- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Combination of OPSY and PhD-PHIP results in enhanced sensitivity in PHIP
摘要： Despite the large degree of polarization in PHIP experiments compared to the Boltzmann factor, the presence of a large amount of non-reacted molecules with thermal polarization is an important obstacle when dealing with very diluted samples. The feasibility of enhancing both sensitivity and resolution in a single experiment by combining two well established pulse sequences, OPSY and PHD-PHIP is presented. OPSY is used as a block for filtering the signals originated from thermally polarized protons. PhD-PHIP, on the other hand, is used as an acquisition block, increasing the resolution and further improving the sensitivity by preventing signal canceling in the presence of magnetic field inhomogeneities. Experiments in a complex sample with very low hyperpolarization levels are presented showing the excellent performance of the method.
关键词： Echo trains,PhD-PHIP,Spin dynamics,CPMG,J-spectroscopy,Hyperpolarization,Pulse sequences,Parahydrogen,SABRE,J-coupling,NMR,OPSY,PHIP
更新于2025-09-23 15:23:52
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Arbitrarily accurate variable rotations on the Bloch sphere by composite pulse sequences
摘要： Composite pulse sequences, which produce arbitrary prede?ned rotations of a two-state system at an angle θ on the Bloch sphere, are presented. The composite sequences can contain arbitrarily many pulses and can compensate experimental errors in the pulse amplitude and duration to any desired order. A special attention is devoted to two classes of π/2 sequences—symmetric and asymmetric—the phases of which are given by simple formulas in terms of rational multiples of π for any number of constituent pulses. This allows one to construct arbitrarily accurate π/2 composite rotations. These π/2 composite sequences are used to construct three classes of arbitrarily long composite θ sequences by pairing two π/2 composite sequences, one of which is shifted by a phase π ? θ with respect to the other one.
关键词： Bloch sphere,quantum control,composite pulses,error compensation,pulse sequences
更新于2025-09-23 15:23:52
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[IEEE 2019 IEEE 58th Conference on Decision and Control (CDC) - Nice, France (2019.12.11-2019.12.13)] 2019 IEEE 58th Conference on Decision and Control (CDC) - Robust Population Transfer for Coupled Spin Ensembles
摘要： Finely manipulating a large population of interacting nuclear spins is an extremely challenging problem arising in wide-ranging applications in quantum science and technology. Prominent examples include the design of robust excitation and inversion pulses for nuclear magnetic resonance spectroscopy and imaging, coordination of spin networks for coherence transfer, and control of superposition and entanglement for quantum computation. In this paper, by integrating the technique of small angle approximation with non-harmonic Fourier analysis, we establish a systematic method to construct robust pulse sequences that neutralize the effect of coupling variations in a spin network. In addition, we explore an alternating optimization procedure for tailoring the constructed pulses to satisfy practical design criteria. We also provide numerical examples to demonstrate the efficacy of the proposed methodology.
关键词： non-harmonic Fourier analysis,small angle approximation,robust pulse sequences,spin ensembles,quantum control
更新于2025-09-19 17:13:59