MIT engineers expand the capabilities of these ultrasensitive nanoscale detectors, with potential uses for biological sensing and quantum computing.

With the ability to detect the most minute variations in magnetic or electrical fields, quantum sensors have enabled precision measurements in materials science and fundamental physics. However, these sensors have limited usefulness because they are only been capable of detecting a few specific frequencies of these fields. Now, MIT researchers have developed a method to enable such sensors to detect any arbitrary frequency, with no loss of their ability to measure nanometer-scale features.

The new method is described in a paper published in the journal Physical Review X by graduate student Guoqing Wang, professor of nuclear science and engineering and of physics Paola Cappellaro, and four others at MIT and Lincoln Laboratory. The team has already applied for patent protection for the new method.

Although quantum sensors can take many forms, at their essence they’re systems in which some particles are in such a delicately balanced state that they are affected by even tiny variations in the fields they are exposed to. These can take the form of neutral atoms, trapped ions, and solid-state spins, and research using such sensors has grown rapidly. For example, physicists use them to investigate exotic states of matter, including so-called time crystals and topological phases, while other scientists use them to characterize practical devices such as experimental quantum memory or computation devices. However, many other phenomena of interest span a much broader frequency range than today’s quantum sensors can detect.