Biografie

Christian Deppe erhielt den Dipl.-Math. Abschluss in Mathematik von der Universität Bielefeld 1996 und den Dr.-Math. von der Universität Bielefeld 1998. Er war Wissenschaftlicher Mitarbeiter und Assistent an der Fakultät für Mathematik an der Universität" in Bielefeld von 1998 bis 2010. Von 2011 bis 2013 war er Projektleiter des Projektes "Sicherheit und Robustheit des Quanten-Repeaters" vom Bundesministerium für Bildung und Forschung an der Fakultät für Mathematik, Universität Bielefeld. 2014 wurde er durch ein DFG-Projekt am Lehrstuhl für Theoretische Informations Technik, Technische Universität München gefördert. 2015 hatte er eine befristete Professur an der Fakultät für Mathematik und Informatik der Friedrich-Schiller-Universität in Jena. Seit 2018 ist er am Lehrstuhl für Nachrichtentechnik an der Technischen Universität München. Er ist Projektleiter von mehreren Projekten gefördert durch das BMBF, der DFG und dem Freistaates Bayern.

Lehre

• SS 2014 Vorlesung: Datenübertragung mit Rückkopplung
• WS 2014/2015 Vorlesung: Quanteninformationstheorie
• SS 2015 Vorlesung: Berechenbarkeit und Komplexität
• SS 2015 Vorlesung: Informationstheorie
• SS 2015 Vorlesung: Numerische Mathematik - Ergänzungen
• WS 2015/2016 Vorlesung: Quanteninformationstheorie
• SS 2016 Vorlesung: Quantum Information Theory
• WS 2016/2017 Vorlesung: Quanteninformationstheorie
• SS 2018 Vorlesung: Multi User Information Theory
• WS 2018/2019 Vorlesung: Nachrichtentechnik II
• SS 2019 Vorlesung: Multi User Information Theory,
• SS 2019 Vorlesung: Algorithms in Quantum Theory (zusammen mit Roberto Ferrara)
• WS 2019/2020 Vorlesung: Nachrichtentechnik 2
• WS 2019/2020 Vorlesung: Information Theory (zusammen mit Gerhard Kramer)
• SS 2020 Vorlesung: Nachrichtensysteme - Kommunikationssysteme (LB)
• SS 2020 Vorlesung: Multi User Information Theory
• WS 2020/21 Vorlesung: Nachrichtentechnik 2
• SS 2021 Vorlesung: Nachrichtensysteme - Kommunikationssysteme (LB)
• SS 2021 Vorlesung: Multi User Information Theory
• WS 2021/22 Vorlesung: Nachrichtentechnik 2
• SS 2022 Vorlesung: Nachrichtensysteme - Kommunikationssysteme (LB)
• SS 2022 Vorlesung: Post Shannon Theory

Forschung

Secrecy Capacity of Classical - Quantum Channels

Investigation into communication via quantum channels started in the 1960s. Quantum mechanics differs significantly from classical mechanics, it has its own laws. Quantum information theory unifies information theory with quantum mechanic, generalizing classical information theory to the quantum world.

A quantum channel can transmit both classical and quantuminformation. We consider the capacity of quantum channels carrying classical information. This is equivalent toconsidering the capacity of classical-quantum channels, where the classical-quantum channels are quantum channels whose sender’s inputs are classical variables. We determine the secrecy capacity of the several channel with (quantum) wiretapper.

 

Message Transmission under Jamming Attacks

Our goal is to investigate in communication that takes place over a channel which is, in addition to the noise, subjected to the action of a jammer which actively manipulates the channel. A channel with a jammer is called an arbitrarily varying channel, where the jammer may change his input in every channel use and is not restricted to use a repetitive probabilistic strategy. In the model of an arbitrarily varying channel, we consider a channel which is not stationary and can change with every use. We interpret this as an attack of a jammer. It works as follows: the sender and the receiver have to select their coding scheme first. After that the jammer makes his choice to sabotage the message transmission. However, due to the physical properties, we assume that the jammer’s changes only take place in a known set. We consider classical and classical-quantum channels with a jammer and determine the (secrecy) capacity.

 

Identification over Channels

The implementation of this communication in today’s systems mostly based on the communication theory of Shannon. In this communication model, it is always assumed that the receiver’s goal is to decode all messages. Due to this strong goal, the coding scheme is inefficient for some cases. Ahlswede and Dueck have shown that there are more efficient solutions when the recipient’s goal changes. Instead of the decoder wanting to decode the message, he is only interested in whether a specific message has been sent. However, the sender does not know which message is interesting for the receiver. This communication task is called identification. We consider classical and classical-quantum channels with a jammer and determine the (secrecy) identification capacity.

 

Error-Correcting Codes with Feedback

We consider the problem of transmitting messages over a noisy channel with noiseless feedback. A sender wants to transmit a message over a noisy binary channel. We have a passive feedback, that means that the sender always knows what has been received. The i-th code letter depends on the message we want to transmit and the (i-1) symbols which have been received before. We suppose that the noise does not change more than a fixed number of symbols of a codeword. We consider several channel models with partial feedback and limited magnitude and construct coding strategies. Furthermore, we determine the capacity error function for these channels.