Quantum Phononic Processor

Quantum computing systems have the potential to outperform classical computers on some tasks, helping to solve complex real-world problems in shorter times. Research teams worldwide have thus been trying to realize this quantum advantage over traditional computers, by creating and testing different quantum systems.

Researchers at Tsinghua University recently developed a new programmable quantum phononic processor with trapped ions. This processor, introduced in a paper in Nature Physics, could be easier to scale up in size than other previously proposed photonic quantum processors, which could ultimately enable better performances on complex problems.

"Originally, we were interested in the proposal of Scott Aaronson and others about Boson sampling, which might show the quantum advantages of simple linear optics and photons," Kihwan Kim, one of the researchers who carried out the study, told Phys.org. "We were wondering if it is possible to realize it with the phonons in a trapped ion system."

The use of phonons (i.e., sound waves or elementary vibrations) to create quantum computing systems was theoretically explored for some time. In recent years, however, physicists created trapped-ion systems created the technology necessary to use phonons as a quantum information processing resource, rather than mere mediators for entangling qubits.

"It has been shown that phonons at a harmonic potential can coherently transfer to the other harmonic potential and these phonons can interfere with each other," Kihwan Kim explained. "When we learned that a modified boson sampling (Gaussian boson sampling) can also be applied to a chemical problem (i.e., vibrational sampling) we demonstrated the sampling of SO2 molecules and developed a method to create a highly entangled phononic state; yet this was limited to a single ion. In this work, we finally implemented the phononic network in a scalable way, overcoming the limits of single ions."

The system created by Kihwan Kim and his colleagues is a programmable bosonic network, a network consisting of a set of bosonic modes, connected to each other via controllable beam splitters. They realized this network using phonons, excitations of collective vibrational modes that are also bosons.  READ MORE...