Programmability and precise control of laser frequency are essential for quantum experiments and applications such as atomic clocks, quantum computers, and cold-atom sensors. Current systems use bulky, power-hungry modulators and frequency shifters which are difficult to integrate and limit portability and scalability. We report an electrically controllable, agile optical frequency source based on a semiconductor laser stabilized to a photonic-integrated, lead zirconate titanate (PZT)-actuated resonator cavity. We demonstrate this approach with precision programmable frequency control of a 780-nm laser that can periodically reference to rubidium spectroscopy followed by fast, programmable, arbitrary frequency tuning sequences for quantum control. We use this approach to demonstrate sub-Doppler cooling of rubidium-87 without any external modulators, achieving atom-cloud temperatures as low as 16 μK. The device achieves a tuning strength up to 1 GHz/V with 11 MHz modulation bandwidth while consuming only 10 nW of electrical power. This work establishes a route toward compact, low-power, and chip-scale laser systems for next-generation quantum and atomic sensing technologies.

Narrow linewidth stabilized lasers are central to precision applications that operate across the visible to short-wave infrared wavelengths, including optical clocks, quantum sensing and computing, ultra-low noise microwave generation, and fiber sensing. Today, these spectrally pure sources are realized using multiple external cavity tabletop lasers locked to bulk-optic free-space reference cavities. Integration of this technology will enable portable precision applications with improved reliability and robustness. Here, we report wavelength-flexible design and operation, over more than an octave span, of an integrated coil-resonator-stabilized Brillouin laser architecture. Leveraging a versatile two-stage noise reduction approach, we achieve low linewidths and high stability with chip-scale laser designs based on the ultra-low-loss, CMOS-compatible silicon nitride platform. We report operation at 674 and 698 nm for applications to strontium neutral and trapped-ion clocks, quantum sensing and computing, and at 1550 nm for applications to fiber sensing and ultra-low phase noise microwave generation. Over this range we demonstrate frequency noise reduction from 1 to 10 MHz resulting in 1.0–17 Hz fundamental and 181–630 Hz integral linewidths and an Allan deviation of 6.5 × 10−13 at 1 ms for 674 nm, 6.0 × 10−13 at 15 ms for 698 nm, and 2.6 × 10−13 at 15 ms for 1550 nm. This work demonstrates the lowest fundamental and integral linewidths and highest stability achieved to date for stabilized Brillouin lasers with integrated coil-resonator references, with over an order of magnitude improvement in the visible wavelength range. These results unlock the potential of integrated, ultra-low-phase-noise stabilized lasers for precision applications and further integration in systems-on-chip solutions.

Frequency-stable lasers enable high-fidelity quantum state manipulation, which forms the basis of optical atomic clocks, quantum sensing, and quantum computation. Performing state manipulations at increasingly high speeds requires attention to laser frequency noise at high Fourier (carrier-offset) frequencies that cannot be addressed by traditional cavity stabilization alone. Scalable operations also benefit from device miniaturization. Here, we demonstrate a hybrid laser stabilization approach that combines ultrahigh frequency stability of a cryogenic silicon cavity with high-Fourier-frequency noise suppression of an integrated Brillouin laser. The combined system suppresses frequency noise over a Fourier span of more than 7 decades, yielding a <1 Hz phase-integrated linewidth and 0.2 Hz^2/Hz frequency noise at Fourier frequencies above 10 MHz. The performance of this hybrid laser is confirmed by sub-Hz Rabi spectroscopy with a three-dimensional ^87Sr lattice clock. This work demonstrates record-low frequency noise at 698 nm over an extensive Fourier frequency range and highlights the promise of precision clock spectroscopy using a chip-scale integrated laser technology.

Modulation and control of lasers and optical signals are necessary for trapped-ion and cold neutral atom quantum systems. Given the diversity of atomic species, experimental modalities, and architectures, integrated optical modulators that are designed to operate across the visible to near-infrared (NIR) spectrum are a key step towards portable, robust, and compact quantum computers, clocks, and sensors. Integrated optical modulators that are wavelength-independent, CMOS-compatible, and capable of maintaining low waveguide losses and a high resonator quality factor (Q), DC-coupled broadband frequency response, and low power consumption are essential for scalable photonic integration. Yet progress towards these goals has remained limited. To show the versatility of this platform, we demonstrate four types of integrated stress-optic lead zirconate titanate (PZT) silicon nitride (Si3N4) modulators - a coil Mach-Zehnder modulator (coil MZM), a coil pure phase modulator, and bus-coupled and add-drop ring resonator modulators, with operation from 493 nm to 780 nm. The PZT-actuated coil MZM operates at 532 nm with a Vπ of 2.8 V, a DC - 0.4 MHz 3-dB bandwidth, and an extinction ratio of 21.5 dB. The PZT-actuated nitride coil phase modulator operates at 493 nm with a Vπ of 2.8 V and low residual amplitude modulation (RAM) of -34 dB at a 10 kHz offset. The bus-coupled ring resonator modulator operates at 493 nm, and the add-drop ring resonator modulator operates at 780 nm. The ring-based modulators have an intrinsic quality factor (Qi) of 3.4 million and 1.9 million, a linear tuning strength of 0.92 GHz/V and 1.01 GHz/V, and a 3-dB bandwidth of DC - 2.6 MHz and DC - 10 MHz, respectively. All four modulator designs maintain the native low optical waveguide loss of SiN, are DC coupled with broadband frequency response, operate independently of wavelength, and consume only tens of nW per actuator. Such solutions unlock the potential for further integration with other precision silicon nitride components to realize chip-scale atomic and quantum systems.

Photonic integrated resonators can be used for laser stabilization and disciplining light to atomic transitions. Such integrated structures hold the potential to augment or replace table-top reference cavities, improve the robustness, lower the cost, and enable portability of precision applications such as atomic quantum sensing and computing, optical clocks, and ultra-low noise microwave generation. Realizing resonators that can span an octave of optical bandwidth will enable stabilization across a wide range of atomic species, quantum architectures, and precision metrology tools. Examples include second-harmonic generation, dual-comb line stabilization, and stability transfer of atomic-disciplined lasers to other lasers operating across large optical bandwidths for applications such as Rydberg sensing. Here, we present an octave-spanning photonic-integrated silicon nitride 4-meter-coil resonator that operates from 780 nm to 1560 nm. The 4-m coil resonator, based on a tunable bus-ring coupler design, provides a spectral resolution of 47 MHz over the octave span with intrinsic quality factors (Qin) from 24 to 77 million over the octave bandwidth. With the same coil resonator, we demonstrate stabilization of lasers operating at 780 nm, 1320 nm, 1550 nm, and 1560 nm, achieving greater than 2 orders of magnitude frequency noise reduction within the 1-10 kHz offset range and thermorefractive noise-limited performance between 1 kHz and 10 kHz at 1320 nm, 1550 nm, and 1560 nm. Additionally, we demonstrate linewidth stabilization that lowers the 1560 nm, 1550 nm, 1320 nm, and 780 nm 1/π reverse integral linewidths (ILW) by an order of magnitude to 159 Hz, 250 Hz, 289 Hz, and 1 kHz, respectively. The resonator is fabricated in the CMOS-compatible silicon nitride platform that supports a wide range of active and passive components, unlocking the potential to integrate precision and quantum systems on-chip.

High precision portable and deployable frequency standards are required for modern navigation and communication technologies. Optical frequency standards are attractive for their improved stability over their microwave counterparts; however, increased complexities have anchored them in the laboratory. Sacrificing sensitivity of the most stable optical clocks has led to the recent development of deployable and portable optical frequency standards, leveraging hot atomic or molecular vapor. The short term limit for a majority of previous reports on two-photon rubidium standards is either the shot-noise or intermodulation limit hindering the one second fractional frequency stability to around 1×10^-13/. The answer for the shot-noise limit is to increase optical power and collected fluorescence, while the intermodulation limit solution requires improvements in laser linewidth, stimulated Brillouin scattering (SBS) lasers are known to reduce frequency noise, suppressing noise of the pump laser at high ofset frequencies. We investigate an optical frequency standard based on the two-photon transition in ^87Rb probed with a narrow linewidth photonic integrated circuit SBS laser with a quality factor over 130 million and instantaneous linewidth < 10 Hz. The use of a narrow linewidth clock laser coupled with operating at higher optical intensities yields clock instabilities of 2×10^-14 at one second, currently the best reported short-term stability for a two-photon rubidium optical frequency standard.

Precision atomic and quantum experiments rely on ultra-stable narrow linewidth lasers constructed using tabletop ultra-low expansion reference cavities. These experiments often require multiple lasers, operating at different wavelengths, to perform key steps used in state preparation and measurement required in quantum sensing and computing. This is traditionally achieved by disciplining a cavity-stabilized laser to a key atomic transition and then transferring the transition linewidth and stability to other lasers using the same reference cavity in combination with bulk-optic frequency shifting such as acousto-optic modulators. Transitioning such capabilities to a future potentially low-cost photonic-integrated platform will enable a wide range of portable, low power, scalable quantum experiments and applications. Yet, today's bulk optic approaches pose challenges related to lack of cavity tunability, large free spectral range, and limited photonic integration potential. Here, we address these challenges with demonstration of an agile photonic-integrated 780 nm ultra-high-Q tunable silicon nitride reference cavity that performs multiple critical experimental steps including laser linewidth narrowing, high resolution rubidium spectroscopy, dual-stage stabilization to a rubidium transition, and stability transfer to other lasers. We achieve up to 20 dB of frequency noise reduction at 10 kHz offset, precision spectroscopy over a 250 MHz range, and dual-stage locking to rubidium with an Allan deviation of 8.5 & times; 10-12 at 1 s and up to 40 dB frequency noise reduction at 100 Hz frequency offset. We further use the rubidium-disciplined cavity to provide atomic-referenced frequency stability to a second laser and demonstrate multi-wavelength Rydberg electrometry quantum sensing. These results pave the path for integrated, compact, and scalable solutions for quantum sensing, computing, and other atomic and trapped ion applications. (c) 2026 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Abstract Photonic integrated stable, ultra-low-noise lasers are essential for scalable and portable quantum information systems. Trapped ions are a leading modality for quantum computing and optical clocks, with room-temperature operation enabling portable applications. Current systems rely on free-space lasers and stabilization cavities, frequency conversion, and cryogenic infrastructure, limiting size, weight, and power. We demonstrate a chip-scale coil-stabilized 674 nm Brillouin laser driving qubit state preparation and measurement and the optical clock transition in a room-temperature surface electrode trapped 88Sr+ ion without a bulk-optic reference cavity. The CMOS compatible silicon nitride integrated 3-meter coil and Brillouin laser achieve 8.8×10-13 stability at 20 ms, sufficient to interrogate the 0.4 Hz quadrupole optical clock transition. The ion-disciplined laser achieves 5.3 $$\times {10}^{-13}/\sqrt{\tau }$$ × 10 − 13 / τ stability, spectroscopy with 1.5 kHz linewidths, and 99.6% qubit state preparation and measurement fidelity. These results light the way towards integration of stabilized lasers with trapped-ion chips for portable and robust quantum technologies.

Trapped ions are a leading technology for quantum computing, but their reliance on bespoke tabletop laser and optical systems remains a major obstacle to scaling and robustness. Integrated silicon nitride lasers, compatible with future monolithic integration with surface electrode ion traps, have recently demonstrated frequency-selective qubit state preparation and measurement as well as interrogation of an optical clock transition. However, coherent qubit gates driven by integrated laser sources have not yet been demonstrated because coherent quantum logic imposes substantially more stringent performance requirements on the laser. Here, we use a visible-wavelength integrated Brillouin laser stabilized to an integrated coil resonator to drive coherent single- and two-qubit gates with ^88Sr^+ optical qubits. We measure an average single-qubit fidelity of 99.61

We demonstrate stabilization of 698 and 674 nm integrated Brillouin lasers to integrated 3-m coil resonators for neutral and trapped-ion strontium clock applications, achieving record-low 17 Hz fundamental and 660 Hz integral linewidths.

We demonstrate a 780 nm PZT-on-Si 3 N 4 stress-optic ring modulator with 2.8 million Q, 11 MHz modulation bandwidth, and 1 GHz/V static tuning. The modulator enables precise laser frequency control for sub-Doppler cooling of rubidium atoms.

We demonstrate a low-power, PZT stress-optic Si3N4 micro-ring blue light modulator with 5.4 million intrinsic Q, 10.5 MHz 3 dB bandwidth, and 760 MHz/V tuning for atomic and quantum applications including trapped barium ions.

We demonstrate a silicon nitride photonic-integrated two-point-coupled 4-meter-coilresonator capable of tunable critical coupling over a 700 nm range, 910-1610 nm, with 48-77 million intrinsic Q.

Precision applications including quantum computing and sensing, mmWave/RF generation, and metrology, demand widely tunable, ultra-low phase noise lasers. Today, these experiments employ table-scale systems with bulk-optics and isolators to achieve requisite noise, stability, and tunability. Photonic integration will enable scalable, reliable and portable solutions. Here we report a hybrid-integrated external cavity widely tunable laser stabilized to a 10 m-long integrated coil-resonator, achieving record-low 3 - 7 Hz fundamental linewidth across a 60 nm tuning range and 27 - 60 Hz integral linewidth with 1.8E-13 ADEV at 6.4 ms across 40 nm, delivering orders of magnitude frequency noise and integral linewidth reduction over state of the art. Stabilization is achieved without an optical isolator, leveraging resilience to optical feedback of 30 dB beyond that of commercial DFB lasers. The laser and reference cavity are fabricated in the same Si3N4 CMOS-compatible process, unlocking a path towards fully integrated visible to ShortWave-IR frequency-stabilized lasers.

Precision applications such as quantum computing, quantum and fiber sensing, and mmWave and RF generation, require ultra-low phase noise stabilized lasers operating at wavelengths across the visible to near-IR. These applications employ widely tunable table-scale laser systems, bulk-optic reference cavities, and optical isolation to achieve ultra-low frequency noise and high stability across wide wavelength ranges. Photonic integration promises to bring these laser systems to the chip-scale, enabling reliable, scalable and portable precision applications. Here we report record-low integrated laser linewidths with a coil-cavity stabilized 1550 nm tunable laser, that achieves 3 to 7 Hz fundamental linewidth across a 60 nm tuning range and 27 - 60 Hz integral linewidths with an Allan deviation of 1.8E-13 at 6.4 ms across 40 nm. These results represent 5 orders of magnitude noise reduction and almost 2-orders magnitude reduction in integral linewidth for widely tunable integrated lasers. The hybrid integrated silicon nitride external cavity tunable laser is stabilized to a silicon nitride 10-meter long integrated coil-resonator without the need for an optical isolator by leveraging the inherent 45 dB isolation. The laser and reference cavity are fabricated in the same 80 nm-thick ultra-low loss silicon nitride waveguide CMOS foundry compatible process, which combined with the inherent isolation, unlocks the path towards fully integrated visible to NIR frequency-stabilized lasers.

We demonstrate a frequency-controllable 778 nm integrated Brillouin laser with 40 Hz fundamental and 5 kHz integral linewidths maintained over> 10kHz modulation. Stabilization to a rubidium two-photon transition results in stability 2e-13 at 100s.

Integrated narrow-linewidth lasers in the visible and near-IR are a critical component of next-generation atomic systems for quantum sensing, time keeping, and navigation. Technologies such as low frequency noise lasers that are tunable and referenced to an absolute frequency set by atomic transitions are required for sensing applications such as cold atom interferometers. While bulk-optic reference cavities can be used for laser noise reduction and stabilization, longer-term frequency drifts are mitigated with a secondary lock to an atomic reference using power-consuming bulk optic technologies such as an acousto-optic frequency shifter. Photonic integrated cavities based on ultra-low-loss silicon nitride (SiN) waveguides enable laser stabilization in a wafer-scale integration platform. Incorporating a secondary lock of these integrated cavities to an atomic reference is an attractive solution for compact chip-scale long term stable references. In this paper we demonstrate the use of a thermo-optic tunable, 118 million Q, 0.44 dB/m loss reference cavity for simultaneous laser frequency noise reduction and absolute frequency referencing to 780 nm rubidium spectroscopy. By tuning the integrated cavity resonance by a range >200 MHz using a thermal tuner with 20 MHz/mW efficiency at over 1 kHz tuning rate, we demonstrate long-term locking of the stabilized laser to rubidium saturation absorption spectroscopy. We achieve up to 4 orders magnitude frequency noise reduction, integral linewidth (beta-separation) reduction from 5 MHz (free-running) to 326 kHz (dual lock) and simultaneously a fractional frequency drift of 8.5e-12 at 1 second, two orders of magnitude improvement compared to locking to the cavity only. These results represent a compact and robust laser for photonic integrated atomic systems that can be extended to probing and locking to narrower linewidth transitions such as the rubidium two-photon at 778 nm and for laser frequency control sequences in cold atom experiments.

We demonstrate a frequency modulated 780 nm Brillouin laser pumped by a semiconductor laser. We achieve a 1.4 kHz 1/p integral linewidth and 24 Hz fundamental linewidth and a 22 kHz modulation bandwidth.

Heterogeneous and monolithic integration of the versatile low loss silicon nitride platform with low temperature materials such as silicon electronics and photonics, III-V compound semiconductors, lithium niobate, organics, and glasses, has been inhibited by the need for high temperature annealing as well as the need for different process flows for thin and thick waveguides. New techniques are needed to maintain the state-of-the-art losses, nonlinear properties, and CMOS compatible processes while enabling this next generation of 3D silicon nitride integration. We report a significant advance in silicon nitride integrated photonics, demonstrating the lowest losses to date for an anneal-free process at a maximum temperature of 250 C, with the same deuterated silane based fabrication flow, for nitride and oxide, for an order of magnitude range in nitride thickness without requiring stress mitigation or polishing. We report record low losses for anneal-free nitride core and oxide cladding, enabling 1.77 dB/m loss and 14.9 million Q for 80 nm nitride core waveguides, more than half an order magnitude lower loss than previously reported 270 C processes, and 8.66 dB/m loss and 4.03 million Q for 800 nm thick nitride. We demonstrate laser stabilization with over 4 orders of magnitude frequency noise reduction using a thin nitride reference cavity. And using a thick nitride micro-resonator, we demonstrate parametric gain and Optical Parametric Oscillation (OPO) with the lowest reported OPO threshold per unit resonator length for low temperature fabricated nitride, and supercontinuum generation over two octaves. These results represent a significant step towards a uniform ultra-low loss silicon nitride homogeneous and heterogeneous platform for both thin and thick waveguides capable of linear and nonlinear photonic circuits and integration with low temperature materials and processes.

A hybrid-integrated external-cavity laser stabilized to an integrated 10-meter-coil-resonator measures 7.1 Hz fundamental and 237 Hz integral linewidths, 3×10 -13 ADEV at 5.1 ms, 7.0 kHz/s drift, 65 dB SMSR, 60nm tuning, and reduced feedback sensitivity.