In spectroscopy, it is conventional to treat pulses much stronger than the linewidth as delta-functions. In NMR, this assumption leads to the prediction that pi pulses do not refocus the dipolar coupling. However, NMR spin echo measurements in dipolar solids defy these conventional expectations when more than one pi pulse is used. Observed effects include a long tail in the CPMG echo train for short delays between pi pulses, an even-odd asymmetry in the echo amplitudes for long delays, an unusual fingerprint pattern for intermediate delays, and a strong sensitivity to pi-pulse phase. Experiments that set limits on possible extrinsic causes for the phenomena are reported. We find that the action of the system's internal Hamiltonian during any real pulse is sufficient to cause the effects. Exact numerical calculations, combined with average Hamiltonian theory, identify novel terms that are sensitive to parameters such as pulse phase, dipolar coupling, and system size. Visualization of the entire density matrix shows a unique flow of quantum coherence from non-observable to observable channels when applying repeated pi pulses.
Direct Observation of Dipolar-Driven Anisotropic Quantum Projection Noise in a Solid-State Spin Ensemble
Massachusetts Institute of Technology（麻省理工学院）；Harvard University（哈佛大学）；University of California, Santa Barbara（加州大学圣塔芭芭拉分校）；California Institute of Technology（加州理工学院）；Boston University（波士顿大学）
Realizing nonlinear optical response in the low photon density limit in solid-state systems has been a long-standing challenge. Semiconductor microcavities in the strong coupling regime hosting exciton-polaritons have emerged as attractive candidates in this context. However, the weak interaction between these quasiparticles has been a hurdle in this quest. Dipolar excitons provide an attractive strategy to overcome this limitation but are often hindered by their weak oscillator strength. The interlayer dipolar excitons in naturally occurring homobilayer MoS$_2$ alleviates this issue owing to …
Experimental observation of a phase transition in the evolution of many-body systems with dipolar interactions
多体系统的非平衡动力学在许多科学分支中都很重要，如凝聚态、量子化学和超冷原子。本文报道了具有偶极相互作用的三维多自旋系统的量子相干动力学的相变的实验观测，并确定了它的临界指数。利用室温下的固态自旋系统的核磁共振（NMR），我们淬灭相互作用哈密顿量来驱动系统的演化。由此产生的系统相干性的动态可以是本地化的或扩展的，这取决于淬火强度。应用有限时间标度分析所观察到的相关自旋的数量的时间演化，我们提取的临界指数v = s = 0.42周围的相变分离本地从离域动力学制度。这些结果清楚地表明，这种基于核自旋的量子模拟可以有效地模拟复杂多体系统的非平衡动力学，例如具有偶极相互作用的3D自旋网络。
A single electron floating on the surface of a condensed noble-gas liquid or solid can act as a spin qubit with ultralong coherence time, thanks to the extraordinary purity of such systems. Previous studies suggest that the electron spin coherence time on a superfluid helium (He) surface can exceed 100 s. In this paper, we present theoretical studies of the electron spin coherence on a solid neon (Ne) surface, motivated by our recent experimental realization of single-electron charge qubit on solid Ne. The major spin decoherence mechanisms investigated include the fluctuating Ne diamagnetic su…
Continuously tracked, stable, large excursion trajectories of dipolar coupled nuclear spins
University of California, Berkeley（加州大学伯克利分校）；Max Planck Institute for the Physics of Complex Systems（马克斯·普朗克复杂系统物理研究所）；Element Six Innovation（Element Six 创新公司）；Tabor Electronics, Inc.（塔博电子公司）；KTH Royal Institute of Technology（皇家理工学院）；St. Kliment Ohridski University of Sofia（索非亚圣克利门特奥赫里德斯基大学）
Quantum theory for electron spin decoherence induced by nuclear spin dynamics in semiconductor quantum computer architectures: Spectral diffusion of localized electron spins in the nuclear solid-state environment
Conventional wisdom holds that macroscopic classical phenomena naturally emerge from microscopic quantum laws. However, despite this mantra, building direct connections between these two descriptions has remained an enduring scientific challenge. In particular, it is difficult to quantitatively predict the emergent "classical" properties of a system (e.g. diffusivity, viscosity, compressibility) from a generic microscopic quantum Hamiltonian. Here, we introduce a hybrid solid-state spin platform, where the underlying disordered, dipolar quantum Hamiltonian gives rise to the emergence of unconv…
Engineering and Probing a One-Dimensional Dipolar Spin Ensemble in Diamond
University of California, Santa Barbara（加州大学圣塔芭芭拉分校）；California Institute of Technology（加州理工学院）；Stanford University（斯坦福大学）；Harvard University（哈佛大学）；Boston University（波士顿大学）；Max-Planck-Institut für Physik Komplexer Systeme（马克斯·普朗克复杂系统物理研究所）
