Scientists develop phononic channels to connect qubits over up to 300 mm — Live Science

Researchers have presented the Quantum Phononic Links (QPLs) architecture, which is intended to transmit quantum information between distant qubits using phonons — quasiparticles that carry vibrational energy. One of the study’s first authors, Maksym Myronov, an associate professor at the University of Warwick in the United Kingdom, said that in this scheme phonons can serve as a “quantum bus.” As Live Science reports, this approach could potentially contribute to the creation of scalable quantum processors, including systems with more than one million qubits.

The problem of communication between qubits

Qubits find it difficult to exchange quantum information if they are not direct neighbors. In large quantum systems, communication between distant qubits is important, in particular, for applying quantum error-correction methods.

QPLs are designed for long-distance communication between qubits via phonons. Unlike some other proposed methods, including surface acoustic waves, this approach, according to the authors’ assessment, does not require such a complex design or additional equipment.

Germanium on silicon

To demonstrate the technology, the researchers created a prototype quantum processor based on silicon with a thin crystalline layer of germanium. The material was described as germanium on silicon with compressive mechanical strain. The scientists noted that germanium has properties that may reduce decoherence — the loss of quantum information due to external influence.

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The architecture is designed for semiconductor hole spin qubits. In such a system, a “hole” means the absence of an electron in the material, but it can behave like a particle and have a spin state suitable for encoding quantum information.

Communication over distance

QPLs consist of specially designed phononic waveguides and resonators that direct and confine acoustic modes in an ultrathin layer of material. The researchers indicated that this technology can connect qubits placed at distances of less than a micrometer as well as at distances of up to 300 mm.

The study on phononic connections for long-distance communication between hole spin qubits was published on June 15 in the journal APL Quantum. The authors believe that combining phononic engineering and hole-spin physics can provide coherent communication over long distances and large-scale integration of quantum circuits.