Merging two revolutions in quantum sensing: biological qubits based on radical pairs in living cells and solid-state spin qubits. A pulsed quantum microscope was developed, combining optical excitation at 450 and 520 nm with nanosecond gating, three-dimensional scanning at diffraction-limited resolution, rapid switching of static and radio-frequency magnetic fields, single-photon detection with picosecond resolution, and microwave control up to 5 GHz, covering resonances of NV centers (2.87 GHz) and radical pairs (0.5–0.8 GHz). Live-cell imaging was demonstrated with both qubit types coexisting in a single cell—multiplexed quantum sensing. This method opens new avenues for studying quantum processes in living systems and lays the groundwork for entangling a solid-state qubit with a protein-based spin qubit.
A living cell constantly emits faint magnetic signals, as if whispering. Scientists eavesdrop on this whisper with two microscopic 'microphones'—magnetic field sensors. One is crafted by nature (a protein), the other is a man-made diamond speck with a flaw (pure carbon) that turns it into an antenna.
The microscope interrogates both sensors in turn: it shines a blue beam on one, a green beam on the other (a technique of spectroscopy—working with color). The sensors respond with their own glow, which is measured with unprecedented precision—this is where photometry (the science of light pulses) comes in. Even the molecular chaos inside the cell (entropy, the measure of disorder) doesn't drown out these signals.
Two sensors in one cell create a stereo effect: just as two ears pinpoint sound more accurately, two sensors provide a three-dimensional picture. The technology, grown from experiments in quantum control by David Wineland, promises to monitor neurons and drugs. If quantum entanglement—the mysterious connection studied by John Stewart Bell—links the sensors in the future, precision will multiply.
🎯 Some proteins in the eyes of migratory birds can sense Earth's magnetic field, acting as natural quantum compasses.
🎬 Reminiscent of the medical tricorder from 'Star Trek': it peers into cells and deciphers their magnetic whispers.