2,090 research outputs found
Low-control and robust quantum refrigerator and applications with electronic spins in diamond
We propose a general protocol for low-control refrigeration and thermometry
of thermal qubits, which can be implemented using electronic spins in diamond.
The refrigeration is implemented by a probe, consisting of a network of
interacting spins. The protocol involves two operations: (i) free evolution of
the probe; and (ii) a swap gate between one spin in the probe and the thermal
qubit we wish to cool. We show that if the initial state of the probe falls
within a suitable range, and the free evolution of the probe is both unital and
conserves the excitation in the -direction, then the cooling protocol will
always succeed, with an efficiency that depends on the rate of spin dephasing
and the swap gate fidelity. Furthermore, measuring the probe after it has
cooled many qubits provides an estimate of their temperature. We provide a
specific example where the probe is a Heisenberg spin chain, and suggest a
physical implementation using electronic spins in diamond. Here the probe is
constituted of nitrogen vacancy (NV) centers, while the thermal qubits are dark
spins. By using a novel pulse sequence, a chain of NV centers can be made to
evolve according to a Heisenberg Hamiltonian. This proposal allows for a range
of applications, such as NV-based nuclear magnetic resonance of photosensitive
molecules kept in a dark spot on a sample, and it opens up possibilities for
the study of quantum thermodynamics, environment-assisted sensing, and
many-body physics
Wide-field strain imaging with preferentially aligned nitrogen-vacancy centers in polycrystalline diamond
We report on wide-field optically detected magnetic resonance imaging of nitrogen-vacancy centers (NVs) in type IIa polycrystalline diamond. These studies reveal a heterogeneous crystalline environment that produces a varied density of NV centers, including preferential orientation within some individual crystal grains, but preserves long spin coherence times. Using the native NVs as nanoscale sensors, we introduce a three-dimensional strain imaging technique with high sensitivity (<10ā»āµHzā»Ā½) and diffraction-limited resolution across a wide field of view.United States. Office of Naval Research (N00014-13-1-0316)United States. Air Force Office of Scientific Research. Multidisciplinary University Research Initiative I(FA9550-14-1-0052)United States. Air Force Office of Scientific Research (Presidential Early Career Award
Global atmospheric sampling program
Automated instruments were installed on a commercial B-747 aircraft, during the program, to obtain baseline data and to monitor key atmospheric constituents associated with emissions of aircraft engines in order to determine if aircraft are contributing to pollution of the upper atmosphere. Data thus acquired on a global basis over the commercial air routes for 5 to 10 years will be analyzed. Ozone measurements in the 29,000 to 45,000 foot altitude were expanded over what has been available from ozonesondes. Limited aerosol composition measurements from filter samples show low levels of sulfates and nitrates in the upper troposphere. Recently installed instruments for measurement of carbon monoxide and condensation nuclei are beginning to return data
Wide-field Magnetic Field and Temperature Imaging using Nanoscale Quantum Sensors
The simultaneous imaging of magnetic fields and temperature (MT) is important
in a range of applications, including studies of carrier transport, solid-state
material dynamics, and semiconductor device characterization. Techniques exist
for separately measuring temperature (e.g., infrared (IR) microscopy,
micro-Raman spectroscopy, and thermo-reflectance microscopy) and magnetic
fields (e.g., scanning probe magnetic force microscopy and superconducting
quantum interference devices). However, these techniques cannot measure
magnetic fields and temperature simultaneously. Here, we use the exceptional
temperature and magnetic field sensitivity of nitrogen vacancy (NV) spins in
conformally-coated nanodiamonds to realize simultaneous wide-field MT imaging.
Our "quantum conformally-attached thermo-magnetic" (Q-CAT) imaging enables (i)
wide-field, high-frame-rate imaging (100 - 1000 Hz); (ii) high sensitivity; and
(iii) compatibility with standard microscopes. We apply this technique to study
the industrially important problem of characterizing multifinger gallium
nitride high-electron-mobility transistors (GaN HEMTs). We spatially and
temporally resolve the electric current distribution and resulting temperature
rise, elucidating functional device behavior at the microscopic level. The
general applicability of Q-CAT imaging serves as an important tool for
understanding complex MT phenomena in material science, device physics, and
related fields
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