Quantum technologies using laser-cooled atoms, such as cold atom interferometersand atomic clocks, have revealed their potential in ground-based instruments. Un-doubtedly, space-based quantum devices could provide orders of improvement undermicro-gravity environments. However, current instruments, including both terrestrialand space-based, rely on complex laser systems, resulting in a high Size, Weight, andPower (SWaP) and high-cost design. Overcoming this bottleneck could enable quantumtechnologies for low-cost experiments and missions using small satellites. This wouldopen the door to new types of scientific experiments and missions, such as constella-tions of quantum sensors, deep space optical communication networks, and cold atomgyroscopes.This research develops the Software Defined Laser (SDL), a compact laser systemarchitecture that applies Software Defined Radio (SDR) concepts to optical frequencycontrol. By combining reconfigurable Field-Programmable Gate Array (FPGA)-basedelectronics with Radio Frequency (RF) techniques and optical modulators, SDL reducesthe number of seed lasers and optical components while maintaining the performancerequired for quantum applications. We derive quantitative requirements for SDL byanalysing existing ground-based and space-based quantum instruments and develop ahighly configurable system-on-chip firmware to support diverse missions.A Python-based SDL model is developed to evaluate RF technologies, frequency-tuning topologies, and noise performance. Comprehensive noise analysis shows that allinvestigated RF sources contribute less than 100 Hz to laser linewidth, satisfying Ramanand optical clock requirements. A novel frequency-tuning method is proposed, main-taining sub-1 kHz linewidth while reducing tuning dead time from 5.8 ms to 200 µs.To improve robustness beyond conventional PID control, SDL enables a multiple-input multiple-output (MIMO) laser controller synthesised using H2 robust control.Both single-input single-output (SISO) and MIMO controllers are evaluated under re-alistic disturbances. The MIMO controller maintains laser frequency noise below 1 kHzand achieves 0.02 % power stability under 17.5 K temperature variations over 6000 s,outperforming state-of-the-art systems. To enable autonomous adaptation, an FPGA-accelerated H2 synthesis module is developed, reducing optimisation time by 30 % andenabling real-time controller reconfiguration during operation.
Quantum technologies using laser-cooled atoms, such as cold atom interferometersand atomic clocks, have revealed their potential in ground-based instruments. Un-doubtedly, space-based quantum devices could provide orders of improvement undermicro-gravity environments. However, current instruments, including both terrestrialand space-based, rely on complex laser systems, resulting in a high Size, Weight, andPower (SWaP) and high-cost design. Overcoming this bottleneck could enable quantumtechnologies for low-cost experiments and missions using small satellites. This wouldopen the door to new types of scientific experiments and missions, such as constella-tions of quantum sensors, deep space optical communication networks, and cold atomgyroscopes.This research develops the Software Defined Laser (SDL), a compact laser systemarchitecture that applies Software Defined Radio (SDR) concepts to optical frequencycontrol. By combining reconfigurable Field-Programmable Gate Array (FPGA)-basedelectronics with Radio Frequency (RF) techniques and optical modulators, SDL reducesthe number of seed lasers and optical components while maintaining the performancerequired for quantum applications. We derive quantitative requirements for SDL byanalysing existing ground-based and space-based quantum instruments and develop ahighly configurable system-on-chip firmware to support diverse missions.A Python-based SDL model is developed to evaluate RF technologies, frequency-tuning topologies, and noise performance. Comprehensive noise analysis shows that allinvestigated RF sources contribute less than 100 Hz to laser linewidth, satisfying Ramanand optical clock requirements. A novel frequency-tuning method is proposed, main-taining sub-1 kHz linewidth while reducing tuning dead time from 5.8 ms to 200 µs.To improve robustness beyond conventional PID control, SDL enables a multiple-input multiple-output (MIMO) laser controller synthesised using H2 robust control.Both single-input single-output (SISO) and MIMO controllers are evaluated under re-alistic disturbances. The MIMO controller maintains laser frequency noise below 1 kHzand achieves 0.02 % power stability under 17.5 K temperature variations over 6000 s,outperforming state-of-the-art systems. To enable autonomous adaptation, an FPGA-accelerated H2 synthesis module is developed, reducing optimisation time by 30 % andenabling real-time controller reconfiguration during operation.
Quantum technologies are nowadays emerging as enabling tools for practical applications, such as quantum sensing, quantum computing and quantum metrology. Lasers play a central role in many of these technological platforms, e.g. for atomic clocks, ion-based or neutral atom-based quantum computers or atom interferometers. Here we present a complete laser system to cool, trap and control strontium atoms in an optical lattice or in tweezer arrays. A sub-Hz linewidth master laser, locked to a high-finesse optical cavity provides the frequency reference for an ultra-low noise comb. The rack-mounted laser system consists of all cooling, repumping, and clock lasers stabilized to the optical frequency comb. Each of the involved laser frequencies can therefore be tuned and mapped in the frequency domain with a high degree of stability. The system is controlled via a software interface, allowing to operate the cold-atom-based physics package autonomously. The system is tailored for the operation of 88Sr or 87Sr optical lattice clocks, or for quantum computing applications, but other sub-Hz lasers could be obtained by phase locking additional clock laser frequencies to the ultra-stable comb, enabling convenient and accurate optical frequency ratio measurements. The laser system architecture and the relevant characterization measurements will be presented, proposing some user-cases such as quantum computing and atom interferometry on strontium atoms. This represents a technological leap for quantum optics, allowing to explore further applications of quantum sensors outside a traditional lab.
Precise control of atomic systems has led to an array of emerging 'quantum' sensor concepts ranging from Rydberg-atom RF-electric probes to cold-atom interferometer gravimeters. Looking forward, the potential impact of these technologies hinges on their capability to be adapted from laboratory-scale experiments to compact and low-power field-deployable instruments. However, existing setups typically require a bulky and power-hungry laser and optics system (LOS) to prepare, control, and interrogate the relevant atomic system using a variety of frequency-referenced and rapidly reconfigurable laser beams. In this work, we investigate the feasibility of using semiconductor optical amplifiers (SOAs) to replace high-power pump lasers and acousto-optic modulators within a simple atom cooling apparatus, looking forward to the ultimate goal of a space-deployable atom interferometer. We find that existing off-the-shelf SOA components operating at relevant wavelengths for Cs and Rb atom cooling (852 and 780 nm, respectively) are able to permit an attractive combination of rapid (sub-microsecond), high extinction ratio (>60-65 dB) switching while acting as power boosters prior to the atom physics package. These attributes enable a radically different, power-efficient approach to LOS design, reducing or eliminating the need for Watt-class laser amplifiers that are unsuitable for flight deployment. Building on these results, we construct a simple and compact all-semiconductor laser/amplifier LOS for atom cooling that is integrated with custom path-to-flight drive electronics. Up to 125 mW of total optical power is delivered to six fiber-coupled channels for magneto-optical-trap-based cooling of a cloud of neutral Cs atoms. The entire LOS, including reference and cooling laser subsystems and control electronics, occupies a volume of 20×20×15 cm and totals DC power consumption of around 13.5 W, and is designed in a modular format so that additional hardware for synthesizing atom interferometry beams may be added through future development efforts. These results indicate the utility of all-semiconductor laser systems for future low-power flyable atom-based sensor instruments.
Abstract 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 resonator cavity with a lead zirconate titanate (PZT) actuator. We demonstrate this approach with precision programmable frequency control of a 780-nm laser that can periodically reference to rubidium-87 ( 87 Rb) spectroscopy followed by fast, programmable, arbitrary frequency tuning sequences for quantum control. We use this approach to demonstrate sub-Doppler cooling of 87 Rb without any external modulators, achieving atom-cloud temperatures as low as 16 μ K. 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.
The creation of cold atoms underpins quantum sensing and precision metrology, computing, timekeeping, and fundamental science experiments. Miniaturizing the lasers and optical infrastructure, which occupy over 80% of the volume of these experiments, through photonic integration could improve robustness, reliability, and manufacturability while reducing cost and enabling portable space-based precision measurements and quantum tools for non-experts. Yet, there has been limited progress towards integration of the laser and optical infrastructure required to generate cold atoms onto a single chip. We demonstrate a photonic engine that generates, controls, and delivers precision light to create cold atoms in a rubidium 3-dimensional magneto-optical trap (3D-MOT). We integrate on a single chip two frequency-agile self-injection-locked lasers, laser frequency and intensity control, passive beam combining and splitting, signal monitoring, and high-efficiency beam delivery to a rubidium vapor cell. The integrated engine is shown to support multiple functions required for generating cold atoms including stable generation of low-noise cooling and repump light, frequency control for atom spectroscopy and stabilization, real-time laser monitoring, routing for laser offset locking, optical power modulation, and large-area three-beam delivery of 3 mW to the physics package. Fully electrically controlled, the engine enables sustained 3D-MOT operation, trapping more than 1 million atoms at an average temperature of 350 uK and supporting atom-number and temperature measurements. These results demonstrate the first single-chip integration of light generation, control, and delivery for cold-atom generation, offering a path toward smaller, more robust, and manufacturable cold-atom systems for applications including cold-atom clocks and sensors.
With quantum optical technologies advancing toward real-world deployment, their success depends on reducing the size, weight, and power (SWaP) of the laser sources that drive them. While photonic integrated circuit (PIC)-based lasers have emerged as promising replacements to traditional bulky lasers, achieving a PIC-based laser system that satisfies both optical and functional requirements demands a system-level co-design of optics, electronics, and software that has not yet been realized. Here, we demonstrate a low-SWaP, tunable, and narrow-linewidth laser system based on PICs and programmable control electronics for the 780 nm region of the near-infrared spectrum. By leveraging the Vernier effect between a Fabry-Pérot laser diode (FPLD) and a microring resonator (MRR), we design the PIC to serve as an external cavity to self-injection lock the FPLD, resulting in a tunable laser with narrow linewidth. We package this PIC-laser into a standard butterfly package and drive it using a custom digital laser controller with a user-friendly interface. We design the programmable control electronics to meet the specific requirements of a PIC-laser as well as enable advanced functionalities that support cutting-edge quantum and classical optical applications. The complete laser system, which also includes optical isolators and fiber coupling, achieves up to 9.5 nm coarse tuning, 50 GHz mode-hop-free fine tuning, 30 mW free-space output power (before isolators), kHz-level intrinsic linewidth, and over 50 dB side-mode suppression ratio (SMSR). To exemplify the applicability of our laser system for quantum technologies, we perform spectroscopy on rubidium D2 transition lines and frequency-lock it to the cycling transition for days in a non-controlled environment with significant temperature fluctuations. We envision that our compact, fully integrated laser system will be a key enabler for scalable and deployable quantum and classical optical technologies.
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.