**Title: **Photon-pair generation by spontaneous four-wave mixing: Modelling real systems

** **

**Supervisor\n**Principal supervisor: Prof. Karsten Rottwitt, DTU Fotonik

**Evaluation Board\n**Dr. Peter Mosley, University of Bath, UK

\nProf. Magnus Karlsson, Chalmars University, Sweden

**Chairman\n**Ass. Prof Niels Gregersen, DTU Fotonik

**Master of the Ceremony\n**To be announced

**Abstract\n**This PhD project has focused on generation of photon pairs using nonlinear processes in optical fibers. By detecting one of the photons in the pair, the remaining photon can be used for quantum photonics applications. Important examples of such applications include optical quantum computing, possibly leading to exponential speed-ups on certain computational problems, or quantum cryptography, promising provably secure communications. When creating pairs of photons in an optical fiber, there are many unwanted effects that can negatively impact the quality of the produced photons. A main topic of the thesis is obtaining accurate descriptions of these effects in order to obtain insight on how to mitigate them. We find that the negative impact of these effects vary greatly between methods for photon-pair generation and fiber designs, leading to guidelines for how to design systems to avoid them.

**Title: **Photon-pair generation by spontaneous four-wave mixing: Modelling real systems

** **

**Supervisor\n**Principal supervisor: Prof. Karsten Rottwitt, DTU Fotonik

**Evaluation Board\n**Dr. Peter Mosley, University of Bath, UK

\nProf. Magnus Karlsson, Chalmars University, Sweden

**Chairman\n**Ass. Prof Niels Gregersen, DTU Fotonik

**Master of the Ceremony\n**To be announced

**Abstract\n**This PhD project has focused on generation of photon pairs using nonlinear processes in optical fibers. By detecting one of the photons in the pair, the remaining photon can be used for quantum photonics applications. Important examples of such applications include optical quantum computing, possibly leading to exponential speed-ups on certain computational problems, or quantum cryptography, promising provably secure communications. When creating pairs of photons in an optical fiber, there are many unwanted effects that can negatively impact the quality of the produced photons. A main topic of the thesis is obtaining accurate descriptions of these effects in order to obtain insight on how to mitigate them. We find that the negative impact of these effects vary greatly between methods for photon-pair generation and fiber designs, leading to guidelines for how to design systems to avoid them.