Description
Persistent spectral-holeburning is ubiquitous in optical spectroscopy, where it’s exploited for a myriad of applications in both classical and quantum signal processing, including laser stabilisation [1], real-time wideband spectral analysis [2], and quantum memory [3].
Prior to our work, however, spectral-holes in the microwave domain had only been observed to last microseconds or less [4, 5]. Here I present the key findings of our recent Nature Communications publication [6], detailing spectroscopic measurements of long-lived microwave spectral holes in an erbium doped crystal of calcium-tungstate (Er:CaWO4). These results were achieved by pumping the electron-spin transition of Er3+ using microwave tones at 7.8GHz, with nuclear spin states of neighbouring W-183 atoms serving as the auxiliary levels. The lifetime of the observed holes rises steeply as the sample temperature is decreased, exceeding a week at 10mK.
Our results demonstrate that rare-earth doped crystals at millikelvin temperatures could open new avenues in microwave signal processing applications and non-linear microwave light-matter interactions.
[1] S. Cook, T. Rosenband and D. R. Leibrandt, Phys. Rev. Lett. 114, 253902, (2015)
[2] Berger, P. et al. J. Lightw. Technol. 34, 4658–4663, (2016)
[3] Lago-Rivera, D., Grandi, S., Rakonjac, J. V., Seri, A. & de Riedmatten, H. Nature 594, 37–40, (2021).
[4] S. Putz, A. Angerer, D. O. Krimer, R. Glattauer et al., Nature Photon. 11, 36–39, (2017)
[5] P. Schosseler, Th. Wacker & A. Schweiger, Chem. Phys. Lett. 224, 319-324, (1994)
[6] Z. Wang, S. Lin, M. Le Dantec, M. Rančić, et al., Nat. Commun. 16, 9032, (2025)
| I am the presenting author | Yes |
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