.014$), high two-photon interference visibility of 0.508 (0.664) and high application-ready rates of 0.75 MHz (1.45 MHz) of polarized photons. The source is based on a QD coupled to a circular Bragg grating cavity combined with spectral filtering. Coherent (incoherent) operation is performed via the novel SUPER scheme (phonon-assisted excitation).

quant-ph↗

arXiv2002

Renormalization of the Minimal Supersymmetric Standard Model

The renormalization of the Minimal Supersymmetric Standard Model (MSSM) is presented. We describe symmetry identities that constitute a framework in which the MSSM is completely characterized and renormalizability can be proven. Furthermore, we discuss applications of this framework for the determination of symmetry-restoring counterterms, the gauge dependence of tan(beta) and the derivation of non-renormalization theorems.

hep-ph↗

arXiv2002

Renormalization of the Minimal Supersymmetric Standard Model

The renormalization of the Minimal Supersymmetric Standard Model of electroweak interactions is presented to all orders of perturbation theory using the algebraic method. Special attention is directed to the issues of soft supersymmetry breaking, gauge fixing, and infrared finiteness. We discuss the implications of $\hbar$-dependent field parametrizations on the counterterm structure and provide a complete set of on-shell normalization conditions.

hep-ph↗

arXiv2002

Supercurrent and Local Coupling in the Wess-Zumino Model

We study the Wess-Zumino model with the coupling extended to a chiral superfield. In order to incorporate the renormalization effects a further external real field has to be introduced. It is then possible to derive a Callan-Symanzik equation and to prove renormalizability. By constructing the supercurrent in this context the whole machinery for describing the superconformal symmetries becomes available. The presence of the external fields allows also to define multiple insertions of all relevant composite operators. Interesting relations to the curved superspace treatment show up.

hep-th↗

arXiv2001

Supersymmetry Transformation of Quantum Fields

In the Wess-Zumino gauge, supersymmetry transformations become non-linear and are usually incorporated together with BRS transformations in the form of Slavnov-Taylor identities, such that they appear at first sight to be even non-local. Furthermore, the gauge fixing term breaks supersymmetry. In the present paper, we clarify in which sense supersymmetry is still a symmetry of the system and how it is realized on the level of quantum fields.

hep-th↗

arXiv1999

Conformal Transformation Properties of the B-type Supercurrent

We investigate the superconformal transformation properties of the supercurrent as well as of the superconformal anomalies themselves in d=4, N=1 supersymmetric quantum field theory. Matter supercurrent and anomalies are coupled to a classical background of minimal supergravity fields. On flat superspace, there exist two different types of the superconformal Ward identity (called S and B) which correspond to the flat space limits of old resp. new minimal background supergravity fields. In the present publication we give particular importance to the new minimal case. A general formalism is set up which is then applied to the massless Wess-Zumino model.

hep-th↗

arXiv1998

Superconformal Ward Identities for Green Functions with Multiple Supercurrent Insertions

Superconformal Ward identities for N=1 supersymmetric quantum field theories in four dimensions are convenienty obtained in the superfield formalism by combining diffeomorphisms and Weyl transformations on curved superspace. Using this approach we study the superconformal transformation properties of Green functions with one or more insertions of the supercurrent to all orders in perturbation theory. For the case of two insertions we pay particular attention to fixing the additional counterterms present, as well as to the purely geometrical anomalies which contribute to the transformation behaviour. Moreover we show in a scheme-independent way how the quasi-local terms in the Ward identities are related to similar terms which contribute to the supercurrent two and three point functions. Furthermore we relate our superfield approach to similar studies which use the component formalism by discussing the implications of our approach for the components of the supercurrent and of the supergravity prepotentials.

hep-th↗

arXiv1998

Geometrical Superconformal Anomalies

We determine the structure of geometrical superconformal anomalies for N=1 supersymmetric quantum field theories on curved superspace to all orders in h bar. For the massless Wess-Zumino model we show how these anomalies contribute to the local Callan-Symanzik equation which expresses the breakdown of superconformal symmetry in terms of the usual beta and gamma functions.

hep-th↗

arXiv1998

Conformal Transformation Properties of the Supercurrent in Four Dimensional Supersymmetric Theories

We investigate the superconformal transformation properties of Green functions with one or more insertions of the supercurrent in N=1 supersymmetric quantum field theories. These Green functions are conveniently obtained by coupling the supercurrent and its trace to a classical supergravity background. We derive flat space superconformal Ward identities from diffeomorphisms and Weyl transformations on curved superspace. For the classification of potential quantum superconformal anomalies in the massless Wess-Zumino model on curved superspace a perturbative approach is pursued, using the BPHZ scheme for renormalisation. By deriving a local Callan-Symanzik equation the usual dilatational anomalies are identified and it is shown that no further superconformal anomalies involving the dynamical fields are present.

hep-th↗