Atom-Photon Quantum Interfaces

atomphyscelltable.jpgHigh efficiency preparation, storage, and control of quantum states in a quantum memory and low-loss entanglement distribution are central for realizations of future quantum networks. We investigate an efficient atom-light interface for preparing entanglement between a long-lived atomic quantum memory and a photonic qubit, which represents an elementary building block for stablishing entanglement over large-scale quantum networks. We use a atomic ensemble of cesium atoms with high optical depth, which will substantially enhance the efficiency of entanglement generation and significantly suppress spurious noise. This will result in a highly efficient entangling atom-light interface, with high entangling fidelity, which is a building block for quantum repeater-based quantum networks.

motwithpic.pngThe 2D MOT is based on two pairs of rectangular coils producing strong confinement of the atoms along the transverse directions, and one pair of end cap circular coils providing confinement along the axial direction. The coils provide independent control of the transverse rectangular magnetic field gradients, allowing for the preparation of the atomic ensemble with different spec ratios. Fast analog control of the coils’ current allows for driving the currents with arbitrary waveforms for MOT compression and fast switching, obtaining optical depths of ~200 with ~ 5.5*108 atoms loaded in the MOT. Such high optical depth increases the light matter interaction, which can be used for the preparation of complex quantum states of collective spins based on quantum measurement backaction.