This paper proposes a multi-band quantum wireless sensing algorithm for the Rydberg atomic receiver. The proposed algorithm first estimates the non-linear wireless channel for the atomic receiver by adopting the biased Gerchberg-Saxton (GS) algorithm to retrieve the eliminated phase information. Thereafter, correlations between the estimated channel and multi-band steering vectors are calculated in the quantized angular grids to detect the angle-of-arrivals (AoAs) of multi-band users in an exhaustive manner. To the best of our knowledge, the proposed algorithm enables multi-band quantum wireless sensing for the first time and is unveiling the theoretical potential of the Rydberg atomic receivers.
This paper proposes a multi-band quantum wireless sensing algorithm for the Rydberg atomic receiver. The proposed algorithm first estimates the non-linear wireless channel for the atomic receiver by adopting the biased Gerchberg-Saxton (GS) algorithm to retrieve the eliminated phase information. Thereafter, correlations between the estimated channel and multi-band steering vectors are calculated in the quantized angular grids to detect the angle-of-arrivals (AoAs) of multi-band users in an exhaustive manner. To the best of our knowledge, the proposed algorithm enables multi-band quantum wireless sensing for the first time and is unveiling the theoretical potential of the Rydberg atomic receivers.
The advancement of Rydberg atoms is driving a paradigm shift from classical receivers to atomic receivers. Capitalizing on the extreme sensitivity of Rydberg atoms to external disturbance, atomic receivers can measure radio waves more precisely than classical receivers to support high-performance wireless communication. Although the atomic receiver is developing rapidly in the field of quantum physics, its integration with wireless communications is at a nascent stage. Particularly, systematic methods to enhance communication performance through this integration are largely uncharted. Motivated by this observation, we propose to incorporate atomic receivers into multiple-input multiple-output (MIMO) communications to implement atomic-MIMO receivers. We establish the framework of atomic-MIMO receivers by exploiting the principle of quantum sensing. Our model reveals that the signal detection of atomic-MIMO systems is intrinsically a nonlinear phase-retrieval problem, as opposed to the linear model in classical MIMO systems. To perform atomic-MIMO signal detection, we propose an Expectation-Maximization-Gerchberg-Saxton (EM-GS) algorithm based on the maximum likelihood (ML) criteria. Its novelty lies in treating the unobserved phase information as a latent variable and thereby decoupling the intricate ML problem into a sequence of tractable linear regression problems with analytical solutions. Experimental results validate the effectiveness of detecting atomic-MIMO signals using the EM-GS algorithm.
The advancement of Rydberg atoms in quantum information technology is driving a paradigm shift from classicalradio-frequency(RF) receivers to Rydberg atomic receivers. Capitalizing on the extreme sensitivity of Rydberg atoms to external electromagnetic fields, Rydberg atomic receivers are capable of realizing more precise radio-wave measurements than RF receivers to support high-performance wireless communication and sensing. Although the atomic receiver is developing rapidly in quantum-physics domain, its integration with wireless communications is at a nascent stage. In particular, systematic methods to enhance communication performance through this integration are yet to be discovered. Motivated by this observation, we propose in this paper to incorporate Rydberg atomic receivers intomultiple-input-multiple-output(MIMO) communication, a prominent 5G technology, as the first attempt on implementing atomic MIMO receivers. To begin with, we provide a comprehensive introduction on the principles of Rydberg atomic receivers and build on them to design the atomic MIMO receivers. Our findings reveal that signal detection of atomic MIMO receivers corresponds to a non-linear biasedphase retrieval(PR) problem, as opposed to the linear Gaussian model adopted in classical MIMO systems. Then, to recover signals from this non-linear model, we modify the Gerchberg-Saxton (GS) algorithm, a typical PR solver, into a biased GS algorithm to solve the biased PR problem. Moreover, we propose a novel Expectation-Maximization GS (EM-GS) algorithm to cope with the unique Rician distribution of the biased PR model. Our EM-GS algorithm introduces a high-pass filter constructed by the ratio of Bessel functions into the iteration procedure of GS, thereby improving the detection accuracy without sacrificing the computational efficiency. Finally, the effectiveness of the devised algorithms and the feasibility of atomic MIMO receivers are demonstrated by theoretical analysis and numerical simulation.
Quantum sensing technologies have experienced rapid progresses since entering the ‘second quantum revolution’. Among various candidates, schemes relying on Rydberg atoms exhibit compelling advantages for detecting radio frequency signals. Based on this, Rydberg atomic quantum receivers (RAQRs) have emerged as a promising solution to classical wireless communication and sensing. To harness the advantages and exploit the potential of RAQRs in wireless sensing, we investigate the realization of the direction of arrival (DOA) estimation by RAQRs. Specifically, we first conceive a Rydberg atomic quantum uniform linear array (RAQ-ULA) aided wireless receiver for multi-target DOA detection and propose the corresponding signal model of this sensing system. Our model reveals that the presence of the radio-frequency local oscillator in the RAQ-ULA creates sensor gain mismatches, which degrade the DOA estimation significantly by employing the classical Estimation of Signal Parameters via Rotational Invariant Techniques (ESPRIT). To solve this sensor gain mismatch problem, we propose the Rydberg atomic quantum ESPRIT (RAQ-ESPRIT) relying on our model. Lastly, we characterize our scheme through numerical simulations, where the results exhibit that it is capable of reducing the estimation error of its classical counterpart on the order of >400- fold and >9000- fold in the PSL and SQL, respectively.
This letter proposes a Quantum-MUSIC, the first multiple signal classification (MUSIC) algorithm for quantum wireless sensing of multi-user. Since the atomic receiver for quantum wireless sensing can only measure a magnitude of the received signal, sensing performance degradation of traditional dipole antenna-based signal processing algorithms is inevitable. To overcome this limitation, the proposed algorithm first retrieves the channel matrix and incorporates the MUSIC algorithm, enabling the multi-user wireless sensing with magnitude-only measurement. Simulation results showed that the proposed algorithm outperforms the classical MUSIC algorithm, validating the theoretical potential of quantum wireless sensing and atomic receiver.
Harnessing multi-level electron transitions, Rydberg Atomic REceivers (RAREs) can detect wireless signals across a wide range of frequency bands, from Megahertz to Terahertz. This capability enables multi-band wireless communications and sensing (CommunSense). Existing research on multi-band RAREs primarily focuses on experimental demonstrations, lacking a tractable model to mathematically characterize their mechanisms. This issue leaves the multi-band RARE as a black box and poses challenges in its practical applications. To fill in this gap, this paper investigates the underlying mechanism of multi-band RAREs and explores their optimal performance. For the first time, an analytical transfer function with a closed-form expression for multi-band RAREs is derived by solving the quantum response of Rydberg atoms. It shows that a multi-band RARE simultaneously serves as amulti-band atomic mixerfor down-converting multi-band signals and amulti-band atomic amplifierthat reflects its sensitivity to each band. Further analysis of the atomic amplifier unveils that the intrinsic gain at each frequency band can be decoupled into aglobal gainterm and aRabi attentionterm. The former determines the overall sensitivity of a RARE to all frequency bands of wireless signals. The latter influences the allocation of the overall sensitivity to each frequency band, representing a unique attention mechanism of multi-band RAREs. The optimal design of the global gain is provided to maximize the overall sensitivity of multi-band RAREs. Subsequently, the optimal Rabi attentions are also derived to maximize the practical multi-band CommunSense performance. An experiment platform is built to validate the effectiveness of the derived transfer function, and numerical results confirm the superiority of multi-band RAREs.
Rydberg atomic quantum receivers (RAQRs) have emerged as highly sensitive receivers for future communication and sensing systems. However, conventional RAQRs are primarily effective for single-carrier and narrowband reception, typically with an operational bandwidth of only a few hundred kilohertz. To enable the reception of multi-carrier signals with larger bandwidth, we propose a multi-carrier Rydberg atomic quantum receiver (MC-RAQR) architecture based on a five-level quantum system model. We analyze the amplitude and phase of the output laser in MC-RAQR and extract the baseband electrical signal for signal processing. Furthermore, we quantify the performance of MC-RAQR in multi-carrier communication and sensing by studying the channel capacity and distance estimation, respectively. Numerical results show that the MC-RAQR is capable of achieving a bandwidth of 7.2 MHz, which is an order of magnitude larger than conventional RAQRs. Besides, compared to conventional receivers, MC-RAQR can improve the capacity and distance estimation by 18-fold and 103-fold, respectively. This validates the superiority of MC-RAQR in receiving multi-carrier signal, and demonstrates its compatibility in detecting waveforms such as orthogonal frequency‐division multiplexing.