Dynamic nuclear polarization and the paradox of Quantum Thermalization

Abstract

Dynamic Nuclear Polarization (DNP) is to date the most effective technique to increase the nuclear polarization up to a factor $100,000$ opening disruptive perspectives for medical applications. In DNP, the nuclear spins are driven to an - out of equilibrium - hyperpolarized state by microwave saturation of the electron spins in interaction with them. Here we show that the electron dipolar interactions compete with the local magnetic fields resulting in two distinct dynamical phases: for strong interactions the electron spins equilibrate to an extremely low effective temperature that boosts DNP efficiency. For weak interaction this spin temperature is not defined and the polarization profile has an 'hole burning' shape characteristic of the non interacting case. The study of the many-body eigenstates reveals that these two phases are intimately related to the problem of thermalization in closed quantum systems where breaking of ergodicity is expected varying the strength of the interactions.

5 pages + 6 pages of supplementary material; 5 figures. Accepted in PRL

References in corpus (8)

• Thermalization and its mechanism for generic isolated quantum systems
• Localization of interacting fermions at high temperature
• Integrals of motion in the Many-Body localized phase
• Periodically driven ergodic and many-body localized quantum systems
• Ergodicity breaking in a model showing many-body localization
• Many-body mobility edge in a mean-field quantum spin glass
• The Quantum Adiabatic Algorithm applied to random optimization problems: the quantum spin glass perspective
• Role of the glassy dynamics and thermal mixing in the dynamic nuclear polarization and relaxation mechanisms of pyruvic acid

Cited by in corpus (18)

• Many-body localization: an introduction and selected topics
• MBL-mobile: Quantum engine based on many-body localization
• Chain breaking and Kosterlitz-Thouless scaling at the many-body localization transition in the random field Heisenberg spin chain
• Pumping approximately integrable systems
• Bath-induced Zeno localization in driven many-body quantum systems
• Localization in spin chains with facilitation constraints and disordered interactions
• Activating many-body localization in solids by driving with light
• Cooling by photo-doping $--$ Light-induced symmetry breaking in the Hubbard model
• Solid effect DNP polarization dynamics in a system of many spins
• Thermalization and many-body localization in systems under dynamic nuclear polarization
• Evidences of spin-temperature in Dynamic Nuclear Polarization: an exact computation of the EPR spectrum
• Nuclear Magnetic Resonance studies of DNP-ready trehalose obtained by solid state mechanochemical amorphization
• Magnetic-field-induced delocalization in hybrid electron-nuclear spin ensembles
• Phase transitions in electron spin resonance under continuous microwave driving
• Tensor-network approach to thermalization in open quantum many-body systems
• Unified understanding of the breakdown of thermal mixing dynamic nuclear polarization: the role of temperature and radical concentration
• An exactly solvable model for Dynamic Nuclear polarization
• Eigenstate versus Zeeman-based approaches to the solid-effect