3,846 research outputs found
Coherent population trapping of a single nuclear spin under ambient conditions
Coherent control of quantum systems has far-reaching implications in quantum
engineering. In this context, coherent population trapping (CPT) involving dark
resonances has played a prominent role, leading to a wealth of major
applications including laser cooling of atoms and molecules, optical
magnetometry, light storage and highly precise atomic clocks. Extending CPT
methods to individual solid-state quantum systems has been only achieved in
cryogenic environments for electron spin impurities and superconducting
circuits. Here, we demonstrate efficient CPT of a single nuclear spin in a room
temperature solid. To this end, we make use of a three-level system with a
-configuration in the microwave domain, which consists of nuclear spin
states addressed through their hyperfine coupling to the electron spin of a
single nitrogen-vacancy defect in diamond. Dark state pumping requires a
relaxation mechanism which, in atomic systems, is simply provided by
spontaneous emission. In this work, the relaxation process is externally
controlled through incoherent optical pumping and separated in time from
consecutive coherent microwave excitations of the nuclear spin
-system. Such a pumping scheme with controlled relaxation allows us
(i) to monitor the sequential accumulation of population into the dark state
and (ii) to reach a new regime of CPT dynamics for which periodic arrays of
dark resonances can be observed, owing to multiple constructive interferences.
This work offers new prospects for quantum state preparation, information
storage in hybrid quantum systems and metrology.Comment: 13 pages including supplementary information, links to figures
correcte
Magnetometry with nitrogen-vacancy defects in diamond
The isolated electronic spin system of the Nitrogen-Vacancy (NV) centre in
diamond offers unique possibilities to be employed as a nanoscale sensor for
detection and imaging of weak magnetic fields. Magnetic imaging with nanometric
resolution and field detection capabilities in the nanotesla range are enabled
by the atomic-size and exceptionally long spin-coherence times of this
naturally occurring defect. The exciting perspectives that ensue from these
characteristics have triggered vivid experimental activities in the emerging
field of "NV magnetometry". It is the purpose of this article to review the
recent progress in high-sensitivity nanoscale NV magnetometry, generate an
overview of the most pertinent results of the last years and highlight
perspectives for future developments. We will present the physical principles
that allow for magnetic field detection with NV centres and discuss first
applications of NV magnetometers that have been demonstrated in the context of
nano magnetism, mesoscopic physics and the life sciences.Comment: Review article, 28 pages, 16 figure
Coherent population trapping of a single nuclear spin under ambient conditions
Coherent control of quantum systems has far-reaching implications in quantum
engineering. In this context, coherent population trapping (CPT) involving dark
resonances has played a prominent role, leading to a wealth of major
applications including laser cooling of atoms and molecules, optical
magnetometry, light storage and highly precise atomic clocks. Extending CPT
methods to individual solid-state quantum systems has been only achieved in
cryogenic environments for electron spin impurities and superconducting
circuits. Here, we demonstrate efficient CPT of a single nuclear spin in a room
temperature solid. To this end, we make use of a three-level system with a
-configuration in the microwave domain, which consists of nuclear spin
states addressed through their hyperfine coupling to the electron spin of a
single nitrogen-vacancy defect in diamond. Dark state pumping requires a
relaxation mechanism which, in atomic systems, is simply provided by
spontaneous emission. In this work, the relaxation process is externally
controlled through incoherent optical pumping and separated in time from
consecutive coherent microwave excitations of the nuclear spin
-system. Such a pumping scheme with controlled relaxation allows us
(i) to monitor the sequential accumulation of population into the dark state
and (ii) to reach a new regime of CPT dynamics for which periodic arrays of
dark resonances can be observed, owing to multiple constructive interferences.
This work offers new prospects for quantum state preparation, information
storage in hybrid quantum systems and metrology.Comment: 13 pages including supplementary information, links to figures
correcte
Admission to psychiatric hospital for mental illnesses 2 years prechildbirth and postchildbirth in Scotland: a health informatics approach to assessing mother and child outcomes
Objective: To identify factors associated with: admission to a specialist mother and baby unit (MBU) and the impact of perinatal mental illness on early childhood development using a data linkage approach in the 2 years prechildbirth and postchildbirth.
Methods: Scottish maternity records (SMR02) were linked to psychiatric hospital admissions (SMR04). 3290 pregnancy-related psychiatric admissions for 1730 women were assessed. To investigate factors associated with MBU admission, the group of mothers admitted to an MBU were compared with those admitted to general psychiatric wards. To assess the impact of perinatal mental illness on early child development, a pragmatic indicator for ‘at potential risk of adversity’, defined as a child who was recorded as requiring intensive treatment at any time under the health plan indicators (HPI) and/or who had no record of completing three doses of the 5-in-1 vaccine by 12 months was generated. Logistic regression models were used to describe the association between each variable and the risk of admission between those with a history of prior psychiatric admission and those without.
Results Women admitted to an MBU were significantly more likely to be admitted with non-affective psychosis (OR=1.97, 95% CI 1.22 to 3.18), affective psychosis (OR=2.44, 95% CI 1.37 to 4.33) and non-psychotic depressive episodes (OR=1.93, 95% CI 1.42 to 2.63). They were less likely to come from deprived areas (OR=0.68 95% CI 0.49 to 0.93). Women with a previous history of psychiatric admission were significantly more likely to be located in the two most deprived quintiles. Almost one-third (29%) of children born to mothers with a pregnancy-related psychiatric admission were assessed as ‘at potential risk of adversity.’
Conclusions: A health informatics approach has potential for improving understanding of social and clinical factors, which contribute to the outcomes of perinatal mental illness, as well as potential adverse developmental outcomes for offspring
Measuring the magnetic moment density in patterned ultrathin ferromagnets with submicron resolution
We present a new approach to infer the surface density of magnetic moments
in ultrathin ferromagnetic films with perpendicular anisotropy. It relies
on quantitative stray field measurements with an atomic-size magnetometer based
on the nitrogen-vacancy center in diamond. The method is applied to
microstructures patterned in a 1-nm-thick film of CoFeB. We report measurements
of with a few percent uncertainty and a spatial resolution in the range
of nm), an improvement by several orders of magnitude over existing
methods. As an example of application, we measure the modifications of
induced by local irradiation with He ions in an ultrathin ferromagnetic
wire. This method offers a new route to study variations of magnetic properties
at the nanoscale.Comment: 9 pages and 7 figures including main text and Supplemental
Informatio
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