Mehdi E, Gundín M, Millet C, Somaschi N, Lemaître A, Sagnes I, Le Gratiet L, Fioretto D A, Belabas N, Krebs O, Senellart P, Lanco L
Université Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France.
Université Paris Cité, Centre de Nanosciences et de Nanotechnologies, 91120, Palaiseau, France.
Nat Commun. 2024 Jan 18;15(1):598. doi: 10.1038/s41467-023-44651-8.
In the framework of optical quantum computing and communications, a major objective consists in building receiving nodes implementing conditional operations on incoming photons, using a single stationary qubit. In particular, the quest for scalable nodes motivated the development of cavity-enhanced spin-photon interfaces with solid-state emitters. An important challenge remains, however, to produce a stable, controllable, spin-dependent photon state, in a deterministic way. Here we use an electrically-contacted pillar-based cavity, embedding a single InGaAs quantum dot, to demonstrate giant polarisation rotations induced on reflected photons by a single electron spin. A complete tomography approach is introduced to extrapolate the output polarisation Stokes vector, conditioned by a specific spin state, in presence of spin and charge fluctuations. We experimentally approach polarisation states conditionally rotated by [Formula: see text], π, and [Formula: see text] in the Poincaré sphere with extrapolated fidelities of (97 ± 1) %, (84 ± 7) %, and (90 ± 8) %, respectively. We find that an enhanced light-matter coupling, together with limited cavity birefringence and reduced spectral fluctuations, allow targeting most conditional rotations in the Poincaré sphere, with a control both in longitude and latitude. Such polarisation control may prove crucial to adapt spin-photon interfaces to various configurations and protocols for quantum information.
在光量子计算和通信的框架下,一个主要目标是构建接收节点,该节点使用单个固定量子比特对入射光子执行条件操作。特别是,对可扩展节点的追求推动了具有固态发射器的腔增强自旋 - 光子接口的发展。然而,以确定性方式产生稳定、可控的自旋相关光子态仍然是一个重要挑战。在这里,我们使用一个电接触的柱状腔,其中嵌入单个铟镓砷量子点,来展示单个电子自旋在反射光子上引起的巨大偏振旋转。引入了一种完整的层析成像方法,以在存在自旋和电荷波动的情况下,推断由特定自旋态条件决定的输出偏振斯托克斯矢量。我们通过实验实现了在庞加莱球中条件旋转角度为[公式:见原文]、π和[公式:见原文]的偏振态,推断保真度分别为(97 ± 1)%、(84 ± 7)%和(90 ± 8)%。我们发现,增强的光 - 物质耦合,以及有限的腔双折射和减少的光谱波动,使得能够在庞加莱球中实现大多数条件旋转,并且在经度和纬度上都能进行控制。这种偏振控制对于使自旋 - 光子接口适应各种量子信息配置和协议可能至关重要。