scholarly journals Posner qubits: spin dynamics of entangled Ca 9 (PO 4 ) 6 molecules and their role in neural processing

2018 ◽  
Vol 15 (147) ◽  
pp. 20180494 ◽  
Author(s):  
Thomas C. Player ◽  
P. J. Hore
Keyword(s):  
Spin Relaxation ◽  
Spin Dynamics ◽  
Relaxation Times ◽  
Neural Processing ◽  
Nuclear Spins ◽  
Physiological Conditions ◽  
Spin Interactions ◽  
Quantum Mechanism ◽  
The Brain ◽  
Fundamental Requirement

It has been suggested that 31 P nuclear spins in Ca 9 (PO 4 ) 6 molecules could form the basis of a quantum mechanism for neural processing in the brain. A fundamental requirement of this proposal is that spins in different Ca 9 (PO 4 ) 6 molecules can become entangled and remain so for periods (estimated at many hours) that hugely exceed typical 31 P spin relaxation times. Here, we consider the coherent and incoherent spin dynamics of Ca 9 (PO 4 ) 6 arising from dipolar and scalar spin-spin interactions and derive an upper bound of 37 min on the entanglement lifetime under idealized physiological conditions. We argue that the spin relaxation in Ca 9 (PO 4 ) 6 is likely to be much faster than this estimate.

scholarly journals Nuclear-spin-pattern control of electron-spin dynamics in a series of V(iv) complexes

2019 ◽  
Vol 10 (36) ◽  
pp. 8447-8454 ◽  
Author(s):  
Cassidy E. Jackson ◽  
Chun-Yi Lin ◽  
Spencer H. Johnson ◽  
Johan van Tol ◽  
Joseph M. Zadrozny
Keyword(s):  
Spin Relaxation ◽  
Electron Spin ◽  
Nuclear Spin ◽  
Spin Dynamics ◽  
Relaxation Times ◽  
Open Shell ◽  
Pattern Control ◽  
Electron Spin Dynamics

This report details how the design of specific nuclear-spin patterns on ligands modulates spin-relaxation times in a set of open-shell vanadium(iv) complexes.

Spin Relaxation Mechanisms in the Organic Semiconductor Alq3

2009 ◽  
Vol 1 (4) ◽  
pp. 20-38 ◽  
Author(s):  
Sridhar Patibandla ◽  
Bhargava Kanchibotla ◽  
Sandipan Pramanik ◽  
Supriyo Bandyopadhyay ◽  
Marc Cahay
Keyword(s):  
Spin Relaxation ◽  
Organic Semiconductor ◽  
Hyperfine Interactions ◽  
Relaxation Times ◽  
The Other ◽  
Phonon Coupling ◽  
Nuclear Spins ◽  
Dominant Mechanism ◽  
Different Temperatures ◽  
Impurity Sites

We have measured the longitudinal (T1) and transverse (T2) spin relaxation times in the organic semiconductor tris(8-hydroxyquinolinolato aluminum)—also known as Alq3—at different temperatures. These measurements shed some light on the spin relaxation mechanisms in the organic. The two most likely mechanisms affecting T1 are hyperfine interactions between carrier and nuclear spins, and the Elliott-Yafet mode. On the other hand, the dominant mechanism affecting T2 of delocalized electrons in Alq3 remains uncertain, but for localized electrons (bound to defect or impurity sites), the dominant mechanism is most likely spin-phonon coupling.

scholarly journals Ligand Control of 59Co Nuclear Spin Relaxation Thermometry

2020 ◽  
Vol 6 (4) ◽  
pp. 58
Author(s):  
Tyler M. Ozvat ◽  
Spencer H. Johnson ◽  
Anthony K. Rappé ◽  
Joseph M. Zadrozny
Keyword(s):  
Spin Relaxation ◽  
Nuclear Spin ◽  
Spin Dynamics ◽  
Coupling Parameter ◽  
Relaxation Times ◽  
Design Principles ◽  
Temperature Dependent ◽  
Quadrupolar Coupling ◽  
Resonance Spin ◽  
The Impact

Studying the correlation between temperature-driven molecular structure and nuclear spin dynamics is essential to understanding fundamental design principles for thermometric nuclear magnetic resonance spin-based probes. Herein, we study the impact of progressively encapsulating ligands on temperature-dependent 59Co T1 (spin–lattice) and T2 (spin–spin) relaxation times in a set of Co(III) complexes: K3[Co(CN)6] (1); [Co(NH3)6]Cl3 (2); [Co(en)3]Cl3 (3), en = ethylenediamine); [Co(tn)3]Cl3 (4), tn = trimethylenediamine); [Co(tame)2]Cl3 (5), tame = triaminomethylethane); and [Co(dinosar)]Cl3 (6), dinosar = dinitrosarcophagine). Measurements indicate that 59Co T1 and T2 increase with temperature for 1–6 between 10 and 60 °C, with the greatest ΔT1/ΔT and ΔT2/ΔT temperature sensitivities found for 4 and 3, 5.3(3)%T1/°C and 6(1)%T2/°C, respectively. Temperature-dependent T2* (dephasing time) analyses were also made, revealing the highest ΔT2*/ΔT sensitivities in structures of greatest encapsulation, as high as 4.64%T2*/°C for 6. Calculations of the temperature-dependent quadrupolar coupling parameter, Δe2qQ/ΔT, enable insight into the origins of the relative ΔT1/ΔT values. These results suggest tunable quadrupolar coupling interactions as novel design principles for enhancing temperature sensitivity in nuclear spin-based probes.

Dominant Spin Relaxation Mechanisms in Organic Semiconductor Alq3

2011 ◽  
pp. 259-278
Author(s):  
Sridhar Patibandla ◽  
Bhargava Kanchibotla ◽  
Sandipan Pramanik ◽  
Supriyo Bandyopadhyay ◽  
Marc Cahay
Keyword(s):  
Electric Fields ◽  
Spin Relaxation ◽  
Organic Semiconductor ◽  
Hyperfine Interactions ◽  
Relaxation Times ◽  
The Other ◽  
Nuclear Spins ◽  
Dominant Mechanism ◽  
Different Temperatures ◽  
Impurity Sites

We have measured the longitudinal (T1) and transverse (T2) spin relaxation times in the organic semiconductor tris(8-hydroxyquinolinolato aluminum) - also known as Alq3 - at different temperatures and under different electric fields driving current. These measurements shed some light on the spin relaxation mechanisms in the organic. The two most likely mechanisms affecting T1 are hyperfine interactions between carrier and nuclear spins, and the Elliott-Yafet mode. On the other hand, the dominant mechanism affecting T2 of delocalized electrons in Alq3 remains uncertain, but for localized electrons (bound to defect or impurity sites), the dominant mechanism is most likely spin-phonon coupling.

Strong Coupling of Electron and Nuclear Spins: Outlook and Prospects

2018 ◽  
Author(s):  
M. M. Glazov
Keyword(s):  
Energy Spectrum ◽  
Charge Carrier ◽  
Strong Coupling ◽  
Nuclear Spin ◽  
Spin Dynamics ◽  
Spin Polaron ◽  
Nuclear Spins ◽  
Deep Impurity ◽  
Impurity Centers ◽  
Ordered State

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.

Electron Spin Decoherence by Nuclei

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.

Magnetoencephalography and the Cortical Dynamics of Language Processing

2019 ◽  
pp. 114-153
Author(s):  
Riitta Salmelin ◽  
Jan Kujala ◽  
Mia Liljeström
Keyword(s):  
Language Processing ◽  
Language Disorders ◽  
Scientific Data ◽  
Neural Processing ◽  
Powerful Method ◽  
Cortical Dynamics ◽  
Brain Correlates ◽  
Adults And Children ◽  
The Brain ◽  
Selection Of

When seeking to uncover the brain correlates of language processing, timing and location are of the essence. Magnetoencephalography (MEG) offers them both, with the highest sensitivity to cortical activity. MEG has shown its worth in revealing cortical dynamics of reading, speech perception, and speech production in adults and children, in unimpaired language processing as well as developmental and acquired language disorders. The MEG signals, once recorded, provide an extensive selection of measures for examination of neural processing. Like all other neuroimaging tools, MEG has its own strengths and limitations of which the user should be aware in order to make the best possible use of this powerful method and to generate meaningful and reliable scientific data. This chapter reviews MEG methodology and how MEG has been used to study the cortical dynamics of language.

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