QuCoLiMa Talk – Vera Schäfer – Continuous lasing and self-regulated frequency pinning of the dressed cavity resonance with strongly-coupled 88Sr atoms in a ring cavity

Speaker:

Vera Schäfer - MPI Heidelberg

Title:

Continuous lasing and self-regulated frequency pinning of the dressed cavity resonance with strongly-coupled 88Sr atoms in a ring cavity

Abstract:

Superradiant lasers are a promising path for realising a narrow-linewidth, high-bandwidth active frequency reference. They shift the phase memory from the optical cavity, which is subject to technical and thermal vibration noise, to an ultra-narrow optical atomic transition of an ensemble of cold atoms trapped inside the cavity. Our previous demonstration of pulsed superradiance on the mHz transition in 87Sr achieved a fractional Allan deviation of 6.7*10−16 at 1s of averaging. Moving towards continuous-wave superradiance promises to further improve the short-term frequency stability by orders of magnitude. A key challenge in realizing a cw superradiant laser is the continuous supply of cold atoms into a cavity, while staying in the collective strong coupling regime.

We demonstrate continuous loading and transport of cold 88Sr atoms inside a ring cavity, after several stages of laser cooling and slowing. We further describe the emergence of distinct zones of collective continuous lasing of the atoms on the 7.5kHz transition, 7x narrower than the cavity linewidth, and pumped by the cooling lasers via inversion of the motional states. The lasing is supported by self-regulation of the number of atoms inside the cavity that pins the dressed cavity frequency to a fixed value over >3MHz of raw applied cavity frequency. In the process up to 80% of the original atoms are expelled from the cavity.

Location:

Saarbrücken

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QuCoLiMa Talks are regular seminars of the collaborative research center TRR 306 QuCoLiMa (Quantum Cooperativity of Light and Matter), where (external) experts are invited to present their work.

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