Photoexcitation of flavoproteins followed by electron transfer reactions between an amino acid donor and s flavin acceptor generates entangled radical pairs. In the presence of a moderate static magnetic field (~ 10 mT), the singlet-triplet splitting energy of this entangled pair occurs in the microwave (1 GHz) range. The single/triplet states have different downstream fates, one of which results in different fluorescence intensity of the flavin. Other biochemical fates are also known, and many are yet to be discovered. Three recent papers have transfected versions of these flavoproteins into live cells that have been genetically engineered to show a large change of fluorescence with static magnetic field, including E-Coli (Oxford [1]), mammalian cells (Uchicago [2]), and C Elegans (Stanford [3]). These systems now have earned the title protein quantum bit, since at low temperature, quantum coherence can be demonstrated via Rabi oscillations of the two level system. Since the flavin redox chemistry is the key step in oxidative phosphorylation, we are engaged in a research program to demonstrate, study, and engineer the quantum bit as a readout of cellular metabolic state. Our results [4] clearly show that pharmacological manipulation of the redox state of the electron transport chain complexes in mitochondria (many of which are flavoproteins themselves) changes the mitochondrial targeted protein quantum bit (transfected into mammalian cells) magnetic field dependent fluorescence, thus demonstrating what we call broadly a “quantum interface with life”. Many open questions remain, including the coherence time in live cells at room temperature, as well as the identity of the flavoproteins, flavins, and amino acids involved. The tools of genetic engineering can be used to address some of these questions[5]. In vitro work of flavins, flavo-proteins, and (recently) DNA-flavin complexes[6] provide a more controlled test bed for dissecting the quantum energy levels and transition rates, requiring pulsed RF and optical setups [7]. Finally, the prospect of quantum actuation of redox states provides an intriguing opportunity for exploitation of quantum information science and technology in affecting rather than sensing biology, broadly writ.