Efficient generation of entangled multiphoton graph states from a single atom

Abstract

The central technological appeal of quantum science resides in exploiting quantum effects, such as entanglement, for a variety of applications, including computing, communication and sensing1. The overarching challenge in these fields is to address, control and protect systems of many qubits against decoherence2. Against this backdrop, optical photons, naturally robust and easy to manipulate, represent ideal qubit carriers. However, the most successful technique so far for creating photonic entanglement3 is inherently probabilistic and, therefore, subject to severe scalability limitations. Here we report the implementation of a deterministic protocol4–6 for the creation of photonic entanglement with a single memory atom in a cavity7. We interleave controlled single-photon emissions with tailored atomic qubit rotations to efficiently grow Greenberger–Horne–Zeilinger (GHZ) states8 of up to 14 photons and linear cluster states9 of up to 12 photons with a fidelity lower bounded by 76(6)% and 56(4)%, respectively. Thanks to a source-to-detection efficiency of 43.18(7)% per photon, we measure these large states about once every minute, which is orders of magnitude faster than in any previous experiment3,10–13. In the future, this rate could be increased even further, the scheme could be extended to two atoms in a cavity14,15 or several sources could be quantum mechanically coupled16, to generate higher-dimensional cluster states17. Overcoming the limitations encountered by probabilistic schemes for photonic entanglement generation, our results may offer a way towards scalable measurement-based quantum computation18,19 and communication20,21.

Multiqubit entanglement due to quantum gravity

“…Multiqubit entanglement plays an important role in quantum information, computation and communica-tion. There are various platforms generating multipartite entanglement with photons or ions [9][10][11][12][13]. Photonic experiments entangled 14 photons to realize Greenberger-Horne-Zeilinger (GHZ) states by interleave single-photon emissions with atomic rotations [9].…”

“…There are various platforms generating multipartite entanglement with photons or ions [9][10][11][12][13]. Photonic experiments entangled 14 photons to realize Greenberger-Horne-Zeilinger (GHZ) states by interleave single-photon emissions with atomic rotations [9]. In a linear Paul trip, GHZ states were produced with up to 24 ions, mediated by the Mølmer-Sørensen gate [13].…”

Two-qubit atomic gates: spatio-temporal control of Rydberg interaction

“…Due to their excellent optical addressability, [1][2][3][4][5] rich many-body physics, [6][7][8][9][10][11][12] and long decoherence times, 13 neutral atoms excited in Rydberg states have been used as vectors for different quantum technologies, including entanglement preparation, [14][15][16][17][18][19][20][21] creation of photonic entanglement, 22 quantum simulators, [23][24][25][26] and quantum computation. 13,19,[27][28][29][30][31][32][33][34] A key step involves trapping the atoms at low temperature in magneto-optical traps (MOT).…”

“…Due to their excellent optical addressability, 1–5 rich many-body physics, 6–12 and long decoherence times, 13 neutral atoms excited in Rydberg states have been used as vectors for different quantum technologies, including entanglement preparation, 14–21 creation of photonic entanglement, 22 quantum simulators, 23–26 and quantum computation. 13,19,27–34…”

Diamond Integrated Quantum Nanophotonics: Spins, Photons and Phonons

“…Advances in spinphoton entanglement [45] paved the way for photon-mediated entanglement of remote qubits [46]- [48], culminating in the recent demonstration of a three-node quantum network [49], [50]. While these demonstrations have been fruitful, it is worth noting that parallel advances have been made with other experimental platforms including trapped atoms and ions [17], [51]- [56], superconducting resonators [57], [58], selfassembled quantum dots [59]- [61], and defect-based qubits in other wide-bandgap semiconductors and dielectrics [62]- [72].…”