Jan 28 2019
A novel concept has been developed by researchers for recording the lowest temperatures ever determined, with the highest precision enabled by the laws of Nature.
Image credit: University of Nottingham
This field of study offers immense potential to transform low-temperature physics and can possibly be used in a variety of applications in evolving quantum technologies.
A new collaborative team from The Institute of Photonic Sciences (Barcelona, Spain) and the University of Nottingham demonstrates that theoretically, temperatures below a billionth of a Kelvin in a cold atomic gas could be measured without affecting it considerably, beating present accuracy standards. The study has been reported in the latest edition of the journal Physical Review Letters.
The investigators modeled a Bose-Einstein condensate for their study. To obtain this condensate, an atomic gas is cooled down to very low temperatures through realistic experimental parameters. The thermometric method would work when an impurity atom is embedded within the atomic condensate, thus enabling it to obtain information about the sample’s temperature through interaction. Especially, its velocity and position become dependent on temperatures that, by tracking them, the temperature can be determined with a high level of precision without affecting the condensate.
Cooling atomic gases
Ultra-cold atomic gases are an extremely versatile experimental platform for several applications like the production of high-quality (cold) electron beams for electron diffraction or electron microscopy, processing of quantum information, or simulation of strongly correlated systems. For the majority of these applications, the atomic gas must be cooled down to the lowest temperatures possible. Accurate determination of the systems’ temperature is also vital for applications.
The most common thermometric techniques currently available for cold atoms are destructive; that is, the sample is destroyed as a result of the measurement. On the other hand, non-destructive techniques usually lack the necessary accuracy at very low temperature. Our research provides a solution that overcomes both of these problems.
Mohammad Mehboudi, Study Lead Author, The Institute of Photonic Sciences
Nowadays, incredible experimental achievements enable high precision thermometry at extremely low temperatures, but based on the particular experimental platform, factors like accuracy, the underlying physical mechanism, and the effective temperature range of varied thermometric schemes differ significantly.
Dr Luis Correa, who also took part in the study, pointed out that “The newly-developed theoretical framework of quantum thermometry seeks to determine the fundamental limits on the precision of temperature measurements close to absolute zero; and it applies universally to any system. Importantly, this can provide clues as to how to improve current low-temperature thermometric standards.”
The research was funded in part by the European Research Council, which awards grants for scientific projects that allow the brightest minds in Europe to address research challenges like health and ageing, climate change, and economic governance.