In a recently published report, the Will Lab team of Columbia University reports success in crossing in BEC threshold and creation of Bose-Eienstein condensate (BEC) of NaCs molecules at a ultracold temperature of 5 nanoKelvin (= 5 X 10-9 Kelvin). The molecular quantum condensate was stable with a lifespan of about 2 seconds. This ends several decades long pursuit of molecular BEC. This is a remarkable achievement and a milestone in science.
It is commonly known that matter would be in either of three states viz. solid, liquid or gas depending on external conditions like temperature and pressure. For example, H2O is found as ice, water or vapour in ordinary external conditions.
When the temperature is above 6000–10,000 Kelvin, matter gets ionised and turns into plasma, the fourth state matter.
What would be state of matter if the temperature is ultra-low close to absolute zero?
In 1924-25, Satyendra Nath Bose and Albert Einstein made a theoretical prediction that if boson particles (viz. entities with an integer spin value) are cooled to an ultra-low temperature near absolute zero, the particles would coalesce into a single, larger entity with shared properties and behaviours governed by the laws of quantum mechanics. Called Bose-Einstein condensate (BEC), this state was thought to be the fifth state of matter.
| States of matter | Temperature range of existence |
| Plasma | above 6000–10,000K |
| Gas | For water, above 100°C at normal atmospheric pressure |
| Liquid | For water, between 4°C to 100°C |
| Solid | For water, below, 0°C |
| Bose-Eisenstein condensate (BEC) | Near absolute zero About 400 nanoKelkin for atomic bosons About 5 nanokelvin for molecular BCE {1 nanoKelvin (nK) = 10 –9 Kelvin} Absolute zero = 0 kelvin = -273°C |
The theoretical prediction of Bose-Einstein condensate (BEC), the fifth state of matter became a reality nearly seven decades later in 1995 when Eric Cornell and Carl Wieman created the first BEC in a gas of rubidium atoms, and shortly thereafter, Wolfgang Ketterle produced a BEC in a gas of sodium atoms. The trio were jointly awarded Nobel Prize in Physics 2001″for the achievement of Bose-Einstein condensation in dilute gases of alkali atoms, and for early fundamental studies of the properties of the condensates“.
Timeline of advances in the science of fifth state of matter
| Milestones |
| 1924-25: The theoretical prediction of the fifth state of matter. Satyendra Nath Bose and Albert Einstein made theoretical prediction that a group of boson particles cooled to a near absolute zero would coalesce into a single, larger super-entity with shared properties and behaviours dictated by the laws of quantum mechanics. |
| 1995: The discovery of the fifth state of matter – first atomic BECs created. The theoretical prediction of Bose and Einstein becomes a reality after 70 years when Eric Cornell and Carl Wieman created the first BEC in a gas of rubidium atoms, and shortly thereafter, Wolfgang Ketterle produced a BEC in a gas of sodium atoms. |
| Molecular BCEs The pursuit of molecular BCEs that requires ultra-cooling in nanoKelvin (10-9 Kelvin) range |
| 2008: Deborah Jin and Jun Ye cooled a gas of potassium-rubidium molecules down to about 350 nanoKelvin. |
| 2023: Ian Stevenson et al created the first ultracold gas of sodium-cesium (Na-Cs) molecules at a temperature of 300 nanoKelvin (nK) using a combination of laser cooling and magnetic manipulations. |
| 2023: Niccolò Bigagli et al used microwaves to extend the lifespan of a bosonic gas of sodium-cesium molecules from a few milliseconds to over one second, a critical first step to cooling them. With their longer-lasting sample, they dropped the temperature to 36 nanoKelvin—just less than the temperature needed for the molecules to form a BEC. |
| 2024: Niccolò Bigagli et al creates BEC of molecular bosons (NaCs molecules) at a ultracold temperature of 5 nanoKelvin (nK) |
Since the discovery in 1995, laboratories across the world and in the International Space Station (ISS) routinely make atomic BECs from different types of atoms.
Molecular Bose-Einstein condensate (BEC)
Atoms are simple, kind of round entities with no polar interactions. Hence, researchers have always thought of creating Bose-Einstein condensate (BEC) from molecules. But, creating BECs of even simple molecules made of two atoms of different elements was not possible due to lack of technology to cool molecules to few nanoKelvin (nK) necessary for formation of molecular BEC.
Researchers at Will Lab of Columbia University have consistently worked towards developing ultracold technology. In 2008, they were able to cool a gas of potassium-rubidium molecules to about 350 nanoKelvin. It helped in performing quantum simulations and in studying molecular collisions and quantum chemistry but could not cross the BEC threshold. Last year in 2023, they used microwaves to extend the lifespan of a bosonic gas of sodium-cesium molecules and were able to achieve lower temperature of 36 nanoKelvin which was closer to the BEC threshold.
In a recently published report, the Will Lab team of Columbia University reports success in crossing in BEC threshold and creation of Bose-Eienstein condensate (BEC) of NaCs molecules at a ultracold temperature of 5 nanoKelvin (= 5 X 10-9 Kelvin). The molecular quantum condensate was stable with a lifespan of about 2 seconds. This ends several decades long pursuit of molecular BEC. This is a remarkable achievement and a milestone in science.
Creation of molecular Bose-Einstein condensates (BES) would have long term relevance for research in fundamental quantum physics, quantum simulations, superfluidity and superconductivity and innovation of new technologies such as new type of quantum computer.
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References:
- Bigagli, N., Yuan, W., Zhang, S. et al. Observation of Bose–Einstein condensation of dipolar molecules. Nature (2024). 03 June 2024. DOI: https://doi.org/10.1038/s41586-024-07492-z Preprint version at arXiv https://arxiv.org/pdf/2312.10965
- Columbia University 2024. Research news – The Coldest Lab in New York Has a New Quantum Offering. Posted on 03 June 2024. Available at https://news.columbia.edu/news/coldest-lab-new-york-has-new-quantum-offering
- The Royal Swedish Academy of Sciences. Advanced information on the Nobel Prize in Physics 2001 – Bose-Einstein Condensation in Alkali Gases. Available at https://www.nobelprize.org/uploads/2018/06/advanced-physicsprize2001-1.pdf
- NASA. The Fifth State of Matter. Available at https://science.nasa.gov/biological-physical/stories/the-fifth-state-of-matter/
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