As it has become possible to detect and interact with well-defined and increasingly complex states of quantum systems, the prospect of using biomolecules to selectively bind or programmably assemble such systems presents an exciting frontier for both science and technology. Presently, such interdisciplinary research relies on scientists with non-overlapping areas of expertise. The InTriQATe NRT will provide a structure in which graduate students can become familiar with the science and adept in the techniques of both quantum state manipulation and detection and biomolecular manipulation, functionalization, and assembly. It will thus prepare a generation of scientists to push the frontier forward in ways unimaginable by the generation that initiated the melding of such disparate fields. The sort of novel, potentially transformative research the NRT will catalyze in this area is illustrated by two research projects involving the co-PIs of InTriQATe and collaborators at UCSB. The first explores the use of DNA nanotechnology to self-assemble structures that host single atomic spins at deterministic locations with nanoscale precision, to enable the construction of complex interacting quantum systems. The second addresses the question of whether biology has evolved to utilize quantum information and quantum logic concepts. Both offer rich opportunities for graduate training across multiple disciplines. Biological heteropolymers derive extraordinary functionality using a small set of specific interactions to control the spatial relationships between reactive moieties. The advent of nucleic acid nanotechnology presents the possibility of leveraging this biological strategy to place effective qubits, or more complex quantum systems, in well-defined, arbitrary arrangements of nm scale resolution and µm-scale extent. An essential first step will be to establish the chemistry for covalently connecting molecular-scale spin systems to DNA without sacrificing long quantum coherence lifetimes. One promising approach is to use the NV center as the local optical readout. Patterning will make it possible to probe the quantum coherence of assembled spins on the single spin level. This project will offer the opportunity for training in state-of-the-art biophysical, physical, and chemical principles to achieve precision control of spin localization. Separately, it has been recently suggested that symmetric phosphorus clusters such as pyrophosphate (PPi) may exhibit quantum phenomena even in biological contexts [5,6]. Intriguingly, separation of the phosphorus pairs in PPi by specific enzymes plays an essential role in many biological processes, especially near synapses. If we could generate, control, and measure quantum entanglement of PPi nuclear spins, this would open up many fascinating avenues of investigation into quantum phenomena in biological systems. Here the concept of quantum dynamical selection rules comes into play: symmetries of the PPi molecule imply strict relations between intrinsic spin and orbital angular momentum, and Fisher argues that only the singlet spin state of the two phosphorous nuclei is compatible with an orbital state that ceases to rotate and would therefore be more favorable for “docking” of the PPi molecule into the active site of the enzyme pyrophosphatase (PPase) designed by nature to break PPi apart [5]. The result would be that one specific type of entanglement would be filtered out for chemical transformations: this would constitute a first-of-its-kind quantum application. A core experimental idea for the exploration of these proposals is to modify the protein PPase by replacing intrinsic Mg2+ ligands by paramagnetic Mn2+ ligands. Mn2+ has a characteristic Electron Paramagnetic Resonance (EPR) signal which changes depending on surrounding spins. This spin detection method can be combined with Nuclear Magnetic Resonance (NMR) measurements of the PPI nuclear spin state. Trainees in this area will have the opportunity to work on profound questions of quantum control in warm wet systems, using a combination of chemistry, biology, and physics approaches and a range of advanced tools of high magnetic field EPR, NMR, and hyperfine magnetic resonance spectroscopy.
