Kolkata, Dec 30 (FN Bureau) Correlations between waves in atomic systems or spin coherences are long-lived at ultralow temperatures, says a new study by scientists who have developed a new technique to measure it. A system with long-lived spin coherences is a better resource as a quantum computer. It allows quantum operations and logic gates to be more efficiently implemented so that the system becomes a better quantum sensor compared to systems where coherence is short-lived. This newly explored property of atomic systems at low temperatures can be exploited for efficient quantum sensing and quantum information processing for application in quantum computation and secure communication, according to a Press Information Bureau release. The newly discovered technique can help study the real-time dynamics of quantum phenomena such as quantum phase transitions in a non-invasive manner. Spin is a fundamental quantum property of atoms and elementary particles such as electrons and protons. As atoms are cooled to lower temperatures, their quantum nature is manifested more prominently.
A team of scientists from Raman Research Institute, Bangalore, an autonomous institute of the Department of Science & Technology, Government of India, have measured the spin properties of atoms cooled to micro-Kelvin temperatures using the new method they have devised. Quantum properties dominate over everyday classical observations at this temperature –- very near absolute zero temperature, and it is for the first time that spin dynamics have been detected at this temperature regime using polarization fluctuation measurements. With the new technique, the scientists measured the properties of spins and the lifetime of an atomic spin state with a million-fold improvement in detection sensitivity compared to the existing technology. They proved that spin coherence at this low temperature is long-lived. The research – led by Sanjukta Roy, Dibyendu Roy, and Saptarishi Chaudhuri and co-authored by Ph.D. students Maheswar Swar and Subhajit Bhar from RRI -increased signal strength of spin noise by a million-fold by using coherent laser drive.
They made the spin noise spectroscopy technique usable for spectroscopists measuring systems where the signal level is too low to detect. The research has been published in the journal Physical Review Research. The work has been financially supported by funding from DST (Department of Science and Technology) and MeitY (Ministry of Electronics and Information Technology).