Rydberg Atomic Quantum MIMO Receivers for The Multi-User Uplink

TL;DR

A flexible architecture for Rydberg atomic quantum multiple-input multiple-output (RAQ-MIMO) receivers in the multi-user uplink is proposed and closed-form asymptotic formulas for the ergodic achievable rate (EAR) of both the maximum-ratio combining (MRC) and zero-forcing (ZF) receivers are derived.

Abstract

Rydberg atomic quantum receivers (RAQRs) have emerged as a promising solution for evolving wireless receivers from the classical to the quantum domain. To further unleash their great potential in wireless communications, we propose a flexible architecture for Rydberg atomic quantum multiple-input multiple-output (RAQ-MIMO) receivers in the multi-user uplink. Then the corresponding signal model of the RAQ-MIMO system is constructed by paving the way from quantum physics to classical wireless communications. Explicitly, we outline the associated operating principles and transmission flow. We also validate the linearity of our model and its feasible region. Based on our model, we derive closed-form asymptotic formulas for the ergodic achievable rate (EAR) of both the maximum-ratio combining (MRC) and zero-forcing (ZF) receivers operating in uncorrelated fading channels (UFC) and the correlated fading channels (CFC), as well as in the standard quantum limit (SQL) and photon shot limit (PSL) regimes, respectively. Furthermore, we unveil that the EAR scales logarithmically without bound with the product of effective number $N_{\text{atom}}$ and coherence time $T_2$ of the atomic ensemble in the SQL regime, but exhibits non-monotonic trade-off between the collective atomic enhancement and optical-depth-dependent attenuation in the PSL regime. More particularly, the transmit power of users can be scaled down quadratically with $N_{\text{atom}} τ$, $τ\in \{ T_2, \frac{ {\cal C} (Ω_{\ell}) }{A_p} \}$, but the EAR per user retains fixed, by increasing $N_{\text{atom}}$ while retaining the sensor number $M \propto N_{\text{atom}} τ$ in the SQL regime or $M \propto \exp \big( \frac{N_{\text{atom}} {\bar χ}}{A_p} \big)$ in the PSL regime....

Figures (6)

• Figure 1: (a) The superheterodyne structure of RAQ-MIMO, (b) the four-level scheme of electron transitions, (c) the balanced coherent optical detection (BCOD) scheme, and (d) the down-conversion and sampling by homodyne receivers (HRs) and the analog-to-digital converters (ADCs).
• Figure 2: (a) Accuracy of the proposed linear signal model and (b) feasible region to retain the linear relationship.
• Figure 3: The EAR scaling behavior of (a) the MRC RAQ-MIMO and (b) ZF RAQ-MIMO receivers in UFC/CFC scenarios. (c) The scaling behavior of ${\cal P}_{s}$ and $M$, as well as (d) the EAR scaling behavior when retaining ${\cal P}_{s} = {\cal E} / (N_{\text{atom}} \tau)^2$.
• Figure 4: The EARs of MRC/ZF RAQ-MIMO receivers vs. (a) transmit power ${\cal P}_{s}$ and (b) number of sensors $M$ for fixed ${\cal P}_{s}$.
• Figure 5: Comparison of RAQ-MIMO to M-MIMO receivers with respect to diverse parameters: (a)(d) EAR vs. number of sensors $M$; (b)(e) EAR vs. number of users $K$; (c)(f) EAR vs. transmit power ${\cal P}_{s}$.

Theorems & Definitions (13)

• Lemma 1
• Lemma 2
• Lemma 3
• Lemma 4
• Theorem 1
• Theorem 2
• Theorem 3
• Theorem 4
• Corollary 1
• Corollary 2