Quantum RF system for detecting, identifying, characterizing, monitoring and tracking RF threats

Abstract

The present invention concerns a quantum radiofrequency system (1) comprising: a wideband quantum radiofrequency sensor (11); a narrowband tunable quantum radiofrequency sensor (12); a control unit (13) that is coupled to the wideband quantum radiofrequency sensor (11) and to the narrowband tunable quantum radiofrequency sensor (12) and is configured to control operation thereof; and a catalogue (14) for storing data related to known radiofrequency signals. The control unit (13) is configured to: operate the wideband quantum radiofrequency sensor (11) to sense surrounding radiofrequency spectrum; analyze the radiofrequency spectrum sensed by the wideband quantum radiofrequency sensor (11) and detect radiofrequency anomalies by comparing the sensed radiofrequency spectrum with the data related to known radiofrequency signals stored on the catalogue (14); if a radiofrequency anomaly is detected, operate the narrowband tunable quantum radiofrequency sensor (12) to characterize radiofrequency signal around the detected radiofrequency anomaly to detect radiofrequency threats; if a radiofrequency threat is detected, monitor / track the detected radiofrequency threat by the wideband quantum radiofrequency sensor (11) and / or the narrowband tunable quantum radiofrequency sensor (12) and counteract said detected radiofrequency threat and / or notify it to a user / operator or to a remote control center / station.

Description

[0001] QUANTUM RF SYSTEM FOR DETECTING, IDENTIFYING, CHARACTERIZING, MONITORING AND TRACKING RF THREATS

[0002] Cross-Reference To Related Applications

[0003] This patent application claims priority from European patent application no. 24194062.6 filed on August 12, 2024, and from Italian patent application no. 102025000003381 filed on February 20, 2025, the entire disclosure of which is incorporated herein by reference.

[0004] Technical Field of the Invention

[0005] The present invention relates, in general, to a quantum radiofrequency (RF) system.

[0006] More specifically, the present invention concerns a quantum RF system capable of detecting, identifying, characterizing, monitoring and tracking potential and real RF threats.

[0007] State of the Art

[0008] As is known, radiofrequency (RF) electromagnetic waves disrupted not only the telecommunications sector, but any other area of modern life such as healthcare, consumer electronics, automotive, transport, defense as well as space sectors .

[0009] With specific reference to the space sector, frequencies comprised between a few GHz and 100 GHz are of fundamental importance, since they are used as carriers and are used for several applications, for example in: radar imaging systems (e.g., Synthetic Aperture Radar - SAR) , satellite communication systems (including Inter-Satellite Links (ISL) and telemetry from / to ground) , navigation systems, Space Situational Awareness (SSA) , etc. The basis of these applications is , therefore , the ability to receive and measure these signals : an RF sensor is thus the key element for enabling new applications and technologies .

[0010] Even i f several technologies exists for making a device capable to sense an oscillating electric and / or magnetic field at RF frequencies , in its most common meaning (which is also the most commercially developed) , an RF sensor is an antenna coupled with passive electronics , wherein the antenna collects the incident electromagnetic waves and the electronics is in charge of filtering, ampli fication and signal processing operations in order to demodulate and measure all the characteristics of an incident signal . The si ze and nature of the antenna determine the optimum operating frequency of the RF sensor, which can be a few kHz for large antennas or tens of GHz for very small ones .

[0011] Nowadays , these RF sensors are ubiquitous in space applications and can be hosted by satellite platforms as dedicated or secondary payload; however, they have some intrinsic limitations :

[0012] • broadband operation : classical ( i . e . , non quantum) RF sensors are designed to operate in a speci fic frequency range that is usually very narrow depending on the central frequency to be received; indeed, the si ze itsel f of the receiving antenna strongly determines the operating frequency range ; for example , a receiver designed for working at 1 GHz cannot be used for working at 40 GHz ; thus , application that requires large bandwidth ( for example enhanced radar for Earth Observation or spectrum monitoring for space assets ' surveillance ) usually require many di f ferent sensors ; it is challenging today to develop a single compact instrument that can enable co-located broadspectrum RF sensing;

[0013] • sensitivity: the sensitivity (i.e., minimum field detectable) of currently used RF sensors is strongly limited by electronics and thermal noise;

[0014] • SWaP-C: physical size and weight of currently used RF sensors are large, especially at low RF frequencies;

[0015] • calibration: classical RF sensors need to be calibrated, meaning that, in order to ensure that their measurements are accurate, reliable and consistent, other RF sensors with known properties must be used to characterize the first ones; but, in turn, the latter must also be calibrated, thus triggering a "dog biting its own tail" type of loop;

[0016] • materials: classical RF sensors are usually made by metal, thus introducing strong RF distortion.

[0017] Quantum RF sensors are a promising technology for solving all of the previously listed issues. Quantum RF sensors are an emerging class of technologies that, based on the unique properties of quantum systems, are destined to disrupt the traditional way of thinking about RF sensors. Nevertheless, also quantum RF sensors show some limitations and tradeoff that will be better described hereinafter.

[0018] Nitrogen-Vacancy (NV) centers in diamonds have been used mostly as detectors of very low static magnetic fields and only recently have been investigated as detectors of oscillating magnetic fields in the microwave frequency regime. As for wideband RF sensing with diamonds, an important results has been reached in 2022 where a signal analyzer has been realized which detects RF signals over a tunable frequency range of 25 GHz with frequency resolution down to 1 MHz, a millisecond temporal resolution and a large dynamic range (40 dB) [Magaletti, S., Mayer, L., Roch, JF. et al., "A quantum radio frequency signal analyzer based on nitrogen vacancy centers in diamond" , Commun Eng 1, 19 (2022) ] . Other works suggest the importance of this quantum system for wideband signal processing [Bai, Ruixin, et al., "Optimized microwave sensing in broad frequency range by a fiber diamond probe" , Applied Physics Letters 120, 4 (2022) ] . Heterodyne microwave magnetic sensing has been proved in [Meinel, Jonas, et al., "Heterodyne sensing of microwaves with a quantum sensor" , Nature communications 12, 1 (2021) : 2737] . A room-temperature quantum sensor of an artificial AC field centered at ~900 kHz with a spectral resolution of 10 kHz has been proved in [Jiang, Zhengzhi, et al., "Quantum sensing of radio- frequency signal with NV centers in SiC" , Science advances 9, 20 (2023) : eadg2080] using an emerging platform based on silicon carbide (SiC) in order to facilitate the integration with conventional electronic circuitry .

[0019] The scientific literature on RE Rydberg atomic detection is large and focused on different methods of detection always considering a single quantum system as sensor (i.e., the gas of alkali atoms excited in Rydberg states) ; among the several papers in literature describing different detection schemes, the following can be considered extremely relevant:

[0020] • measuring the electric field amplitude of a resonant (or-quasi resonant) incoming microwave field using the A-T (Autler-Townes ) splitting [Sedlacek, J., Schwettmann, A., Ktibler, H. et al., "Microwave electrometry with Rydberg atoms in a vapour cell using bright atomic resonances" , Nature Phys 8, 819-824, (2012) , https: / / doi.org / 10.1038 / nphys2423] ; this method ca be extended in order to be able to measure polarization [D. A. Anderson, E. G. Paradis, and G. Raithel, Applied Physics Letters 113, 073501 (2018) ] , imaging [H. Q. Fan, S. Kumar, R. Daschner, H. Ktibler, and J. P. Shaffer, Optics Letters 39, 3030 (2014) ] , measurements at high

[0021] (millimeter wave and terahertz) frequency [Y. Zhou, R. Peng, J. Zhang, L. Zhang, Z. Song, Z. Feng, and Y. Peng, IEEE Photonics Journal 14, 1 (2022) ] and measurement of strong fields [D. A. Anderson, S. A. Miller, G. Raithel, J. A. Gordon, M. L. Butler, and C. L. Holloway, Physical Review Applied 5, 034003 (2016) ] ;

[0022] • measuring low-frequency off-resonant RE fields using AC Stark energy level shifts [Y. Jiao, X. Han, Z. Yang, J. Li, G. Raithel, J. Zhao, and S. Jia, Physical Review A 94, 023832 (2016) ] ;

[0023] • detection of modulated fields [A. B. Deb and N. Kjaergaard, Applied Physics Letters 112, 211106 (2018) ] with practical demonstrations included audio streaming [C. L. Holloway, M. T. Simons, A. H. Haddab, C. J. Williams, and M. W. Holloway, AIP Advances 9, 065110 (2019) ] , video streaming [N. Prajapati, A. P. Rotunno, S. Berweger, M. T. Simons, A. B. Artusio-Glimpse, S. D. Voran, and C. L. Holloway, AVS Quantum Science 4, 035001 (2022) ] , pulse detection [S. M. Bohaichuk, D. Booth, K. Nickerson, H. Tai, and J. P. Shaffer, Physical Review Applied 18, 034030 (2022) ] and sensing at distance [J. S. Otto, M. Chilcott, A. B. Deb, and N. Kjaergaard, Applied Physics Letters 123, 144003 (2023) ] ;

[0024] • superheterodyne schemes [M. Jing, Y. Hu, J. Ma, H. Zhang, L. Zhang, L. Xiao, and S. Jia, Nature Physics 16, 911 (2020) ] using Rydberg atoms as a RE mixer to improve the detection sensitivity by several orders of magnitude and enable various new types of measurements such as phase- modulated signals [Y. Cai, S. Shi, Y. Zhou, Y. Li, J. Yu, W. Li, and L. Li, Physical Review Applied 19, 044079 (2023) ] , measurement of angle-of-arrival [A. K. Robinson, N. Prajapati, D. Senic, M. T. Simons, and C. L. Holloway, Applied Physics Letters 118, 114001 (2021) ] , enhanced receiving of AM signals [M. Cai, S. You, S. Zhang, Z. Xu, and H. Liu, Applied Physics Letters 122, 161103 (2023) ] , multifrequency microwave recognition [Z.-K. Liu, L.-H. Zhang, B. Liu, Z.-Y. Zhang, G.-C. Guo, D.-S. Ding, and B.- S. Shi, Nature Communications 13, 1997 (2022) ] , measurement of RF polarization [Y. Wang, F. Jia, J. Hao, Y. Cui, F. Zhou, X. Liu, J. Mei, Y. Yu, Y. Liu, J. Zhang, F. Xie, and Z. Zhong, Optics Express 31, 10449 (2023) ] , detecting a satellite radio signal [P. K. Elgee, J. C. Hill, K.-J. E. LeBlanc, G. D. Ko, P. D. Kunz, D. H. Meyer, and K. C. Cox, Applied Physics Letters 123, 084001 (2023) ] , demonstration of soil moisture sensing [D. Arumugam, J.-H. Park, B. Feyissa, J. Bush, and S. P. Mysore Nagaraja, Scientific Reports 14, 18025 (2024) ] and presenting a QAM (quadrature amplitude-modulated) receiver [J. Nowosielski, M. Jastrzgbski, P. Halavach, K. Lukanowski, M. Jarzyna, M. Mazelanik, W. Wasilewski, and M. Parniak, Optics Express 32, 30027 (2024) ] .

[0025] Additionally, EP 3 308 146 B2, that relates to an atombased electromagnetic radiation electric-field sensor, discloses a method for measuring the electric field of electromagnetic radiation using the spectroscopic responses of Rydberg atoms to the electromagnetic radiation field. The method entails implementing quantitative models of the Rydberg atom response to the electromagnetic radiation field to provide predetermined atomic properties or spectra for field amplitudes and / or frequencies of interest , spectroscopically measuring the response ( spectrum) of Rydberg atoms exposed to an unknown electromagnetic radiation field, and obtaining the electric field amplitude and / or frequency of the unknown electromagnetic radiation by using features extracted from the measured spectrum and comparing them to features in a predetermined spectrum among the set of predetermined spectra .

[0026] US 11 , 774 , 482 B2 , that concerns an atom-based electromagnetic field sensing element and a related measurement system, describes methods and apparatus for sensing or measuring an electromagnetic field . The method entails excitation into a distribution of Rydberg states of atoms of a gas occupying a test volume coextensive with the electromagnetic field . Transmission along a path traversing the test volume o f at least one probe beam of electromagnetic radiation is measured at one or more frequencies overlapping a spectral feature , and a physical characteristic of the electromagnetic field is derived based on variation of the spectral feature . The electromagnetic field may be placed in interferometric relation with another electromagnetic field . Time-varying electric field amplitude , frequency, phase and noise spectral distribution may be measured, and thus AM and FM modulated fields , as well as magnetic fields of about 1 Tesla . The apparatus for measuring the electromagnetic field may be unilateral ly coupled to a probe field and detector or array of detectors .

[0027] US 11 , 002 , 777 B2 , that relates to a microwave sensor using Rydberg particles , discloses a microwave sensor that includes a cloud of particles , e . g . , Rubidium 87 atoms . A probe laser beam transitions ground-state particles in its path to an excited state . A set of one or more coupling laser beams causes excited particles to transition to a first Rydberg state so that particles in the intersection of the laser beams are in a dark superposition which is transparent to the probe laser beam so that a frequency spectrum of the probe laser beam shows a transmission peak at the laser frequency . A microwave lens focuses a microwave vector ( e . g . , a microwave signal ) within the intersection, causing particles in the first Rydberg state to transition to a second Rydberg state , splitting the transmission peak into a pair of peaks . The intensity of the microwave vector can be calculated based on the frequency di f ference between the pair of peaks . The direction of the microwave vector can be determined from the location of the laser-beam intersection .

[0028] US 11 , 630 , 143 B2 , that concerns a microwave sensor using Autler-Townes splitting, describes a microwave sensor which determines an electric- field strength of a microwave field populated by quantum particles in an ultra-high vacuum (UHV) cell . A probe laser beam and a coupling laser beam are directed into the UHV cell so that they are generally orthogonal to each other and intersect to define a "Rydberg" intersection, so-called as the quantum particles within the Rydberg intersection transition to a pair of Rydberg states . The frequency of the probe laser beam is swept so that a frequency spectrum of the probe laser beam can be captured . The frequency spectrum is analyzed to determine a frequency di f ference between Autler-Townes peaks . The electric- field strength of the microwave field within the Rydberg intersection is then determined based on this frequency di f ference . US 10 , 979 , 147 B2 , that relates to a Rydberg atom mixer and a determining phase of modulated carrier radiation, discloses a Rydberg atom mixer which determines a phase of modulated carrier radiation and includes : a reference radiofrequency source for reference radiofrequency radiation; a modulated carrier source for modulated carrier radiation; a vapor cell to contain gas atoms and that receives reference radiofrequency radiation and modulated carrier radiation, such that the gas atoms produce modulated light modulated; and a transmission detector that receives the modulated light from the vapor cell and produces a transmission signal from the transmission detector for determination of a phase of the modulated carrier radiation, wherein the Rydberg atom mixer mixes the reference radiofrequency radiation and the modulated carrier radiation by the gas atoms in a Rydberg electronic state to produce the intermediate frequency ( I F) that corresponds directly to the phase of the modulated carrier radiation .

[0029] US 11 , 165 , 505 B2 , that concerns a quantum atomic receiving antenna and a quantum sensing of radiofrequency radiation, describes a quantum atomic receiving antenna that includes : a probe laser ; a coupling laser ; an atomic vapor cell that includes : a spherically-shaped or parallelepipedshaped atomic vapor space and Rydberg antenna atoms that undergo a radiofrequency Rydberg transition to produce quantum antenna light from probe light such that an intensity of the quantum antenna light depends on an amount of radiofrequency radiation received by the Rydberg antenna atoms , the quantum antenna light including a strength, direction and polari zation of the radiofrequency radiation; and a quantum antenna light detector in optical communication with the atomic vapor cell .

[0030] US 2020 / 0136727 Al , that relates to methods and apparatus for implementing an optical transceiver using a vapor cell , discloses a transmitter, receiver and transceiver system that may be used for both transmitting and receiving modulated signals . The system includes an Electrical-to- Optical (E2O) converter that receives an RE signal and transmits an optical signal and / or an Optical-to-Optical ( 020) that performs a wavelength translation from one wavelength to another wavelength . The Electrical-to-Optical (E20) converter includes a vapor cell that converts the RE signal to an optical signal .

[0031] US 10 , 763 , 966 Bl , that concerns a data communications system using an optical antenna , describes an apparatus for converting an analogue RE signal to an optical signal . The apparatus may include : a vapor cel l enclosing a gas of atoms ; a probing light source configured to propagate a probing light beam through the vapor cell , a frequency of the probing light beam being tuned across a range in which the atoms transition from a first quantum state to a second quantum state ; and a coupling light source configured to propagate a coupling light beam through the vapor cell , a frequency of the coupling light beam being resonant or of f-resonant with transition of the atoms from the second quantum state to a Rydberg state ; wherein the vapor cell is configured such that on exposure thereof to an RE field carrying information from the RE signal , the apparatus is configured to encode the RE signal into the probing light beam .

[0032] US 12 , 032 , 010 Bl , that relates to a deployable Rydberg RE sensor, discloses an electrometer that includes a housing, a vapor cell , a micro-optical system, an electric field generator, and a control electronic subsystem . The vapor cell has a top and a bottom and includes a vapor of quantum particles . The micro-optical system is configured to route laser fields through the vapor cell in a direction transverse to the top and the bottom . The electric field generator is configured to provide an electric field in the vapor cell . The housing includes a surface adapted to mate to a portion of a fuselage surrounding a hole .

[0033] Object and Summary of the Invention

[0034] Obj ect of the present invention is that of providing a technology such that to alleviate, at least in part , the above technical drawbacks of the classical RF sensors by exploiting in an innovative way di f ferent quantum RF sensors and by overcoming, at the same time , also the limitations of the single quantum RF sensors .

[0035] This and other obj ects are achieved by the present invention in that it relates to a quantum RF system, as defined in the appended claims .

[0036] In particular, the quantum RF system according to the present invention comprises :

[0037] • a wideband quantum RF sensor ;

[0038] • a narrowband tunable quantum RF sensor ;

[0039] • a control unit that is coupled to the wideband quantum RF sensor and to the narrowband tunable quantum RF sensor and is configured to control operation thereof ; and

[0040] • a catalogue for storing data related to known RF signals .

[0041] The control unit is configured to :

[0042] • operate the wideband quantum RF sensor to sense surrounding RF spectrum; • analyze the RF spectrum sensed by the wideband quantum RF sensor and detect RF anomalies by comparing the sensed RF spectrum with the data related to known RF signals stored on the catalogue ;

[0043] • i f a RF anomaly is detected, operate the narrowband tunable quantum RF sensor to characteri ze RF signal around the detected RF anomaly to detect RF threats ;

[0044] • i f a RF threat is detected, monitor / track the detected RF threat by the wideband quantum RF sensor ( 11 ) and / or the narrowband tunable quantum RF sensor ( 12 ) and counteract said detected RF threat and / or noti fy it to a user / operator or to a remote control center / station .

[0045] Preferably, the control unit is configured, i f multiple RF anomalies are detected, to :

[0046] • determine for, and assign to , each detected RF anomaly a respective priority; and

[0047] • operate the narrowband tunable quantum RF sensor to characteri ze RF signal around the detected RF anomalies according to ( i . e . , following) the assigned priorities .

[0048] Conveniently, the control unit is configured to determine , for each detected RF threat , a respective risk associated with said detected RF threat .

[0049] Brief Description of the Drawings

[0050] For a better understanding of the present invention, preferred embodiments , which are intended purely by way of non-limiting, non-binding examples , will now be described with reference to the attached drawings ( all not to scale ) , wherein :

[0051] • Figure 1 schematically illustrates a functional architecture and operating principles of a quantum RF system according to an embodiment of the present invention;

[0052] • Figure 2 shows an example of image produced by a wideband quantum RF sensor of the quantum RF system in Figure 1 ;

[0053] • Figure 3 shows an example of output of a prioriti zation process performed by a control unit of the quantum RF system in Figure 1 ;

[0054] • Figure 4 shows examples of information estimated by a narrowband quantum RF sensor of the quantum RF system in Figure 1 ;

[0055] • Figure 5 schematically illustrates an example of operating logic o f the control unit of the quantum RF system according to an embodiment of the present invention ;

[0056] • Figure 6 schematically illustrates an example of architecture for implementing the quantum RF system according to an embodiment of the present invention .

[0057] Description of Embodiments of the Invention

[0058] The following description is presented to enable a person skilled in the art to comprehend, make and use the invention . Various modi fications to the embodiments will be readily apparent to those skilled in the art , without departing from the scope of the present invention as claimed . Thence , the present invention is not intended to be limited to the embodiments shown and described but is to be accorded the widest scope of protection consistent with the features defined in the appended claims .

[0059] Quantum RF sensors are incredibly promising in solving many of the aforementioned issues of the classical RF sensors , in particular they could enable large-bandwidth applications with one and the same RF sensor . However, several technological platforms have been proposed by the scienti fic community for exploiting the unique features of quantum mechanics and each one has its pros and cons .

[0060] At the present day, it seems that there is no ef fort for studying how these technologies could be integrated in order to reali ze a single quantum RF sensors platform able to overcome all of current limitations . Conversely, given the distinct competencies and skills required for working with each one of these sensors , the scienti fic community seems more focused on working on, and developing each single sensor in order to demonstrate its superiority against the others rather than developing innovative ways with which compensate their issues .

[0061] On the contrary, the present invention concerns an innovative way of integrating existing quantum RF sensors into a single platform by exploiting and handling their respecting pros and cons .

[0062] Nowadays , the following quantum RF sensors are considered the most promising ones for sensing oscillating electric or magnetic fields at RF frequencies :

[0063] • Rydberg Atoms ,

[0064] • NV-centers in diamonds ,

[0065] • Optically Pumped Magnetometers ( OPM) ,

[0066] • Superconductors ( Superconducting Quantum Interference Device - SQUID - arrays ) .

[0067] As previously explained, the main advantage of each of said quantum RF sensors with respect to classical RF sensor technology is the improvement they can give in terms of bandwidth . In particular, the concept of operation bandwidth is related to the capability of operate a sensor at frequencies which can di f fer even by several orders of magnitude (up to hundreds of GHz) ; but even if a device can operate at these large frequency ranges, this doesn't mean that all of these frequencies can be sensed simultaneously by the device: this is the concept of "instantaneous bandwidth". Obviously, an ideal RF sensor would have both a large operating and instantaneous bandwidth.

[0068] One fundamental limitation common to all existing quantum RF sensors is a tradeoff between "operating" and "instantaneous" bandwidth. Crucial for a solution is the possibility to divide quantum RF sensors into two categories:

[0069] • Wideband Quantum RF Sensors (WQRFS) : they have large instantaneous bandwidth (> at least a few GHz) , but a reduced operating bandwidth (not only because of fundamental limitations, but maybe because it is difficult to change the operating conditions in order to adjust the sensor to properly work at a different frequency range) ;

[0070] • Narrowband tunable Quantum RF Sensors (NQRFS) : they have a small instantaneous bandwidth (up to tens of MHz) but could be operated at frequencies very different from each other with little adjustments to the physical parameters of the device (for example from hundreds of MHz to hundreds of GHz) .

[0071] However, this empirical distinction is not "hard" but it can be quite flexible; possibly, the thresholds defining instantaneous and operating frequency ranges will be defined based on the specific application.

[0072] The following table lists the above RF quantum technologies and their pros and cons:

[0073]

[0074]

[0075] The present invention concerns a system that combines multiple quantum RF sensors (wideband and tunable narrowband) in order to better exploit the advantages of each one of them enabling the reali zation of a large tunable operating bandwidth sensor system able to monitor the RF spectrum and to fully characterize (frequency, modulation, amplitude, phase, polarization, Direction of Arrival - DoA) unknown incoming signals, with the final goal of identifying, monitoring and tracking potential and real threats.

[0076] More specifically, the system includes a NQRFS and a WQRFS operated and controlled by a control unit to implement a new sensor system with enhanced performance and capabilities, offering features impossible to achieve with individual quantum RF sensors.

[0077] The two type of quantum RF sensors (i.e., NQRFS and WQRFS) are designed to jointly gather a complete set of information required to monitor the entire RF spectrum and detect threats, with each assuming a specific role:

[0078] • the WQRFS provides continuous, instantaneous images of a broad portion of the RF spectrum, revealing a "low-quality" spectrum status; it is characterized by limited frequency and amplitude resolutions, offering only a few parameters for each signal component in the spectrum; while this sensor can be locally tuned and optimized, its main limitations remain; for the overall system, this sensor provides the control unit with a rough spectrum status, serving as the primary input for further analysis by the other NQRFS;

[0079] • the NQRFS delivers high-speed, detailed analysis and information on a tunable, limited portion of the spectrum, primarily focusing on a single signal component; it identifies a greater number of characteristics, such as amplitude, phase, polarization, signal demodulation, Direction of Arrival (DoA) , and modulation type; driven by the control unit, this sensor performs a detailed inspection of identified suspicious signals, filling in the information gaps of the WQRFS. The control unit implements the logic of the system, collecting feedbacks from the two sensors, and instructing them on how to proceed with the goal of producing an accurate panorama of the whole RF spectrum, identifying suspicious signals and analyzing them in order to determine the actual risks they convey. It is also in charge of activating notifications and actions to counteract possible identified threats .

[0080] More specifically, the control unit continuously collects RF spectrum pictures proposed by the WQRFS, analyzes them to identify their compliance with that expected (coming from a catalogue) and proposes an evaluation for each of the signal components identified. Once identified, it proposes priorities for each signal proportional to the suspiciousness and risk associated with each signal component. This is then used to control the NQRFS, being tuned and guided to perform specific analysis on the signal, trying to analyze those components of the signal needed to confirm or complement the threat analysis.

[0081] Figure 1 schematically illustrates a functional architecture and operating principles of a quantum RF system (denoted as a whole by 1) according to a preferred embodiment of the present invention.

[0082] In particular, as shown in Figure 1, the quantum RF system 1 includes a Wideband Quantum RF Sensor (WQRFS) 11, a Narrowband Quantum RF Sensor (NQRFS) 12, a control unit 13 (conveniently implemented by means of a processing unit - i.e., a processor) and a catalogue of RF spectrum allocation 14 (conveniently implemented by means of a database - DB) . The control unit 13 is designed to control operation of the WQRFS 11 which, in use, is operated to receive incoming unknown RF signal s with a wideband ( e . g . , a few GHz ) and to carry out a rough analysis of the RF spectrum by measuring involved RF frequencies (block 15 shown in Figure 1 ) . Based on this analysis and by comparing the RF scenario measured by the WQRFS 11 with those stored on the catalogue of RF spectrum allocation 14 , the control unit 13 operates the NQRFS 12 to perform a f ine analysi s of the RF spectrum with full characteri zation of the incoming signals and classi fication of the potential threats (block 16 shown in Figure 1 ) . The quantum RF system 1 can be conveniently installed on board a space platform, such as a spacecraft or a satellite . Anyway, it is worth noting that the quantum RF system 1 can be advantageously installed also on board an aircraft or drone or on board a terrestrial vehicle or naval unit , as well as at a fixed ground station / center , such as an airport or a military base .

[0083] The technical advantages of the quantum RF system 1 overcome the main limitations previously described for the single quantum RF sensors , enabling novel kind of applications otherwise unachievable . Indeed, the quantum RF system 1 is capable of achieving :

[0084] • extremely wide instantaneous spectrum monitoring, tracking changes and triggering feedback upon spectrum changes , providing a rough set of guiding information ;

[0085] • capability of performing detailed analysis , inspection and monitoring of any unexpected or suspicious signals covering any section of the RF spectrum;

[0086] • capability of data fusion and integration to generate detailed spectrum health and threat identi fication, tracking and monitoring .

[0087] Indeed, none of the available RF sensors in literature would be capable of providing all the information required to perform a full spectrum detailed analysis of threats.

[0088] As previously described, the quantum RF system 1 is a control-based system, relying on a local catalogue 14 containing information related to the RF spectrum allocation and conveniently also security relevant information, which manages two types of quantum RF sensors (i.e., the WQRFS 11 and the NQRFS 12) to monitor the whole RF spectrum, identifying possible threats and proposing actions to react.

[0089] The following are high-level operating steps conveniently performed, in use, by the quantum RF system 1:

[0090] 1) the WQRFS 11 (e.g., OPM or NV-centers in diamonds) produces instant "pictures" of the spectrum intensity in a wide (tunable) range; in this connection, Figure 2 shows an example of image produced by the WQRFS 11, where on x-axis a very wide range of frequencies is represented, and received signal amplitudes are shown on y-axis;

[0091] 2) the control unit 13 measures the frequency components based on the measured spectrum;

[0092] 3) the control unit 13, that controls both the WQRFS 11 and NQRFS 12, can exploit the information coming from the WQRFS 11 to classify the spectrum tones;

[0093] 4) additional information are available to the control unit 13 from the catalogue 14 to identify and extrapolate only suspicious components of the incoming signal and propose prioritization of the most critical signals to monitor anomalies; this could include a number of factors, related to the criticality of the specific frequency under analysis and to the probability and magnitude of the anomalies identified on the received spectrum; in this connection, Figure 3 shows an example of output of the prioritization process performed by the control unit 13;

[0094] 5) the control unit 13, selected the next signal tone to analyze based on the above priorities, proceeds optimizing and tuning the mechanisms to drive the NQRFS 12 (e.g., Rydberg Atoms or SQUID arrays) , setting the proper laser lambda to trigger the reception on the proper RF frequency band, and to enable the kind of analysis needed, depending on the anomaly identified in the suspicious tone;

[0095] 6) the properly tuned NQRFS 12 can fully characterize the signal (amplitude, polarization, DoA, modulation, phase) by selectively analyzing each component one at time; in this connection, Figure 4 shows examples of information estimated by the NQRFS 12;

[0096] 7) these sets of information evaluated using the NQRFS 12 can then be merged with data fusion techniques to produce an accurate RF spectrum health status, incorporating the wide picture view coming from the WQRFS 11, with the additional information of detail coming from the NQRFS 12;

[0097] 8) the control unit 13 collects all those information items, performs a risk analysis, taking into consideration all the information available and takes a decision on the analyzed tones, by updating the overall status, and refining the step 4 related to prioritization;

[0098] 9) evaluation of possible threats is performed with the available data, further classifying the incoming signals and proposing notification to ground or triggering automatic reaction to face the identified threats.

[0099] Figure 5 schematically illustrates, in greater detail, an example of operating logic of the control unit 13 according to a preferred embodiment of the present invention.

[0100] In particular, as shown in Figure 5: • the control unit 13 sets a gradient of the magnetic field of the WQRFS 11 - block 501 ;

[0101] • the WQRFS 11 starts scanning the surrounding electromagnetic scenario - block 502 ;

[0102] • the control unit 13 analyzes the RF spectrum sensed by the WQRFS 11 - block 503 ;

[0103] • the control unit 13 performs a preliminary anomaly detection by comparing the RF spectrum sensed by the WQRFS 11 with known RF signals stored on the catalogue 14 - block 504 ;

[0104] • i f anomalies are detected - block 505 , the control unit 13

[0105] - tunes operating parameters of the WQRFS 11 to optimi ze its sensitivity to anomalies - block 506 ,

[0106] - sets wavelengths of the laser of the NQRFS 12 - block 507 - thereby achieving accurate signal characteri zation based on the known RF signals stored on the catalogue 14 - block 508 , and

[0107] - performs risk estimation based on security requirements and other sensors ' data stored on the catalogue 14 - block 509 ;

[0108] • instead, i f no anomaly is detected - block 505 , the control unit 13 analyzes again the RF spectrum sensed by the WQRFS 11 - block 503 ;

[0109] • as for the risk estimation performed by the control unit 13 - block 509 , the latter detects whether potential threats are present or not - block 510 ;

[0110] • i f potential threats are present , the control unit 13

[0111] - classi fies a respective risk associated with each detected potential threat - block 511 ,

[0112] - triggers an autonomous reaction from the space / satellite platform - block 512 - and / or

[0113] - sends the information to ground - block 513 ;

[0114] • instead, i f no potential threat is present - block 510 , the control unit 13 analyzes again the RF spectrum sensed by the WQRFS 11 - block 503 .

[0115] In this way, the quantum RF system 1 implements a full monitoring of the whole RF spectrum and is capable of dynamically identi fying and monitoring suspicious threats , triggering automatic reactions and noti fying potential threats when identi fied .

[0116] Given the existence of several technological platforms for both the WQRFS 11 and the NQRFS 12 , there are many ways of implementing the quantum RF system 1 . Preferably, the WQRFS 11 is implemented based on NV-centers in diamonds technology while the NQRFS 12 is implemented based on Rydberg atoms technology given the room-temperature operation and the low complexity of the setup . Anyway, other choices are not excluded and can be adapted based on speci fic application' s requirements .

[0117] Figure 6 schematically illustrates an example of architecture for implementing the quantum RF system 1 according to a preferred embodiment of the present invention .

[0118] In particular, as shown in Figure 6 , the quantum RF system 1 includes hardware modules 610 that , in turn, comprise :

[0119] • the WQRFS 11 and the NQRFS 12 ( i . e . , quantum hardware 611 ) ;

[0120] • the processing unit 13 preferably including a Central Processing Unit ( CPU) 612 , a Graphics Processing Unit ( GPU) 613 and a Field Programmable Gate Array ( FPGA) 614 ;

[0121] • a high-speed link gateway 615 ; • a clock unit 616 ;

[0122] • a test and calibration unit 617 ; and

[0123] • a power supply unit 618 .

[0124] Additionally, the quantum RF system 1 includes also a software stack 620 that , in turn, comprises the following software layers / modules :

[0125] • data processing 621 ;

[0126] • test and calibration 622 ;

[0127] • control and decision making 623 ;

[0128] • user interface 624 ;

[0129] • data acquisition 625 ;

[0130] • synchroni zation 626 .

[0131] As for the quantum RF sensors , as previously explained,

[0132] • the NQRFS 12 is focused on a speci fic, adj ustable frequency range for high sensitivity and precision on target frequencies , while

[0133] • the WQRFS 11 captures a broad frequency spectrum and is ideal for scanning a wide range of signals and quickly identi fying potential areas of interest .

[0134] It is worth noting that the quantum RF system 1 might also include more than one NQRFS and more than one WQRFS .

[0135] The processing unit 13 acts as a central manager, handling data flow, synchroni zing the quantum RF sensors , handling signal processing, and applying algorithms to detect , analyze , and respond to signals . The processing unit 13 applies a filter or an algorithm to analyze the wideband data, identi fying frequency bands of interest . When a potential signal of interest is detected in the wideband data, the processing unit 13 sends a command to the narrowband sensor 12 to fine-tune its frequency range to the target signal , allowing for more detailed analysis . For systems requiring high-speed parallel processing, an FPGA or GPU can of fload intensive computations from the processing unit 13 .

[0136] The high-speed link gateway 615 serves as data interface and for communications ; in fact , a high-speed data bus or optical link for low-latency communication between the quantum RF sensors and the processing unit 13 is conveniently provided .

[0137] The clock unit 616 is designed for synchroni zation between the WQRFS 11 and the NQRFS 12 since the latter is critical , as the processing unit 13 must ensure that the two quantum RF sensors are accurately aligned in both time and frequency . This can be achieved by implementing a real-time clock or time-stamping system within the processor .

[0138] As for the software layer for data processing 621 :

[0139] • algorithms such as Fast Fourier Trans forms ( FFT ) for initial signal detection, machine learning models for signal classi fication, and adaptive filters to reduce noise ;

[0140] • adaptive algorithms within the processor can enhance the dynamic frequency allocation and adaptation feature of the system, adj usting in real-time based on interference , signal strength, and environmental conditions ;

[0141] • data fusion techniques to combine information from many sensors , yielding a richer understanding of the signal environment and providing comprehensive situational awareness (based on fused data, the processing unit 13 might trigger automated responses , like logging speci fic signal patterns , activating recording features , or alerting operators ) .

[0142] As for software for system control & user interface : a User Interface (UI ) on top of the processor allows operators to monitor real-time data, configure sensor parameters , and manually control the narrowband sensor i f necessary; the UI can also display processed results , such as spectral graphs , identi fied signal types , and any patterns detected by the machine learning model

[0143] Supporting hardware :

[0144] • interference shielding ( optional ) ,

[0145] • testing and calibration .

[0146] The innovative features and technical advantages of the present invention are immediately clear from the foregoing .

[0147] The present invention can be advantageously exploited for Earth observation, navigation, telecommunications , RE ref lectometry, RE spectrum monitoring, space surveillance , radiometer calibration missions . In conclusion, it is clear that numerous modi fications and variants can be made to the present invention, all falling within the scope of the invention, as defined in the appended claims .

Claims

CLAIMS1. Quantum radiofrequency system (1) comprising:• a wideband quantum radiofrequency sensor (11) ;• a narrowband tunable quantum radiofrequency sensor (12) ;• a control unit (13) that is coupled to the wideband quantum radiofrequency sensor (11) and to the narrowband tunable quantum radiofrequency sensor (12) and is configured to control operation thereof; and• a catalogue (14) for storing data related to known radiofrequency signals; wherein the control unit (13) is configured to:• operate the wideband quantum radiofrequency sensor (11) to sense surrounding radiofrequency spectrum;• analyze the radiofrequency spectrum sensed by the wideband quantum radiofrequency sensor (11) and detect radiofrequency anomalies by comparing the sensed radiofrequency spectrum with the data related to known radiofrequency signals stored on the catalogue (14) ;• if a radiofrequency anomaly is detected, operate the narrowband tunable quantum radiofrequency sensor (12) to characterize radiofrequency signal around the detected radiofrequency anomaly to detect radiofrequency threats;• if a radiofrequency threat is detected, monitor / track the detected radiofrequency threat by the wideband quantum radiofrequency sensor (11) and / or the narrowband tunable quantum radiofrequency sensor (12) and counteract said detected radiofrequency threat and / or notify it to a user / operator or to a remote control center / station .

2. The quantum radiofrequency system of claim 1, the control unit (13) is configured, if multiple radiofrequencyanomalies are detected, to:• determine for, and assign to, each detected radiofrequency anomaly a respective priority; and• operate the narrowband tunable quantum radiofrequency sensor (12) to characterize radiofrequency signal around the detected radiofrequency anomalies according to the assigned priorities .

3. The quantum radiofrequency system according to claim 1 or 2, the control unit (13) is configured to determine, for each detected radiofrequency threat, a respective risk associated with said detected radiofrequency threat.

4. The quantum radiofrequency system according to any claim 1-3, wherein the narrowband tunable quantum radiofrequency sensor (12) is operable to characterize radiofrequency signals in terms of amplitude, polarization, direction of arrival, modulation and phase.

5. The quantum radiofrequency system according to any preceding claim, wherein the wideband quantum radiofrequency sensor (11) is based on NV-centers in diamonds technology and the narrowband tunable quantum radiofrequency sensor (12) is based on Rydberg atoms technology.

6. The quantum radiofrequency system according to any preceding claim, wherein the wideband quantum radiofrequency sensor (11) and the narrowband tunable quantum radiofrequency sensor (12) are designed to be synchronized in time and in frequency.

7. The quantum radiofrequency system of claim 6, wherein the wideband quantum radiofrequency sensor (11) and the narrowband tunable quantum radiofrequency sensor (12) are coupled to a clock unit (616) thereby being synchronized in time and in frequency.8 . Space platform equipped with the quantum radiofrequency system as claimed in any claim 1-7 .

9. The space platform of claim 8 , wherein said space platform is a spacecraft or a satellite .10 . Air platform equipped with the quantum radiofrequency system as claimed in any claim 1-7 .11 . The air platform of claim 10 , wherein said air platform is an aircraft or a drone .12 . Terrestrial vehicle equipped with the quantum radiofrequency system as claimed in any claim 1-7 .

13. Naval unit equipped with the quantum radiofrequency system as claimed in any claim 1-7 .14 . Ground station / center equipped with the quantum radiofrequency system as claimed in any claim 1-7 .15 . Computer program product comprising software and / or firmware code portions that are loadable on processing means that are coupled to a wideband quantum radiofrequency sensor ( 11 ) and to a narrowband tunable quantum radiofrequency sensor ( 12 ) , such that said processing means become configured as the control unit ( 13 ) of the quantum radiofrequency system as claimed in any claim 1-7 .

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