Towards Coherent Excitation to Rydberg States for Quantum Computing using home-made Continuous Wave (CW) Lasers

Rydberg excitation plays a pivotal role in quantum computing and simulation with cold atoms trapped in optical tweezers, specifically in the implementation of two qubit quantum gates¹ or the realization of Ising spin models². A crucial characteristic for high fidelity operation is a low phase/frequency noise of the lasers driving the Rydberg excitation³. Towards this end, we report on a homebuilt 780 nm laser incorporating a two-stage phase/frequency noise stabilization. The laser source is a 780 nm External Cavity Diode Laser (ECDL) using an interference filter⁴ to select a single longitudinal mode. The first stage of phase stabilization is a standard Pound-Drever-Hall scheme⁵ stabilizing the laser phase/frequency up to Fourier frequencies of ~1 MHz (microsecond timescale), limited by the feedback loop bandwidth. To further extend the stabilization to faster timescale, we added a fast feedforward cancellation system to suppress noise in the 0.1-10 MHz frequency band⁶.

References:

¹Jaksch, Dieter, et al. "Fast quantum gates for neutral atoms." Phys. Rev. Lett. 85, 2208 (2000)

²Browaeys, Antoine, and Thierry Lahaye. "Many-body physics with individually controlled Rydberg atoms.” Nat. Phys. 16, 132 (2020)

³de Léséleuc, Sylvain, et al. "Analysis of imperfections in the coherent optical excitation of single atoms to Rydberg states." Phys. Rev. A 97, 053803 (2018)

⁴Baillard, Xavier, et al. "Interference-filter-stabilized external-cavity diode lasers." Opt. Commun. 266, 609 (2006)

⁵Black, Eric D. "An introduction to Pound–Drever–Hall laser frequency stabilization" Am. J. Phys. 69, 79 (2001)

⁶Denecker-Desmonts, Tom, et al. Harry, et al. "Fast feed-forward cancellation of laser phase noise for cold atom experiments." N01.00138, Poster, DAMOP2023