Frequency metrology in quantum degenerate helium
We have measured the absolute frequency of the 1557-nm doubly forbidden transition between the two metastable states of helium, 2 3S1 (lifetime 8000 s) and 2 1S0 (lifetime 20 ms), with 1 kHz precision. With an Einstein coefficient of 10−7 s−1 this is one of weakest optical transitions ever measured....
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| Format: | Article |
| Language: | English |
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EDP Sciences
2013-08-01
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| Series: | EPJ Web of Conferences |
| Online Access: | http://dx.doi.org/10.1051/epjconf/20135702006 |