Facing the trend of 5G/6G communications toward high spectral efficiency and low power consumption, RF receivers urgently need to overcome the triple challenges of high sensitivity, terahertz (THz) coverage, and system integration. Conventional approaches are limited by electronic thermal noise, band correlation and antenna perturbation effects. In this context, sensors based on the Rydberg atom become a promising alternative, with his large electric dipole moment bringing extremely high sensitivity, inherent frequency selectivity, and the potential to build low-power integrated photonic platforms. This paper describes a Rydberg atomic RF sensor using a quantum coherent mechanism to receive and demodulate quadrature AM signals. The core innovations include: (1) a scheme for 4QAM signal splitting and demodulation within the atomic resonance region via precise signal control; and (2) dynamic, real-time control of the demodulation channels (I/Q paths) by exploiting the phase difference between the local oscillator (LO) and signal (SIG) fields. The proposed architecture can support demodulation of quadrature AM signals, demonstrating its great potential as a versatile next-generation communications platform.
Facing the trend of 5G/6G communications toward high spectral efficiency and low power consumption, RF receivers urgently need to overcome the triple challenges of high sensitivity, terahertz (THz) coverage, and system integration. Conventional approaches are limited by electronic thermal noise, band correlation and antenna perturbation effects. In this context, sensors based on the Rydberg atom become a promising alternative, with his large electric dipole moment bringing extremely high sensitivity, inherent frequency selectivity, and the potential to build low-power integrated photonic platforms. This paper describes a Rydberg atomic RF sensor using a quantum coherent mechanism to receive and demodulate quadrature AM signals. The core innovations include: (1) a scheme for 4QAM signal splitting and demodulation within the atomic resonance region via precise signal control; and (2) dynamic, real-time control of the demodulation channels (I/Q paths) by exploiting the phase difference between the local oscillator (LO) and signal (SIG) fields. The proposed architecture can support demodulation of quadrature AM signals, demonstrating its great potential as a versatile next-generation communications platform.
The highly-excited Rydberg states are with a unique property of radio-frequency (RF) resonance, and Rydberg atoms at room temperature are promising for developing a broadband RF electric field sensor and relevant metrology standards. In this paper, the working mechanism of an atomic amplitude-modulation(AM) radio receiver is investigated in detail, and various factors affecting the communication quality are discussed. The modulation RF signal can be directly retrieved by measuring the transmission of a probe laser at resonance of rubidium D2 transition using a fast photo-diode detector, without any conventional demodulation process. Various communication experiments are tested at a 10.22 GHz carrier, and a modulation bandwidth of 1 MHz and an acceptable data transfer rate of about 1 Mbps have been achieved using current detection techniques. Owing to a potential high sensitivity and ultra-broadband capability of free-space RF field sensing, the quantum receiver has great significance compared with conventional electronics-based receivers, including but not limited to a weak signal, long-distance, and broadband communication in free space or via a fiber link.
Rydberg atomic quantum receivers (RAQRs) are emerging quantum precision sensing platforms designed for receiving radio frequency (RF) signals. It relies on the creation of Rydberg atoms from normal atoms by exciting one or more electrons to a very high energy level, thereby making the atom sensitive to RF signals. RAQRs realize RF-to-optical conversions based on atom-light interactions relying on the so-called electromagnetically induced transparency (EIT) and Autler- Townes splitting (ATS) so that the desired RF signal can be read out optically. The large dipole moments of Rydberg atoms associated with rich choices of Rydberg states facilitate an ultra-high sensitivity (~nv⁄cm/√Hz) and an ultra-broadband tunability (direct-current to Terahertz). RAQRs also exhibit compelling scalability and lend themselves to the construction of innovative, compact receivers. Initial experimental studies have demonstrated their capabilities in classical wireless communications and sensing. To fully harness their potential in a wide variety of applications, we commence by outlining the underlying fundamentals of Rydberg atoms, followed by the principles and schemes of RAQRs. Then, we overview the state-of-the-art studies from both physics and communication societies. Furthermore, we conceive Rydberg atomic quantum single-input single-output (RAQ-SISO) and multiple-input multiple- output (RAQ-MIMO) schemes to facilitate the integration of RAQRs with classical wireless systems. Finally, we conclude with a set of potent research directions.
Next-generation Internet-of-Things (IoT) is evolving toward a ubiquitous, ultra-low-power, and multi-band heterogeneous networking paradigm that seamlessly integrates terrestrial, non-terrestrial, and ambient devices. This vision places unprecedented demands on conventional radio frequency (RF) receivers, whose fundamental bottlenecks in sensitivity, power consumption, coverage, and multi-band operation are rooted in the RF antenna. To tackle these issues, we show that the quantum properties of Rydberg atomic quantum receivers (RAQRs), including ultra-high sensitivity, broad frequency agility, and diverse reception modalities, provide a physically distinct receiver-side path that replaces the conventional antenna-and-low-noise-amplifier chain. Using LoRa, narrowband IoT, and ambient IoT as case studies, this article shows that RAQRs deliver significant gains in weak-uplink, low-power, and battery-free regimes. A stochastic-geometry analysis in cellular and cell-free architectures then maps these device-level gains onto network coverage, where the RAQR retains roughly a 4 dB half-coverage advantage over the RF receiver in sparse deployments at λ∼10−5m−2, with the gain eroded as device density grows. The open challenges are presented to stand between current RAQR prototypes and deployable IoT infrastructure.
As a key enabler for next-generation wireless systems, integrated sensing and communication (ISAC) requires significantly higher receiver sensitivity than conventional architectures to achieve long-range target detection, thereby introducing new challenges in receiver design. Among potential solutions, Rydberg atomic quantum receivers (RAQRs) have attracted growing attention for their unique quantum sensing capabilities. By exploiting the exceptional responsiveness of Rydberg atoms to electromagnetic fields, RAQRs enable direct and highly sensitive measurement of radio-frequency (RF) signals without relying on traditional antenna-based front ends. However, this enhanced sensitivity also renders them more vulnerable to interference, particularly from undesired targets and long-delay multipath components. To address this limitation, this article presents practical strategies for improving the interference robustness and selective reception performance of RAQRs in ISAC scenarios. Specifically, we begin with a comprehensive overview of RAQR principles and identify the interference-related challenges encountered in ISAC applications. Building on this foundation, we introduce the Actively Selective RAQR (AS-RAQR) architecture, which integrates tunable gating mechanisms to actively suppress unwanted signals. The proposed design is validated through representative case studies, followed by a discussion of open challenges and future research directions.
Rydberg atoms are neutral atoms excited to high principal quantum number states, which endows them with exaggerated properties such as large electric dipole moments, long lifetimes, and extreme sensitivity to external electromagnetic fields. These characteristics form the foundation of Rydberg atom-based sensors, an emerging class of quantum devices capable of optically detecting electric fields across frequencies from DC to the terahertz regime. Rydberg-based electrometry operates through both Autler–Townes (AT) splitting of resonant Rydberg transitions and Stark-shift measurements for high-frequency or far-detuned fields, enabling broadband field sensing from DC to the THz regime. Using ladder-type electromagnetically induced transparency (EIT) and AT splitting, these sensors enable non-invasive, SI-traceable measurements of field amplitude, frequency, phase, and polarization. Recent developments have demonstrated broadband electric field probes, voltage calibration standards, and compact RF receivers based on thermal vapor cells and integrated photonic architectures. Furthermore, innovations in multi-photon EIT, superheterodyne readout, and multi wave mixing have expanded the dynamic range and bandwidth of Rydberg-based electrometry. Despite challenges related to environmental perturbations, linewidth broadening, and laser stabilization, ongoing advances in atomic control, hybrid photonic integration, and EIT-based readout promise scalable, chip-compatible sensors. This review summarizes the physical principles, experimental progress, and emerging applications of Rydberg atom-based sensing, emphasizing their potential for next generation quantum metrology, wireless communication, and precision field mapping.
Ground-satellite links for 6G networks face critical challenges, including severe path loss, tight size-weight-power limits, and congested spectrum, all of which significantly hinder the performance of traditional radio frequency (RF) front ends. This article introduces the Rydberg Atomic Quantum Receiver (RAQR) for onboard satellite systems, a millimetre-scale front end that converts radio fields to optical signals through atomic electromagnetically induced transparency. RAQR’s high sensitivity and high frequency selectivity have the potential to address link-budget, payload, and interference challenges while fitting within space constraints. Theoretically, a hybrid atomic–electronic design that is supported by a consistent signal model achieves spectral efficiency exceeding 6 bit/s/Hz, extends coverage by up to 1000 km, and improves sensing accuracy by two orders of magnitude relative to conventional RF receivers. The paper concludes with integration strategies, distributed-satellite concepts, and open research challenges for bringing RAQR-enabled satellite payloads into service.