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Scientists at MIT have developed a way to allow such quantum sensors to detect any arbitrary frequency, with no lack of their capacity to measure nanometer-scale options.
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.
MIT researchers have developed a method to enable quantum sensors to detect any arbitrary frequency, with no loss of their ability to measure nanometer-scale features. Quantum sensors detect the most minute variations in magnetic or electrical fields, but until now they have only been capable of detecting a few specific frequencies, limiting their usefulness. Credit: Guoqing Wang
The new system the team devised, which they call a quantum mixer, injects a second frequency into the detector using a beam of microwaves. This converts the frequency of the field being studied into a different frequency — the difference between the original frequency and that of the added signal — which is tuned to the specific frequency that the detector is most sensitive to. This simple process enables the detector to home in on any desired frequency at all, with no loss in the nanoscale spatial resolution of the sensor.
In their experiments, the team used a specific device based on an array of nitrogen-vacancy centers in diamond, a widely used quantum sensing system, and successfully demonstrated the detection of a signal with a frequency of 150 megahertz, using a qubit detector with a frequency of 2.2 gigahertz — a detection that would be impossible without the quantum multiplexer. They then did detailed analyses of the process by deriving a theoretical framework, based on Floquet theory, and testing the numerical predictions of that theory in a series of experiments.
While their tests used this specific system, Wang says, “the same principle can be also applied to any kind of sensors or quantum devices.” The system would be self-contained, with the detector and the source of the second frequency all packaged in a single device.
Wang says that this system could be used, for example, to characterize in detail the performance of a microwave antenna. “It can characterize the distribution of the field [generated by the antenna] with nanoscale decision, so it’s very promising in that course,” he says.
There are different methods of altering the frequency sensitivity of some quantum sensors, however these require using massive gadgets and robust magnetic fields that blur out the fantastic particulars and make it not possible to attain the very excessive decision that the brand new system affords. In such programs in the present day, Wang says, “you need to use a strong magnetic field to tune the sensor, but that magnetic field can potentially break the quantum material properties, which can influence the phenomena that you want to measure.”
The system could open up new purposes in biomedical fields, based on Cappellaro, as a result of it could possibly make accessible a spread of frequencies {of electrical} or magnetic exercise on the stage of a single cell. It can be very tough to get helpful decision of such indicators utilizing present quantum sensing programs, she says. It could also be potential to make use of this technique to detect output indicators from a single neuron in response to some stimulus, for instance, which usually contains quite a lot of noise, making such indicators arduous to isolate.
The system may be used to characterize intimately the habits of unique supplies resembling 2D supplies which can be being intensely studied for his or her electromagnetic, optical, and bodily properties.
In ongoing work, the staff is exploring the potential of discovering methods to increase the system to have the ability to probe a spread of frequencies directly, relatively than the current system’s single frequency concentrating on. They may also be persevering with to outline the system’s capabilities utilizing extra highly effective quantum sensing gadgets at Lincoln Laboratory, the place some members of the analysis staff are primarily based.
Reference: “Sensing of Arbitrary-Frequency Fields Using a Quantum Mixer” by Guoqing Wang, Yi-Xiang Liu, Jennifer M. Schloss, Scott T. Alsid, Danielle A. Braje and Paola Cappellaro, 17 June 2022, Physical Review X.
DOI: 10.1103/PhysRevX.12.021061
The staff included Yi-Xiang Liu at MIT and Jennifer Schloss, Scott Alsid and Danielle Braje at Lincoln Laboratory. The work was supported by the Defense Advanced Research Projects Agency (DARPA) and Q-Diamond.
