Schematic of Variational Quantum Metrology Based on Loschmidt Echo (IMAGE) Science China Press Caption Schematic of Variational Quantum Metrology Based on Loschmidt Echo Credit ©Science China Press Usage Restrictions Use with credit. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.