Universität Stuttgart

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Institute: search.filters.UBSInstitut.Stuttgart Research Centre of Photonic Engineering (SCoPE)Institute: search.filters.UBSInstitut.3. Physikalisches InstitutPublication Type: search.filters.UBSTyp.ZeitschriftenartikelStart date: 2013End date: 2019

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    Photo-induced ionization dynamics of the nitrogen vacancy defect in diamond investigated by single-shot charge state detection
    (2013) Aslam, Nabeel; Waldherr, Gerald; Neumann, Philipp; Jelezko, Fedor; Wrachtrup, Jörg
    The nitrogen-vacancy centre (NV) has drawn much attention for over a decade, yet detailed knowledge of the photophysics needs to be established. Under typical conditions, the NV can have two stable charge states, negative (NV-) or neutral (NV0), with photo-induced interconversion of these two states. Here, we present detailed studies of the ionization dynamics of single NV centres in bulk diamond at room temperature during illumination and its dependence on the excitation wavelength and power. We apply a recent method which allows us to directly measure the charge state of a single NV centre, and observe its temporal evolution. We find that the steady-state NV− population is always ⩽75% for 450–610 nm excitation wavelength. In combination with saturation measurements, we show that the optimal excitation wavelength is around 510-540 nm. Furthermore, the relative absorption cross-section of NV- is determined for 540-610 nm, revealing a double-peak structure. Finally, the energy of the NV- ground state of 2.6 eV below the conduction band is measured. These results reveal new insights into the charge state dynamics of the NV centre.
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    Measuring the defect structure orientation of a single NV- centre in diamond
    (2014) Doherty, Marcus W.; Michl, Julia; Dolde, Florian; Jakobi, Ingmar; Neumann, Philipp; Manson, Neil B.; Wrachtrup, Jörg
    The negatively charged nitrogen-vacancy (NV- ) centre in diamond has many exciting applications in quantum nano-metrology, including magnetometry, electrometry, thermometry and piezometry. Indeed, it is possible for a single NV- centre to measure the complete three-dimensional vector of the local electric field or the position of a single fundamental charge in ambient conditions. However, in order to achieve such vector measurements, near complete knowledge of the orientation of the centreʼs defect structure is required. Here, we demonstrate an optically detected magnetic resonance (ODMR) technique employing rotations of static electric and magnetic fields that precisely determines the orientation of the centreʼs major and minor trigonal symmetry axes. Thus, our technique is an enabler of the centreʼs existing vector sensing applications and also motivates new applications in multi-axis rotation sensing, NV growth characterization and diamond crystallography.
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    Ambient nanoscale sensing with single spins using quantum decoherence
    (2013) McGuinness, Liam P.; Hall, Liam T.; Stacey, Alastair; Simpson, David A.; Hill, Charles D.; Cole, Jared H.; Ganesan, Koushik; Gibson, Brant C.; Prawer, Steven; Mulvaney, Paul; Jelezko, Fedor; Wrachtrup, Jörg; Scholten, Robert E.; Hollenberg, Lloyd C. L.
    Magnetic resonance detection is one of the most important tools used in life-sciences today. However, as the technique detects the magnetization of large ensembles of spins it is fundamentally limited in spatial resolution to mesoscopic scales. Here we detect the natural fluctuations of nanoscale spin ensembles at ambient temperatures by measuring the decoherence rate of a single quantum spin in response to introduced extrinsic target spins. In our experiments 45 nm nanodiamonds with single nitrogen-vacancy (NV) spins were immersed in solution containing spin 5/2 Mn2+ ions and the NV decoherence rate measured though optically detected magnetic resonance. The presence of both freely moving and accreted Mn spins in solution were detected via significant changes in measured NV decoherence rates. Analysis of the data using a quantum cluster expansion treatment of the NV-target system found the measurements to be consistent with the detection of  2500 motionally diffusing Mn spins over an effective volume of (16 nm)3 in 4.2 s, representing a reduction in target ensemble size and acquisition time of several orders of magnitude over conventional, magnetic induction approaches to electron spin resonance detection. These measurements provide the basis for the detection of nanovolume spins in solution, such as in the internal compartments of living cells, and are directly applicable to scanning probe architectures.