New materials will bring the next generation of quantum computers

Technologies powered by quantum science will help researchers better understand the natural world and harness quantum phenomena to benefit society. They will transform healthcare, transportation and communications and increase resilience to cyberthreats and climate disasters. For example, quantum magnetic field sensors will enable functional imaging of the brain; quantum optical communications will enable encrypted communications; and quantum computers will facilitate the discovery of next-generation materials for photovoltaics and medicines.

Currently, these technologies rely on materials that are expensive and complicated to prepare, and they often require expensive and bulky cryogenic refrigeration to work. Such equipment depends on precious raw materials such as liquid helium, which is becoming increasingly expensive as global supply dwindles. 2023 will see a revolution in innovations in quantum materials that will transform quantum technologies. In addition to reducing environmental requirements, these materials will operate at room temperature and allow for energy savings, while also being inexpensive and having simple processing requirements. To optimize their quantum properties, research laboratories can manipulate the chemical structure and molecular packing. The good news is that physicists and engineers have been busy, and in 2023 these materials will move from science labs to the real world.

Recently, the UK Engineering and Physical Sciences Research Council announced a vision for innovation in materials for quantum technologies, led by Imperial College London and the University of Manchester. The London Center for Nanotechnology – a collaboration of hundreds of researchers from Imperial, King’s and University College London – has considerable expertise in the simulation and characterization of quantum systems. The UK’s home base for measurements – the National Physical Laboratory – has just opened the Quantum Metrology Institute, a multimillion-pound facility dedicated to the characterisation, validation and commercialization of quantum technologies. By working together, researchers and industry will usher in a new era in pharmaceuticals, cryptography and cybersecurity.

Qubits, the building blocks of quantum computers, are based on materials with quantum properties, such as electron spin, that can be manipulated. Once we can harness these properties, we can control them using light and magnetic fields, creating quantum phenomena such as entanglement and superposition. Superconducting qubits, the current state-of-the-art for qubit technology, include Josephson junctions that act as superconductors (materials that can conduct electricity without resistance) at super-low temperatures (–273ºC). The stringent temperature and high-frequency operating requirements mean that even the most basic aspects of these superconducting qubits – the dielectrics – are tricky to design. Currently, qubits contain materials such as silicon nitride and silicon oxide, which have so many defects that the qubits themselves must be millimeters in size to store electric field energy, and crosstalk between adjacent qubits causes significant noise. With these materials, it would be impossible to get the millions of qubits needed for a practical quantum computer.

In 2023 there will be more innovation in materials design for quantum technologies. Of the many great candidates considered so far (e.g. diamonds with nitrogen vacancy defects, van der Waals/2D materials and high temperature superconductors), I am most excited about using molecular materials. These materials are designed around carbon-based organic semiconductors, an established class of materials for the scalable production of consumer electronics (which have revolutionized the multibillion-dollar OLED display industry). We can use chemistry to control their optical and electronic properties, and the infrastructure around their development is based on established expertise.

For example, chiral molecular materials, molecules that exist as a pair of non-superimposable mirror images, will revolutionize quantum technologies. Single-handed thin layers of these remarkably versatile molecules can be used to control the spin of electrons at room temperature. At the same time, the long spin coherence times and good thermal and chemical stability of metal phthalocyanines mean that they are used to transfer quantum information.

While 2023 will no doubt bring more bombastic headlines about the operating speeds of quantum computers, materials scientists will study, discover and design the next generation of low-cost, highly efficient and sustainable quantum technologies.

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