Superdense coding: Difference between revisions

Revision as of 16:44, 22 February 2025

Revision as of 17:18, 22 February 2025

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== Experimental ==

The protocol of superdense coding has been actualized in several experiments using different systems to varying levels of channel capacity and fidelities. In 2004, trapped [[beryllium-9]] ions were used in a maximally entangled state to achieve a channel capacity of 1.16 with a fidelity of 0.85.<ref name="Schaetz2004">{{Cite journal |last=Schaetz |first=T. |last2=Barrett |first2=M. D. |last3=Leibfried |first3=D. |last4=Chiaverini |first4=J. |last5=Britton |first5=J. |last6=Itano |first6=W. M. |last7=Jost |first7=J. D. |last8=Langer |first8=C. |last9=Wineland |first9=D. J. |date=2004-07-22 |title=Quantum Dense Coding with Atomic Qubits |url=https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.93.040505 |journal=Physical Review Letters |volume=93 |issue=4 |pages=040505 |doi=10.1103/PhysRevLett.93.040505}}</ref> In 2017, a channel capacity of 1.665 was achieved with a fidelity of 0.87 through optical fibers.<ref name="William2017">{{Cite journal |last=Williams |first=Brian P. |last2=Sadlier |first2=Ronald J. |last3=Humble |first3=Travis S. |date=2017-02-01 |title=Superdense Coding over Optical Fiber Links with Complete Bell-State Measurements |url=https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.050501 |journal=Physical Review Letters |volume=118 |issue=5 |pages=050501 |doi=10.1103/PhysRevLett.118.050501}}Williams, B. P., Sadlier, R. J., & Humble, T. S. (2017). Superdense Coding over Optical Fiber Links with Complete Bell-State Measurements. Physical Review Letters, 118(5).</ref> High-dimensional [[ququarts]] (states formed in photon pairs by non-degenerate [[spontaneous parametric down-conversion]]) were used to reach a channel capacity of 2.09 (with a limit of 2.32) with a fidelity of 0.98.<ref name="Hu2018">{{Cite journal |last=Hu |first=Xiao-Min |last2=Guo |first2=Yu |last3=Liu |first3=Bi-Heng |last4=Huang |first4=Yun-Feng |last5=Li |first5=Chuan-Feng |last6=Guo |first6=Guang-Can |date=2018-07-06 |title=Beating the channel capacity limit for superdense coding with entangled ququarts |url=https://www.science.org/doi/10.1126/sciadv.aat9304 |journal=Science Advances |language=en |volume=4 |issue=7 |doi=10.1126/sciadv.aat9304 |issn=2375-2548 |pmc=PMC60545066054506 |pmid=30035231}}</ref> [[Nuclear magnetic resonance]] (NMR) has also been used to share among three parties.<ref name="Wei2004">{{Cite journal |last=Wei |first=Daxiu |last2=Yang |first2=Xiaodong |last3=Luo |first3=Jun |last4=Sun |first4=Xianping |last5=Zeng |first5=Xizhi |last6=Liu |first6=Maili |date=2004-03-01 |title=NMR experimental implementation of three-parties quantum superdense coding |url=https://link.springer.com/article/10.1007/BF02900957 |journal=Chinese Science Bulletin |language=en |volume=49 |issue=5 |pages=423–426 |doi=10.1007/BF02900957 |issn=1861-9541}}</ref>

==References==