Quantum storage of photonic entanglement in a crystal

By C. Clausen, I. Usmani, F. Bussières, Nicolas Sangouard, M. Afzelius, Hugues de Riedmatten, Nicolas Gisin. Nature, 2010

455 citations recorded by the source corpus.

Entanglement is the fundamental characteristic of quantum physics—much experimental effort is devoted to harnessing it between various physical systems. In particular, entanglement between light and material systems is interesting owing to their anticipated respective roles as ‘flying’ and stationary qubits in quantum information technologies (such as quantum repeaters and quantum networks). Here we report the demonstration of entanglement between a photon at a telecommunication wavelength (1,338 nm) and a single collective atomic excitation stored in a crystal. One photon from an energy–time entangled pair is mapped onto the crystal and then released into a well-defined spatial mode after a predetermined storage time. The other (telecommunication wavelength) photon is sent directly through a 50-metre fibre link to an analyser. Successful storage of entanglement in the crystal is proved by a violation of the Clauser–Horne–Shimony–Holt inequality by almost three standard deviations (S = 2.64 ± 0.23). These results represent an important step towards quantum communication technologies based on solid-state devices. In particular, our resources pave the way for building multiplexed quantum repeaters for long-distance quantum networks.

Subfields: Artificial Intelligence, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/fb46993b4f681f23a9b2f9de66c950a5776a5091

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Citations in the corpus

Coherence time of over a second in a telecom-compatible quantum memory storage material (2016, methodology): “This technique could be applied to achieve long coherence times in other Kramers ions considered for quantum memories such as Nd [12, 24, 37, 38].”
Nonseparable States of Light: From Quantum to Classical (2022, background): “Importantly, there are still some quantum effects which have not found their parallel with nonseparable states, some of which might never find it, these is the case, for example, of quantum imaging [199] or quantum storage [200].”
Quantum storage of entangled telecom-wavelength photons in an erbium-doped optical fibre (2014, methodology): “pairs that are suitable for quantum teleportation, and, furthermore, would allow storing the 795 nm photon in our Tm:LiNbO3 quantum memory[22].”
Superconducting nanowire single-photon detectors: physics and applications (2012, methodology): “Key demonstrations employing SNSPDs in this way include the demonstration of the first telecom wavelength controlled-NOT gate (the basic building block of a quantum computer) [116], long distance entanglement swapping [117] and quantum storage of entanglement [118].”
Advances in quantum cryptography (2019, unknown): “Multi-mode structures for quantum memories have also been proposed and implemented to improve the performance in repeater setups [659–661].”
Nonlinear optical signals and spectroscopy with quantum light (2016, background): “The HBL limit is natural for long-term quantum memories where entanglement is achieved with telecom photons, proved the possibility of quantum internet (Clausen et al., 2011; Saglamyurek et al., 2011).”