Frequency-modulated continuous-wave (FMCW) lidar offers high precision and strong interference resistance, capable of synchronously measuring target motion speed and vibration information. However, extracting target information using single-photon signal levels poses a critical challenge in extreme conditions. In this study, we propose a single-photon level FMCW lidar scheme. Quantum compressed sensing (QCS) is employed to simultaneously extract target distance and vibration information. Experimental results demonstrate successful synchronous detection at a beat frequency of 27.304 kHz and a vibration frequency of 500 Hz within an integration time of 0.125 s at a photon counting rate of 9 kcps. This approach provides a new, to the best of our knowledge, solution for FMCW radar application in extreme environments or long-range scenarios.
Frequency-modulated continuous-wave (FMCW) lidar offers high precision and strong interference resistance, capable of synchronously measuring target motion speed and vibration information. However, extracting target information using single-photon signal levels poses a critical challenge in extreme conditions. In this study, we propose a single-photon level FMCW lidar scheme. Quantum compressed sensing (QCS) is employed to simultaneously extract target distance and vibration information. Experimental results demonstrate successful synchronous detection at a beat frequency of 27.304 kHz and a vibration frequency of 500 Hz within an integration time of 0.125 s at a photon counting rate of 9 kcps. This approach provides a new, to the best of our knowledge, solution for FMCW radar application in extreme environments or long-range scenarios.
Frequency-modulated continuous-wave (FMCW) Lidar has the characteristics of high-ranging accuracy, noise immunity, and synchronous speed measurement, which makes it a candidate for the next generation of vehicle Lidar.In this work, an FMCW Lidar working at the single-photon level is demonstrated based on quantum compressed sensing, and the target distance is recovered from the sparse photon detection, in which the detection sensitivity, bandwidth, and compression ratio are improved significantly.Our Lidar system can achieve 3 GHz bandwidth detection at photon count rates of a few thousand, making ultra-long-distance FMCW Lidar possible.
The range and speed of a moving object can be ascertained using the sensing technique known as light detection and ranging (LiDAR). It has recently been suggested that quantum LiDAR, which uses entangled states of light, can enhance the capabilities of LiDAR. Entangled pulsed light is used in prior quantum LiDAR approaches to assess both range and velocity at the same time using the pulses' time of flight and Doppler shift. The entangled pulsed light generation and detection, which are crucial for pulsed quantum LiDAR, are often inefficient. Here, we study a quantum LiDAR that operates on a frequency-modulated continuous wave (FMCW), as opposed to pulses. We first outline the design of the quantum FMCW LiDAR using entangled frequency-modulated photons in a Mach-Zehnder interferometer, and we demonstrate how it can increase accuracy and resolution for range and velocity measurements by n and n, respectively, with n entangled photons. We also demonstrate that quantum FMCW LiDAR may perform simultaneous measurements of the range and velocity without the need for quantum pulsed compression, which is necessary in pulsed quantum LiDAR. Since the generation of entangled photons is the only inefficient nonlinear optical process needed, the quantum FMCW LiDAR is better suited for practical implementations. Additionally, most measurements in the quantum FMCW LiDAR can be carried out electronically by down-converting optical signal to microwave region.
The range and velocity of a moving object can be ascertained using the sensing technique known as light detection and ranging (lidar). It has recently been suggested that quantum lidar, which uses entangled states of light, can enhance the capabilities of lidar. Entangled pulsed light is used in prior quantum lidar approaches to assess both range and velocity at the same time using the time of flight and Doppler shift. However, the detection of entangled pulsed light is often inefficient and constrained by the temporal resolution of the detectors. Here, we investigate a quantum lidar utilizing a linear interferometer operating on a frequency-modulated continuous wave (FMCW) instead of pulses. Our findings demonstrate that the quantum FMCW lidar enables simultaneous measurements of range and velocity with quantum-enhanced accuracy and resolution, as well as superresolution phase imaging. Through self-heterodyne detection with a linear optical design, the signals of the quantum FMCW lidar with entangled photon pair can be efficiently carried out electronically by down-converting the optical signal to the microwave region. As a result, it is better suited for practical implementations.
Quantum light detection and ranging (LiDAR) utilizes quantum entanglement and correlation to improve precision, noise resilience and covertness of target detection. Despite recent advances, the development of a quantum LiDAR system that simultaneously achieves high precision and a large measurement range remains challenging. Here, we demonstrate a quantum amplitude-modulated continuous wave LiDAR with micrometer precision achievable via increased acquisition time and meter-scale measurement range. In our demonstration, the signal photons directly illuminate the target, while the idler photons are non-locally modulated with a high-frequency cosine wave and never interact with the target. By leveraging the non-local modulation and the quantum correlation, the target detection is achieved with a precision of 0.64 ± 0.06 mm within one second over a measurement range of 2-8 m. As the acquisition time is up to 500 s, the system achieves a precision of 29 ±4μm. Furthermore, our system realizes a 50 times precision improvement over the classical single-photon scheme in a background noise 37 dB stronger than the returned probe photons. With these advantages, our method will open venues for the development of high-precision, long-range, and noise-resilient target detection.
Light Detection and Ranging (LiDAR) has emerged as a pivotal sensor across diverse domains such as autonomous driving, mapping, and remote sensing, owing to its exceptional orientation capabilities and high resolution. The detection mechanism of LiDAR is fundamentally categorized into non-coherent detection and coherent detection. Non-coherent detection employs the direct detection method, which involves measuring changes in the intensity of the reflected light signal to achieve detection. Pulse LiDAR, which determines the target range through pulsed time-of-flight measurements, falls within this classification. On the other hand, coherent detection employs heterodyne detection techniques and achieves detection by measuring the frequency or phase difference between the echo signal and the local oscillator signal. This approach is utilized in frequency modulation continuous wave (FMCW) LiDAR and Doppler speed LiDAR. LiDAR systems employing coherent detection methods can attain heightened sensitivity while operating at lower transmission power levels. However, due to the limitations posed by quantum noise, conventional LiDAR systems have encountered challenges in terms of detection sensitivity and resolution, prompting the need for advancement. In recent times, spurred by the emergence of quantum metrology, a quantum version of LiDAR has been conceptualized, promising superior precision and resolution. Leveraging the enhanced signal-to-noise ratio made possible by quantum advancements, quantum LiDAR demonstrates the potential to extend detection ranges, elevate detection accuracy, bolster anti-jamming capabilities, and enhance anti-stealth performance beyond that of classical LiDAR, all while operating at equivalent transmission signal power levels. As an emerging technology, quantum LiDAR is currently in its exploratory phase, and several challenges must be confronted prior to its practical implementation. These challenges encompass a restricted array of methods for the effective generation of quantum light sources, the vulnerability of quantum states to environmental factors, resulting in their deterioration, the constrained techniques for modulating quantum light sources, and the critical necessity to augment detector sensitivity. Furthermore, present quantum LiDAR efforts primarily concentrate on imaging and ranging capabilities, with limited research dedicated to simultaneous velocity measurement and ranging. Hence, forthcoming investigations into quantum LiDAR will center around optimizing quantum light source efficiency, exploring high-dimensional modulation techniques, and advancing high-sensitivity detectors. These efforts aim to enhance system stability and enable miniaturization, ultimately leading to superior target detection performance. This review centers on the evaluation of ranging and velocity measurement performance within quantum LiDAR systems. Following a concise introduction to two renowned categories of classical LiDAR—namely, pulse LiDAR and FMCW LiDAR, the paper delves into the progress made in quantum pulsed LiDAR and quantum interferometric LiDAR. In particular, this review highlights the advancements in quantum FMCW LiDAR, a system proposed for achieving simultaneous range and velocity measurements with quantum enhancement. By conducting a thorough assessment of the current accomplishments in quantum LiDAR research, the study seeks to attain a more profound comprehension of prevailing research focal points and obstacles, thus offering invaluable insights to steer its prospective advancement.
Interferometric LiDAR is a device that is used to achieve distance, velocity and phase estimation with high precision and resolution through the use of frequency-modulated continuous wave (FMCW). In this instance, we study quantum enhancement detection techniques for a Mach-Zender interferometer with a FMCW coherent state input. Various quantum detection methods-including NOON state detection, coincidence detection, and sum of parity detection-are applied to the FMCW coherent state and compared against the classical heterodyne detection technique. The findings reveal the potential to trade maximum detectable distance for resolution enhancement. Furthermore, classical Fisher information is utilized to validate and quantify the precision limits of each detection technique. In scenarios characterized by high losses, it is observed that the precision limits of coincidence detection, sum of parity detection, and classical detection techniques are comparable. Therefore, this study offers practical guidance for designing quantum-enhanced receivers for FMCW LiDAR systems.