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Introduction:
In the realm of modern warfare, communication is paramount. The ability to transmit critical information swiftly and securely can mean the difference between success and failure on the battlefield. Recognizing this, militaries worldwide are embarking on a groundbreaking journey into the realm of quantum communication technology. At the forefront of this revolution is the development of quantum receivers employing Rydberg atoms, promising ultrasensitive, ultrawideband, and fast communication capabilities for soldiers in the field.
The world stands on the cusp of a second quantum revolution, with the manipulation of individual atoms and electrons poised to transform industries across the board. Among the myriad applications of quantum technology, quantum communication stands out as a beacon of promise, offering unprecedented sensitivity, bandwidth, and security. At the forefront of this revolution lies the development of quantum receivers utilizing Rydberg atoms, heralding a new era in soldier communications.
Unraveling Quantum Sensing:
Quantum sensing, driven by the extraordinary sensitivity of quantum states to the environment, holds the key to transformative advancements in both military and civilian domains. Quantum Sensors could be transformative, enabling autonomous vehicles that can “see” around corners, underwater navigation systems, early-warning systems for volcanic activity and earthquakes, and portable scanners that monitor a person’s brain activity during daily life.
One application of Quantum Sensors that Researchers are in Radio frequency (RF) technologies that are revolutionizing a broad range of industries such as healthcare, entertainment, communications, and radar. The RF spectrum has evolved into a commodity valued at over 1 trillion dollars annually because of its widespread use. The far infrared (FI), or terahertz, region of the spectrum is an active area of research and promises many new application.
Particularly Researchers are interested in Quantum radio receiver. Radio receiver, a wireless or simply a radio is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna. The antenna intercepts radio waves (electromagnetic waves) and converts them to tiny alternating currents which are applied to the receiver, and the receiver extracts the desired information. The receiver uses electronic filters to separate the desired radio frequency signal from all the other signals picked up by the antenna, an electronic amplifier to increase the power of the signal for further processing, and finally recovers the desired information through demodulation.
Unveiling the Quantum Radio Receiver:
In the realm of radio frequency (RF) technologies, quantum radio receivers represent a paradigm shift with far-reaching implications. Traditional receivers are limited in their ability to detect signals across the entire RF spectrum, requiring multiple systems for comprehensive coverage. In contrast, quantum receivers employing Rydberg atoms offer soldiers the capability to detect communication signals over the entire spectrum, from 0 to 100 GHz, with unparalleled sensitivity and accuracy. This breakthrough opens the door to a new era of fast, reliable, and secure soldier communications.
Rydberg atoms, characterized by an electron elevated to an exceptionally high energy level, lie at the heart of this revolutionary communication system. Leveraging the unique properties of Rydberg atoms, quantum receivers can detect and decode radio signals with unparalleled precision and sensitivity. Unlike conventional antennas, these receivers operate at lower power levels, enabling long-range communication while maintaining covert operations.
Rydberg atoms as electric field sensors and communications receivers
Atom-based measurements of length, time, gravity, inertial forces and electromagnetic fields are receiving increasing attention. Atoms possess properties that suggest clear advantages as self calibrating platforms for measurements of these quantities. The accuracy and repeatability of atom-based measurements significantly surpass conventional methods because the stable properties of atoms and molecules are advantageous for precision measurement. Atom-based measurements have been successfully utilized for magnetometery , time and frequency standards, inertial force sensing as well as searches for local Lorentz invariance and intrinsic electric dipole moments of the neutron and electron , amongst others. Atom-based quantum techniques are also emerging as a completely new and promising tool for
advanced communications.
Rydberg atoms, characterized by their highly excited states, serve as remarkable quantum sensors for RF electric field measurements. These atoms are created from alkali metals like rubidium, possessing a single valence electron that responds strongly to electric fields due to its weak binding. It has long been understood that the large Rydberg atom polarizability and strong dipole transitions between energetically nearby states are highly sensitive to electric fields. By exciting the outer electron with lasers, Rydberg atoms become sensitive to a broad range of frequencies, from 100 MHz to over 1 THz.
Electromagnetically induced transparency (EIT) is employed to measure RF electric fields using Rydberg atoms. This technique utilizes optical phenomena where laser fields are transmitted instead of absorbed by atomic vapor in the presence of specific electromagnetic fields. By tuning lasers to atomic transitions, the transparency region is split, with the frequency separation directly proportional to the RF field strength. This enables high-resolution spectroscopy and absolute measurements of RF field magnitude.
While Rydberg atoms excel in measuring RF field magnitude, measuring phase remains challenging. However, researchers have devised schemes using Rydberg atoms as mixers to down-convert RF fields to intermediate frequencies, where the phase corresponds directly to the RF field phase.
NIST researchers demonstrated a scheme for measuring the phase of an RF field by using Rydberg atoms as a mixer to down-convert an RF field at 20 GHz to an intermediate frequency on the order of kHz. The phase of the intermediate frequency corresponds directly to the phase of the RF field
Block diagram of the Rydberg atom ‘mixer’. The Rydberg atoms separate the difference frequency (IF) from two RF signals
(LO and SIG). This demodulated signal is carried in the probe laser.
This technique, applicable over a wide frequency range, enables the measurement of amplitude, polarization, and phase in a single setup, enhancing the capabilities of Rydberg atom-based sensors from 500 MHz to 1 THz.
Ultrasensitive Communication:
One of the most remarkable aspects of quantum receivers is their extraordinary sensitivity. Rydberg atoms, with their large separation between the nucleus and the electron, exhibit heightened responsiveness to electromagnetic fields. This sensitivity allows for the detection of faint signals, providing soldiers with enhanced situational awareness and the ability to communicate effectively even in challenging environments.
Rydberg atoms exhibit far greater sensitivity than conventional antennas, enabling communication at lower power levels and across extended distances. Rydberg atoms, characterized by their highly excited states, possess remarkable sensitivity to electric fields, making them ideal candidates for RF electric field measurements.
Through techniques such as electromagnetically induced transparency (EIT), Rydberg atoms can detect and measure RF electric fields across a broad frequency range, from 100 MHz to over 1 THz. This sensitivity, combined with advancements in digital communication protocols, holds the promise of high-speed data transfer and enhanced spectrum awareness for soldiers on the battlefield.
Ultrawideband Capabilities:
While Current receivers are only able to receive over a portion of spectrum band or range of frequencies whereas a quantum receiver could give Soldiers a way to detect communication signals over the entire radio frequency spectrum, from 0 to 100 GHz. Such wide spectral coverage by a single antenna is impossible with a traditional receiver system, and would require multiple systems of individual antennas, amplifiers and other components.
Traditional communication systems are often constrained by bandwidth limitations, restricting the volume of data that can be transmitted simultaneously. However, quantum receivers employing Rydberg atoms transcend these limitations by operating across ultrawideband frequencies. This enables soldiers to transmit vast amounts of data rapidly, facilitating real-time information exchange and decision-making on the battlefield.
Fast and Secure Communication:
In addition to sensitivity and bandwidth, quantum receivers offer unparalleled speed and security. By harnessing the principles of quantum mechanics, these receivers ensure secure communication channels that are impervious to interception or hacking attempts. This enhanced security is of utmost importance in modern warfare, where the protection of sensitive information is paramount.
Leveraging the inherent quantum properties of atoms ensures robust security, as the communication method operates on fundamental atomic principles, making it exceedingly resilient to hacking or eavesdropping attempts. Selectivity: The distinct energy levels of Rydberg atoms permit precise narrowband filtering, imparting resistance against interference from other radio signals or jamming attempts.
Military Applications
By harnessing the unique properties of Rydberg atoms, quantum sensors have the potential to revolutionize autonomous navigation, early-warning systems, and brain activity monitoring, among other applications.
The deployment of quantum receivers with Rydberg atoms holds immense potential across various military applications. From tactical communications between soldiers on the ground to command and control operations at headquarters, this technology promises to revolutionize the way militaries communicate and collaborate in dynamic and challenging environments.
The integration of Rydberg-based quantum receivers into military communication systems promises to provide soldiers with a decisive advantage in the modern battlefield. From spectrum awareness and electronic warfare to sensing and communications, quantum sensors offer unparalleled capabilities that transcend the limitations of traditional electronics. As research and development continue to advance, the potential for quantum technology to reshape the landscape of soldier communications becomes increasingly evident.
The research has primarily been in the United States, Europe, and China.
China’s Advancements
Chinese researchers have made substantial strides in the realm of Rydberg-atom-based digital communication, offering innovative solutions to address the growing demand for efficient spectrum utilization and high-speed data transfer. In March 2019, scientists from the Chinese Academy of Sciences unveiled a pioneering approach leveraging Rydberg atoms for digital communication. Rather than focusing on retrieving signals on specific carrier frequencies, they aimed to exploit the frequency band near the carrier frequency determined by the energy gap between neighboring Rydberg states. This approach enables different communication channels to operate concurrently in closely spaced RF-carrier frequencies, significantly enhancing communication capacity.
Their experimental setup involved a Rydberg-atom-based RF receiver with differential detection, utilizing electromagnetically induced transparency (EIT) in a rubidium vapor cell. The receiver demonstrated reliable digital communication at a rate of 500 kbps within a tunable bandwidth of 200 MHz near a 10.22 GHz carrier frequency. However, challenges such as increased bit error rates beyond this range prompted further research and development efforts.
Subsequent advancements in China have showcased the continuous evolution of Rydberg-atom-based communication technology. Researchers at Huazhong University of Science and Technology unveiled a phase-modulation receiver with enhanced sensitivity, enabling communication with low signal strength and high data rates. Moreover, studies have explored the application of Rydberg atoms for frequency division multiplexing (FDM), enabling the transmission of multiple signals simultaneously on a single carrier for increased data capacity.
Continuous tuning capabilities have also been achieved, with researchers at Zhejiang University demonstrating Rydberg-atom-based digital communication using a continuously tunable radio-frequency carrier. These developments significantly enhance flexibility and adaptability compared to fixed-frequency approaches, paving the way for more dynamic and efficient communication systems.
Despite these advancements, challenges such as increasing data rates, miniaturization, and integration with existing infrastructure persist. However, Chinese researchers remain at the forefront of Rydberg-atom-based communication research, driving innovation and pushing the boundaries of what is achievable in secure and high-performance communication systems. With continued dedication and collaboration, these advancements hold promise for realizing the full potential of Rydberg-atom-based digital communication in the near future.
US Army
In 2018, Army scientists made significant strides in the realm of quantum technology by developing a groundbreaking quantum antenna utilizing Rydberg atoms. Led by Drs. Paul Kunz, Kevin Cox, David Meyer, and Fredrik Fatemi from the laboratory’s Quantum Technology Branch, this research aimed to equip future soldiers with highly accurate sensors operating with minimal background noise. By harnessing atoms prepared into exotic quantum states known as Rydberg states, which exhibit remarkable sensitivity to electric fields, the team achieved communication rates far surpassing those of traditional antennas. Their findings, published in Applied Physics Letters, marked a significant milestone in quantum communication research within military applications.
The development of a quantum receiver utilizing Rydberg atoms represented a pioneering achievement by Army scientists. David Meyer, a scientist at the U.S. Army Combat Capabilities Development Command’s Army Research Laboratory, highlighted the groundbreaking nature of this achievement, emphasizing that their receiver outperformed existing technologies by orders of magnitude. Leveraging the extreme sensitivity of Rydberg atoms to electric fields, the receiver demonstrated exceptional channel capacity, laying the groundwork for advanced communication systems tailored for military use.
The subsequent research endeavors by Army scientists further underscored the potential of Rydberg-atom-based sensors in military applications. In January 2021, the development of an ultra-broadband quantum receiver capable of analyzing the entire radio-frequency spectrum up to 20 GHz was reported. This breakthrough enabled the detection of diverse communication signals, including AM, FM radio, Bluetooth, and Wi-Fi, empowering soldiers with enhanced spectrum awareness and electronic warfare capabilities. Dr. Kevin Cox emphasized the transformative impact of this technology, envisioning quantum sensors as a dominant force in the complex electromagnetic battlespace of the future.
The continuous refinement of Rydberg-atom-based sensors holds promise for revolutionizing military communication and sensing capabilities. While significant progress has been made, ongoing efforts focus on enhancing signal sensitivity and expanding detection protocols to encompass a wider range of signals and frequencies. As the Army remains at the forefront of Rydberg sensor development, researchers are committed to overcoming technical challenges and advancing towards the integration of quantum sensors into field-testable devices. With quantum constituents emerging as a top priority for future military technologies, Rydberg sensors represent a pivotal step towards achieving technical superiority and ensuring mission success in the evolving battlefield landscape.
US Army tests long-range quantum radio communication
The U.S. military, recognizing the significance of quantum sensing, is spearheading cutting-edge research to leverage this technology for submarine detection, geolocation, and communications.
Rydberg Technologies’ recent partnership with the U.S. Army in demonstrating long-range radio communication using an atomic quantum receiver stands as a groundbreaking achievement in secure communication technology. The backbone of this receiver is the Rydberg atom, specifically a cesium atom with an electron elevated to an exceptionally high energy level. This configuration results in a substantial separation between the nucleus and the electron, rendering it remarkably responsive to electromagnetic fields. The manipulation of Rydberg atoms through specific radio frequencies induces detectable changes in their energy states, facilitating precise signal detection and decoding.
Challenges and Future Prospects:
Despite its promising potential, the existing prototype operates at relatively low bandwidths and necessitates further research to enhance data transmission rates and downsize the technology for practical deployment.
Scalability: Scaling the technology for widespread military implementation demands substantial advancements in manufacturing techniques and infrastructure development.
Integration: Seamless integration of the atomic receiver with existing communication systems and networks is pivotal for its effective adoption across diverse operational environments.
In essence, Rydberg Technologies’ demonstration represents a significant stride forward in quantum communication technology. While certain challenges persist, the prospect of highly secure and long-range communication underscores the profound implications of this technology for both military and civilian domains alike.
As research and development in quantum communication technology continue to advance, the possibilities are limitless. Militaries are exploring avenues to further refine and integrate quantum receivers into existing communication systems, paving the way for a future where soldiers possess unprecedented communication capabilities on the battlefield.
Conclusion:
In the pursuit of technological superiority, militaries are turning to quantum communication technology as a game-changer in modern warfare. The emergence of quantum receivers employing Rydberg atoms represents a pivotal moment in the evolution of soldier communications. By harnessing the unique properties of Rydberg atoms, quantum receivers offer soldiers ultrasensitive, ultrawideband, and fast communication capabilities, revolutionizing the way information is transmitted and received on the battlefield.
With the ability to detect, analyze, and respond to communication signals across the RF spectrum, these quantum sensors offer soldiers a decisive advantage in an increasingly complex electromagnetic battlespace. As the U.S. military continues to lead the charge in quantum research and development, the future of soldier communications looks brighter than ever before.
References and Resources also include:
https://phys.org/news/2021-02-quantum-entire-radio-frequency-spectrum.html
