Diamonds can be used in quantum sensing.

Diamonds can be used in quantum sensing.

University of Tsukuba researchers demonstrated how ultrafast spectroscopy can be used to improve the temporal resolution of quantum sensing.

By measuring the direction of coherent spins within the diamond network, they showed that magnetic fields can be measured even in very short times. 

This work may allow advancing the field of ultra-precise measurements known as a quantum metric, as well as "spintronic" quantum computers that operate on the basis of electron spin.

Quantum sensing offers the possibility of extremely accurate monitoring of temperature, as well as magnetic and electric fields, with nanometer precision. 

By observing how these properties affect energy level differences within the sensing molecule, new avenues in nanotechnology and quantum computing may become viable. 

However, the temporal resolution of conventional quantum sensing methods was previously limited to the microsecond range due to the limited fluorescence lifetime. A new approach is needed to help improve quantum sensing.

Now, a team of researchers led by the University of Tsukuba has developed a new method for carrying out magnetic field measurements in a known quantum sensing system

Nitrogen vacancy (NV) centers are specific defects in diamonds in which two adjacent carbon atoms have been replaced by a nitrogen atom and a vacancy. 

The spin state of an additional electron at this location can be read or coherently manipulated using light pulses.

"For example, even at room temperature, the NV negative spin state can be used as a quantum magnetometer with a full optical reading system," says first author Ryosuke Sakurai. The team used the "inverse mouton cotton" effect to test their method. 

The normal Cotton-Mouton effect occurs when a transverse magnetic field results in refraction, which can change linearly polarized light into elliptical polarization. In this experiment, the scientists did the opposite, using light of different polarizations to create small, controlled local magnetic fields.

"Using nonlinear magnetic-optical quantum sensing, it will be possible to measure local magnetic fields, or spin currents, in advanced materials with the high spatio-temporal resolution," senior author Munyaki Hass and colleague Tosho Ann at the Japan Advanced Institute of Science and Technology said, for example. example. 

The team hopes that this work will help enable quantum electronic computers that are sensitive spin states, rather than just an electric charge as is the case with current computers. The research may also enable new experiments to observe dynamic changes in magnetic fields or perhaps even individual cycles under realistic device operating conditions.


Materials are provided by the University of Tsukuba


Ryosuke Sakurai, Yuta Kainuma, Toshu An, Hidemi Shigekawa, Muneaki Hase. Ultrafast opto-magnetic effects induced by nitrogen-vacancy centers in diamond crystals. APL Photonics, 2022; 7 (6): 066105 DOI: 10.1063/5.0081507


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