An Ultra-Scalable Quantum Squeezer Through Acoustic Parametric Amplification in a Piezoelectric-2DEG Heterostructure

We theoretically demonstrate an ultra-scalable quantum squeezer through degenerate acoustic parametric amplification using a heterostructure consisting of a two-dimensional electron gas (2DEG) stacked on top of a piezoelectric material. Two acoustic waveguides, respectively carrying the pump and signal/idler fields, merge to provide the input. The 2DEG electrons mediate nonlinear multi-phonon mixing in the piezoelectric material, yielding the necessary 3-wave-mixing. We combine the second-order susceptibility (governing the amplification rate per unit electric field amplitude of each of the 3 fields) with the first-order susceptibility (governing the electric field amplitude per phonon) to derive the parametric gain per unit length per unit pump amplitude. We use this result to optimize the material parameters, specifically carrier density and mobility. Employing open-quantum-systems theory, we then derive the time-evolution of the quadrature operators' expectation values and uncertainties in the presence of loss and thermal noise. The calculations reveal an extremely high gain-to-loss ratio, potentially leading to a strongly squeezed signal source with critical applications in quantum sensing and computing.