Quantum Saturation of the Electro-Optic Effect

TL;DR

This paper demonstrates that quantum fluctuations can be harnessed to create electro-optic materials with stable, high-performance responses at cryogenic temperatures, overcoming traditional temperature sensitivity near phase transitions.

Contribution

It introduces a novel approach using quantum fluctuations to achieve temperature-insensitive electro-optic effects by tuning phase boundaries to 0 K in ferroelectric materials.

Findings

Quantum fluctuations induce saturation in electro-optic response below 25 K.

Tuning phase boundaries enhances cryogenic electro-optic performance.

Performance exceeds traditional BaTiO3-on-Si by over an order of magnitude.

Abstract

Future quantum computing architectures require electro-optic materials that maintain a strong, stable performance at cryogenic temperatures. In conventional electro-optic materials, large electro-optic coefficients are often confined to narrow temperature windows near structural phase transitions, where small changes in temperature lead to large changes in the electro-optic response. Using thermodynamic analysis, phase-field simulations, experimental growth and cryogenic optical measurements we show that quantum fluctuations can be harnessed to overcome this trade-off. By tuning the ferroelectric phase boundaries down to 0 K, quantum fluctuations induce a saturation regime in which a large electro-optic response becomes nearly temperature-independent below 25 K. We demonstrate that the phase boundaries can be tuned through either strain in BaTiO3 or through chemical composition in Ba1-xCaxTiO3, leading to a large, temperature insensitive, cryogenic electro-optic effect comparable to bulk BaTiO3 at room temperature; the performance exceeds BaTiO3-on-Si by over an order of magnitude. These findings establish a general design principle for engineering high-performance electro-optic materials for cryogenic applications.