Fig. 1: Computational model of single-photon pulse interacting with Nā>ā100 qubit system.
From: Single-photon pulse induced giant response in Nā>ā100 qubit system
The interacting spin qubits at the bottom, which can function as a quantum amplifier, are critically biased close to the first-order quantum phase transition (QPT) point. The three states in the absorber on the top form a Ī-structure. After absorption of a single-photon pulse, the absorber is excited from the ground state \(\left|g\right\rangle\) and finally relaxes to the meta-stable state \(\left|e\right\rangle\). After the \(\left|g\right\rangle \to \left|e\right\rangle\) transition, the absorber exerts an effective magnetic field on the amplifier qubits. This magnetic field triggers a QPT in the qubits underneath. Initially, the spin qubits are polarized in the yz-plane (a). After the phase transition, the spins rotate to the xz-plane (b).
