Abstract We present a self-assembled ultra-low expansion (ULE) cavity system designed for high-precision laser frequency stabilization. The cavity mirrors are bonded to the ULE spacer using a low thermal expansion adhesive, and the assembled cavity exhibits a finesse of nearly
3×104. A custom-designed multilayer aluminum housing was developed to passively isolate the cavity from environmental fluctuations. Long-term performance characterization reveals a frequency drift of approximately 164 kHz per day.After locking a diode laser to the cavity using the Pound-Drever-Hall technique, we achieve a linewidth of approximately
19.4kHz and a fractional frequency stability of
6.4×10−13 at 1 s.To validate the reliability of this frequency-stabilized laser system, we applied it to Rydberg excitation spectroscopy via trap-loss measurements of cold
87Rb atoms. Compared to conventional wavelength meter locking, the cavity-stabilized system significantly improves spectral resolution, reducing the linewidth of the trap-loss spectrum from 34 MHz to 6 MHz. Our system offers a robust and cost-effective solution for high-resolution spectroscopy, with applications in coherent control of Rydberg atoms.
We demonstrate a method to simultaneously suppress the linewidths and stabilize the long-term frequency drifts of both 780-nm and 960-nm lasers to the 10-kHz level. We first use an iodine frequency stabilization laser as a frequency reference to stabilize the length of a tunable high-finesse transfer cavity (THFTC). Then two slave lasers of 780 nm and 960 nm are locked to this THFTC. In this way, the linewidths of slave lasers are suppressed to the order of 10 kHz, which are measured by delayed self-heterodyne measurements. Meanwhile, the long-term frequency drifts are stabilized to be less than 22 kHz for 10 h. With the locked lasers, we realize the coherent Rydberg excitation of a single Rb87 atom and keep the exciting stable and repeatable for 10 h, which is essential for Rydberg-mediated single-atom quantum information processing. This dual-laser frequency stabilization and transfer method can also be used in other high-resolution experiments in atomic physics, precision metrology, and molecular spectroscopy.
Neutral atoms provide an excellent resource for quantum information processing, combining the long atomic coherence times of the hyperfine ground-state with strong dipole-dipole interactions of highly excited Rydberg states for generating deterministic entanglement between qubits separated by < 10 µm [1]. Scalable long-range interactions can be obtained by coupling the atomic array to a superconducting microwave cavity enabling hybrid quantum information processing where the cavity-mediated entanglement allows atoms to be coupled over cm length scales. We present the first steps towards such an experiment incorporating high fidelity readout using an sCMOS camera [2] and the ability to drive fast, optically addressable rotations of the hyperfine-encoded qubits to the Rydberg state. Using our sub-kHz cavitystabilised laser system [3] we demonstrate coherent control of single Rydberg atoms, performing Ramsey spectroscopy to determine coherence time and to generate entanglement between a pair of atoms separated by 6 µm. Combining this excitation scheme with our ground-state Raman lasers we show progress towards the implementation of a mesoscopic Rydberg gate based on electromagnetically induced transparency (EIT) offering robust entanglement of multi-atom ensembles [4].