The Einstein-Podolsky-Rosen (EPR) paradox, which was formulated to argue for the incompleteness of quantum mechanics, has since metamorphosed into a resource for quantum information. The EPR entanglement describes the strength of linear correlations between two objects in terms of a pair of conjugate observables in relation to the Heisenberg uncertainty limit. We propose that entanglement can be extended to include nonlinear correlations. We examine two driven harmonic oscillators that are coupled via third-order nonlinearity can exhibit quadraticlike nonlinear entanglement which, after a projective measurement on one of the oscillators, collapses the other into a cat state of tunable size.

A high-performance CMOS readout integrated circuit (ROIC) with a new temperature and power supply independent background current and dark current suppression technique for room-temperature infrared focal plane array applications is proposed. The structure is composed of an improved switched current integration stage, a new current-mode background suppression circuit, and a high linearity, high voltage swing output stage. An experimental readout chip has been designed and fabricated using the Chartered 0.35 µm CMOS process. Both the function and performance of the proposed readout circuit have been verified by experimental results. The test results show that the detector bias error in this structure is less than 0.1 mV. The input resistance is close to an ideal value of zero, and the injection efficiency is almost 100%. The output voltage linearity of the designed circuit is more than 99%. The background suppression level is tunable between 8 nA-1.5 µA, and the background suppression uniformity is as high as 100%. A unit-cell occupies a 10 µm × 15 µm area and consumes less than 0.07 mW power.