Experimental detection of qubit-ququart pseudo-bound entanglement using three nuclear spins

In this chapter, some prospects in the field of electron and nuclear spin dynamics are outlined. Particular emphasis is put ona situation where the hyperfine interaction is so strong that it leads to a qualitative rearrangement of the energy spectrum resulting in the coherent excitation transfer between the electron and nucleus. The strong coupling between the spin of the charge carrier and of the nucleus is realized, for example in the case of deep impurity centers in semiconductors or in isotopically purified systems. We also discuss the effect of the nuclear spin polaron, that is ordered state, formation at low enough temperatures of nuclear spins, where the orientation of the carrier spin results in alignment of the spins of nucleus interacting with the electron or hole.

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Electron Spin Decoherence by Nuclei

10.1093/oso/9780198807308.003.0007 ◽

2018 ◽

Author(s):

M. M. Glazov

Keyword(s):

Electron Spin ◽

Spin Dynamics ◽

Magnetic Moments ◽

Host Lattice ◽

Spin Model ◽

Relaxation Processes ◽

Nuclear Spins ◽

Model Calculations ◽

Spin Decoherence ◽

Quantum Mechanical Approach

The discussion of the electron spin decoherence and relaxation phenomena via the hyperfine interaction with host lattice spins is presented here. The spin relaxation processes processes limit the conservation time of spin states as well as the response time of the spin system to external perturbations. The central spin model, where the spin of charge carrier interacts with the bath of nuclear spins, is formulated. We also present different methods to calculate the spin dynamics within this model. Simple but physically transparent semiclassical treatment where the nuclear spins are considered as largely static classical magnetic moments is followed by more advanced quantum mechanical approach where the feedback of electron spin dynamics on the nuclei is taken into account. The chapter concludes with an overview of experimental data and its comparison with model calculations.

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A simulation study investigating potential diffusion-based MRI signatures of microstrokes

Scientific Reports ◽

10.1038/s41598-021-93503-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Rafat Damseh ◽

Yuankang Lu ◽

Xuecong Lu ◽

Cong Zhang ◽

Paul J. Marchand ◽

...

Keyword(s):

Magnetic Field ◽

Statistical Power ◽

Barrel Cortex ◽

Signal Loss ◽

Nuclear Spins ◽

Directional Diffusion ◽

Ischemic Tissue ◽

Significant Difference ◽

Before And After ◽

Experimental Validations

AbstractRecent studies suggested that cerebrovascular micro-occlusions, i.e. microstokes, could lead to ischemic tissue infarctions and cognitive deficits. Due to their small size, identifying measurable biomarkers of these microvascular lesions remains a major challenge. This work aims to simulate potential MRI signatures combining arterial spin labeling (ASL) and multi-directional diffusion-weighted imaging (DWI). Driving our hypothesis are recent observations demonstrating a radial reorientation of microvasculature around the micro-infarction locus during recovery in mice. Synthetic capillary beds, randomly- and radially-oriented, and optical coherence tomography (OCT) angiograms, acquired in the barrel cortex of mice (n = 5) before and after inducing targeted photothrombosis, were analyzed. Computational vascular graphs combined with a 3D Monte-Carlo simulator were used to characterize the magnetic resonance (MR) response, encompassing the effects of magnetic field perturbations caused by deoxyhemoglobin, and the advection and diffusion of the nuclear spins. We quantified the minimal intravoxel signal loss ratio when applying multiple gradient directions, at varying sequence parameters with and without ASL. With ASL, our results demonstrate a significant difference (p < 0.05) between the signal-ratios computed at baseline and 3 weeks after photothrombosis. The statistical power further increased (p < 0.005) using angiograms measured at week 4. Without ASL, no reliable signal change was found. We found that higher ratios, and accordingly improved significance, were achieved at lower magnetic field strengths (e.g., B0 = 3T) and shorter echo time TE (< 16 ms). Our simulations suggest that microstrokes might be characterized through ASL-DWI sequence, providing necessary insights for posterior experimental validations, and ultimately, future translational trials.

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Optical spin-state polarization in a binuclear europium complex towards molecule-based coherent light-spin interfaces

Nature Communications ◽

10.1038/s41467-021-22383-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Kuppusamy Senthil Kumar ◽

Diana Serrano ◽

Aline M. Nonat ◽

Benoît Heinrich ◽

Lydia Karmazin ◽

...

Keyword(s):

Ground State ◽

Quantum Information Processing ◽

Optical Transition ◽

Molecular Engineering ◽

Coherent Light ◽

Nuclear Spins ◽

Rare Earth Ion ◽

Molecular Systems ◽

Homogeneous Linewidth ◽

State Spin

AbstractThe success of the emerging field of solid-state optical quantum information processing (QIP) critically depends on the access to resonant optical materials. Rare-earth ion (REI)-based molecular systems, whose quantum properties could be tuned taking advantage of molecular engineering strategies, are one of the systems actively pursued for the implementation of QIP schemes. Herein, we demonstrate the efficient polarization of ground-state nuclear spins—a fundamental requirement for all-optical spin initialization and addressing—in a binuclear Eu(III) complex, featuring inhomogeneously broadened 5D0 → 7F0 optical transition. At 1.4 K, long-lived spectral holes have been burnt in the transition: homogeneous linewidth (Γh) = 22 ± 1 MHz, which translates as optical coherence lifetime (T2opt) = 14.5 ± 0.7 ns, and ground-state spin population lifetime (T1spin) = 1.6 ± 0.4 s have been obtained. The results presented in this study could be a progressive step towards the realization of molecule-based coherent light-spin QIP interfaces.

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Room-temperature control and electrical readout of individual nitrogen-vacancy nuclear spins

Nature Communications ◽

10.1038/s41467-021-24494-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Michal Gulka ◽

Daniel Wirtitsch ◽

Viktor Ivády ◽

Jelle Vodnik ◽

Jaroslav Hruby ◽

...

Keyword(s):

Dipolar Interaction ◽

Coherence Time ◽

Wide Bandgap ◽

Nitrogen Vacancy ◽

Ambient Conditions ◽

Nuclear Spins ◽

Quantum Device ◽

Nanoscale Electronics ◽

Quantum Processor ◽

Processor Unit

AbstractNuclear spins in semiconductors are leading candidates for future quantum technologies, including quantum computation, communication, and sensing. Nuclear spins in diamond are particularly attractive due to their long coherence time. With the nitrogen-vacancy (NV) centre, such nuclear qubits benefit from an auxiliary electronic qubit, which, at cryogenic temperatures, enables probabilistic entanglement mediated optically by photonic links. Here, we demonstrate a concept of a microelectronic quantum device at ambient conditions using diamond as wide bandgap semiconductor. The basic quantum processor unit – a single 14N nuclear spin coupled to the NV electron – is read photoelectrically and thus operates in a manner compatible with nanoscale electronics. The underlying theory provides the key ingredients for photoelectric quantum gate operations and readout of nuclear qubit registers. This demonstration is, therefore, a step towards diamond quantum devices with a readout area limited by inter-electrode distance rather than by the diffraction limit. Such scalability could enable the development of electronic quantum processors based on the dipolar interaction of spin-qubits placed at nanoscopic proximity.

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