Experimental demonstration of memory-enhanced quantum communication

Abstract

The ability to communicate quantum information over long distances is of central importance in quantum science and engineering [1]. For example, it enables secure quantum key distribution (QKD) [2, 3] relying on fundamental physical principles that prohibit the "cloning" of unknown quantum states [4,5]. While QKD is already being successfully deployed [6-9], its range is currently limited by photon losses and cannot be extended using straightforward measure-and-repeat strategies without compromising its unconditional security [10]. Alternatively, quantum repeaters [11], which utilize intermediate quantum memory nodes and error correction techniques, can extend the range of quantum channels. However, their implementation remains an outstanding challenge [12][13][14][15][16][17], requiring a combination of efficient and high-fidelity quantum memories, gate operations, and measurements. Here we report the experimental realization of memory-enhanced quantum communication. We use a single solid-state spin memory integrated in a nanophotonic diamond resonator [18][19][20] to implement asynchronous photonic Bell-state measurements. This enables a four-fold increase in the secret key rate of measurement device independent (MDI)-QKD over the loss-equivalent direct-transmission method while operating at megahertz clock rates. Our results represent a significant step towards practical quantum repeaters and large-scale quantum networks [21,22].

Extending Quantum Links: Modules for Fiber‐ and Memory‐Based Quantum Repeaters

“…Although all necessary components have been demonstrated to some extent individually, combining these into a fully operational (and hence scalable) repeater system is demanding and first experimental demonstrations in this direction are now only beginning to be reported. [ 24 ]…”

Stimuli‐Enabled Artificial Synapses for Neuromorphic Perception: Progress and Perspectives

“…Nevertheless, the recent development of synaptic devices based on stimuli-responsive materials and structures greatly enhances the ability of these devices to perceive complex information, including internal electrical signals and external stimuli such as light, pressure, temperature, and magnetic fields. The development of stimuli-enabled ANNs [134][135][136][137] based on an understanding of synaptic behavior will be the next research frontier in the area of neuromorphic science.…”

Making Diamond Qubits Talk to Light

“…While much of this process has been reported previously [36], improvements in our nanofabrication process, including the simultaneous implementation of IBE, masked implantation, and on-chip CPWs have enabled many ordersof-mangnitude improvement in the cavity cooperativity (C > 100 [39]). Future improvements in diamond device performance will be predicated on improvements of the fabrication technology.…”

“…The entanglement fidelity between a photonic qubit and the SiV center is competitive with that achievable in other systems [8,60,61], and is limited primarily by residual reflections from the cavity. This can be straightforwardly increased, allowing for recent demonstrations of high-fidelity (F 97%) spinphoton entangled states [39], which are a fundamental resource for quantum communication [2] and quantum computing schemes [5], and can be used, for example, to demonstrate heralded storage of a photonic qubit into memory [29].…”