216 research outputs found
Variational semi-blind sparse deconvolution with orthogonal kernel bases and its application to MRFM
We present a variational Bayesian method of joint image reconstruction and point spread function (PSF) estimation when the PSF of the imaging device is only partially known. To solve this semi-blind deconvolution problem, prior distributions are specified for the PSF and the 3D image. Joint image reconstruction and PSF estimation is then performed within a Bayesian framework, using a variational algorithm to estimate the posterior distribution. The image prior distribution imposes an explicit atomic measure that corresponds to image sparsity. Importantly, the proposed Bayesian deconvolution algorithm does not require hand tuning. Simulation results clearly demonstrate that the semi-blind deconvolution algorithm compares favorably with previous Markov chain Monte Carlo (MCMC) version of myopic sparse reconstruction. It significantly outperforms mismatched non-blind algorithms that rely on the assumption of the perfect knowledge of the PSF. The algorithm is illustrated on real data from magnetic resonance force microscopy (MRFM)
170 Nanometer Nuclear Magnetic Resonance Imaging using Magnetic Resonance Force Microscopy
We demonstrate one-dimensional nuclear magnetic resonance imaging of the
semiconductor GaAs with 170 nanometer slice separation and resolve two regions
of reduced nuclear spin polarization density separated by only 500 nanometers.
This is achieved by force detection of the magnetic resonance, Magnetic
Resonance Force Microscopy (MRFM), in combination with optical pumping to
increase the nuclear spin polarization. Optical pumping of the GaAs creates
spin polarization up to 12 times larger than the thermal nuclear spin
polarization at 5 K and 4 T. The experiment is sensitive to sample volumes
containing Ga. These results
demonstrate the ability of force-detected magnetic resonance to apply magnetic
resonance imaging to semiconductor devices and other nanostructures.Comment: Submitted to J of Magnetic Resonanc
Magnetic Resonance Force Microscopy Measurement of Entangled Spin States
We simulate magnetic resonance force microscopy measurements of an entangled
spin state. One of the entangled spins drives the resonant cantilever
vibrations, while the other remote spin does not interact directly with the
quasiclassical cantilever. The Schr\"odinger cat state of the cantilever
reveals two possible outcomes of the measurement for both entangled spins.Comment: 3 pages RevTe
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