Solid state quantum light matter interface for polarization qubits

10 May 2012

Our first experimental paper made at ICFO has been published in Physical Review Letter. We show that a crystal can act as a quantum memory for photonic polarization qubits, with more than 95% fidelity on storage and retrieval processes – beyond the maximal fidelity achievable by a classical memory. The study has been published in Physical Review Letters and highlighted in Physics and Physics World.

Figure 4

Fig. Average fidelity measured as a function of the mean number of photon per pulse μ.

Rare-earth doped crystals are promising materials for quantum memory applications. Unfortunately, these materials have an absorption that is dependent on the polarization of the light, which means that to date, only one polarization state could be stored in these crystals. This is a strong limitation taking into account that quantum bits are often encoded in the polarization of photons. The authors overcome this limitation by coherently storing the two polarization components of a weak coherent light field at the single photon level in two different spatial modes of a Praseodymium doped crystal.

Ref: Quantum Storage of a Photonic Polarization Qubit in a Solid
Mustafa Gündoğan, Patrick M. Ledingham, Attaallah Almasi, Matteo Cristiani, and Hugues de Riedmatten
Phys. Rev. Lett. 108, 190504, 2012