title: Protecting a quantum memory for a photonic polarization qubit in a cold atomic ensemble by dynamical decoupling.
abstract: We report an experimental demonstration of storage of photonic polarization qubit (PPQ) protected by dynamical decoupling (DD). PPQ's states are stored as a superposition of two spin waves by electromagnetically-induced-transparency (EIT). Carr-Purcell-Meiboom-Gill (CPMG) DD sequences are applied to the spin-wave superposition to suppress its decoherence. Thus, the quantum process fidelity remains better than 0.8 for up to 800 μs storage time, which is 3.4-times longer than the corresponding storage time of ~180 μs without the CPMG sequences. This work is a key step towards the storage of single-photon polarization qubit protected by the CPMG sequences.
authors.forename: Yuelong
authors.initials: Y
authors.lastname: Wu
authors.forename: Lirong
authors.initials: L
authors.lastname: Chen
authors.forename: Zhongxiao
authors.initials: Z
authors.lastname: Xu
authors.forename: Hai
authors.initials: H
authors.lastname: Wang
mesh_terms: D007554:Isotopes; D055095:Optics and Photonics; D017785:Photons; D011789:Quantum Theory
chemical_list: D007554:Isotopes