The research group for the first time realized the quantum strengthening of an extremely weak magnetic field using a dark back, reaching an increase in the magnetic field more than 5000 times and the accuracy of measuring a single magnetic field at 0.1 femt tesls (FT). The study is published in the journal Procedings of the National Academy of Sciences.
Quantum amplification is an effective way for accurate measurement of a weak electromagnetic field. However, its productivity is limited due to problems with the initialization of the gaseous back, the time of coherence and the sensitivity of reading. Overcoming these restrictions is critical of disclosing the full potential of quantum amplification.
In order to solve the above problems, the researchers proposed the concept of quantum reinforcement of the back in a dark state and conducted experiments in a mixed system of gaseous xenon and rubidi atoms. This system is used as amplifier material, and Rubidium atoms polarized by a laser – as a means of polarization and reading of the back of the kernel of the xenon.
Unlike previous experiments, where mixed gaseous atoms were in the same space, the processes of polarization, amplification and reading are usually carried out simultaneously. Researchers have found a new way of separating these processes by manipulating experimental conditions, such as a laser, polarizing rubid atoms, and a displaced magnetic field of xenon atoms. This allowed the backs of Xenon nuclei to be in a dark state in the process of quantum amplification, which excludes the intervention of polarized Rubidium atoms and realizes the greater potential of quantum amplification.
Scientists found that the time of coherence of the back of the Ksenon nucleus in a dark state in this system reaches six minutes, which is an order of magnitude higher than before. The observed strengthening of a weak magnetic signal with a long dark back was increased by about 5400 times. The use of this method in combination with an atomic magnetometer allows the minimum detected magnetic field to reach the level of subfemtotes (1 ft = 10^-15 Tesla) in one dimension that occupies about 500 seconds.
This work opens up new opportunities in the biomedical areas, such as magnetic diagnosis of the heart and brain, the measurement of the extremely weak magnetic fields of chemical molecules and the detection of dark matter.
The research group was headed by Professor Peng Sinhua and Associate Professor Jian Min from the University of Science