Entanglement distribution with wavevector-multiplexed quantum memory

Abstract

Feasible distribution of quantum entanglement over long distances remains a fundamental step towards quantum secure communication and quantum network implementations. Quantum repeater nodes based on quantum memories promise to overcome exponential signal decay inherent to optical implementations of quantum communication. While performance of current quantum memories hinders their practical application, multimode solutions with multiplexing can offer tremendous increase in entanglement distribution rates. We propose to use a wavevector-multiplexed atomic quantum memory (WV-MUX-QM) as a fundamental block of a multiplexed quantum repeater architecture. We show the WV-MUX-QM platform to provide quasi-deterministic entanglement generation over extended distances, mitigating the fundamental issue of optical loss even with currently available quantum memory devices, and exceeding performance of repeaterless solutions as well as other repeater-based protocols such as temporal multiplexing. We establish the entangled-bit (ebit) rate per number of employed nodes as a practical figure of merit reflecting the cost-efficiency of larger inter-node distances.

Fast imaging of multimode transverse-spectral correlations for twin photons

“…p (r, t) = E p d 2 k p,⊥ dω p A p (k p,⊥ , ω p ) exp[i(k p • r − ω p t)], (5) where E p denotes the pump pulse amplitude, k p,⊥ its transverse wavevector and A p corresponds to the normalized slowly varying envelope of the pulse. From the wavefunction of the state generated in SPDC we shall consider only the biphoton part [41], which can be denoted as:…”

“…Photonic qubits can be easily created in entangled states, communicated over many-km distances and efficiently measured [1]. Tremendous effort has been devoted to improving the success rates of quantum enhanced protocols and multimode solutions, often accompanied with active multiplexing, are one of the most promising branches of this development [2][3][4][5][6][7][8][9][10][11], enabling both faster transfer and generation of photonic quantum states. In particular, systems harnessing several degrees of freedom (DoF) offer superior performance [12][13][14] especially in selected protocols such as superdense coding [15], quantum teleporation [16] or complete Bell-state analysis [17].…”