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 technologies are already revolutionizing life on Earth. But they also have the potential to change the way we operate in space.
Quantum Sensing exploits the high sensitivity of quantum systems to external disturbances to develop highly sensitive sensors. Quantum sensors are measuring device that takes advantage of quantum correlations, such as states in a quantum superposition or entanglement, for better sensitivity and resolution than can be obtained by classical systems. These sensors offer a particularly high level of sensitivity based on certain delicate quantum phenomena, such as quantum decoherence and quantum entanglement.
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.
Quantum sensors include atomic clocks, single-photon detectors, PAR sensors, quantum LiDAR and quantum radar, gravity sensors, atomic interferometers, magnetometers, quantum imaging devices, spin-qubit-based sensors, and quantum rotation sensors, among others. Quantum sensing covers motion – including acceleration, rotation and gravity – electric and magnetic fields, and imaging.
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.
The benefits to quantum sensing include: Measuring electric and magnetic fields very accurately across many frequencies; Measuring physical quantities against atomic properties, so there is no drift or need to calibrate; Using quantum entanglement to improve sensitivity or precision.
Space-based Quantum sensors
Given the extreme effects of global warming that mankind is facing, earth observation is maybe the most important scientific endeavour of our times. Already today, the study of global mass transport phenomena via satellite gravimetry provides important insights for the evolution of our planet and climate change, by improving our understanding of the distribution of water and its changes.
The changes of Earth’s gravity scarred by earthquakes gives valuable data for predicting future earthquakes. Its data is also being used to improve models of Earth’s geology, indicating the potential locations of subsurface energy sources. Just like gravitational waves herald a new age in astronomy, mapping the earth’s gravitational field proves an immensely valuable tool in understanding earth. ESA and NASA are working on future versions of their gravity missions, which will have much improved resolution and sensitivity.
However, it has become clear that the classical measurements cannot be pushed much further. Classical accelerometers used so far in gravity missions exhibit increased noise at low frequency and have large long-term drifts. This severely limits the ability of faithfully reconstructing the earth gravity field at low degrees and precisely modelling its temporal fluctuations. The NASA future geodesy mission, Mass Change (MC) mission, is under preparation for launch by 2026.
Quantum mapping of the Earth’ mass dynamics
Today, the study of global mass transport phenomena via satellite gravimetry provides important insights for the evolution of our planet and the climatic change. Atom interferometry will play an instrumental role to improve satellite-based measurements for space-geodesy. Classical electrostatic accelerometers used so far in gravity missions exhibit increased noise at low frequency and long-term drifts pose severe limits. This is particularly true for the ability to faithfully reconstruct the earth gravity field at low degrees and even more for precisely models of its temporal fluctuations.
Take for example, atom interferometry with quantum sensors. These devices can measure with unprecedented accuracy any change in motion of a satellite in orbit as it is buffeted by tiny variations in the Earth’s gravitational field. These changes are caused by factors such as the movement of cooler, higher density water flows in the deep ocean, flooding, by the movement of the continents and by ice flows.
That’s why these kinds of quantum sensors will pave the way for a new era of Earth observation. These studies will reveal hard-to-observe effects of climate change on deep ocean currents, how stresses are building in continents as they move and will help us better understand Earth’s geology. “Space-based quantum sensors will enable better monitoring of the Earth’s resources and improve the predictions of Earthquakes and the adverse effects of climate change, like droughts and floods,” says Rainer Kaltenbaek at the Institute for Quantum Optics and Quantum Information, in Austria, and colleagues throughout Europe.
Europe’s pioneering of space quantum sensing
Atom-interferometric quantum sensors offer far superior long-term stability and higher sensitivity. For this reason, quantum sensors are already officially considered by ESA as a potential instrument, or a demonstrator. ESA future geodesy mission classified as Mission of Opportunity, Next Generation Gravity Mission, will include laser ranging but consider quantum sensors as a candidate for the following mission if the technology is ready at that time
Since 2000, missions exploiting Inertial quantum sensors (IQS were proposed to ESA. In 2010, an ESA road map highlighted space-borne IQS for fundamental physics in space, such as gravitational wave detection. IQS were selected for studies by ESA for satellite gravimetry (CAI), the Lense-Thirring effect (HYPER), as transportable devices (SAI) and, most recently, was among the three selected candidate missions for a quantum test of the equivalence principle (STE-QUEST). Concerns of technological immaturity prevented selection and motivated support for some critical payload sub-components.
Since the first decade of this century, national agencies supported space-borne quantum-sensor development. Important milestone were achieved by ICE (France) on parabolic flight studies for dual-species interferometry, by QUANTUS/MAIUS (Germany) establishing interferometry with Bose-Einstein condensates in space based on drop-tower and sounding-rocket experiments, and by CAL (USA), where US teams including German scientists explore physics with Bose-Einstein condensates in orbit. Benefiting from the space activities, novel terrestrial sensors and commercial spin-offs were created and will continue to emerge as industry starts to engage in the development of cold atom payloads.
Interferometry of atomic matter waves has been demonstrated for the first time in orbit in April 2021
A recent upgrade to NASA’s Cold Atom Lab has enabled atom interferometry on the International Space Station (ISS), forming the basis of a new generation of exquisitely precise quantum sensors that scientists can use to explore the universe. Applications of these spaceborne quantum sensors include tests of general relativity, searches for dark energy and gravitational waves, spacecraft navigation and drag referencing, and gravity science, including planetary geodesy—the study of a planet’s shape, orientation, and gravity field.
The wave-particle duality of matter is a cornerstone of quantum mechanics. First hypothesized by Louis De Broglie in 1924, it postulates that every particle or quantum object can be described as either a particle or a wave, depending on how we measure the properties of the object.
A natural consequence of the wave-like nature of quantum matter is that it can simultaneously exist in more than one place. When experimentalists measure the particle location, the simultaneous paths taken by the particle “collapse” to a single traceable trajectory. Quantum interferometry starts with particles in the same lowest energy state and then puts some of them in the first excited state and measures the phase difference between these two groups after they traverse a region of interest. Matter-wave interferometers have been experimentally demonstrated on Earth with numerous types of particles, including electrons, neutrons, atoms, antimatter, and even biomolecules.
View of the atom interferometry-capable Science Module inside two layers of magnetic shields during the pre-launch build/testing phase at JPL.
Over the last few decades, technology advancements have enabled cooling of atoms to temperatures below 1 microKelvin to form a fifth (purely quantum) state of matter called a Bose-Einstein condensate (BEC), making ultracold atom interferometers using this unique matter a leading candidate for future precision sensing of inertial forces. Analogous to high-precision optical interferometers (such as the Laser Interferometer Gravitational-Wave Observatory [LIGO], which recently detected gravitational waves using highly stable optical waves), atom interferometers with BECs utilize extremely pure, low-velocity quantum gases to achieve high-precision, phase-sensitive measurements of fundamental forces including gravity. They also promise to deliver unprecedented acceleration and rotation sensitivity for inertial navigation. In fact, such atom interferometers are shown to be sensitive enough to detect variations in a gravitational field, and thus could be used to map the interior density of planets.
Achieving atom interferometry in space had been a long-sought goal of NASA and the fundamental physics community. “The promise of very low temperature gases and effectively limitless free-fall time for space-based atom interferometry is expected to open a new regime of precision for inertial force and rotation measurements that could revolutionize both contemporary gravity science and spacecraft navigation capabilities in the near future,” said Dr. Jason Williams, a Principal Investigator for atom interferometry studies onboard ISS.
In May 2020, atom interferometry with an ultracold BEC of rubidium atoms was demonstrated for the first time on an orbiting platform. This experiment was realized by NASA’s multi-user Cold Atom Lab (CAL), which has been operating onboard the ISS since 2018. In January 2020, CAL received a Science Module capable of atom interferometry as part of an on-orbit upgrade. For the May 2020 demonstration, a laser pulse acted as the beam splitter for an atomic wave packet. Subsequent laser pulses then recombined the atoms and mixed them to produce an interference pattern which was read out by taking pictures of atoms occupying the spatially separated outputs. This demonstration of matter-wave interferometry in space heralds a future in which space-based quantum sensors become a widely used tool for scientific exploration of the universe. Applications of the new technology include tests of general relativity, searches for dark energy and gravitational waves, spacecraft navigation, and prospecting for subsurface minerals on the moon and other planetary bodies.
The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). Images courtesy of NASA/JPL-Caltech. Designed and built at JPL, Cold Atom Lab is sponsored by the Biological and Physical Sciences (BPS) Division of NASA’s Science Mission Directorate at the Agency’s headquarters in Washington DC and the International Space Station Program at NASA’s Johnson Space Center in Houston, Texas.
Space-based quantum clocks
Better quantum clocks are also set to become influential. The key technology here is not so much the ability to keep time but the ability to transfer this information to another location with high precision. This ability will lead to networks of space-based clocks that are synchronized more precisely than anything available today. Time-keeping networks are already considered foundational—global navigation satellites systems, such as GPS are good examples. And better timekeeping will allow more accurate geolocation services.
But this is just the beginning. One important application will be to create synthetic aperture telescopes for visible light. The idea here is to record the arrival time of light waves at two different locations and then to compute an image of their source, such as a distant star. The resolution of this technique matches the resolution of a conventional telescope with an aperture equal to the distance between these points, which can be thousands of kilometers apart — hence the term synthetic aperture. This has long been possible with longer wavelength radiation such as radio waves. Indeed, the first images of a supermassive black hole were made in 2019 using this technique for radio waves. But visible light has a wavelength measured in nanometers rather than meters. That requires much more precise timing measurements to record their arrival, something that the next generation of space-based quantum time-keeping devices should enable.
These kinds of synthetic aperture telescopes will be vastly more sensitive than anything we can build today, potentially allowing astronomers to study planets around other stars in huge detail. Space-based gravitational wave observatories should also benefit, allowing them to pick up fainter signals from colliding neurons stars and their ilk.
University of Sussex has developed a monitoring and control system blueprint for quantum devices and experiments, reported in Feb 2022
The system is presented in a peer reviewed paper published in Quantum Science and Technology. The paper details how the University’s Quantum Systems and Devices group has established remote access to monitor and control the environmental factors in their ultracold quantum laboratories.
The research has wider implications for operating quantum devices and carrying out experiments in inaccessible and unpredictable environments such as space, underground or those with unstable weather conditions, as well as for artificial intelligence (AI) and human collaboration and for online learning.
This could involve using quantum sensors in space to further our understanding of the fundamental laws of physics, in boats for GPS-free navigation, in electric vehicles to check the state of health of batteries or in hospitals for brain imaging.
Due to the high sensitivity of quantum apparatus, a stable environment is essential. The team has developed ways of keeping an eye on their experiments from afar by using remote monitoring technology to access information on factors such as temperature, pressure, laser beams and magnetic fields. Everyone in the team can see this information on dashboards so issues can be dealt with before they destabilize or disrupt experiments.
As the complexity of quantum technologies grows, the likelihood of breakdowns and severe delays increases. Environmental disturbances are usually only noticed when something goes wrong and then dealt with retrospectively. However, as the monitoring system allows the uninterrupted collection of environmental data, issues can be resolved in real-time.
Professor Peter Krüger, Principal Investigator in the group explains this latest development: “What our group have achieved here is a technical step towards automation, with less time spent debugging devices and the need to be onsite. Furthermore, this advancement has far-reaching implications that could pave the way to new smart technologies utilizing AI/human collaboration.
“An algorithm can be written to source information from a mixture of human input, sensors and AI. As quantum technology become more complex, for example with more sophisticated sensors and quantum computers, these types of monitoring systems will become crucial. There are countless application possibilities. In the future you could find these systems monitoring quantum devices in places such as spacecraft, inside glaciers or closer to home in electric vehicles or hospitals.”
Q-CTRL has plans to send ultra-sensitive quantum sensors and navigation devices to space
Quantum company Q-CTRL has plans to send ultra-sensitive quantum sensors and navigation devices to space, as part of a mission to explore the moon for water and other resources that will support NASA astronauts in future landings. The Australian company, which applies the principles of control engineering to improve the hardware performance of quantum devices, will provide the quantum technology to assist un-crewed missions organized by the Seven Sisters space industry consortium, and planned to start in 2023.
“Quantum-control-defined sensors will give us a new set of eyes on the Earth to monitor climate health, improve mining productivity and reduce its environment impact, and bolster our defenses with a completely new tool for gathering geospatial intelligence,” Biercuk said. “The use of advanced sensors in all industries is projected to be a $300-billion market by 2025. We’re excited to capture as much value as possible and deliver strategic advantage among our Five Eyes partners.”
Q-CTRL awarded $3.5 million grant from Australian government for space-based quantum sensors
Q-CTRL, a startup that applies the principles of control engineering to power quantum technology, has been awarded a $3.5 million grant (USD) from the Australian government’s Modern Manufacturing Initiative (MMI) to expand the development and manufacture of quantum-based remote sensing technologies for space deployment.
Q-CTRL’s quantum sensors leverage the physics of the sub-atomic world to detect and measure extremely small signals in nature. Its quantum-based gravity and magnetic field sensors offer new low-cost Earth observation technologies with global persistent coverage for climate monitoring, minerals, and geospatial intelligence.
The company will apply the MMI funding to support high-value quantum hardware development with a focus on measurements of Earth’s magnetic field from small-form satellites. When fully developed this capability will provide massive strategic advantages for defense and new scientific insights for geophysics. And by contributing to global geomagnetic models used in navigation, it complements Q-CTRL’s portfolio of space-based quantum sensors for positioning, navigation, and timing (PNT).
“We are grateful to the Australian government for its support of our team and technology,” said Q-CTRL CEO Michael J. Biercuk. “The MMI grant is a great validation of how we’re translating decades of science into a valuable business, focused on building and operating the most advanced remote sensing technologies in the world – and off of it.
Biercuk added that Q-CTRL is building the sensor hardware as well as fine-tuning its performance with the company’s unique quantum control software capabilities. The company’s software tools are available broadly in the market and already helping researchers deliver maximum performance from their devices.
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