Category Archives: NV Centers

[NMR] Postdoc/PhD position available on high-frequency microwave engineering for NV-diamond NMR

Dear colleagues

a postdoc/PhD/staff position is available in the Bucher lab at the Technical University of Munich in the frame of the EU HORIZON 2020 ERC programme.

Topic: High-frequency microwave engineering for NV-diamond NMR

Description of the work: In recent years, defects in diamonds have been shown to act as atomic-sized sensors for nanoscale nuclear magnetic resonance (NMR) experiments. Here, this innovative quantum technology will be further developed for real-world applications in chemistry, material and life sciences. The project will be highly interdisciplinary at the unique interface between quantum technology and chemistry. The research position is situated in the Chemistry Department (physical chemistry) at the Technischen Universität München and is funded by the European Union. More information can be found on www.bucherlab.org.

Current microscale NV-NMR experiments typically work at low magnetic fields (< 0.1T) which limits their application due to a lack of chemical specificity. In this Postdoc position, a new NV-NMR setup with an increased spectral resolution at higher magnetic fields (0.5-1.5 T) will be developed. Thus, microwave pulses at high power and frequencies (10-40 GHz) will be generated, and a suitable resonator will be designed. The application of this new technique will be in biology and material sciences.

Further information: www.bucherlab.org

https://qt.eu/engage/jobs/high-frequency-microwave-engineering-for-quantum-sensing-applications/

Specific Requirements: Prospective candidates should have a Masters/PhD degree in electrical engineering, physics, spectroscopy, or related field, interested in technology development and have extensive hands-on experience in high-frequency microwave engineering. While not required, experience in one or more of the following topics are advantageous: NV-quantum sensing / NMR / EPR spectroscopy

Biomolecular Quantum Sensing

Dr. Dominik Bucher

TUM Junior Fellow

Lichtenbergstr. 4

D-85748 Garching

Tel.: +49 89/28913435

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NMR web database:

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[NMR] PhD position with NV centres in diamond at the Helmholtz Zentrum Berlin

Dear colleagues and friends,

we are searching for a highly motivated PhD candidate within the DFG funded project “Quantum many body interactions in a two dimensional solid state system”. The goal is to create and use single spins in diamond (nitrogen vacancy centres, shortly NV) to control nanoscale two dimensional (2D) arrays of nuclear spins, with the final goal being the realisation of a solid state quantum simulator.

The description of the position and a link for application can be found here:

https://recruitingapp-5181.de.umantis.com/Vacancies/1131/Description/2?lang=eng

For further information feel free to contact me.

I would be very grateful if you could distribute this email to any suitable candidates of whom you are aware.

Thank you very much!

Best wishes,

Boris Naydenov

Dr. Boris Naydenov

Helmholtz-Zentrum Berlin für Materialien und Energie (HZB)

Institute for Nanospectroscopy

Kekuléstraße. 5

D-12489 Berlin

Germany

Telefon:

+49 30 8062 – 41373

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Helmholtz-Zentrum Berlin für Materialien und Energie GmbH

Mitglied der Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren e.V.

Aufsichtsrat: Vorsitzender Dr. Volkmar Dietz, stv. Vorsitzende Dr. Jutta Koch-Unterseher

Geschäftsführung: Prof. Dr. Bernd Rech (Sprecher), Prof. Dr. Jan Lüning, Thomas Frederking

Sitz Berlin, AG Charlottenburg, 89 HRB 5583

Postadresse:

Hahn-Meitner-Platz 1

D-14109 Berlin

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http://www.drorlist.com/nmrlist.html

NMR web database:

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Carbon-13 dynamic nuclear polarization in diamond via a microwave-free integrated cross effect #DNPNMR

Henshaw, Jacob, Daniela Pagliero, Pablo R. Zangara, María B. Franzoni, Ashok Ajoy, Rodolfo H. Acosta, Jeffrey A. Reimer, Alexander Pines, and Carlos A. Meriles. “Carbon-13 Dynamic Nuclear Polarization in Diamond via a Microwave-Free Integrated Cross Effect.” Proceedings of the National Academy of Sciences 116, no. 37 (September 10, 2019): 18334–40.

https://doi.org/10.1073/pnas.1908780116

Color-center–hosting semiconductors are emerging as promising source materials for low-field dynamic nuclear polarization (DNP) at or near room temperature, but hyperfine broadening, susceptibility to magnetic field heterogeneity, and nuclear spin relaxation induced by other paramagnetic defects set practical constraints difficult to circumvent. Here, we explore an alternate route to color-center–assisted DNP using nitrogen-vacancy (NV) centers in diamond coupled to substitutional nitrogen impurities, the so-called P1 centers. Working near the level anticrossing condition—where the P1 Zeeman splitting matches one of the NV spin transitions—we demonstrate efficient microwave-free 13C DNP through the use of consecutive magnetic field sweeps and continuous optical excitation. The amplitude and sign of the polarization can be controlled by adjusting the low-to-high and high-to-low magnetic field sweep rates in each cycle so that one is much faster than the other. By comparing the 13C DNP response for different crystal orientations, we show that the process is robust to magnetic field/NV misalignment, a feature that makes the present technique suitable to diamond powders and settings where the field is heterogeneous. Applications to shallow NVs could capitalize on the greater physical proximity between surface paramagnetic defects and outer nuclei to efficiently polarize target samples in contact with the diamond crystal.

Enhanced Dynamic Nuclear Polarization via Swept Microwave Frequency Combs #DNPNMR

Ajoy, A., R. Nazaryan, K. Liu, X. Lv, B. Safvati, G. Wang, E. Druga, et al. “Enhanced Dynamic Nuclear Polarization via Swept Microwave Frequency Combs.” Proceedings of the National Academy of Sciences 115, no. 42 (October 16, 2018): 10576–81. 

https://doi.org/10.1073/pnas.1807125115.

Dynamic nuclear polarization (DNP) has enabled enormous gains in magnetic resonance signals and led to vastly accelerated NMR/MRI imaging and spectroscopy. Unlike conventional cw-techniques, DNP methods that exploit the full electron spectrum are appealing since they allow direct participation of all electrons in the hyperpolarization process. Such methods typically entail sweeps of microwave radiation over the broad electron linewidth to excite DNP but are often inefficient because the sweeps, constrained by adiabaticity requirements, are slow. In this paper, we develop a technique to overcome the DNP bottlenecks set by the slow sweeps, using a swept microwave frequency comb that increases the effective number of polarization transfer events while respecting adiabaticity constraints. This allows a multiplicative gain in DNP enhancement, scaling with the number of comb frequencies and limited only by the hyperfine-mediated electron linewidth. We demonstrate the technique for the optical hyperpolarization of 13C nuclei in powdered microdiamonds at low fields, increasing the DNP enhancement from 30 to 100 measured with respect to the thermal signal at 7T. For low concentrations of broad linewidth electron radicals [e.g., TEMPO ((2,2,6,6- tetramethylpiperidin-1-yl)oxyl)], these multiplicative gains could exceed an order of magnitude.

Orientation-independent room temperature optical 13C hyperpolarization in powdered diamond #DNPNMR

Ajoy, Ashok, Kristina Liu, Raffi Nazaryan, Xudong Lv, Pablo R. Zangara, Benjamin Safvati, Guoqing Wang, et al. “Orientation-Independent Room Temperature Optical 13C Hyperpolarization in Powdered Diamond.” Science Advances 4, no. 5 (May 1, 2018):

 https://doi.org/10.1126/sciadv.aar5492

Dynamic nuclear polarization via contact with electronic spins has emerged as an attractive route to enhance the sensitivity of nuclear magnetic resonance beyond the traditional limits imposed by magnetic field strength and temperature. Among the various alternative implementations, the use of nitrogen vacancy (NV) centers in diamond—a paramagnetic point defect whose spin can be optically polarized at room temperature—has attracted widespread attention, but applications have been hampered by the need to align the NV axis with the external magnetic field. We overcome this hurdle through the combined use of continuous optical illumination and a microwave sweep over a broad frequency range. As a proof of principle, we demonstrate our approach using powdered diamond with which we attain bulk 13C spin polarization in excess of 0.25% under ambient conditions. Remarkably, our technique acts efficiently on diamond crystals of all orientations and polarizes nuclear spins with a sign that depends exclusively on the direction of the microwave sweep. Our work paves the way toward the use of hyperpolarized diamond particles as imaging contrast agents for biosensing and, ultimately, for the hyperpolarization of nuclear spins in arbitrary liquids brought in contact with their surface.

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