Artificial Atom on a Chip Based on Coupling Between 2DEG and Piezo Resonator

A key requirement for designing a two-level quantum system for generating a qubit is ensuring anharmonic energy levels, such that a unique energy gap separates the target energy level pair for hosting a qubit. Atoms serve as a natural example of such a system but face challenges regarding scalability for quantum computing. Superconducting qubits provide a more scalable alternative but are sensitive to charge noise. Here, we propose a piezoelectric resonator coupled to a 2D electron gas (2DEG) as a scalable and resilient qubit-hosting platform. The quasi-acoustic field stored in the piezoelectric resonator manifests itself as a harmonic ladder of states. This quasi-acoustic wave contains an electric field, which interacts with the 2DEG electrons, giving rise to an anharmonic energy ladder of composite states. We determine the energy spectrum for this composite system in two steps: first, by introducing the second quantization and deriving the harmonic frequency for the quasi-acoustic field, and second, by solving for the piezo-2DEG coupling coefficient. We also show that, for an appropriate set of material dimensions and parameters, the energy-anharmonicity of the composite states is robust to the decoherence-induced spectral broadening.