Paper in New Journal of Physics
In their latest issue, New Journal of Physics published our paper on Optimal linear optical implementation of a single-qubit damping channel. In our paper we experimentally demonstrate a single-qubit decohering quantum channel using linear optics. We show how to implement the channel using a single, static optical setup and in particular, we realize the channel in an optimal way, maximizing the probability of success, i.e. the probability for the photonic qubit to remain in its encoding. This experiment closely follows a recent theoretical result from our friends and colleagues at IQC (Piani et al. Phys. Rev. A 84 032304 (2011)). The damping channels we implemented are important for quantum information processing (QIP), as they include the the familiar amplitude-damping channel and the bit-flip channel, both which lead to decoherence. Being able to model them reliably in the lab might lead to new insights in how to best protect the quantum information in the first place and furthermore allows to stringently test various QIP schemes experimentally. In our work we use polarization encoded photons as the information carriers. We characterize the channel using ancilla-assisted process tomography and find average process fidelities larger than 0.98, which demonstrates the high quality of our implementation.