Quantum Critical Detector : Amplifying Weak Signals Using First-Order Dynamical Quantum Phase Transitions

Understand

We introduce a first-order quantum-phase-transition model, which exhibits giant sensitivity $\chi \propto N^2$ at the critical point.

• Exploiting this effect, we propose a quantum critical detector (QCD) to amplify weak input signals.
• The time-dynamic QCD functions by triggering a first-order dynamical quantum phase transition in a system of spins with long-range interactions coupled to a bosonic mode.
• We numerically demonstrate features of the dynamical quantum phase transition, which leads to a time-dependent quantum gain.