Rydberg atom-based AM receiver with a weak continuous frequency carrier

Abstract

We demonstrate an atom-based amplitude-modulation (AM) receiver for digital communication with a weak continuous frequency carrier using a Rydberg AC Stark effect in a vapor cell and achieve the operating carrier frequency continuously from 0.1 GHz to 5 GHz at a single Rydberg state. A strong local oscillator (LO) field E LO acts as a gain to shift the Rydberg level to a high sensitivity region, and a weak carrier field E Carr keeps the same frequency with the LO field. The digital baseband signals are encoded onto the E Carr using the amplitude modulation technique with the different modulation frequency. The response of Rydberg atom to the baseband signal is probed via a Rydberg electromagnetically induced transparency (EIT). The measured instantaneous bandwidth of the system is about 230 kHz. To demonstrate the performance of our system for an actual communication, we consider a color image as an example, the received image displays that the bit error rate (BER) is less than 5% when the maximum data transfer rate is about 238 kbps. Meanwhile, our system shows the weak carrier field of E Carr ≥ 13.52 μV/cm can be used for the practical communication with BER less than 5%. Our works break the limitation that EIT-AT based atomic receivers only operate at the near resonant frequencies of the Rydberg transitions, making this emerging of quantum technology close to the practical application with high sensitivity and broad bandwidth.

Sensitivity of Rydberg-atom receiver to frequency and amplitude modulation of microwaves

“…The weakest measured AM field (Fig. 5, Ω 𝑀 = 1.6•2𝜋MHz) has the amplitude 𝐴 𝑀 = 490 𝜇V 𝑐𝑚 , which does not come close to <10 𝜇V 𝑐𝑚 achieved by other groups [1,14,16,29,39], however, as the area of detection is extremely small, ∼3800𝜇m 2 , in terms of measured power we achieve 𝑃 = 12fW, or 1.3•10 9 microwave photons per second.…”

“…Nevertheless, our realization remains relatively simple and can be further improved in demanding applications. For example, highest sensitivity to AM or FM is achieved with additional probe-reference field [12,15,29] or if atoms are used as a mixer with an external local oscillator (LO) [14,39,40], which increases complexity of the entire setup. Additionally, it was proposed to combine Rydberg sensor with conventional antenna [41].…”

“…In recent years Rydberg-atom based microwave sensors have attracted attention of many researchers, owing to substantial sensitivity of Rydberg-to-Rydberg microwave (MW) transitions and straightforward measurement scheme. Atomic transitions have been proposed as easily reproducible electric field amplitude standard in the MW regime [1], and various realizations of MW modulation have led to enhanced detection sensitivity [2,3] (likewise did modulation of optical fields [4]), as well as to transmitting both analogue [5][6][7][8][9] and digital [10][11][12][13][14][15] information via Rydberg atomic receivers. There were also successful attempts at further characterizing measured MW field properties, such as frequency [16], phase [16][17][18][19], polarization [20,21], and angle-of-arrival [22].…”

High-Sensitivity Rydberg-Atom-Based Phase-Modulation Receiver for Frequency-Division-Multiplexing Communication

“…This non-destructive process allows the Rydberg sensors to exceed the Chu limit in the conventional dipole antenna 5 , and is important to avoid the electromagnetic interference and miniaturize the whole device. Recently, many electric-field sensing schemes with Rydberg atoms have been proposed and demonstrated involving periodic modulation [5][6][7][8][9][10] , which show their advantages over traditional dipole antennas including high sensitivity, broad operating frequency range and nondestructive interactions with the MW field 11 .…”

“…Previously, amplitude modulation (AM) [11][12][13] and frequency modulation (FM) 9,14 based schemes are used for enconding information in the MW fields. For AM scheme, the photonshot-noise limited Rydberg receiver has achieved the symbol rate 10 kSym/s with the carrier field amplitude being 130 µVcm −113 .…”