The new method, for which the team has already applied for patent protection, is described in the journal Physical Review X in a paper by graduate student Guoqing Wang, professor of nuclear science and engineering and physics Paola Cappellaro and four others at MIT and Lincoln Laboratory.
Quantum sensors can take many forms; they are systems where some particles are in such a state that they are affected by even the slightest variation in the fields in which they are exposed. This can take the form of neutral atoms, trapped ions, and solid-state spins, and research using such nerves has grown exponentially. For example, physicists use them to investigate unusual phenomena, including so-called time crystals and topological clauses. In contrast, other researchers use them to illustrate real-life objects such as quantum memory or counting devices. But many other exciting events take up a much more comprehensive range of frequencies than modern quantum sensors.
The group’s new system, called the quantum mixer, injects a second frequency into the detector using a beam of microwaves. This converts the frequency of the study field into a different frequency – the difference between the original frequency and that of the additional signal – which is determined by the frequency at which the detector is most sensitive. This simple procedure allows the detector to return home at any frequency without losing the local nanoscale sensor adjustment.
The team used a device based on multitasking nitrogen space diamonds in their experiments and a widely used quantum sensor system. They successfully demonstrated a 150 megahertz frequency signal using a 2.2 gigahertz frequency qubit detector — an unlikely detection without a quantum multiplexer. They then performed a detailed analysis of the process by obtaining a theoretical framework based on Floquet’s theory and evaluating the numerical prediction of that theory in a series of experiments.