Dynamic photon storage

Richard J. Fitzgerald

Zhifang Guo, Qingzhong Huang

We propose a novel dynamic two-ring-two-bus system to achieve photon storage. We have demonstrated numerically that the photon can be stopped and released by tuning the ring coupled to two buses in a short time. The two-ring-two-bus system is fabricated on the silicon-on-insulator platform, with the Q factor changing significantly when shifting one resonance. Due to the flexibility and simplicity, it is a promising candidate for the future optical storage and buffering device.

Yuelong Wu, Lirong Chen, Zhongxiao Xu +1 more

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.

Richard J. Fitzgerald

Kwang-Je Kim, Andrew M. Sessler

Luigi Giannelli, Tom Schmit, Giovanna Morigi

Abstract Attenuated laser pulses are often employed in place for single photons in order to test the efficiency of the elements of a quantum network. In this work we analyze theoretically the dynamics of storage of an attenuated light pulse (where the pulse intensity is at the single photon level) propagating along a transmission line and impinging on the mirror of a high finesse cavity. Storage is realized by the controlled transfer of the photonic excitations into a metastable state of an atom confined inside the cavity and occurs via a Raman transition with a suitably tailored laser pulse, which drives the atom and minimizes reflection at the cavity mirror. We determine the storage efficiency of the weak coherent pulse which is reached by protocols optimized for single-photon storage. We determine the figures of merit and we identify the conditions on an arbitrary pulse for which the storage dynamics approaches the one of a single photon. Our formalism can be extended to arbitrary types of input pulses and to quantum memories composed by spin ensembles, and serves as a basis for identifying the optimal protocols for storage and readout.