Research Summary:
The inter-disciplinary, experimental research group focuses on applications of quantum mechanics, especially to nuclear and electronic spin systems. One important test-bed of quantum physics are two-level quantum mechanical systems, called qubits. Electrons and spin-1/2 nuclei are natural candidates to act as qubits. At the Spin Physics Group at the SSE, we use nuclear magnetic resonance (NMR) and electron spin resonance (ESR) to study fudamental properties of these quantum entities.
We also investigate novel ways of analyzing and improving NMR to enhance our ability to
(a) study chemical reactions and catalytic processes, espcially in microfludic settings,
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| (b) magnetically image structures with higher precision and sensitivity, |
| (c) interpret phenomena arising out of the purely geometrical and mathematical structure of quantum state spaces, |
| (d) applying spin-based techniques, often combining NMR and ESR, to demonstrate quantum information processes and |
| (e) precise, robust effective control of these processes, borrowing heavily from geometric and group-theoretical control theory. |
Active Research Themes:
- algorithmic cooling of spin states and recyclable spin polarization
- power of a single bit of quantum information in the context of NMR
- efficient quantum state tomography with a given quorum of observables
- density matrix renormalization group theory applied to multi-spin states
- geometric phases in magnetic resonance imaging
- ENDOR based quantum computing
- quantum control
- nanoparticle MRI
Research Highlights :
Microreactor Catalytic MRI
Catalysis is vital to industrial chemistry, and the optimization of catalytic reactors attracts considerable resources. It has proven challenging to correlate the active regions in heterogeneous catalyst beds with morphology and to monitor multistep reactions within the bed. We demonstrate techniques, using magnetic resonance imaging and para-hydrogen (p-H2) polarization, that allow direct visualization of gas-phase flow and the density of active catalyst in a packed-bed microreactor, as well as control over the dynamics of the polarized state in space and time to facilitate the study of subsequent reactions. These procedures are suitable for characterizing reactors and reactions in microfluidic devices where low sensitivity of conventional magnetic resonance would otherwise be the limiting factor. |
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For details see:
“Imaging of catalytic hydrogenation in microreactors using para-hydrogen ”, L.-S. Bouchard, S.R. Burt, M.S. Anwar, K.V.
Kovtunov, I.V. Koptyug and A. Pines, Science 319, 442 (2008). Reviews of this work have been published in:
| Chemical Engineering Progress, p. 15, March 2008. |
| Nature, 451, 502 (2008). |
Controlled Spin Precession
The shaping of magnetic fields is important in many areas of physics, including magnet shimming, electromagnetic traps, magnetic domain switching, and controlled spin precession in nuclear magnetic resonance (NMR). We examine the method of target field matching by orthogonal projection and its application to NMR, whereby the phase of nuclear spins in a strongly inhomogeneous field is corrected through stroboscopic ac irradiation using matching fields. Three-dimensional shaping of static and ac fields can restore the spectral resolution by orders of magnitude using simple linear combinations of a small number of independent sources. Results suggest the possibility of substantially pushing the current limits of high-resolution NMR spectroscopy in weak and inhomogeneous fields. We also discuss conditions under which concomitant gradient effects are important in high magnetic fields and the geometric-phase errors they introduce during precession in ac fields. |
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For details see:
“Synthesis of matched magnetic fields for controlled spin precession”, L.-S. Bouchard, M.S. Anwar, Physical Review B 71, 011430 (2007).
Group Members:
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Collaborators:
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Open positions :
Currently we are inviting applications from prospective Ph.D. and advanced B.Sc./M.Sc. students in (physics, chemistry, electrical engineering). Please contact us here by sending a cover letter, a two-page CV and a brief statement of your research interests.
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Last updated June 5, 2008.. |
