Cassandra Mercury is working on future-proofing the safety of the world's data.
"There is a big event coming and that's quantum computing. It will be able to break every existing encryption code in seconds, so I'm developing a technology to encrypt our data in a way that can't be broken," she says.
Mercury, the Space Quantum Technology Lead at Glasgow-based Craft Prospect, is working on a quantum key distribution payload for a satellite, which uses a laser to create an encrypted security key.
"Quantum key distribution is based on the philosophy that you can't measure a particle without altering it," she explains. "If you're sending photons in four different quantum states and you have an eavesdropper, that will alter what's been sent. That can be detected by the reconciliation algorithms so that you'll know to abort. If there is no eavesdropper, you'll have a secure key at the end of it."
Mercury says there are only three things to consider when it comes to putting things into space, and they go by the acronym SWAP: size, weight, and power. This mantra also sums up the development parameters of the lasers needed for many quantum applications.
"We're working with the University of Bristol to create a quantum laser with low power requirements so that we can launch it at the end of 2022. We want to test quantum key distribution and then launch a whole constellation of satellites. The problem with the quantum lasers is the R&D costs are so high. The higher the volume of lasers we can produce, the cheaper they become," she says.
As Mercury alluded, lasers enable quantum technology, and yet the current state of laser technology is a roadblock to further development, because the size, cost, and reliability of today's lasers are prohibitive for wide-scale deployment. Although costs have come down and stability has increased for some lasers, like those used in telecom, quantum sensors operate at diverse wavelengths and have more stringent power, linewidth, and optical isolation requirements. These types of lasers do not have enough commercial demand to justify the production volume that would drive costs down.
Light sources are essential components to quantum networks like the one Mercury describes, because photons are the natural carriers of quantum states over long distances.
Wilhelm Kaenders, CTO of TOPTICA Photonics AG, points out that photons are quantum objects in themselves. "Photons have wonderful degrees of quantumness," he said at a panel on quantum industry at Photonics West 2020.
Kaenders emphasized that photons are needed everywhere in quantum: They are used to prepare cold atoms, probe quantum states, initiate quantum coherence, and read quantum information. Lasers are essential components in many quantum computers, quantum sensors, and optical clocks.
Indeed, quantum technology will enhance many industries we take for granted. Take satellite navigation, for example—it's a tool we recognize as GPS on our smartphones and our vehicle dashboards. However, GPS signals from satellites can be fragile, and easily disrupted by tall buildings or trees.
The field of quantum sensing could provide satellite-free navigation, freeing us from the frustration of GPS dead zones. In fact, such a product is already commercially available through another Glasgow-based company, M Squared. Their quantum accelerometer uses highly sensitive atom interferometry to measure accelerations along a horizontal axis.
Quantum accelerometers exploit quantum interference to achieve a combination of sensitivity and stability. They are critical components of a quantum inertial navigation unit, which can offer satellite-free navigation with long-term accuracy.
Nils Hempler, Head of Innovation at M Squared, says there has been a significant shift in the global quantum community of late.
"In the beginning, we were talking about the potential of quantum in the decades to come. It has now become clear that quantum will have a profound impact on society. A quantum industry is forming and it is gaining momentum, as evidenced by the number of companies pivoting into quantum, from blue chips through to system integrators, startups, and university spin-outs. Take quantum computing, for example, it is starting to disrupt the entire industry as hardware and software developers are mobilizing and end users, such as banks, prepare."
Fields like mining, surveying, and earth observation could be revolutionized by quantum tech, like M Squared's quantum gravimeter. It uses quantum interference of matter waves to measure the local value of gravitational acceleration, or ‘g', with very high precision. If this sounds familiar, LIGO uses this same method to detect cosmic gravitational waves. However, gravimeter applications translate from astronomical observations to more terrestrial ones. Objects with different mass cause small fluctuations in the value of g measured on the surface of the Earth. The quantum gravimeter can be used to sense these objects—like oil fields, for example—hidden under the surface. Quantum clocks, which could be used to help spacecraft orient themselves and navigate autonomously, are also of increasing interest.
Craft Prospect has begun discussions with researchers at the University of Strathclyde to advise on reducing a quantum clock to the size of a CubeSat—which is 101010 cm.
Such a goal is noteworthy not only for the compact size, but also for the stability such a system would require. Most of today's optical clocks fill optical benches in laboratories and require a team of grad students to keep running.
M Squared, meanwhile, is working on the strontium lattice clock project, which aims to create the world's first commercially available fully integrated optical frequency atomic clock. This clock will be compact, transportable, easy to use, and based on optical lattice technology enabled by the company's SolsTiS laser. The strontium lattice clock will achieve frequency uncertainties below 10-17, a level unprecedented on the global market. Its applications span industries as diverse as high-frequency financial trading, power grid management, and gravitational wave detection.
"Right now we're seeing quantum programs and their outputs being driven more and more by use cases," Hempler adds.
"In computing, these use cases include drug simulation, cryptography, communications, traffic optimization, climate change, and artificial intelligence. In quantum sensing, we've made notable progress on gravimeters, accelerometers, and clocks, and it is enabling us to address target markets in navigation, advanced surveying, and earth observation technology and time standards."
As lasers for quantum applications increase in availability and decrease in price, we can hope to see these use cases move nearer on the horizon.
Kim McAllister is a freelance business writer and broadcaster on BBC Radio Scotland. She also has an eight-part podcast called Edinburgh: Space Data Capital, which is available on Spotify.
