Quantum state magnification

TL;DR

This paper demonstrates a method for entanglement-enhanced quantum measurements that surpass the standard quantum limit without requiring low-noise detection, simplifying implementation for advanced quantum sensors.

Contribution

It experimentally shows that quantum state magnification enables surpassing the standard quantum limit without low-noise detectors, broadening practical quantum metrology applications.

Findings

Achieved 8 dB squeezing below SQL with high-noise detection system

Implemented a magnification step to enhance measurement sensitivity

Simplified quantum sensing setup without low-noise detection requirements

Abstract

Quantum metrology exploits entangled states of particles to improve sensing precision beyond the limit achievable with uncorrelated particles. All previous methods required detection noise levels below this standard quantum limit to realize the benefits of the intrinsic sensitivity provided by these states. Remarkably, a recent proposal has shown that, in principle, such low-noise detection is not a necessary requirement. Here, we experimentally demonstrate a widely applicable method for entanglement-enhanced measurements without low-noise detection. Using an intermediate magnification step, we perform squeezed state metrology 8 dB below the standard quantum limit with a detection system that has a noise floor 10 dB above the standard quantum limit. Beyond its conceptual significance, this method eases implementation complexity and is expected to find application in next generation quantum sensors.