Bang-bang optimal control of large spin systems: Enhancement of 13C-13C singlet-order at natural abundance

Deepak Khurana; T S Mahesh

doi:10.1016/j.jmr.2017.09.006

Bang-bang optimal control of large spin systems: Enhancement of ¹³C-¹³C singlet-order at natural abundance

J Magn Reson. 2017 Nov:284:8-14. doi: 10.1016/j.jmr.2017.09.006. Epub 2017 Sep 14.

Authors

Deepak Khurana¹, T S Mahesh²

Affiliations

¹ Department of Physics and NMR Research center, Indian Institute of Science Education and Research, Pune 411008, India. Electronic address: deepak.khurana@students.iiserpune.ac.in.
² Department of Physics and NMR Research center, Indian Institute of Science Education and Research, Pune 411008, India; Center for Energy Sciences, Indian Institute of Science Education and Research, Pune 411008, India. Electronic address: mahesh.ts@iiserpune.ac.in.

PMID: 28938135
DOI: 10.1016/j.jmr.2017.09.006

Abstract

Using a bang-bang optimal control technique, we transfer polarization from a set of abundant high-γ nuclei directly to singlet order of a low-γ spin-pair. This approach is analogous to algorithmic cooling (AC) procedure used in quantum state purification. Specifically, we apply this method for enhancing the singlet order in a natural abundant ¹³C- ¹³C spin pair by exploiting nine equivalent protons of an 11-spin system. Compared to the standard method not involving polarization transfer, we find an enhancement of singlet order by about 3.4 times. In addition, since the singlet magnetization is contributed by the faster relaxing protons, the recycle delay is halved. Thus effectively we observe a reduction in the overall experimental time by a factor of 23. We also discuss a possible extension of AC, known as heat-bath algorithmic cooling (HBAC).

Keywords: Algorithmic cooling; Bang-bang optimal control; Long lived singlet state.

Publication types

Research Support, Non-U.S. Gov't