Quantum sensors detect small variations in electric or magnetic fields. They have been used to make precise fundamental Physics and measurements in materials science. They are not able to detect specific frequencies. This limits their utility. Researchers from MIT have found a way to make such sensors detect any frequency, without mislaying the ability to measure features at the nanometer scale.
A new method was patent-covered by the team. It’s now being described in Physical Review X. The paper was written by Guoqing Wang (graduating student in engineering, nuclear science, and physics Paola Cappellaro and a few other researchers at MIT.
There are many kinds of quantum sensors. These systems are made up of particles that are in an inexorable condition and are susceptible to small changes in the field they are under. They can detect neutral atoms or trapped ions. The use of these sensors is rapidly increasing. They are used by scientists to study exotic states such as topological phases or time crystals. Researchers also use them to characterize devices such as quantum memory and computation devices. Other phenomena can also be of interest, and quantum sensors can detect them.
Their quantum mixer system, which they name “quantum mixing”, injects the second frequency in the detector through a beam made from microwaves. This changes the frequency of a field under investigation into a different frequency. The difference in frequency between the original frequency and that added to the signal is converted to a frequency tuned for the detector’s most sensitive frequency. This process allows detectors to find any frequency they desire, without losing their nanoscale spatial resolution.
The team tested a tool based on a diamond array containing nitrogen-vacancy centers. This is a well-known quantum sensing system. A qubit detector with 2.2 gigahertz was used by the team to detect a signal of 150 megahertz. This detection would have been impossible if quantum multiplexer doesn’t support it. The team performed a thorough analysis of the process and came up with a theoretical frame based on Floquet’s theories. The predictions were tested numerically through a series of experiments.
Wang indicated that this system was being tested and that the same principle could also be useful to other types of sensors or quantum devices. One device would contain the detector, source for the second frequency and all other parts.
Wang says that the system might be used for a detailed analysis of the characteristics and performance of microwave antennas. Wang claims that the system can be used with a nanoscale resolution to determine the strength and distributions of the electromagnetic field generated from an antenna. This is a significant step forward.
Although there are other methods to change the frequency sensitivity of certain quantum sensors, these require strong magnetic fields and large devices. This blur the fine details making it difficult for the system to achieve its high resolution. Wang said that such systems need a sturdy magnetic field to tune them. This can also cause quantum material properties to change, which could have an impact on the phenomena you are trying to measure.
Cappellaro claims that the system can open up better opportunities for biomedical fields because it can access wide ranges of electromagnetic or electrical activity frequencies at one cell level. This system can detect the output signals of one neuron that responds to a stimulus. These signals can sometimes be contaminated with noise making it problematic to identify. According to her, it would be difficult for quantum sensing systems to solve such calls.