Ongoing project.

Magnetic resonance spectroscopy (EPR, NMR) is an important tool for molecular structure determination, but is currently limited to ensemble measurements. This makes elusive the detailed analysis of large complicated molecules, such as proteins. In this project we seek to demonstrate structure-resolving magnetic resonance spectroscopy and imaging of single molecules.

The nitrogen-vacancy (NV) center in diamond is an optically addressable single-spin magnetometer with sufficient sensitivity for rudimentary NMR spectroscopy of nanoscale samples [1] and even single proteins [2]. In addition, the NV center can be used to coherently control a single electron spin near the diamond surface [3]. If this electron spin resides unpaired on a molecule, its coupling to spin-carrying nuclei of the molecule can be resolved by a shallow NV center in the diamond to pinpoint the locations of the nuclei, thus producing a patial magnetic resonance image (MRI) of the molecule.

As initial imaging targets, we chose molecular qubits: molecules hosting stable unpaired electrons with long coherence times. These can further be used as spin labels to image more complicated molecules of interest.

Separatey, molecular qubits can be assembled into dipolar-interacting spin networks of desired geometry and size. With quantum control of these networks enabled by the proximal NV center, this is a promising system for investigating quantum many-body dynamics.

Relevant work:
[1] Lovchinsky et. al., "Magnetic resonance spectroscopy of an atomically thin material using a single-spin qubit", Science, 507, 503–507 (2017)
[2] Lovchinsky et. al., "Nuclear magnetic resonance detection and spectroscopy of single proteins using quantum logic", Science, 351, 836–841 (2016)
[3] Sushkov et. al., "Magnetic Resonance Detection of Individual Proton Spins Using Quantum Reporters", Physical Review Letters, 113, 197601 (2014)