Dynamic Nuclear Polarization with Quantum Point Contacts.

Self-compensated comagnetometers, employing overlapping samples of spin-polarized alkali and noble gases (for example K- ${}^{3}\mathrm{He}$ ) are promising sensors for exotic beyond-the-standard-model fields and high-precision metrology such as rotation sensing. When the comagnetometer operates in the so-called self-compensated regime, the effective field, originating from contact interactions between the alkali valence electrons and the noble-gas nuclei, is compensated with an applied magnetic field. When the comagnetometer begins operation in a given magnetic field, spin-exchange optical pumping establishes an equilibrium between the alkali electron-spin polarization and the nuclear-spin polarization. Subsequently, when the magnetic field is tuned to the compensation point, the spin polarization is brought out of the equilibrium conditions. This causes a practical issue for long measurement times. We report on a method for closed-loop control of the compensation field. This method allows optimization of the operating parameters, especially magnetic field gradients, in spite of the inherently slow (hours to days) dynamics of the system. With the optimization, higher stable nuclear polarization, longer relaxation times, and stronger electron-nuclear coupling are achieved which is useful for nuclear-spin-based quantum memory, spin amplifiers, and gyroscopes. The optimized sensor demonstrates a sensitivity comparable to the best previous comagnetometer but with four times lower noble-gas density. This paves the way for applications in both fundamental and applied science.Self-compensated comagnetometers, employing overlapping samples of spin-polarized alkali and noble gases (for example K-${}^{3}\mathrm{He}$) are promising sensors for exotic beyond-the-standard-model fields and high-precision metrology such as rotation sensing. When the comagnetometer operates in the so-called self-compensated regime, the effective field, originating from contact interactions between the alkali valence electrons and the noble-gas nuclei, is compensated with an applied magnetic field. When the comagnetometer begins operation in a given magnetic field, spin-exchange optical pumping establishes an equilibrium between the alkali electron-spin polarization and the nuclear-spin polarization. Subsequently, when the magnetic field is tuned to the compensation point, the spin polarization is brought out of the equilibrium conditions. This causes a practical issue for long measurement times. We report on a method for closed-loop control of the compensation field. This method allows optimization of the operating parameters, especially magnetic field gradients, in spite of the inherently slow (hours to days) dynamics of the system. With the optimization, higher stable nuclear polarization, longer relaxation times, and stronger electron-nuclear coupling are achieved which is useful for nuclear-spin-based quantum memory, spin amplifiers, and gyroscopes. The optimized sensor demonstrates a sensitivity comparable to the best previous comagnetometer but with four times lower noble-gas density. This paves the way for applications in both fundamental and applied science.

arXiv:2210.07687Physical Review AppliedApr 28, 202335 citations

Dynamics of nuclear spins at high polarizations

Edward B. Fel’dman, Anatoly K. Khitrin

Journal of Experimental and Theoretical PhysicsOct 1, 19951 citation

MULTIPLE QUANTUM RESONANCE SPECTROSCOPY THROUGH WEAKLY CONNECTED SUPERCONDUCTORS

Arnold H. Silver, James Edward Zimmerman

Voltage-biased superconducting weak contacts have been used as oscillating detectors to observe radio-frequency absorption spectra including the Co59 nuclear magnetic resonance in ferromagnetic cobalt. The detection is attributed to multiple quantum processes and differentiation of the dynamic I-V characteristics. Used as a spectrometer, the point contact is shown to be a continusously tunable ultra-low power oscillator-detector from 0 to 3 × 108 Hz. It is likely that the frequency limit could be extended to the superconducting gap frequency.Voltage-biased superconducting weak contacts have been used as oscillating detectors to observe radio-frequency absorption spectra including the Co59 nuclear magnetic resonance in ferromagnetic cobalt. The detection is attributed to multiple quantum processes and differentiation of the dynamic I-V characteristics. Used as a spectrometer, the point contact is shown to be a continusously tunable ultra-low power oscillator-detector from 0 to 3 × 108 Hz. It is likely that the frequency limit could be extended to the superconducting gap frequency.

Applied Physics LettersMar 1, 196757 citations

Dynamic polarization in a system of optically oriented atomic nuclei

T. G. Izyumova, V. P. Putyrskii

OptSpMay 1, 19750 citations

Thermalization and many-body localization in systems under dynamic nuclear polarization

Andrea De Luca, Inés Rodríguez-Arias, Markus Müller +1 more

We study the role of dipolar interactions in the standard protocol used to achieve dynamic nuclear polarization (DNP). We point out that a critical strength of interactions is required to obtain significant nuclear hyperpolarization. Otherwise, the electron spins do not thermalize among each other, due to the incipient many-body localization transition in the electron spin system. Only when the interactions are sufficiently strong, in the so-called spin-temperature regime, they establish an effective thermodynamic behavior in the out-of-equilibrium stationary state. The highest polarization is reached at a point where the spin temperature is just not able to establish itself anymore. We provide numerical predictions for the level of nuclear hyperpolarization and present an analytical technique to estimate the spin temperature as a function of interaction strength and quenched disorder. We show that, at sufficiently strong coupling, nuclear spins perfectly equilibrate to the spin temperature that establishes among the spins of radicals.We study the role of dipolar interactions in the standard protocol used to achieve dynamic nuclear polarization (DNP). We point out that a critical strength of interactions is required to obtain significant nuclear hyperpolarization. Otherwise, the electron spins do not thermalize among each other, due to the incipient many-body localization transition in the electron spin system. Only when the interactions are sufficiently strong, in the so-called spin-temperature regime, they establish an effective thermodynamic behavior in the out-of-equilibrium stationary state. The highest polarization is reached at a point where the spin temperature is just not able to establish itself anymore. We provide numerical predictions for the level of nuclear hyperpolarization and present an analytical technique to estimate the spin temperature as a function of interaction strength and quenched disorder. We show that, at sufficiently strong coupling, nuclear spins perfectly equilibrate to the spin temperature that establishes among the spins of radicals.

arXiv:1602.01931Physical review. B./Physical review. BJul 6, 201617 citations

Self-compensated comagnetometers, employing overlapping samples of spin-polarized alkali and noble gases (for example K-

{}^{3}\mathrm{He}

) are promising sensors for exotic beyond-the-standard-model fields and high-precision metrology such as rotation sensing. When the comagnetometer operates in the so-called self-compensated regime, the effective field, originating from contact interactions between the alkali valence electrons and the noble-gas nuclei, is compensated with an applied magnetic field. When the comagnetometer begins operation in a given magnetic field, spin-exchange optical pumping establishes an equilibrium between the alkali electron-spin polarization and the nuclear-spin polarization. Subsequently, when the magnetic field is tuned to the compensation point, the spin polarization is brought out of the equilibrium conditions. This causes a practical issue for long measurement times. We report on a method for closed-loop control of the compensation field. This method allows optimization of the operating parameters, especially magnetic field gradients, in spite of the inherently slow (hours to days) dynamics of the system. With the optimization, higher stable nuclear polarization, longer relaxation times, and stronger electron-nuclear coupling are achieved which is useful for nuclear-spin-based quantum memory, spin amplifiers, and gyroscopes. The optimized sensor demonstrates a sensitivity comparable to the best previous comagnetometer but with four times lower noble-gas density. This paves the way for applications in both fundamental and applied science.