Suppression of alkali metal vapor spin decoherence extends coherence time and improves quantum sensor performance
New research shows that electron spins—tiny magnetic properties of atoms that can store information—can be protected from de-coherence (the loss of their quantum state) more effectively than previously thought, simply by applying weak magnetic fields. Typically, these spins quickly lose their coherence when they interact with other particles or absorb certain types of light, limiting their usefulness in technologies such as quantum sensors or atomic clocks. But researchers have found that even interactions that directly release or disrupt spin can be significantly suppressed using weak magnetic fields. This finding expands our understanding of how quantum systems are controlled and opens up new possibilities for developing more stable and precise quantum devices.
A new study by researchers at the Hebrew University of Jerusalem and Cornell University reveals a powerful new method for significantly suppressing spin decoherence in alkali metal gases, with the potential to revolutionize quantum sensing and information technologies. The findings, published in Physical Review Letters, demonstrate an order of magnitude reduction in spin relaxation rates at low magnetic fields.
The research was led by Mark Dikopoltsev and Avraham Barbi, under the supervision of Prof. Uriel Levy from the Institute of Applied Physics and the Center for Nanoscience at the Hebrew University and Prof. Or Katz from Cornell University.
Spin decoherence, the process by which quantum spin information is lost due to environmental interactions, is a major obstacle to the development of quantum technologies. This study specifically examined the decoherence of hot cesium spins, which are mainly affected by spin-spin interactions during collisions with nitrogen molecules and through near-resonant absorption of light.
The team demonstrated that these decoherence effects can be dramatically suppressed by applying low magnetic fields—achieving an order of magnitude reduction in spin relaxation rates. This suppression goes beyond previously known regimes such as spin-exchange relaxation-free (SERF), and shows that magnetic fields can also control the mechanisms that relax electron spins, not just preserve them.
"Our results show that low magnetic fields are not only useful for avoiding decoherence from random spin-shifting interactions," said Dikopoltsev. "They can actively suppress more harmful relaxation processes, giving us a powerful tool for preserving spin coherence."
This discovery improves the fundamental understanding of spin dynamics and provides new strategies for controlling quantum states in hot atomic vapors. It lays the foundation for future advances in atomic clocks, quantum memory, magnetometry, and other technologies where long spin coherence times are critical.
More of the topic in Hayadan:
