Nonlinear oscillators bring tools for quantum information processing
Obeying the laws of classical physics, the operation and memory of conventional computers is based on the binary numbers 0 and 1, with the state of each bit (the smallest unit of information) set to one or the other. The extraordinary prospect of quantum computing is that the basic units of information known as quantum bits or ‘qubits’ can be both 0 and 1 simultaneously ('in superposition’). The weird phenomenon of quantum entanglement, whereby two or more objects in superposition are inextricably linked, even if separated by great distance, means that qubits can be coupled to function as quantum-logic gates for the processing of information in parallel. As the understanding of the underlying science, along with investment, grows, quantum computing is fast becoming a reality and real-world applications could be in sight within a few years. Towards this end, the EU-supported project Suptango, set out to develop microwave nonlinear superconducting resonators and nonclassical states of microwave radiation, and to apply these systems to quantum information science. Quantum algorithms Introducing the scale of the potential, lead researcher Prof. Jonas Bylander says, “By devising clever quantum algorithms, we can program a quantum computer to solve problems that in some cases wouldn’t be tractable on a regular computer in millions of years.” Suptango demonstrated a novel and scalable method based on non-linear oscillators for the ultra-sensitive detection of the state of a quantum bit of information, used to glean the information resulting from a quantum computation. The project also demonstrated amplification of microwaves at the ultimate limit of sensitivity, which is important because the quantum information encoded into single quanta (photons) of the field can easily drown in even the smallest amount of noise. A source of quantum entangled microwave photons was also demonstrated, which may find applications in continuous-variable quantum computing, quantum communication, or quantum sensing. Maintaining the EU’s quantum edge The momentous potential that quantum computing holds out, makes it a very competitive field. The Suptango results represent solid steps toward continuous-variable quantum information processing enabled through the exploitation of nonclassical states of microwave radiation. Due to the supreme control this approach exerts on quantum microwaves by using superconducting devices, this is currently a booming field and of significant strategic interest to the EU. Taking the work to the next level and towards commercialization requires, “Bold investments into the development of quantum hardware, software, control systems, and application use cases, as in the new EU Flagship on Quantum Technology,” says Bylander. Towards this end, Bylander is now part of a team working to build a superconducting quantum processor, with partial funding from the new Flagship consortium www.opensuperq.eu (OpenSuperQ).
Keywords
Suptango, quantum, qubit, computing, information, entanglement, superposition, superconducting, microwave radiation, photons, algorithms
