A new approach to building noise-resistant quantum sensors
Quantum sensors, devices that collect measurements by exploiting quantum-mechanical phenomena, could potentially detect extremely weak magnetic, gravitational and electromagnetic signals with greater sensitivity than classical sensors. Some quantum sensors leverage entanglement, a phenomenon that prompts distant particles to become so strongly linked that the physical state of one particle…
A novel method has been devised to create quantum sensors that are resilient to noise, according to researchers at the Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area. Quantum sensors, which utilize quantum-mechanical phenomena to detect extremely weak signals, can often be hindered by environmental noise. This new approach, detailed in a paper published in Physical Review Letters, leverages a variational quantum circuit to identify optimal probe states for measurements under specific noise conditions.
The technique combines a parameter encoding stage with an experimentally measured out-of-time-order correlator (OTOC) to evaluate sensing performance. The out-of-time-order correlator, which measures how disturbances spread through a quantum system, is connected to the quantum Fisher information, providing a theoretical bound on parameter estimation uncertainty.
By using this connection, the researchers developed a noise-adaptive quantum metrology scheme that identifies optimal probe states for large-scale quantum hardware. In initial tests, the scheme improved precision by up to 0.698 decibels compared to a standard GHZ state when sensing a fixed magnetic field, demonstrating its potential for enhancing the sensitivity of quantum sensors in real-world applications.
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