Controllable non-Hermitian qubit-qubit Coupling in Superconducting quantum Circuit

With a high-loss resonator supplying the non-Hermiticity, we study the Energy level degeneracy and quantum state evolution in tunable coupling superconducting quantum circuit. The qubit’s effective energy level and damping rate can be continually tuned in superconducting circuit, and the positions and numbers of level degenerate points are controllable. The efficient of quantum state exchange and the asymmetry of quantum state evolution can be tuned with non-hermitian and nonreciprocal coupling between two qubits. The controllable non-Hermiticity provides new insights and methods for exploring the unconventional quantum effects in superconducting quantum circuit.