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Quantum technology (QT) applies quantum mechanical properties such as quantum entanglement, quantum superposition, and No-cloning theorem to quantum systems such as atoms, ions, electrons, photons, or molecules.
Quantum bit is the basic unit of quantum information. Whereas in a classical system, a bit is either in one state or the another. However, quantum qubits can exist in large number of states simultaneously, property called Superposition.
Quantum entanglement is a phenomenon where entangled particles can stay connected in the sense that the actions performed on one of the particles affects the other no matter what’s the distance between them. No-cloning theorem tells us that quantum information (qubit) cannot be copied.
Quantum technology has many Quantum applications that can be classified in three major classes: Quantum computers shall bring power of massive parallel processing, equivalent of supercomputer to a single chip. They can consider different possible solutions to a problem simultaneously, quickly converge on the correct solution without check each possibility individually. This dramatically speed up certain calculations, such as number factoring.
Quantum communication refers to a quantum information exchange that uses photons as quantum information carriers over optical fibre or free-space channels. Today, quantum data transfer rates remain quite low, and so communicating entire messages is not yet practical. Instead, Quantum Cryptography or Quantum key distribution (QKD) is being used that employs single or entangled photons to generate shared secret key between the parties that is perfectly secure. The security is guaranteed by Heisenberg’s uncertainty principle. This ensures that any attempts to intercept and measure quantum transmissions, will introduce an anomalously high error rate in the transmissions and therefore will be detectable
Communication using QKD can be delivered through fiber-optic networks, over the air, and drones to satellites. Current limitations of QKD are high cost of dedicated hardware, limited transmission speed and distance, and the need for repeaters. Currently Most Quantum Communication links are direct point-to-point links through telecom optical fibers and, limited to about 300-600 kms due to losses in the fiber.
Quantum Sensing exploit high sensitivity of quantum systems to external disturbances to develop highly sensitive sensors. They can measure Quantities such as time, magnetic and electrical fields, inertial forces, temperature, and many others. They employ quantum systems such as NV centers, atomic vapors, Rydberg atoms, and trapped ions.
Current atomic clocks based on Cesium or Rubidium loses just a second in 100 million years. These next generation Quantum clocks based on single atoms will lose only a second in a billion years.
Quantum Gravimeters can measure gravity with greater sensitivity and reliability while more robust against external noise sources.
Quantum navigation could be far more accurate than using current accelerometers and gyroscopes and will provide backup to GPS, if GPS fails or navigation in places where GPS is not available.
Quantum imaging exploits quantum entanglement of the electromagnetic field to image objects with a high resolution under low light levels, or in the presence of strong background illumination. It has applications in 3D cameras, behind the corner cameras, quantum radar and lidar.
Quantum Geopolitics
The world’s leading economies are betting big on quantum to tackle myriad issues, from addressing climate change to eradicating hunger and disease and fending off cyber threats. Global Quantum computing market is projected to grow more than $14 billion in 2025. Quantum cryptography will be worth $25 billion, and Quantum Sensors Market is expected to reach more than USD 700 million.
Quantum is dual use technology, it present both a risk as well as opportunity, has both commercial as well as military applications. Quantum technologies will revolutionize warfare by introducing new capabilities such as quantum computers, quantum radar, and quantum key distribution, increase effectiveness of the current technologies such as quantum optimization, quantum machine learning, quantum cryptoanalysis, sensing capabilities and accuracy of position, navigation, and timing services.
The economic and military advantages are driving intense Quantum race among countries, led by China, United States, Europe, Canada, and Australia
According to a McKinsey report, publicly announced investments into quantum technology companies in 2021 amounted to $1.7 billion, which represents approximately 20 times the amount raised by the sector five years prior and more than a twofold increase on 2020. Various other reports observe a higher number of quantum startups entering the ecosystem as well as increased government funding of research and development. The U.S., China, Canada, Great Britain and Germany have established themselves as global leaders in venture funding, and the Indian government launched the National Mission on Quantum Technologies and Applications, providing more than $1 billion for the establishment of several institutes dedicated to quantum computing, communications and cryptography.
Quantum Technologies will be driver of New Space revolution
Global space activity has intensified and diversified considerably over the past decade. While only 110 spacecraft were launched on average per year between 2000 and 2013, recent years have seen a paradigm shift, especially with the launch of new satellite “mega-constellation” projects. A new record was set in 2020, with 266 spacecraft launched into outer space. As a direct result of this surge, the number of operating satellites has doubled in less than a decade.
Quantum and space domains have both become strategically important technology sectors for major powers around the world, including for European countries and the European Union (EU). Using QT in the space environment is a very specific use of the technology but one that is being explored more and more, as evidenced by several recent satellite demonstration missions carrying quantum cryptography payloads.
Space applications of QT are a fast-growing domain, with patent filings increasing by more than 400% over the last five years. According to the quantum technologies and space report prepared by the EPO and the European Space Policy Institute (ESPI) in collaboration with the European Space Agency (ESA), quantum key distribution is currently the leading application in space-related quantum technologies. This growth is driven primarily by innovation in quantum key distribution, which accounted for the majority of the analysed dataset (78%). At the same time, space applications of QT remain a niche segment, representing only a fraction of the overall QT domain. Most space-related QT innovations originate outside Europe, with the US and China leading the global patent filings. The majority of patent filings in quantum key distribution, cold atom clocks and cold atom interferometers are not from the same key players, pointing to a high level of specialisation and limited synergies.
in the U.S., the ISS National Laboratory is conducting research in space to determine the viability of potential applications. These include “communication solutions (time keeping for banking, GPS), coded satellite-based transmissions (‘quantum cryptography’), and very sensitive sensors for faster computers and improved communications, navigation, and healthcare.”
Quantum Computers in Space
Cold: Quantum computers function at their best at temperatures nearing absolute zero. That kind of cold is difficult and extremely expensive to produce on Earth, even in frigid polar regions. But outside Earth’s atmosphere, extremely cold temperatures can be achieved by simply providing shade. Instruments on the James Webb Space Telescope can deliver incredible infrared pictures of deep space because of extreme cold. The instruments on Webb were cooled to 447 degrees below zero, a condition that’s cost prohibitive to attain on Earth but can be reached with relative ease in space.
Controlled environment: To reach correct answers, quantum computing needs its subatomic parts to function in an interference-free vacuum. That’s another piece that is difficult and expensive to attain on Earth but comparatively simple and cheap in space.
Quantum communications in Space
Primary uses of QT in space are in secure communications, in time and frequency transfer, and in Earth sensing and observation. Three key QT that enable these main applications:
— quantum key distribution:
— cold atom clocks
— cold atom interferometers
The quantum secure systems developed so far provide secure communication on ground. The extension to space and air will be the necessary complement to reach different networks of distant nodes. Satellite-based quantum communication will provide a means for reaching global distances and secure space assets. The technology of terrestrial components (ground stations and management centres) and space components (satellite or satellite networks) need to be adapted to different use-cases.
The relevance of space applications of QT has been investigated and demonstrated in recent years with the success
of several dedicated satellite missions carrying QT payloads, such as China’s Micius satellite in 2016 or the SpooQy-mission by the National University of Singapore in 2019. Numerous other satellite projects exploring the potential of space-based QT for distributing keys in the field of cryptography are under development, e.g. at the ESA (SAGA, Quartz or QKDSAT as a partnership project with Arqit) and in the UK (ROKS), Germany (QUBE) or Canada (QEYSSAT).
In secure communications, space-based quantum key distribution and related technologies (e.g. entangled photon sources, single-photon detectors, quantum random number generators) will play a major role as fibre-based quantum key distribution has major signal and security limitations which currently prevent long-distance key distribution for encrypting communication links.
The deployment on ground of receiver of keys to be used in pan-European as well as national secure communications will be the most immediate results of such Space QKD system. The development of compact receivers, suitable for the roof of a normal building, would allow the demonstration of QKD to all Member States regardless of their geographical location, much before the development of a continental repeater network based on fibers.
Quantum Sensors in Space
Two further key space-related quantum technologies, namely cold atom clocks and cold atom interferometers. New-generation cold atom clocks allow for improved positioning, navigation and timing applications, while cold atom interferometers can be used in Earth sensing and observation technologies.
In Earth sensing and observation, R&D of space-based QT sensors is targeting multiple applications. Current priorities seem to be cold atom interferometry for gravimetry and geodesy purposes. Other research avenues
include quantum-enhanced radiofrequency or optical signal processing for monitoring spectrum utilisation, or space-borne quantum radars for various risk-detection and early-warning purposes.
Gravity field mapping from space provides crucial information for the understanding climate change, hydro- and biosphere evolution, and tectonics and earthquake prediction. The recent advent of macroscopic quantum matter such as Bose-Einstein condensates and the associated Nobel-prize winning protocols, have led to inertial quantum sensors based on atom interferometry. Quantum gravity sensors use coherent quantum matter waves as test masses, which leads to far more sensitive and precise instruments. Space based quantum sensors will enable better monitoring of the earth’s resources and improve the predictions of earth-quakes and the adverse effects of climate changes like the draughts and floods
Time standards and frequency transfer are fundamental for many modern day applications with high societal value. Fundamental TFT techniques are well established today enabling services in the fields of communication, metrology and GNSS. With the availability of optical atomic clocks and optical frequency transfer, QT allows to boost the TFT performance by several orders of magnitude. This new performance permits to keep pace
with the development of needs in communications (timekeeping) and GNSS (geolocation), and enables new applications (geodesy, gravitational wave observation, synthetic aperture optical astronomy). A space component is
relevant to the enhanced applications by enabling long range transfer, enhanced security and global availability.
Fundamentally TFT is based on two technological elements: precision time standards (clocks) and the ability to transfer frequency (more precisely the phase of the clock) over a large distance with high precision. State of the art
commercial atomic clocks operate at radio frequencies (several GHz) and achieve accuracies down to 10-15. Current time standards are defined on improved clocks of the same type with accuracies of 10-16. The limitation of
these clocks is given by the fundamental frequency of operation (GHz) and the ability to measure these. Phase (and frequency) transfers are standard methods in high frequency RF communications and have been demonstrated
on satellite links with a performance of 10-15 – with the same fundamental limitations imposed by the frequency used for the transfer. These technologies are about to be demonstrated at increased accuracy in space in
ESA’s ISS based ACES project, which contains both frequency standards and transfer capabilities to ground.
The fundamental improvement enabled by QT is given by an increase in fundamental frequency from the radio frequency domain into the optical domain by a factor of 105. This step is possible based on the evolution of laser
technology (stable optical oscillators and frequency combs) and optical clock development (quantum state control). Optical clocks have been demonstrated in laboratory environment to have a fractional uncertainty of less 10-18 with further improvements expected (optical lattice clock and single ion clock). Frequency transfers have been demonstrated on a ground-based optical fiber link with a length of 920km at an accuracy of better than 4×10-19.
ESA has studied the implementation of a sequel mission to ACES based on an optical atomic clock and optical links concept (ISS Space Optical Clock – ISOC) with a possible implementation until the early 2020s. These experiments
clearly show the superior performance of the QT based optical TFT which have an improved the performance at this early stage of development already by three orders of magnitude.
Making use of the technological advancement will allow improving the quality of existing applications or allowing building more efficient system architectures. Time dissemination services and metrology will have a direct
improvement of three orders of magnitude. High precision clocks in space will provide a secure (i.e. hard to jam) and independent time base for global time keeping. Combined with space-space and space-ground optical links they will allow global TFT. Such space-based time standard and time distribution system will provide an efficient globally available infrastructure (compared to fiber networks which are only available in densely populated areas) for all of the above applications. For GNS Systems, the system architecture is suggested to be improved with a more efficient implementation then possible and a higher accuracy for specific use cases.
With the accuracy of optical clocks and the capability to compare these at large distances, new applications now become feasible. As the relative gravitational red shift is 10-18 per cm of geopotential height, clocks and optical
transfers can be used to measure the geopotential difference of two locations. If one location is e.g. in orbit the absolute geopotential on earth’s surface can be characterized (geodesy application). Similar to this application
gravitational waves can be detected by comparing two optical clocks on two distant satellites. This concept augments the ESA/NASA LISA system in the fact that it has very high sensitivity to gravitational waves at low frequency –complementary to LISA. Finally, in analogy the radio frequency synthetic aperture observation concept, an optical synthetic aperture telescope can be envisaged by the fact that a set of fully synchronized optical clocks enables a phase measurement of the impinging light wave at several locations with large separation. This allows synthesizing by analysis a telescope with an aperture size comparable to the separation of the locations (potentially 1000s of kms) leading to the capability of direct observation of planets
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