Out-of-equilibrium Rydberg gases exhibit emergent many-body phases due to mode competition. Sustained limit cycle oscillations (OSC) emerge when driven by B-fields at room-temperature, forming robust Rydberg dissipative time crystals (DTC). These driven-dissipative Rydberg DTC have recently been shown to develop an effective transition centered at the OSC frequency (-10dB bandwidth of ~1.7kHz, centered at 9.8kHz). Weak RF signals injected within this emergent transition perturb and emerge on the OSC spectrum, from which sensitive and high-resolution sensing of E-fields (~1.6-2.3 uVcm-1Hz-1/2) near the OSC frequencies can be achieved. In this article, it is demonstrated that DC and AC Stark fields in the sub-kHz regime can be used effectively to shift (DC) or modulate (AC) the OSC frequency of Rydberg DTC at room-temperature. The AC-Stark driven modulation of the OSC is shown as an effective technique to sense weak AC E-fields in the sub-kHz regime. With a modest setup, a sensitivity of ~7.8 uVcm-1Hz-1/2 for AC signals at 300Hz (~8.7x improvement over state-of-art Rydberg atom techniques), and high-resolution detection to as low as sub-Hz is demonstrated. This approach enables the development of ultra-compact, extremely low-frequency E-field detectors for applications in remote sensing, communications, navigation, and bio-medical technologies.
Out-of-equilibrium Rydberg gases exhibit emergent many-body phases due to mode competition. Sustained limit cycle oscillations (OSC) emerge when driven by B-fields at room-temperature, forming robust Rydberg dissipative time crystals (DTC). These driven-dissipative Rydberg DTC have recently been shown to develop an effective transition centered at the OSC frequency (-10dB bandwidth of ~1.7kHz, centered at 9.8kHz). Weak RF signals injected within this emergent transition perturb and emerge on the OSC spectrum, from which sensitive and high-resolution sensing of E-fields (~1.6-2.3 uVcm-1Hz-1/2) near the OSC frequencies can be achieved. In this article, it is demonstrated that DC and AC Stark fields in the sub-kHz regime can be used effectively to shift (DC) or modulate (AC) the OSC frequency of Rydberg DTC at room-temperature. The AC-Stark driven modulation of the OSC is shown as an effective technique to sense weak AC E-fields in the sub-kHz regime. With a modest setup, a sensitivity of ~7.8 uVcm-1Hz-1/2 for AC signals at 300Hz (~8.7x improvement over state-of-art Rydberg atom techniques), and high-resolution detection to as low as sub-Hz is demonstrated. This approach enables the development of ultra-compact, extremely low-frequency E-field detectors for applications in remote sensing, communications, navigation, and bio-medical technologies.
Out-of-equilibrium Rydberg gases exhibit emergent many-body phases due to mode competition. Sustained limit cycle oscillations (OSC) emerge when driven by B-fields at room temperature, forming robust Rydberg dissipative time crystals (DTC). Here we show that DC and AC Stark fields in the sub-kHz regime can be used to precisely shift (DC) or modulate (AC) the oscillation frequency of these DTCs, providing a powerful method for controllable time-domain dynamics in a room-temperature system. The AC Stark modulation induces frequency modulation (FM) of the OSC spectrum, enabling narrowband detection of extremely weak AC electric fields in the sub-kHz regime, with DC fields detected via Stark-induced shifts of the oscillation frequency. With a modest setup, a sensitivity of ~ 7.8µVcm − 1 Hz − 1/2 at 300 Hz is demonstrated — an ~ 8.7× improvement over state-of-art in the sub-kHz regime. Unlike on-resonant DTC sensing that is limited to operation close to the emergent limit cycle oscillations (10–15 kHz), the present approach is effective in the DC-600 Hz sub-kHz regime. This approach overcomes the size and bandwidth limitations of classical antennas at ultra-low frequencies and establishes a new class of ultra-compact ( ≪ λ/10⁶) Rydberg-based electric-field sensors. These results open opportunities for compact extremely low-frequency (ELF) sensors in remote sensing, communications, geophysics, and biomedical diagnostics.
Mode competition in nonequilibrium Rydberg gases enables the exploration of emergent many-body phases. This work leverages this emergent phase for electric field detection at room temperature. Sensitive frequency-resolved electric field measurements at very low-frequencies (VLF) are of central importance in a wide range of applications where deep-penetration is required in communications, navigation and imaging or surveying. The long wavelengths on order of 10–100 km (3–30 kHz) limit the efficiency, sensitivity, and bandwidth of compact classical detectors that are constrained by Chu’s limit. Rydberg-atom electrometers are an attractive approach for microwave electric-field sensors but have reduced sensitivity at lower-frequencies. Very recent efforts to advance the standard Rydberg-atoms approach is based on DC electric-field (E-field) Stark shifting and have resulted in sensitivities between 67.9 and 2.2 uVcm -1 Hz -1/2 (0.1–10 kHz) by fine optimization of the DC E-field. A major challenge in these approaches is the need for embedded electrodes or plates due to DC E-field Stark screening effect, which can perturb coupling of VLF signals when injected from external sources. In this article, it is demonstrated that state-of-art sensitivity ((1.60 ± 0.23) uVcm -1 Hz -1/2 ) can instead be achieved using limit-cycle oscillations in driven-dissipative Rydberg atoms by using a magnetic field (B-field) to develop mode-competition between nearby Rydberg states. The mode-competition between nearby Rydberg-states develop an effective transition centered at the oscillation frequency capable of supporting external VLF E-field coupling in the ~ 10–15kHz regime without the requirement for fine optimization of the B-field magnitude.
Non-equilibrium Rydberg gases exhibit exotic many-body phases stabilized by the interplay of coherent interactions and dissipation. Strong Rydberg interactions drive sustained limit cycle oscillations, whose robustness, long-range temporal order, and spontaneous time-translation symmetry breaking establish a dissipative time crystal (DTC). Collective self-entrainment in driven ensembles leads to global synchronization and a dominant oscillation frequency. Here, injection locking of a Rydberg DTC is demonstrated using a radio-frequency (RF) electric field that gradually pulls the intrinsic oscillation toward the injected frequency. Above a critical threshold, full synchronization occurs, with the locking bandwidth scaling linearly with RF amplitude. This includes synchronization of higher-order harmonics, revealing entrainment of the system’s nonlinear temporal dynamics. The phenomenon parallels injection locking in classical nonlinear systems, but emerges here in a strongly interacting quantum medium. This approach establishes a new method for stabilizing and controlling time-crystalline temporal order, with applications in precision sensing, quantum metrology, and timekeeping. Non-equilibrium Rydberg gases exhibit unique many-body phases arising from the interplay of coherent interactions and dissipation, yet controlling their temporal order remains challenging. This work demonstrates injection locking of a Rydberg dissipative time crystal using a radio-frequency electric field, achieving full synchronization and revealing dynamical behavior relevant to precision sensing and quantum metrology.
Non-equilibrium Rydberg gases exhibit exotic many-body phases stabilized by the interplay of coherent interactions and dissipation. Strong Rydberg interactions drive sustained limit cycle oscillations, whose robustness, long-range temporal order, and spontaneous time-translation symmetry breaking establish a dissipative time crystal (DTC). Collective self-entrainment in driven ensembles leads to global synchronization and a dominant oscillation frequency. Here, injection locking of a Rydberg DTC is demonstrated using a radio-frequency (RF) electric field that gradually pulls the intrinsic oscillation toward the injected frequency. Above a critical threshold, full synchronization occurs, with the locking bandwidth scaling linearly with RF amplitude. This includes synchronization of higher-order harmonics, revealing entrainment of the system's nonlinear temporal dynamics. The phenomenon parallels injection locking in classical nonlinear systems, but emerges here in a strongly interacting quantum medium. This approach establishes a new method for stabilizing and controlling time-crystalline temporal order, with applications in precision sensing, quantum metrology, and timekeeping.
Microwave power-to-frequency transduction is demonstrated using the emergent oscillation frequency of a magnetically initiated Rydberg dissipative time crystal (DTC). In a room-temperature 87Rb vapor, a ~14 G magnetic field establishes a self-sustained DTC near 21 kHz, while a near-resonant 8.325 GHz field coupling the 63D3/2 to 64P3/2 manifold continuously shifts the autonomous oscillation frequency. The resulting field-to-frequency transfer function is strongly nonlinear, with a total fundamental-frequency excursion of ~6.7 kHz and peak responsivity approaching 1 kHz/(mV/cm). The nonlinear transition is substantially steeper than a simple quadratic saturation response and is captured by a self-consistent mean-field picture in which microwave-driven Rydberg-population redistribution modifies the collective resonance condition. Higher DTC harmonics preserve the same normalized transfer function while exhibiting approximately linear growth of absolute responsivity with harmonic order. These results establish an intrinsic many-body atomic route to RF amplitude-to-frequency conversion, enabling continuous frequency-domain sensing through an emergent atomic frequency without an externally engineered RF feedback oscillator, repeated optical spectral scans, or resolved Autler Townes splitting.
Rydberg atoms have emerged as a versatile and efficient platform for high-sensitivity quantum sensing of free-space electric fields, with remarkable progress in detecting low-frequency signals. To date, low-frequency Rydberg receivers have relied on a constant bias field, typically realized via intra-cell electrodes or Rydberg plasmas generated by photoelectric effects or inter-atomic interactions. While these approaches improve sensitivity, they suffer from inherent challenges in calibration, long-term stability, and robustness, hindering practical deployment. Here, we propose, design, and experimentally demonstrate a quantum sensing scheme for low-frequency electric signals using modulated auxiliary fields in Rydberg atoms. Unlike conventional methods that employ external DC electric fields that are often fully shielded by adsorbed atom layers on the cell walls, we introduce an AC-field modulation strategy. The incoming low-frequency signal mixes with the auxiliary field, and together they induce Stark shifts of the Rydberg level. These shifts are mapped onto the probe laser via electromagnetically induced transparency (EIT), in a manner analogous to heterodyne detection. We demonstrate a sensitivity of 7.5±2.6μV/(cm⋅Hz1/2) at 5 kHz and a minimal detectable field of 0.26±0.04μV/cm with an integration time of 1000 s. Furthermore, we extend this approach to systematically analyze the performance of generalized auxiliary fields containing multiple frequency components. By virtue of modulated auxiliary field and quantum frequency mixing, our results establish a robust and systematic framework for quantum sensing of low-frequency electric fields with Rydberg atoms, offering improved sensitivity, stability, and immunity to environmental drifts.