Method For Achieving Minute-Long Spin Relaxation Times For Alkali Atoms

Tech ID: 20935 / UC Case 2010-139-0

Patent Status

Country Type Number Dated Case
United States Of America Published Application 20120112749 05/10/2012 2010-139

Brief Description

Alkali-vapor atomic magnetometers are the world’s most sensitive magnetic-field measuring devices. In these sensors, a droplet of alkali metal (such as potassium, rubidium, or cesium) is heated within a glass cell to provide an atomic vapor which is then spin-polarized using a pump laser. In an applied magnetic field these spins will precess, much like a spinning top that has been pushed off the vertical. The strength of the field can be detected by using a probe laser to monitor the spin precession frequency.

The sensitivity of an atomic magnetometer is fundamentally limited by the spin relaxation time of its atoms, i.e., the amount of time it takes the pumped atoms to lose their polarization. Atomic collisions with the cell wall are usually depolarizing, so inert gases are often added to the vapor cells to prevent alkali diffusion to the cell walls. Alternatively, the inner walls of the cell can be coated with an anti-relaxation film, such as an alkane-based paraffin wax. This allows for longer relaxation times and obviates the need for additional gases within the cell.

Researchers at UC Berkeley have developed a novel, alkene-based anti-relaxation coating which allows spin-relaxation times of more than a minute, an improvement of two orders of magnitude over prior technologies. This directly translates to improved magnetometric sensitivity and promises to deliver the most sensitive atomic magnetometers to date.

Suggested uses

- Atomic clocks
- Magnetometers
- Slow light
- Quantum memory
- Atomic gyroscopes


- Relaxation time > 60 seconds
- Room temperature operation

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  • Budker, Dmitry
  • Ledbetter, Micah

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