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Experimental Sensitivity Enhancement of a Quantum Rydberg Atom-Based RF Receiver with a Metamaterial GRIN Lens

Anton Tishchenko, Demos Serghiou, Ashwin Thelappilly Joy, Paul Marsh, Paul Martin, Tim Brown, Gabriele Gradoni, Mohsen Khalily, Rahim Tafazolli

Abstract

We experimentally demonstrate enhanced sensitivity of an atom-based Rydberg radio frequency (RF) receiver integrated with a gradient refractive index (GRIN) Luneburg-type metamaterial lens. By analyzing the electromagnetically induced transparency (EIT) effect in Cesium vapor, we compare receiver performance with and without the GRIN lens under a 2.2~GHz and a 3.6~GHz far-field excitation. Our measurements reveal a significant amplification of the EIT transparency window when the lens is introduced, consistent with the theoretical prediction that the local E-field enhancement at the vapor cell reduces the minimum detectable electric field and increases the signal-to-noise ratio (SNR) of the Rydberg RF receiver. This experimental validation highlights the potential of metamaterial-assisted quantum sensing to overcome the inherent bandwidth and sensitivity limitations of bare Rydberg receivers for a variety of applications, such as electromagnetic compatibility (EMC) testing, quantum radar, and wireless communications.

Experimental Sensitivity Enhancement of a Quantum Rydberg Atom-Based RF Receiver with a Metamaterial GRIN Lens

Abstract

We experimentally demonstrate enhanced sensitivity of an atom-based Rydberg radio frequency (RF) receiver integrated with a gradient refractive index (GRIN) Luneburg-type metamaterial lens. By analyzing the electromagnetically induced transparency (EIT) effect in Cesium vapor, we compare receiver performance with and without the GRIN lens under a 2.2~GHz and a 3.6~GHz far-field excitation. Our measurements reveal a significant amplification of the EIT transparency window when the lens is introduced, consistent with the theoretical prediction that the local E-field enhancement at the vapor cell reduces the minimum detectable electric field and increases the signal-to-noise ratio (SNR) of the Rydberg RF receiver. This experimental validation highlights the potential of metamaterial-assisted quantum sensing to overcome the inherent bandwidth and sensitivity limitations of bare Rydberg receivers for a variety of applications, such as electromagnetic compatibility (EMC) testing, quantum radar, and wireless communications.

Paper Structure

This paper contains 2 sections, 5 equations, 4 figures.

Table of Contents

  1. Data Availability
  2. References

Figures (4)

  • Figure 1: GRIN Luneburg-type metamaterial design, centred at 3.5 GHz, showing: (a) the unit cell with size $c=({\lambda}/6)^3\approx(14\text{mm})^3$ and the geometrical variable $b$, (b) the refractive index $n$ variation as a function of $b$, simulated in CST Microwave Studio, and c) the assembled GRIN Luneburg-type metamaterial lens, consisting of eight 3D-printed fragments and made from the PLA material.
  • Figure 2: Schematic diagram of the proposed experiment, showing the Rydberg receiver with a metamaterial GRIN lens, including Cesium energy level diagrams at 2.2 GHz and 3.6 GHz.
  • Figure 3: Anechoic chamber testing, showing: a) test setup, b) x-axis (beam waist) measurement vs. CST simulation at 3.6 GHz, and c) z-axis (focal length) measurement vs. CST simulation at 3.6 GHz.
  • Figure 4: Experimental results, showing: (a) the Rydberg receiver and a GRIN Luneburg-type metamaterial lens test setup, b) the EIT window enhancement with and without the lens at 2.2 GHz, and (c) the EIT window enhancement with and without the lens at 3.6 GHz.