Linear dynamic range of a Rydberg-atom microwave superheterodyne receiver

In recent years, electric field measurement techniques based on Rydberg atoms have shown unique advantages in high sensitivity and wideband applications and miniaturization. The Rydberg atom receiver senses the electromagnetic signal using the quantum coherence effect, which overcomes the inherent defects of traditional electronic receivers in terms of thermal noise, insertion loss of microwave devices, and the use of wavelength-dependent antennas, thus providing the Rydberg atomic receivers the potential to become the next generation of microwave receivers. For some particular application scenarios such as radar and communication, superheterodyne reception is a critical technical approach, and the linear dynamic range is an essential factor in evaluating the performance of the superheterodyne receivers. It is challenging to promote the Rydberg atomic receiver without figuring out the influence of system parameters on the linear dynamic range. This paper starts with the response mechanism of the Rydberg atomic superheterodyne receiver, and a theoretical model is established to simulate the atom-microwave responses. Then the harmonics' generation mechanism is discussed, and the atomic linear dynamic range under different probe light Rabi frequencies is studied further. Furthermore, a method to evaluate the antiblocking performance of the system is proposed. This work is expected to provide theoretical guidance for the design and performance optimization of the Rydberg atomic superheterodyne receiver.

Figure 1

(a) The Rydberg atomic four-level system; (b) EIT spectra obtained by scanning ${\mathrm{\Delta }}_{\text{c}}$ under different ${\mathrm{\Omega }}_{\text{MW}}$; (c) the relationship curve between $P_{\mathrm{T}}$ and ${\mathrm{\Omega }}_{\text{MW}}$ (solid red line) at ${\mathrm{\Delta }}_{\text{c}}=0$, and the dotted blue line is the linear fitting result of the solid red line. When ${\mathrm{\Omega }}_{\text{MW}}$ changes with time $t$ (dotted purple line), the relationship of $P_{\mathrm{T}}$ and $t$ (dotted orange line) can be obtained through the red solid line mapping.

Figure 2

(a) The EIT-AT spectra under different ${\mathrm{\Omega }}_p$; (b) the relationships of the spectral profile height (solid blue line) and the FWHM linewidth (dashed red line) vs ${\mathrm{\Omega }}_p$.

Figure 3

(a) The relation curves of ${\mathrm{\Omega }}_{\text{MW}}$ vs $P_{\mathrm{T}}$ under different ${\mathrm{\Omega }}_p$; (b) the relation curves of ${\mathrm{\Omega }}_{\mathrm{opt}}$ (dashed red line) and ${\left|\kappa \right|}_{\max }$(solid blue line) vs ${\mathrm{\Omega }}_p$.

Figure 4

The relationship curve of (a) $P_{\mathrm{TFF}}$, (b) $P_{\mathrm{TSH}}$, and (c) $P_{\mathrm{TSH}}/P_{\mathrm{TFF}}$ vs ${\mathrm{\Omega }}_{\text{s}}$ under different ${\mathrm{\Omega }}_p$ when ${\mathrm{\Omega }}_{\text{LO}}={\mathrm{\Omega }}_{\mathrm{opt}}$.

Figure 5

The LDR vs ${\mathrm{\Omega }}_p$ in (a) cold atomic model and (c) thermal atomic model; 1 dB compression point ${\mathrm{\Omega }}_{\text{1dB}}$ and minimum detectable MSUT Rabi frequency ${\mathrm{\Omega }}_{\text{min}}$ vs ${\mathrm{\Omega }}_p$ in (b) cold atomic model and (d) thermal atomic model.

Figure 6

(a) Spectrum of $P_{\mathrm{T}}$ with interference, where $d=0.76$ mm, ${\mathrm{\Omega }}_{\text{LO}}={\mathrm{\Omega }}_{\text{opt}}, {\mathrm{\Omega }}_p=6$ MHz, ${\mathrm{\Omega }}_{\text{int}}={\mathrm{\Omega }}_{\text{s}}=500\mathrm{kHz}\ll {\mathrm{\Omega }}_{\mathrm{opt}}, \mathrm{\Delta }{f}_1=100$ kHz, $\mathrm{\Delta }{f}_2=250$ kHz; (b) $P_{\mathrm{TFF}}$ vs ${\mathrm{\Omega }}_{\text{int}}$ under different ${\mathrm{\Omega }}_p$ when ${\mathrm{\Omega }}_{\text{s}}=1$ kHz.

Figure 7

${\mathrm{\Omega }}_{\mathrm{int}3}$ vs ${\mathrm{\Omega }}_p$ under the cold and thermal atomic model.